Merge tag 'kvm-x86-docs-6.7' of https://github.com/kvm-x86/linux into HEAD

[thirdparty/kernel/stable.git] / drivers / net / virtio_net.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* A network driver using virtio.
 *
 * Copyright 2007 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
 */
//#define DEBUG
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/module.h>
#include <linux/virtio.h>
#include <linux/virtio_net.h>
#include <linux/bpf.h>
#include <linux/bpf_trace.h>
#include <linux/scatterlist.h>
#include <linux/if_vlan.h>
#include <linux/slab.h>
#include <linux/cpu.h>
#include <linux/average.h>
#include <linux/filter.h>
#include <linux/kernel.h>
#include <net/route.h>
#include <net/xdp.h>
#include <net/net_failover.h>
#include <net/netdev_rx_queue.h>

static int napi_weight = NAPI_POLL_WEIGHT;
module_param(napi_weight, int, 0444);

static bool csum = true, gso = true, napi_tx = true;
module_param(csum, bool, 0444);
module_param(gso, bool, 0444);
module_param(napi_tx, bool, 0644);

/* FIXME: MTU in config. */
#define GOOD_PACKET_LEN (ETH_HLEN + VLAN_HLEN + ETH_DATA_LEN)
#define GOOD_COPY_LEN   128

#define VIRTNET_RX_PAD (NET_IP_ALIGN + NET_SKB_PAD)

/* Amount of XDP headroom to prepend to packets for use by xdp_adjust_head */
#define VIRTIO_XDP_HEADROOM 256

/* Separating two types of XDP xmit */
#define VIRTIO_XDP_TX           BIT(0)
#define VIRTIO_XDP_REDIR        BIT(1)

#define VIRTIO_XDP_FLAG BIT(0)

/* RX packet size EWMA. The average packet size is used to determine the packet
 * buffer size when refilling RX rings. As the entire RX ring may be refilled
 * at once, the weight is chosen so that the EWMA will be insensitive to short-
 * term, transient changes in packet size.
 */
DECLARE_EWMA(pkt_len, 0, 64)

#define VIRTNET_DRIVER_VERSION "1.0.0"

static const unsigned long guest_offloads[] = {
        VIRTIO_NET_F_GUEST_TSO4,
        VIRTIO_NET_F_GUEST_TSO6,
        VIRTIO_NET_F_GUEST_ECN,
        VIRTIO_NET_F_GUEST_UFO,
        VIRTIO_NET_F_GUEST_CSUM,
        VIRTIO_NET_F_GUEST_USO4,
        VIRTIO_NET_F_GUEST_USO6,
        VIRTIO_NET_F_GUEST_HDRLEN
};

#define GUEST_OFFLOAD_GRO_HW_MASK ((1ULL << VIRTIO_NET_F_GUEST_TSO4) | \
                                (1ULL << VIRTIO_NET_F_GUEST_TSO6) | \
                                (1ULL << VIRTIO_NET_F_GUEST_ECN)  | \
                                (1ULL << VIRTIO_NET_F_GUEST_UFO)  | \
                                (1ULL << VIRTIO_NET_F_GUEST_USO4) | \
                                (1ULL << VIRTIO_NET_F_GUEST_USO6))

struct virtnet_stat_desc {
        char desc[ETH_GSTRING_LEN];
        size_t offset;
};

struct virtnet_sq_stats {
        struct u64_stats_sync syncp;
        u64 packets;
        u64 bytes;
        u64 xdp_tx;
        u64 xdp_tx_drops;
        u64 kicks;
        u64 tx_timeouts;
};

struct virtnet_rq_stats {
        struct u64_stats_sync syncp;
        u64 packets;
        u64 bytes;
        u64 drops;
        u64 xdp_packets;
        u64 xdp_tx;
        u64 xdp_redirects;
        u64 xdp_drops;
        u64 kicks;
};

#define VIRTNET_SQ_STAT(m)      offsetof(struct virtnet_sq_stats, m)
#define VIRTNET_RQ_STAT(m)      offsetof(struct virtnet_rq_stats, m)

static const struct virtnet_stat_desc virtnet_sq_stats_desc[] = {
        { "packets",            VIRTNET_SQ_STAT(packets) },
        { "bytes",              VIRTNET_SQ_STAT(bytes) },
        { "xdp_tx",             VIRTNET_SQ_STAT(xdp_tx) },
        { "xdp_tx_drops",       VIRTNET_SQ_STAT(xdp_tx_drops) },
        { "kicks",              VIRTNET_SQ_STAT(kicks) },
        { "tx_timeouts",        VIRTNET_SQ_STAT(tx_timeouts) },
};

static const struct virtnet_stat_desc virtnet_rq_stats_desc[] = {
        { "packets",            VIRTNET_RQ_STAT(packets) },
        { "bytes",              VIRTNET_RQ_STAT(bytes) },
        { "drops",              VIRTNET_RQ_STAT(drops) },
        { "xdp_packets",        VIRTNET_RQ_STAT(xdp_packets) },
        { "xdp_tx",             VIRTNET_RQ_STAT(xdp_tx) },
        { "xdp_redirects",      VIRTNET_RQ_STAT(xdp_redirects) },
        { "xdp_drops",          VIRTNET_RQ_STAT(xdp_drops) },
        { "kicks",              VIRTNET_RQ_STAT(kicks) },
};

#define VIRTNET_SQ_STATS_LEN    ARRAY_SIZE(virtnet_sq_stats_desc)
#define VIRTNET_RQ_STATS_LEN    ARRAY_SIZE(virtnet_rq_stats_desc)

struct virtnet_interrupt_coalesce {
        u32 max_packets;
        u32 max_usecs;
};

/* The dma information of pages allocated at a time. */
struct virtnet_rq_dma {
        dma_addr_t addr;
        u32 ref;
        u16 len;
        u16 need_sync;
};

/* Internal representation of a send virtqueue */
struct send_queue {
        /* Virtqueue associated with this send _queue */
        struct virtqueue *vq;

        /* TX: fragments + linear part + virtio header */
        struct scatterlist sg[MAX_SKB_FRAGS + 2];

        /* Name of the send queue: output.$index */
        char name[16];

        struct virtnet_sq_stats stats;

        struct virtnet_interrupt_coalesce intr_coal;

        struct napi_struct napi;

        /* Record whether sq is in reset state. */
        bool reset;
};

/* Internal representation of a receive virtqueue */
struct receive_queue {
        /* Virtqueue associated with this receive_queue */
        struct virtqueue *vq;

        struct napi_struct napi;

        struct bpf_prog __rcu *xdp_prog;

        struct virtnet_rq_stats stats;

        struct virtnet_interrupt_coalesce intr_coal;

        /* Chain pages by the private ptr. */
        struct page *pages;

        /* Average packet length for mergeable receive buffers. */
        struct ewma_pkt_len mrg_avg_pkt_len;

        /* Page frag for packet buffer allocation. */
        struct page_frag alloc_frag;

        /* RX: fragments + linear part + virtio header */
        struct scatterlist sg[MAX_SKB_FRAGS + 2];

        /* Min single buffer size for mergeable buffers case. */
        unsigned int min_buf_len;

        /* Name of this receive queue: input.$index */
        char name[16];

        struct xdp_rxq_info xdp_rxq;

        /* Record the last dma info to free after new pages is allocated. */
        struct virtnet_rq_dma *last_dma;

        /* Do dma by self */
        bool do_dma;
};

/* This structure can contain rss message with maximum settings for indirection table and keysize
 * Note, that default structure that describes RSS configuration virtio_net_rss_config
 * contains same info but can't handle table values.
 * In any case, structure would be passed to virtio hw through sg_buf split by parts
 * because table sizes may be differ according to the device configuration.
 */
#define VIRTIO_NET_RSS_MAX_KEY_SIZE     40
#define VIRTIO_NET_RSS_MAX_TABLE_LEN    128
struct virtio_net_ctrl_rss {
        u32 hash_types;
        u16 indirection_table_mask;
        u16 unclassified_queue;
        u16 indirection_table[VIRTIO_NET_RSS_MAX_TABLE_LEN];
        u16 max_tx_vq;
        u8 hash_key_length;
        u8 key[VIRTIO_NET_RSS_MAX_KEY_SIZE];
};

/* Control VQ buffers: protected by the rtnl lock */
struct control_buf {
        struct virtio_net_ctrl_hdr hdr;
        virtio_net_ctrl_ack status;
        struct virtio_net_ctrl_mq mq;
        u8 promisc;
        u8 allmulti;
        __virtio16 vid;
        __virtio64 offloads;
        struct virtio_net_ctrl_rss rss;
        struct virtio_net_ctrl_coal_tx coal_tx;
        struct virtio_net_ctrl_coal_rx coal_rx;
        struct virtio_net_ctrl_coal_vq coal_vq;
};

struct virtnet_info {
        struct virtio_device *vdev;
        struct virtqueue *cvq;
        struct net_device *dev;
        struct send_queue *sq;
        struct receive_queue *rq;
        unsigned int status;

        /* Max # of queue pairs supported by the device */
        u16 max_queue_pairs;

        /* # of queue pairs currently used by the driver */
        u16 curr_queue_pairs;

        /* # of XDP queue pairs currently used by the driver */
        u16 xdp_queue_pairs;

        /* xdp_queue_pairs may be 0, when xdp is already loaded. So add this. */
        bool xdp_enabled;

        /* I like... big packets and I cannot lie! */
        bool big_packets;

        /* number of sg entries allocated for big packets */
        unsigned int big_packets_num_skbfrags;

        /* Host will merge rx buffers for big packets (shake it! shake it!) */
        bool mergeable_rx_bufs;

        /* Host supports rss and/or hash report */
        bool has_rss;
        bool has_rss_hash_report;
        u8 rss_key_size;
        u16 rss_indir_table_size;
        u32 rss_hash_types_supported;
        u32 rss_hash_types_saved;

        /* Has control virtqueue */
        bool has_cvq;

        /* Host can handle any s/g split between our header and packet data */
        bool any_header_sg;

        /* Packet virtio header size */
        u8 hdr_len;

        /* Work struct for delayed refilling if we run low on memory. */
        struct delayed_work refill;

        /* Is delayed refill enabled? */
        bool refill_enabled;

        /* The lock to synchronize the access to refill_enabled */
        spinlock_t refill_lock;

        /* Work struct for config space updates */
        struct work_struct config_work;

        /* Does the affinity hint is set for virtqueues? */
        bool affinity_hint_set;

        /* CPU hotplug instances for online & dead */
        struct hlist_node node;
        struct hlist_node node_dead;

        struct control_buf *ctrl;

        /* Ethtool settings */
        u8 duplex;
        u32 speed;

        /* Interrupt coalescing settings */
        struct virtnet_interrupt_coalesce intr_coal_tx;
        struct virtnet_interrupt_coalesce intr_coal_rx;

        unsigned long guest_offloads;
        unsigned long guest_offloads_capable;

        /* failover when STANDBY feature enabled */
        struct failover *failover;
};

struct padded_vnet_hdr {
        struct virtio_net_hdr_v1_hash hdr;
        /*
         * hdr is in a separate sg buffer, and data sg buffer shares same page
         * with this header sg. This padding makes next sg 16 byte aligned
         * after the header.
         */
        char padding[12];
};

struct virtio_net_common_hdr {
        union {
                struct virtio_net_hdr hdr;
                struct virtio_net_hdr_mrg_rxbuf mrg_hdr;
                struct virtio_net_hdr_v1_hash hash_v1_hdr;
        };
};

static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf);
static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf);

static bool is_xdp_frame(void *ptr)
{
        return (unsigned long)ptr & VIRTIO_XDP_FLAG;
}

static void *xdp_to_ptr(struct xdp_frame *ptr)
{
        return (void *)((unsigned long)ptr | VIRTIO_XDP_FLAG);
}

static struct xdp_frame *ptr_to_xdp(void *ptr)
{
        return (struct xdp_frame *)((unsigned long)ptr & ~VIRTIO_XDP_FLAG);
}

/* Converting between virtqueue no. and kernel tx/rx queue no.
 * 0:rx0 1:tx0 2:rx1 3:tx1 ... 2N:rxN 2N+1:txN 2N+2:cvq
 */
static int vq2txq(struct virtqueue *vq)
{
        return (vq->index - 1) / 2;
}

static int txq2vq(int txq)
{
        return txq * 2 + 1;
}

static int vq2rxq(struct virtqueue *vq)
{
        return vq->index / 2;
}

static int rxq2vq(int rxq)
{
        return rxq * 2;
}

static inline struct virtio_net_common_hdr *
skb_vnet_common_hdr(struct sk_buff *skb)
{
        return (struct virtio_net_common_hdr *)skb->cb;
}

/*
 * private is used to chain pages for big packets, put the whole
 * most recent used list in the beginning for reuse
 */
static void give_pages(struct receive_queue *rq, struct page *page)
{
        struct page *end;

        /* Find end of list, sew whole thing into vi->rq.pages. */
        for (end = page; end->private; end = (struct page *)end->private);
        end->private = (unsigned long)rq->pages;
        rq->pages = page;
}

static struct page *get_a_page(struct receive_queue *rq, gfp_t gfp_mask)
{
        struct page *p = rq->pages;

        if (p) {
                rq->pages = (struct page *)p->private;
                /* clear private here, it is used to chain pages */
                p->private = 0;
        } else
                p = alloc_page(gfp_mask);
        return p;
}

static void enable_delayed_refill(struct virtnet_info *vi)
{
        spin_lock_bh(&vi->refill_lock);
        vi->refill_enabled = true;
        spin_unlock_bh(&vi->refill_lock);
}

static void disable_delayed_refill(struct virtnet_info *vi)
{
        spin_lock_bh(&vi->refill_lock);
        vi->refill_enabled = false;
        spin_unlock_bh(&vi->refill_lock);
}

static void virtqueue_napi_schedule(struct napi_struct *napi,
                                    struct virtqueue *vq)
{
        if (napi_schedule_prep(napi)) {
                virtqueue_disable_cb(vq);
                __napi_schedule(napi);
        }
}

static void virtqueue_napi_complete(struct napi_struct *napi,
                                    struct virtqueue *vq, int processed)
{
        int opaque;

        opaque = virtqueue_enable_cb_prepare(vq);
        if (napi_complete_done(napi, processed)) {
                if (unlikely(virtqueue_poll(vq, opaque)))
                        virtqueue_napi_schedule(napi, vq);
        } else {
                virtqueue_disable_cb(vq);
        }
}

static void skb_xmit_done(struct virtqueue *vq)
{
        struct virtnet_info *vi = vq->vdev->priv;
        struct napi_struct *napi = &vi->sq[vq2txq(vq)].napi;

        /* Suppress further interrupts. */
        virtqueue_disable_cb(vq);

        if (napi->weight)
                virtqueue_napi_schedule(napi, vq);
        else
                /* We were probably waiting for more output buffers. */
                netif_wake_subqueue(vi->dev, vq2txq(vq));
}

#define MRG_CTX_HEADER_SHIFT 22
static void *mergeable_len_to_ctx(unsigned int truesize,
                                  unsigned int headroom)
{
        return (void *)(unsigned long)((headroom << MRG_CTX_HEADER_SHIFT) | truesize);
}

static unsigned int mergeable_ctx_to_headroom(void *mrg_ctx)
{
        return (unsigned long)mrg_ctx >> MRG_CTX_HEADER_SHIFT;
}

static unsigned int mergeable_ctx_to_truesize(void *mrg_ctx)
{
        return (unsigned long)mrg_ctx & ((1 << MRG_CTX_HEADER_SHIFT) - 1);
}

static struct sk_buff *virtnet_build_skb(void *buf, unsigned int buflen,
                                         unsigned int headroom,
                                         unsigned int len)
{
        struct sk_buff *skb;

        skb = build_skb(buf, buflen);
        if (unlikely(!skb))
                return NULL;

        skb_reserve(skb, headroom);
        skb_put(skb, len);

        return skb;
}

/* Called from bottom half context */
static struct sk_buff *page_to_skb(struct virtnet_info *vi,
                                   struct receive_queue *rq,
                                   struct page *page, unsigned int offset,
                                   unsigned int len, unsigned int truesize,
                                   unsigned int headroom)
{
        struct sk_buff *skb;
        struct virtio_net_common_hdr *hdr;
        unsigned int copy, hdr_len, hdr_padded_len;
        struct page *page_to_free = NULL;
        int tailroom, shinfo_size;
        char *p, *hdr_p, *buf;

        p = page_address(page) + offset;
        hdr_p = p;

        hdr_len = vi->hdr_len;
        if (vi->mergeable_rx_bufs)
                hdr_padded_len = hdr_len;
        else
                hdr_padded_len = sizeof(struct padded_vnet_hdr);

        buf = p - headroom;
        len -= hdr_len;
        offset += hdr_padded_len;
        p += hdr_padded_len;
        tailroom = truesize - headroom  - hdr_padded_len - len;

        shinfo_size = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));

        /* copy small packet so we can reuse these pages */
        if (!NET_IP_ALIGN && len > GOOD_COPY_LEN && tailroom >= shinfo_size) {
                skb = virtnet_build_skb(buf, truesize, p - buf, len);
                if (unlikely(!skb))
                        return NULL;

                page = (struct page *)page->private;
                if (page)
                        give_pages(rq, page);
                goto ok;
        }

        /* copy small packet so we can reuse these pages for small data */
        skb = napi_alloc_skb(&rq->napi, GOOD_COPY_LEN);
        if (unlikely(!skb))
                return NULL;

        /* Copy all frame if it fits skb->head, otherwise
         * we let virtio_net_hdr_to_skb() and GRO pull headers as needed.
         */
        if (len <= skb_tailroom(skb))
                copy = len;
        else
                copy = ETH_HLEN;
        skb_put_data(skb, p, copy);

        len -= copy;
        offset += copy;

        if (vi->mergeable_rx_bufs) {
                if (len)
                        skb_add_rx_frag(skb, 0, page, offset, len, truesize);
                else
                        page_to_free = page;
                goto ok;
        }

        /*
         * Verify that we can indeed put this data into a skb.
         * This is here to handle cases when the device erroneously
         * tries to receive more than is possible. This is usually
         * the case of a broken device.
         */
        if (unlikely(len > MAX_SKB_FRAGS * PAGE_SIZE)) {
                net_dbg_ratelimited("%s: too much data\n", skb->dev->name);
                dev_kfree_skb(skb);
                return NULL;
        }
        BUG_ON(offset >= PAGE_SIZE);
        while (len) {
                unsigned int frag_size = min((unsigned)PAGE_SIZE - offset, len);
                skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page, offset,
                                frag_size, truesize);
                len -= frag_size;
                page = (struct page *)page->private;
                offset = 0;
        }

        if (page)
                give_pages(rq, page);

ok:
        hdr = skb_vnet_common_hdr(skb);
        memcpy(hdr, hdr_p, hdr_len);
        if (page_to_free)
                put_page(page_to_free);

        return skb;
}

static void virtnet_rq_unmap(struct receive_queue *rq, void *buf, u32 len)
{
        struct page *page = virt_to_head_page(buf);
        struct virtnet_rq_dma *dma;
        void *head;
        int offset;

        head = page_address(page);

        dma = head;

        --dma->ref;

        if (dma->need_sync && len) {
                offset = buf - (head + sizeof(*dma));

                virtqueue_dma_sync_single_range_for_cpu(rq->vq, dma->addr,
                                                        offset, len,
                                                        DMA_FROM_DEVICE);
        }

        if (dma->ref)
                return;

        virtqueue_dma_unmap_single_attrs(rq->vq, dma->addr, dma->len,
                                         DMA_FROM_DEVICE, DMA_ATTR_SKIP_CPU_SYNC);
        put_page(page);
}

static void *virtnet_rq_get_buf(struct receive_queue *rq, u32 *len, void **ctx)
{
        void *buf;

        buf = virtqueue_get_buf_ctx(rq->vq, len, ctx);
        if (buf && rq->do_dma)
                virtnet_rq_unmap(rq, buf, *len);

        return buf;
}

static void *virtnet_rq_detach_unused_buf(struct receive_queue *rq)
{
        void *buf;

        buf = virtqueue_detach_unused_buf(rq->vq);
        if (buf && rq->do_dma)
                virtnet_rq_unmap(rq, buf, 0);

        return buf;
}

static void virtnet_rq_init_one_sg(struct receive_queue *rq, void *buf, u32 len)
{
        struct virtnet_rq_dma *dma;
        dma_addr_t addr;
        u32 offset;
        void *head;

        if (!rq->do_dma) {
                sg_init_one(rq->sg, buf, len);
                return;
        }

        head = page_address(rq->alloc_frag.page);

        offset = buf - head;

        dma = head;

        addr = dma->addr - sizeof(*dma) + offset;

        sg_init_table(rq->sg, 1);
        rq->sg[0].dma_address = addr;
        rq->sg[0].length = len;
}

static void *virtnet_rq_alloc(struct receive_queue *rq, u32 size, gfp_t gfp)
{
        struct page_frag *alloc_frag = &rq->alloc_frag;
        struct virtnet_rq_dma *dma;
        void *buf, *head;
        dma_addr_t addr;

        if (unlikely(!skb_page_frag_refill(size, alloc_frag, gfp)))
                return NULL;

        head = page_address(alloc_frag->page);

        if (rq->do_dma) {
                dma = head;

                /* new pages */
                if (!alloc_frag->offset) {
                        if (rq->last_dma) {
                                /* Now, the new page is allocated, the last dma
                                 * will not be used. So the dma can be unmapped
                                 * if the ref is 0.
                                 */
                                virtnet_rq_unmap(rq, rq->last_dma, 0);
                                rq->last_dma = NULL;
                        }

                        dma->len = alloc_frag->size - sizeof(*dma);

                        addr = virtqueue_dma_map_single_attrs(rq->vq, dma + 1,
                                                              dma->len, DMA_FROM_DEVICE, 0);
                        if (virtqueue_dma_mapping_error(rq->vq, addr))
                                return NULL;

                        dma->addr = addr;
                        dma->need_sync = virtqueue_dma_need_sync(rq->vq, addr);

                        /* Add a reference to dma to prevent the entire dma from
                         * being released during error handling. This reference
                         * will be freed after the pages are no longer used.
                         */
                        get_page(alloc_frag->page);
                        dma->ref = 1;
                        alloc_frag->offset = sizeof(*dma);

                        rq->last_dma = dma;
                }

                ++dma->ref;
        }

        buf = head + alloc_frag->offset;

        get_page(alloc_frag->page);
        alloc_frag->offset += size;

        return buf;
}

static void virtnet_rq_set_premapped(struct virtnet_info *vi)
{
        int i;

        /* disable for big mode */
        if (!vi->mergeable_rx_bufs && vi->big_packets)
                return;

        for (i = 0; i < vi->max_queue_pairs; i++) {
                if (virtqueue_set_dma_premapped(vi->rq[i].vq))
                        continue;

                vi->rq[i].do_dma = true;
        }
}

static void free_old_xmit_skbs(struct send_queue *sq, bool in_napi)
{
        unsigned int len;
        unsigned int packets = 0;
        unsigned int bytes = 0;
        void *ptr;

        while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
                if (likely(!is_xdp_frame(ptr))) {
                        struct sk_buff *skb = ptr;

                        pr_debug("Sent skb %p\n", skb);

                        bytes += skb->len;
                        napi_consume_skb(skb, in_napi);
                } else {
                        struct xdp_frame *frame = ptr_to_xdp(ptr);

                        bytes += xdp_get_frame_len(frame);
                        xdp_return_frame(frame);
                }
                packets++;
        }

        /* Avoid overhead when no packets have been processed
         * happens when called speculatively from start_xmit.
         */
        if (!packets)
                return;

        u64_stats_update_begin(&sq->stats.syncp);
        sq->stats.bytes += bytes;
        sq->stats.packets += packets;
        u64_stats_update_end(&sq->stats.syncp);
}

static bool is_xdp_raw_buffer_queue(struct virtnet_info *vi, int q)
{
        if (q < (vi->curr_queue_pairs - vi->xdp_queue_pairs))
                return false;
        else if (q < vi->curr_queue_pairs)
                return true;
        else
                return false;
}

static void check_sq_full_and_disable(struct virtnet_info *vi,
                                      struct net_device *dev,
                                      struct send_queue *sq)
{
        bool use_napi = sq->napi.weight;
        int qnum;

        qnum = sq - vi->sq;

        /* If running out of space, stop queue to avoid getting packets that we
         * are then unable to transmit.
         * An alternative would be to force queuing layer to requeue the skb by
         * returning NETDEV_TX_BUSY. However, NETDEV_TX_BUSY should not be
         * returned in a normal path of operation: it means that driver is not
         * maintaining the TX queue stop/start state properly, and causes
         * the stack to do a non-trivial amount of useless work.
         * Since most packets only take 1 or 2 ring slots, stopping the queue
         * early means 16 slots are typically wasted.
         */
        if (sq->vq->num_free < 2+MAX_SKB_FRAGS) {
                netif_stop_subqueue(dev, qnum);
                if (use_napi) {
                        if (unlikely(!virtqueue_enable_cb_delayed(sq->vq)))
                                virtqueue_napi_schedule(&sq->napi, sq->vq);
                } else if (unlikely(!virtqueue_enable_cb_delayed(sq->vq))) {
                        /* More just got used, free them then recheck. */
                        free_old_xmit_skbs(sq, false);
                        if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) {
                                netif_start_subqueue(dev, qnum);
                                virtqueue_disable_cb(sq->vq);
                        }
                }
        }
}

static int __virtnet_xdp_xmit_one(struct virtnet_info *vi,
                                   struct send_queue *sq,
                                   struct xdp_frame *xdpf)
{
        struct virtio_net_hdr_mrg_rxbuf *hdr;
        struct skb_shared_info *shinfo;
        u8 nr_frags = 0;
        int err, i;

        if (unlikely(xdpf->headroom < vi->hdr_len))
                return -EOVERFLOW;

        if (unlikely(xdp_frame_has_frags(xdpf))) {
                shinfo = xdp_get_shared_info_from_frame(xdpf);
                nr_frags = shinfo->nr_frags;
        }

        /* In wrapping function virtnet_xdp_xmit(), we need to free
         * up the pending old buffers, where we need to calculate the
         * position of skb_shared_info in xdp_get_frame_len() and
         * xdp_return_frame(), which will involve to xdpf->data and
         * xdpf->headroom. Therefore, we need to update the value of
         * headroom synchronously here.
         */
        xdpf->headroom -= vi->hdr_len;
        xdpf->data -= vi->hdr_len;
        /* Zero header and leave csum up to XDP layers */
        hdr = xdpf->data;
        memset(hdr, 0, vi->hdr_len);
        xdpf->len   += vi->hdr_len;

        sg_init_table(sq->sg, nr_frags + 1);
        sg_set_buf(sq->sg, xdpf->data, xdpf->len);
        for (i = 0; i < nr_frags; i++) {
                skb_frag_t *frag = &shinfo->frags[i];

                sg_set_page(&sq->sg[i + 1], skb_frag_page(frag),
                            skb_frag_size(frag), skb_frag_off(frag));
        }

        err = virtqueue_add_outbuf(sq->vq, sq->sg, nr_frags + 1,
                                   xdp_to_ptr(xdpf), GFP_ATOMIC);
        if (unlikely(err))
                return -ENOSPC; /* Caller handle free/refcnt */

        return 0;
}

/* when vi->curr_queue_pairs > nr_cpu_ids, the txq/sq is only used for xdp tx on
 * the current cpu, so it does not need to be locked.
 *
 * Here we use marco instead of inline functions because we have to deal with
 * three issues at the same time: 1. the choice of sq. 2. judge and execute the
 * lock/unlock of txq 3. make sparse happy. It is difficult for two inline
 * functions to perfectly solve these three problems at the same time.
 */
#define virtnet_xdp_get_sq(vi) ({                                       \
        int cpu = smp_processor_id();                                   \
        struct netdev_queue *txq;                                       \
        typeof(vi) v = (vi);                                            \
        unsigned int qp;                                                \
                                                                        \
        if (v->curr_queue_pairs > nr_cpu_ids) {                         \
                qp = v->curr_queue_pairs - v->xdp_queue_pairs;          \
                qp += cpu;                                              \
                txq = netdev_get_tx_queue(v->dev, qp);                  \
                __netif_tx_acquire(txq);                                \
        } else {                                                        \
                qp = cpu % v->curr_queue_pairs;                         \
                txq = netdev_get_tx_queue(v->dev, qp);                  \
                __netif_tx_lock(txq, cpu);                              \
        }                                                               \
        v->sq + qp;                                                     \
})

#define virtnet_xdp_put_sq(vi, q) {                                     \
        struct netdev_queue *txq;                                       \
        typeof(vi) v = (vi);                                            \
                                                                        \
        txq = netdev_get_tx_queue(v->dev, (q) - v->sq);                 \
        if (v->curr_queue_pairs > nr_cpu_ids)                           \
                __netif_tx_release(txq);                                \
        else                                                            \
                __netif_tx_unlock(txq);                                 \
}

static int virtnet_xdp_xmit(struct net_device *dev,
                            int n, struct xdp_frame **frames, u32 flags)
{
        struct virtnet_info *vi = netdev_priv(dev);
        struct receive_queue *rq = vi->rq;
        struct bpf_prog *xdp_prog;
        struct send_queue *sq;
        unsigned int len;
        int packets = 0;
        int bytes = 0;
        int nxmit = 0;
        int kicks = 0;
        void *ptr;
        int ret;
        int i;

        /* Only allow ndo_xdp_xmit if XDP is loaded on dev, as this
         * indicate XDP resources have been successfully allocated.
         */
        xdp_prog = rcu_access_pointer(rq->xdp_prog);
        if (!xdp_prog)
                return -ENXIO;

        sq = virtnet_xdp_get_sq(vi);

        if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK)) {
                ret = -EINVAL;
                goto out;
        }

        /* Free up any pending old buffers before queueing new ones. */
        while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
                if (likely(is_xdp_frame(ptr))) {
                        struct xdp_frame *frame = ptr_to_xdp(ptr);

                        bytes += xdp_get_frame_len(frame);
                        xdp_return_frame(frame);
                } else {
                        struct sk_buff *skb = ptr;

                        bytes += skb->len;
                        napi_consume_skb(skb, false);
                }
                packets++;
        }

        for (i = 0; i < n; i++) {
                struct xdp_frame *xdpf = frames[i];

                if (__virtnet_xdp_xmit_one(vi, sq, xdpf))
                        break;
                nxmit++;
        }
        ret = nxmit;

        if (!is_xdp_raw_buffer_queue(vi, sq - vi->sq))
                check_sq_full_and_disable(vi, dev, sq);

        if (flags & XDP_XMIT_FLUSH) {
                if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq))
                        kicks = 1;
        }
out:
        u64_stats_update_begin(&sq->stats.syncp);
        sq->stats.bytes += bytes;
        sq->stats.packets += packets;
        sq->stats.xdp_tx += n;
        sq->stats.xdp_tx_drops += n - nxmit;
        sq->stats.kicks += kicks;
        u64_stats_update_end(&sq->stats.syncp);

        virtnet_xdp_put_sq(vi, sq);
        return ret;
}

static void put_xdp_frags(struct xdp_buff *xdp)
{
        struct skb_shared_info *shinfo;
        struct page *xdp_page;
        int i;

        if (xdp_buff_has_frags(xdp)) {
                shinfo = xdp_get_shared_info_from_buff(xdp);
                for (i = 0; i < shinfo->nr_frags; i++) {
                        xdp_page = skb_frag_page(&shinfo->frags[i]);
                        put_page(xdp_page);
                }
        }
}

static int virtnet_xdp_handler(struct bpf_prog *xdp_prog, struct xdp_buff *xdp,
                               struct net_device *dev,
                               unsigned int *xdp_xmit,
                               struct virtnet_rq_stats *stats)
{
        struct xdp_frame *xdpf;
        int err;
        u32 act;

        act = bpf_prog_run_xdp(xdp_prog, xdp);
        stats->xdp_packets++;

        switch (act) {
        case XDP_PASS:
                return act;

        case XDP_TX:
                stats->xdp_tx++;
                xdpf = xdp_convert_buff_to_frame(xdp);
                if (unlikely(!xdpf)) {
                        netdev_dbg(dev, "convert buff to frame failed for xdp\n");
                        return XDP_DROP;
                }

                err = virtnet_xdp_xmit(dev, 1, &xdpf, 0);
                if (unlikely(!err)) {
                        xdp_return_frame_rx_napi(xdpf);
                } else if (unlikely(err < 0)) {
                        trace_xdp_exception(dev, xdp_prog, act);
                        return XDP_DROP;
                }
                *xdp_xmit |= VIRTIO_XDP_TX;
                return act;

        case XDP_REDIRECT:
                stats->xdp_redirects++;
                err = xdp_do_redirect(dev, xdp, xdp_prog);
                if (err)
                        return XDP_DROP;

                *xdp_xmit |= VIRTIO_XDP_REDIR;
                return act;

        default:
                bpf_warn_invalid_xdp_action(dev, xdp_prog, act);
                fallthrough;
        case XDP_ABORTED:
                trace_xdp_exception(dev, xdp_prog, act);
                fallthrough;
        case XDP_DROP:
                return XDP_DROP;
        }
}

static unsigned int virtnet_get_headroom(struct virtnet_info *vi)
{
        return vi->xdp_enabled ? VIRTIO_XDP_HEADROOM : 0;
}

/* We copy the packet for XDP in the following cases:
 *
 * 1) Packet is scattered across multiple rx buffers.
 * 2) Headroom space is insufficient.
 *
 * This is inefficient but it's a temporary condition that
 * we hit right after XDP is enabled and until queue is refilled
 * with large buffers with sufficient headroom - so it should affect
 * at most queue size packets.
 * Afterwards, the conditions to enable
 * XDP should preclude the underlying device from sending packets
 * across multiple buffers (num_buf > 1), and we make sure buffers
 * have enough headroom.
 */
static struct page *xdp_linearize_page(struct receive_queue *rq,
                                       int *num_buf,
                                       struct page *p,
                                       int offset,
                                       int page_off,
                                       unsigned int *len)
{
        int tailroom = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
        struct page *page;

        if (page_off + *len + tailroom > PAGE_SIZE)
                return NULL;

        page = alloc_page(GFP_ATOMIC);
        if (!page)
                return NULL;

        memcpy(page_address(page) + page_off, page_address(p) + offset, *len);
        page_off += *len;

        while (--*num_buf) {
                unsigned int buflen;
                void *buf;
                int off;

                buf = virtnet_rq_get_buf(rq, &buflen, NULL);
                if (unlikely(!buf))
                        goto err_buf;

                p = virt_to_head_page(buf);
                off = buf - page_address(p);

                /* guard against a misconfigured or uncooperative backend that
                 * is sending packet larger than the MTU.
                 */
                if ((page_off + buflen + tailroom) > PAGE_SIZE) {
                        put_page(p);
                        goto err_buf;
                }

                memcpy(page_address(page) + page_off,
                       page_address(p) + off, buflen);
                page_off += buflen;
                put_page(p);
        }

        /* Headroom does not contribute to packet length */
        *len = page_off - VIRTIO_XDP_HEADROOM;
        return page;
err_buf:
        __free_pages(page, 0);
        return NULL;
}

static struct sk_buff *receive_small_build_skb(struct virtnet_info *vi,
                                               unsigned int xdp_headroom,
                                               void *buf,
                                               unsigned int len)
{
        unsigned int header_offset;
        unsigned int headroom;
        unsigned int buflen;
        struct sk_buff *skb;

        header_offset = VIRTNET_RX_PAD + xdp_headroom;
        headroom = vi->hdr_len + header_offset;
        buflen = SKB_DATA_ALIGN(GOOD_PACKET_LEN + headroom) +
                SKB_DATA_ALIGN(sizeof(struct skb_shared_info));

        skb = virtnet_build_skb(buf, buflen, headroom, len);
        if (unlikely(!skb))
                return NULL;

        buf += header_offset;
        memcpy(skb_vnet_common_hdr(skb), buf, vi->hdr_len);

        return skb;
}

static struct sk_buff *receive_small_xdp(struct net_device *dev,
                                         struct virtnet_info *vi,
                                         struct receive_queue *rq,
                                         struct bpf_prog *xdp_prog,
                                         void *buf,
                                         unsigned int xdp_headroom,
                                         unsigned int len,
                                         unsigned int *xdp_xmit,
                                         struct virtnet_rq_stats *stats)
{
        unsigned int header_offset = VIRTNET_RX_PAD + xdp_headroom;
        unsigned int headroom = vi->hdr_len + header_offset;
        struct virtio_net_hdr_mrg_rxbuf *hdr = buf + header_offset;
        struct page *page = virt_to_head_page(buf);
        struct page *xdp_page;
        unsigned int buflen;
        struct xdp_buff xdp;
        struct sk_buff *skb;
        unsigned int metasize = 0;
        u32 act;

        if (unlikely(hdr->hdr.gso_type))
                goto err_xdp;

        buflen = SKB_DATA_ALIGN(GOOD_PACKET_LEN + headroom) +
                SKB_DATA_ALIGN(sizeof(struct skb_shared_info));

        if (unlikely(xdp_headroom < virtnet_get_headroom(vi))) {
                int offset = buf - page_address(page) + header_offset;
                unsigned int tlen = len + vi->hdr_len;
                int num_buf = 1;

                xdp_headroom = virtnet_get_headroom(vi);
                header_offset = VIRTNET_RX_PAD + xdp_headroom;
                headroom = vi->hdr_len + header_offset;
                buflen = SKB_DATA_ALIGN(GOOD_PACKET_LEN + headroom) +
                        SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
                xdp_page = xdp_linearize_page(rq, &num_buf, page,
                                              offset, header_offset,
                                              &tlen);
                if (!xdp_page)
                        goto err_xdp;

                buf = page_address(xdp_page);
                put_page(page);
                page = xdp_page;
        }

        xdp_init_buff(&xdp, buflen, &rq->xdp_rxq);
        xdp_prepare_buff(&xdp, buf + VIRTNET_RX_PAD + vi->hdr_len,
                         xdp_headroom, len, true);

        act = virtnet_xdp_handler(xdp_prog, &xdp, dev, xdp_xmit, stats);

        switch (act) {
        case XDP_PASS:
                /* Recalculate length in case bpf program changed it */
                len = xdp.data_end - xdp.data;
                metasize = xdp.data - xdp.data_meta;
                break;

        case XDP_TX:
        case XDP_REDIRECT:
                goto xdp_xmit;

        default:
                goto err_xdp;
        }

        skb = virtnet_build_skb(buf, buflen, xdp.data - buf, len);
        if (unlikely(!skb))
                goto err;

        if (metasize)
                skb_metadata_set(skb, metasize);

        return skb;

err_xdp:
        stats->xdp_drops++;
err:
        stats->drops++;
        put_page(page);
xdp_xmit:
        return NULL;
}

static struct sk_buff *receive_small(struct net_device *dev,
                                     struct virtnet_info *vi,
                                     struct receive_queue *rq,
                                     void *buf, void *ctx,
                                     unsigned int len,
                                     unsigned int *xdp_xmit,
                                     struct virtnet_rq_stats *stats)
{
        unsigned int xdp_headroom = (unsigned long)ctx;
        struct page *page = virt_to_head_page(buf);
        struct sk_buff *skb;

        len -= vi->hdr_len;
        stats->bytes += len;

        if (unlikely(len > GOOD_PACKET_LEN)) {
                pr_debug("%s: rx error: len %u exceeds max size %d\n",
                         dev->name, len, GOOD_PACKET_LEN);
                dev->stats.rx_length_errors++;
                goto err;
        }

        if (unlikely(vi->xdp_enabled)) {
                struct bpf_prog *xdp_prog;

                rcu_read_lock();
                xdp_prog = rcu_dereference(rq->xdp_prog);
                if (xdp_prog) {
                        skb = receive_small_xdp(dev, vi, rq, xdp_prog, buf,
                                                xdp_headroom, len, xdp_xmit,
                                                stats);
                        rcu_read_unlock();
                        return skb;
                }
                rcu_read_unlock();
        }

        skb = receive_small_build_skb(vi, xdp_headroom, buf, len);
        if (likely(skb))
                return skb;

err:
        stats->drops++;
        put_page(page);
        return NULL;
}

static struct sk_buff *receive_big(struct net_device *dev,
                                   struct virtnet_info *vi,
                                   struct receive_queue *rq,
                                   void *buf,
                                   unsigned int len,
                                   struct virtnet_rq_stats *stats)
{
        struct page *page = buf;
        struct sk_buff *skb =
                page_to_skb(vi, rq, page, 0, len, PAGE_SIZE, 0);

        stats->bytes += len - vi->hdr_len;
        if (unlikely(!skb))
                goto err;

        return skb;

err:
        stats->drops++;
        give_pages(rq, page);
        return NULL;
}

static void mergeable_buf_free(struct receive_queue *rq, int num_buf,
                               struct net_device *dev,
                               struct virtnet_rq_stats *stats)
{
        struct page *page;
        void *buf;
        int len;

        while (num_buf-- > 1) {
                buf = virtnet_rq_get_buf(rq, &len, NULL);
                if (unlikely(!buf)) {
                        pr_debug("%s: rx error: %d buffers missing\n",
                                 dev->name, num_buf);
                        dev->stats.rx_length_errors++;
                        break;
                }
                stats->bytes += len;
                page = virt_to_head_page(buf);
                put_page(page);
        }
}

/* Why not use xdp_build_skb_from_frame() ?
 * XDP core assumes that xdp frags are PAGE_SIZE in length, while in
 * virtio-net there are 2 points that do not match its requirements:
 *  1. The size of the prefilled buffer is not fixed before xdp is set.
 *  2. xdp_build_skb_from_frame() does more checks that we don't need,
 *     like eth_type_trans() (which virtio-net does in receive_buf()).
 */
static struct sk_buff *build_skb_from_xdp_buff(struct net_device *dev,
                                               struct virtnet_info *vi,
                                               struct xdp_buff *xdp,
                                               unsigned int xdp_frags_truesz)
{
        struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp);
        unsigned int headroom, data_len;
        struct sk_buff *skb;
        int metasize;
        u8 nr_frags;

        if (unlikely(xdp->data_end > xdp_data_hard_end(xdp))) {
                pr_debug("Error building skb as missing reserved tailroom for xdp");
                return NULL;
        }

        if (unlikely(xdp_buff_has_frags(xdp)))
                nr_frags = sinfo->nr_frags;

        skb = build_skb(xdp->data_hard_start, xdp->frame_sz);
        if (unlikely(!skb))
                return NULL;

        headroom = xdp->data - xdp->data_hard_start;
        data_len = xdp->data_end - xdp->data;
        skb_reserve(skb, headroom);
        __skb_put(skb, data_len);

        metasize = xdp->data - xdp->data_meta;
        metasize = metasize > 0 ? metasize : 0;
        if (metasize)
                skb_metadata_set(skb, metasize);

        if (unlikely(xdp_buff_has_frags(xdp)))
                xdp_update_skb_shared_info(skb, nr_frags,
                                           sinfo->xdp_frags_size,
                                           xdp_frags_truesz,
                                           xdp_buff_is_frag_pfmemalloc(xdp));

        return skb;
}

/* TODO: build xdp in big mode */
static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
                                      struct virtnet_info *vi,
                                      struct receive_queue *rq,
                                      struct xdp_buff *xdp,
                                      void *buf,
                                      unsigned int len,
                                      unsigned int frame_sz,
                                      int *num_buf,
                                      unsigned int *xdp_frags_truesize,
                                      struct virtnet_rq_stats *stats)
{
        struct virtio_net_hdr_mrg_rxbuf *hdr = buf;
        unsigned int headroom, tailroom, room;
        unsigned int truesize, cur_frag_size;
        struct skb_shared_info *shinfo;
        unsigned int xdp_frags_truesz = 0;
        struct page *page;
        skb_frag_t *frag;
        int offset;
        void *ctx;

        xdp_init_buff(xdp, frame_sz, &rq->xdp_rxq);
        xdp_prepare_buff(xdp, buf - VIRTIO_XDP_HEADROOM,
                         VIRTIO_XDP_HEADROOM + vi->hdr_len, len - vi->hdr_len, true);

        if (!*num_buf)
                return 0;

        if (*num_buf > 1) {
                /* If we want to build multi-buffer xdp, we need
                 * to specify that the flags of xdp_buff have the
                 * XDP_FLAGS_HAS_FRAG bit.
                 */
                if (!xdp_buff_has_frags(xdp))
                        xdp_buff_set_frags_flag(xdp);

                shinfo = xdp_get_shared_info_from_buff(xdp);
                shinfo->nr_frags = 0;
                shinfo->xdp_frags_size = 0;
        }

        if (*num_buf > MAX_SKB_FRAGS + 1)
                return -EINVAL;

        while (--*num_buf > 0) {
                buf = virtnet_rq_get_buf(rq, &len, &ctx);
                if (unlikely(!buf)) {
                        pr_debug("%s: rx error: %d buffers out of %d missing\n",
                                 dev->name, *num_buf,
                                 virtio16_to_cpu(vi->vdev, hdr->num_buffers));
                        dev->stats.rx_length_errors++;
                        goto err;
                }

                stats->bytes += len;
                page = virt_to_head_page(buf);
                offset = buf - page_address(page);

                truesize = mergeable_ctx_to_truesize(ctx);
                headroom = mergeable_ctx_to_headroom(ctx);
                tailroom = headroom ? sizeof(struct skb_shared_info) : 0;
                room = SKB_DATA_ALIGN(headroom + tailroom);

                cur_frag_size = truesize;
                xdp_frags_truesz += cur_frag_size;
                if (unlikely(len > truesize - room || cur_frag_size > PAGE_SIZE)) {
                        put_page(page);
                        pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
                                 dev->name, len, (unsigned long)(truesize - room));
                        dev->stats.rx_length_errors++;
                        goto err;
                }

                frag = &shinfo->frags[shinfo->nr_frags++];
                skb_frag_fill_page_desc(frag, page, offset, len);
                if (page_is_pfmemalloc(page))
                        xdp_buff_set_frag_pfmemalloc(xdp);

                shinfo->xdp_frags_size += len;
        }

        *xdp_frags_truesize = xdp_frags_truesz;
        return 0;

err:
        put_xdp_frags(xdp);
        return -EINVAL;
}

static void *mergeable_xdp_get_buf(struct virtnet_info *vi,
                                   struct receive_queue *rq,
                                   struct bpf_prog *xdp_prog,
                                   void *ctx,
                                   unsigned int *frame_sz,
                                   int *num_buf,
                                   struct page **page,
                                   int offset,
                                   unsigned int *len,
                                   struct virtio_net_hdr_mrg_rxbuf *hdr)
{
        unsigned int truesize = mergeable_ctx_to_truesize(ctx);
        unsigned int headroom = mergeable_ctx_to_headroom(ctx);
        struct page *xdp_page;
        unsigned int xdp_room;

        /* Transient failure which in theory could occur if
         * in-flight packets from before XDP was enabled reach
         * the receive path after XDP is loaded.
         */
        if (unlikely(hdr->hdr.gso_type))
                return NULL;

        /* Now XDP core assumes frag size is PAGE_SIZE, but buffers
         * with headroom may add hole in truesize, which
         * make their length exceed PAGE_SIZE. So we disabled the
         * hole mechanism for xdp. See add_recvbuf_mergeable().
         */
        *frame_sz = truesize;

        if (likely(headroom >= virtnet_get_headroom(vi) &&
                   (*num_buf == 1 || xdp_prog->aux->xdp_has_frags))) {
                return page_address(*page) + offset;
        }

        /* This happens when headroom is not enough because
         * of the buffer was prefilled before XDP is set.
         * This should only happen for the first several packets.
         * In fact, vq reset can be used here to help us clean up
         * the prefilled buffers, but many existing devices do not
         * support it, and we don't want to bother users who are
         * using xdp normally.
         */
        if (!xdp_prog->aux->xdp_has_frags) {
                /* linearize data for XDP */
                xdp_page = xdp_linearize_page(rq, num_buf,
                                              *page, offset,
                                              VIRTIO_XDP_HEADROOM,
                                              len);
                if (!xdp_page)
                        return NULL;
        } else {
                xdp_room = SKB_DATA_ALIGN(VIRTIO_XDP_HEADROOM +
                                          sizeof(struct skb_shared_info));
                if (*len + xdp_room > PAGE_SIZE)
                        return NULL;

                xdp_page = alloc_page(GFP_ATOMIC);
                if (!xdp_page)
                        return NULL;

                memcpy(page_address(xdp_page) + VIRTIO_XDP_HEADROOM,
                       page_address(*page) + offset, *len);
        }

        *frame_sz = PAGE_SIZE;

        put_page(*page);

        *page = xdp_page;

        return page_address(*page) + VIRTIO_XDP_HEADROOM;
}

static struct sk_buff *receive_mergeable_xdp(struct net_device *dev,
                                             struct virtnet_info *vi,
                                             struct receive_queue *rq,
                                             struct bpf_prog *xdp_prog,
                                             void *buf,
                                             void *ctx,
                                             unsigned int len,
                                             unsigned int *xdp_xmit,
                                             struct virtnet_rq_stats *stats)
{
        struct virtio_net_hdr_mrg_rxbuf *hdr = buf;
        int num_buf = virtio16_to_cpu(vi->vdev, hdr->num_buffers);
        struct page *page = virt_to_head_page(buf);
        int offset = buf - page_address(page);
        unsigned int xdp_frags_truesz = 0;
        struct sk_buff *head_skb;
        unsigned int frame_sz;
        struct xdp_buff xdp;
        void *data;
        u32 act;
        int err;

        data = mergeable_xdp_get_buf(vi, rq, xdp_prog, ctx, &frame_sz, &num_buf, &page,
                                     offset, &len, hdr);
        if (unlikely(!data))
                goto err_xdp;

        err = virtnet_build_xdp_buff_mrg(dev, vi, rq, &xdp, data, len, frame_sz,
                                         &num_buf, &xdp_frags_truesz, stats);
        if (unlikely(err))
                goto err_xdp;

        act = virtnet_xdp_handler(xdp_prog, &xdp, dev, xdp_xmit, stats);

        switch (act) {
        case XDP_PASS:
                head_skb = build_skb_from_xdp_buff(dev, vi, &xdp, xdp_frags_truesz);
                if (unlikely(!head_skb))
                        break;
                return head_skb;

        case XDP_TX:
        case XDP_REDIRECT:
                return NULL;

        default:
                break;
        }

        put_xdp_frags(&xdp);

err_xdp:
        put_page(page);
        mergeable_buf_free(rq, num_buf, dev, stats);

        stats->xdp_drops++;
        stats->drops++;
        return NULL;
}

static struct sk_buff *receive_mergeable(struct net_device *dev,
                                         struct virtnet_info *vi,
                                         struct receive_queue *rq,
                                         void *buf,
                                         void *ctx,
                                         unsigned int len,
                                         unsigned int *xdp_xmit,
                                         struct virtnet_rq_stats *stats)
{
        struct virtio_net_hdr_mrg_rxbuf *hdr = buf;
        int num_buf = virtio16_to_cpu(vi->vdev, hdr->num_buffers);
        struct page *page = virt_to_head_page(buf);
        int offset = buf - page_address(page);
        struct sk_buff *head_skb, *curr_skb;
        unsigned int truesize = mergeable_ctx_to_truesize(ctx);
        unsigned int headroom = mergeable_ctx_to_headroom(ctx);
        unsigned int tailroom = headroom ? sizeof(struct skb_shared_info) : 0;
        unsigned int room = SKB_DATA_ALIGN(headroom + tailroom);

        head_skb = NULL;
        stats->bytes += len - vi->hdr_len;

        if (unlikely(len > truesize - room)) {
                pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
                         dev->name, len, (unsigned long)(truesize - room));
                dev->stats.rx_length_errors++;
                goto err_skb;
        }

        if (unlikely(vi->xdp_enabled)) {
                struct bpf_prog *xdp_prog;

                rcu_read_lock();
                xdp_prog = rcu_dereference(rq->xdp_prog);
                if (xdp_prog) {
                        head_skb = receive_mergeable_xdp(dev, vi, rq, xdp_prog, buf, ctx,
                                                         len, xdp_xmit, stats);
                        rcu_read_unlock();
                        return head_skb;
                }
                rcu_read_unlock();
        }

        head_skb = page_to_skb(vi, rq, page, offset, len, truesize, headroom);
        curr_skb = head_skb;

        if (unlikely(!curr_skb))
                goto err_skb;
        while (--num_buf) {
                int num_skb_frags;

                buf = virtnet_rq_get_buf(rq, &len, &ctx);
                if (unlikely(!buf)) {
                        pr_debug("%s: rx error: %d buffers out of %d missing\n",
                                 dev->name, num_buf,
                                 virtio16_to_cpu(vi->vdev,
                                                 hdr->num_buffers));
                        dev->stats.rx_length_errors++;
                        goto err_buf;
                }

                stats->bytes += len;
                page = virt_to_head_page(buf);

                truesize = mergeable_ctx_to_truesize(ctx);
                headroom = mergeable_ctx_to_headroom(ctx);
                tailroom = headroom ? sizeof(struct skb_shared_info) : 0;
                room = SKB_DATA_ALIGN(headroom + tailroom);
                if (unlikely(len > truesize - room)) {
                        pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
                                 dev->name, len, (unsigned long)(truesize - room));
                        dev->stats.rx_length_errors++;
                        goto err_skb;
                }

                num_skb_frags = skb_shinfo(curr_skb)->nr_frags;
                if (unlikely(num_skb_frags == MAX_SKB_FRAGS)) {
                        struct sk_buff *nskb = alloc_skb(0, GFP_ATOMIC);

                        if (unlikely(!nskb))
                                goto err_skb;
                        if (curr_skb == head_skb)
                                skb_shinfo(curr_skb)->frag_list = nskb;
                        else
                                curr_skb->next = nskb;
                        curr_skb = nskb;
                        head_skb->truesize += nskb->truesize;
                        num_skb_frags = 0;
                }
                if (curr_skb != head_skb) {
                        head_skb->data_len += len;
                        head_skb->len += len;
                        head_skb->truesize += truesize;
                }
                offset = buf - page_address(page);
                if (skb_can_coalesce(curr_skb, num_skb_frags, page, offset)) {
                        put_page(page);
                        skb_coalesce_rx_frag(curr_skb, num_skb_frags - 1,
                                             len, truesize);
                } else {
                        skb_add_rx_frag(curr_skb, num_skb_frags, page,
                                        offset, len, truesize);
                }
        }

        ewma_pkt_len_add(&rq->mrg_avg_pkt_len, head_skb->len);
        return head_skb;

err_skb:
        put_page(page);
        mergeable_buf_free(rq, num_buf, dev, stats);

err_buf:
        stats->drops++;
        dev_kfree_skb(head_skb);
        return NULL;
}

static void virtio_skb_set_hash(const struct virtio_net_hdr_v1_hash *hdr_hash,
                                struct sk_buff *skb)
{
        enum pkt_hash_types rss_hash_type;

        if (!hdr_hash || !skb)
                return;

        switch (__le16_to_cpu(hdr_hash->hash_report)) {
        case VIRTIO_NET_HASH_REPORT_TCPv4:
        case VIRTIO_NET_HASH_REPORT_UDPv4:
        case VIRTIO_NET_HASH_REPORT_TCPv6:
        case VIRTIO_NET_HASH_REPORT_UDPv6:
        case VIRTIO_NET_HASH_REPORT_TCPv6_EX:
        case VIRTIO_NET_HASH_REPORT_UDPv6_EX:
                rss_hash_type = PKT_HASH_TYPE_L4;
                break;
        case VIRTIO_NET_HASH_REPORT_IPv4:
        case VIRTIO_NET_HASH_REPORT_IPv6:
        case VIRTIO_NET_HASH_REPORT_IPv6_EX:
                rss_hash_type = PKT_HASH_TYPE_L3;
                break;
        case VIRTIO_NET_HASH_REPORT_NONE:
        default:
                rss_hash_type = PKT_HASH_TYPE_NONE;
        }
        skb_set_hash(skb, __le32_to_cpu(hdr_hash->hash_value), rss_hash_type);
}

static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
                        void *buf, unsigned int len, void **ctx,
                        unsigned int *xdp_xmit,
                        struct virtnet_rq_stats *stats)
{
        struct net_device *dev = vi->dev;
        struct sk_buff *skb;
        struct virtio_net_common_hdr *hdr;

        if (unlikely(len < vi->hdr_len + ETH_HLEN)) {
                pr_debug("%s: short packet %i\n", dev->name, len);
                dev->stats.rx_length_errors++;
                virtnet_rq_free_unused_buf(rq->vq, buf);
                return;
        }

        if (vi->mergeable_rx_bufs)
                skb = receive_mergeable(dev, vi, rq, buf, ctx, len, xdp_xmit,
                                        stats);
        else if (vi->big_packets)
                skb = receive_big(dev, vi, rq, buf, len, stats);
        else
                skb = receive_small(dev, vi, rq, buf, ctx, len, xdp_xmit, stats);

        if (unlikely(!skb))
                return;

        hdr = skb_vnet_common_hdr(skb);
        if (dev->features & NETIF_F_RXHASH && vi->has_rss_hash_report)
                virtio_skb_set_hash(&hdr->hash_v1_hdr, skb);

        if (hdr->hdr.flags & VIRTIO_NET_HDR_F_DATA_VALID)
                skb->ip_summed = CHECKSUM_UNNECESSARY;

        if (virtio_net_hdr_to_skb(skb, &hdr->hdr,
                                  virtio_is_little_endian(vi->vdev))) {
                net_warn_ratelimited("%s: bad gso: type: %u, size: %u\n",
                                     dev->name, hdr->hdr.gso_type,
                                     hdr->hdr.gso_size);
                goto frame_err;
        }

        skb_record_rx_queue(skb, vq2rxq(rq->vq));
        skb->protocol = eth_type_trans(skb, dev);
        pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
                 ntohs(skb->protocol), skb->len, skb->pkt_type);

        napi_gro_receive(&rq->napi, skb);
        return;

frame_err:
        dev->stats.rx_frame_errors++;
        dev_kfree_skb(skb);
}

/* Unlike mergeable buffers, all buffers are allocated to the
 * same size, except for the headroom. For this reason we do
 * not need to use  mergeable_len_to_ctx here - it is enough
 * to store the headroom as the context ignoring the truesize.
 */
static int add_recvbuf_small(struct virtnet_info *vi, struct receive_queue *rq,
                             gfp_t gfp)
{
        char *buf;
        unsigned int xdp_headroom = virtnet_get_headroom(vi);
        void *ctx = (void *)(unsigned long)xdp_headroom;
        int len = vi->hdr_len + VIRTNET_RX_PAD + GOOD_PACKET_LEN + xdp_headroom;
        int err;

        len = SKB_DATA_ALIGN(len) +
              SKB_DATA_ALIGN(sizeof(struct skb_shared_info));

        buf = virtnet_rq_alloc(rq, len, gfp);
        if (unlikely(!buf))
                return -ENOMEM;

        virtnet_rq_init_one_sg(rq, buf + VIRTNET_RX_PAD + xdp_headroom,
                               vi->hdr_len + GOOD_PACKET_LEN);

        err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp);
        if (err < 0) {
                if (rq->do_dma)
                        virtnet_rq_unmap(rq, buf, 0);
                put_page(virt_to_head_page(buf));
        }

        return err;
}

static int add_recvbuf_big(struct virtnet_info *vi, struct receive_queue *rq,
                           gfp_t gfp)
{
        struct page *first, *list = NULL;
        char *p;
        int i, err, offset;

        sg_init_table(rq->sg, vi->big_packets_num_skbfrags + 2);

        /* page in rq->sg[vi->big_packets_num_skbfrags + 1] is list tail */
        for (i = vi->big_packets_num_skbfrags + 1; i > 1; --i) {
                first = get_a_page(rq, gfp);
                if (!first) {
                        if (list)
                                give_pages(rq, list);
                        return -ENOMEM;
                }
                sg_set_buf(&rq->sg[i], page_address(first), PAGE_SIZE);

                /* chain new page in list head to match sg */
                first->private = (unsigned long)list;
                list = first;
        }

        first = get_a_page(rq, gfp);
        if (!first) {
                give_pages(rq, list);
                return -ENOMEM;
        }
        p = page_address(first);

        /* rq->sg[0], rq->sg[1] share the same page */
        /* a separated rq->sg[0] for header - required in case !any_header_sg */
        sg_set_buf(&rq->sg[0], p, vi->hdr_len);

        /* rq->sg[1] for data packet, from offset */
        offset = sizeof(struct padded_vnet_hdr);
        sg_set_buf(&rq->sg[1], p + offset, PAGE_SIZE - offset);

        /* chain first in list head */
        first->private = (unsigned long)list;
        err = virtqueue_add_inbuf(rq->vq, rq->sg, vi->big_packets_num_skbfrags + 2,
                                  first, gfp);
        if (err < 0)
                give_pages(rq, first);

        return err;
}

static unsigned int get_mergeable_buf_len(struct receive_queue *rq,
                                          struct ewma_pkt_len *avg_pkt_len,
                                          unsigned int room)
{
        struct virtnet_info *vi = rq->vq->vdev->priv;
        const size_t hdr_len = vi->hdr_len;
        unsigned int len;

        if (room)
                return PAGE_SIZE - room;

        len = hdr_len + clamp_t(unsigned int, ewma_pkt_len_read(avg_pkt_len),
                                rq->min_buf_len, PAGE_SIZE - hdr_len);

        return ALIGN(len, L1_CACHE_BYTES);
}

static int add_recvbuf_mergeable(struct virtnet_info *vi,
                                 struct receive_queue *rq, gfp_t gfp)
{
        struct page_frag *alloc_frag = &rq->alloc_frag;
        unsigned int headroom = virtnet_get_headroom(vi);
        unsigned int tailroom = headroom ? sizeof(struct skb_shared_info) : 0;
        unsigned int room = SKB_DATA_ALIGN(headroom + tailroom);
        unsigned int len, hole;
        void *ctx;
        char *buf;
        int err;

        /* Extra tailroom is needed to satisfy XDP's assumption. This
         * means rx frags coalescing won't work, but consider we've
         * disabled GSO for XDP, it won't be a big issue.
         */
        len = get_mergeable_buf_len(rq, &rq->mrg_avg_pkt_len, room);

        buf = virtnet_rq_alloc(rq, len + room, gfp);
        if (unlikely(!buf))
                return -ENOMEM;

        buf += headroom; /* advance address leaving hole at front of pkt */
        hole = alloc_frag->size - alloc_frag->offset;
        if (hole < len + room) {
                /* To avoid internal fragmentation, if there is very likely not
                 * enough space for another buffer, add the remaining space to
                 * the current buffer.
                 * XDP core assumes that frame_size of xdp_buff and the length
                 * of the frag are PAGE_SIZE, so we disable the hole mechanism.
                 */
                if (!headroom)
                        len += hole;
                alloc_frag->offset += hole;
        }

        virtnet_rq_init_one_sg(rq, buf, len);

        ctx = mergeable_len_to_ctx(len + room, headroom);
        err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp);
        if (err < 0) {
                if (rq->do_dma)
                        virtnet_rq_unmap(rq, buf, 0);
                put_page(virt_to_head_page(buf));
        }

        return err;
}

/*
 * Returns false if we couldn't fill entirely (OOM).
 *
 * Normally run in the receive path, but can also be run from ndo_open
 * before we're receiving packets, or from refill_work which is
 * careful to disable receiving (using napi_disable).
 */
static bool try_fill_recv(struct virtnet_info *vi, struct receive_queue *rq,
                          gfp_t gfp)
{
        int err;
        bool oom;

        do {
                if (vi->mergeable_rx_bufs)
                        err = add_recvbuf_mergeable(vi, rq, gfp);
                else if (vi->big_packets)
                        err = add_recvbuf_big(vi, rq, gfp);
                else
                        err = add_recvbuf_small(vi, rq, gfp);

                oom = err == -ENOMEM;
                if (err)
                        break;
        } while (rq->vq->num_free);
        if (virtqueue_kick_prepare(rq->vq) && virtqueue_notify(rq->vq)) {
                unsigned long flags;

                flags = u64_stats_update_begin_irqsave(&rq->stats.syncp);
                rq->stats.kicks++;
                u64_stats_update_end_irqrestore(&rq->stats.syncp, flags);
        }

        return !oom;
}

static void skb_recv_done(struct virtqueue *rvq)
{
        struct virtnet_info *vi = rvq->vdev->priv;
        struct receive_queue *rq = &vi->rq[vq2rxq(rvq)];

        virtqueue_napi_schedule(&rq->napi, rvq);
}

static void virtnet_napi_enable(struct virtqueue *vq, struct napi_struct *napi)
{
        napi_enable(napi);

        /* If all buffers were filled by other side before we napi_enabled, we
         * won't get another interrupt, so process any outstanding packets now.
         * Call local_bh_enable after to trigger softIRQ processing.
         */
        local_bh_disable();
        virtqueue_napi_schedule(napi, vq);
        local_bh_enable();
}

static void virtnet_napi_tx_enable(struct virtnet_info *vi,
                                   struct virtqueue *vq,
                                   struct napi_struct *napi)
{
        if (!napi->weight)
                return;

        /* Tx napi touches cachelines on the cpu handling tx interrupts. Only
         * enable the feature if this is likely affine with the transmit path.
         */
        if (!vi->affinity_hint_set) {
                napi->weight = 0;
                return;
        }

        return virtnet_napi_enable(vq, napi);
}

static void virtnet_napi_tx_disable(struct napi_struct *napi)
{
        if (napi->weight)
                napi_disable(napi);
}

static void refill_work(struct work_struct *work)
{
        struct virtnet_info *vi =
                container_of(work, struct virtnet_info, refill.work);
        bool still_empty;
        int i;

        for (i = 0; i < vi->curr_queue_pairs; i++) {
                struct receive_queue *rq = &vi->rq[i];

                napi_disable(&rq->napi);
                still_empty = !try_fill_recv(vi, rq, GFP_KERNEL);
                virtnet_napi_enable(rq->vq, &rq->napi);

                /* In theory, this can happen: if we don't get any buffers in
                 * we will *never* try to fill again.
                 */
                if (still_empty)
                        schedule_delayed_work(&vi->refill, HZ/2);
        }
}

static int virtnet_receive(struct receive_queue *rq, int budget,
                           unsigned int *xdp_xmit)
{
        struct virtnet_info *vi = rq->vq->vdev->priv;
        struct virtnet_rq_stats stats = {};
        unsigned int len;
        void *buf;
        int i;

        if (!vi->big_packets || vi->mergeable_rx_bufs) {
                void *ctx;

                while (stats.packets < budget &&
                       (buf = virtnet_rq_get_buf(rq, &len, &ctx))) {
                        receive_buf(vi, rq, buf, len, ctx, xdp_xmit, &stats);
                        stats.packets++;
                }
        } else {
                while (stats.packets < budget &&
                       (buf = virtnet_rq_get_buf(rq, &len, NULL)) != NULL) {
                        receive_buf(vi, rq, buf, len, NULL, xdp_xmit, &stats);
                        stats.packets++;
                }
        }

        if (rq->vq->num_free > min((unsigned int)budget, virtqueue_get_vring_size(rq->vq)) / 2) {
                if (!try_fill_recv(vi, rq, GFP_ATOMIC)) {
                        spin_lock(&vi->refill_lock);
                        if (vi->refill_enabled)
                                schedule_delayed_work(&vi->refill, 0);
                        spin_unlock(&vi->refill_lock);
                }
        }

        u64_stats_update_begin(&rq->stats.syncp);
        for (i = 0; i < VIRTNET_RQ_STATS_LEN; i++) {
                size_t offset = virtnet_rq_stats_desc[i].offset;
                u64 *item;

                item = (u64 *)((u8 *)&rq->stats + offset);
                *item += *(u64 *)((u8 *)&stats + offset);
        }
        u64_stats_update_end(&rq->stats.syncp);

        return stats.packets;
}

static void virtnet_poll_cleantx(struct receive_queue *rq)
{
        struct virtnet_info *vi = rq->vq->vdev->priv;
        unsigned int index = vq2rxq(rq->vq);
        struct send_queue *sq = &vi->sq[index];
        struct netdev_queue *txq = netdev_get_tx_queue(vi->dev, index);

        if (!sq->napi.weight || is_xdp_raw_buffer_queue(vi, index))
                return;

        if (__netif_tx_trylock(txq)) {
                if (sq->reset) {
                        __netif_tx_unlock(txq);
                        return;
                }

                do {
                        virtqueue_disable_cb(sq->vq);
                        free_old_xmit_skbs(sq, true);
                } while (unlikely(!virtqueue_enable_cb_delayed(sq->vq)));

                if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS)
                        netif_tx_wake_queue(txq);

                __netif_tx_unlock(txq);
        }
}

static int virtnet_poll(struct napi_struct *napi, int budget)
{
        struct receive_queue *rq =
                container_of(napi, struct receive_queue, napi);
        struct virtnet_info *vi = rq->vq->vdev->priv;
        struct send_queue *sq;
        unsigned int received;
        unsigned int xdp_xmit = 0;

        virtnet_poll_cleantx(rq);

        received = virtnet_receive(rq, budget, &xdp_xmit);

        if (xdp_xmit & VIRTIO_XDP_REDIR)
                xdp_do_flush();

        /* Out of packets? */
        if (received < budget)
                virtqueue_napi_complete(napi, rq->vq, received);

        if (xdp_xmit & VIRTIO_XDP_TX) {
                sq = virtnet_xdp_get_sq(vi);
                if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) {
                        u64_stats_update_begin(&sq->stats.syncp);
                        sq->stats.kicks++;
                        u64_stats_update_end(&sq->stats.syncp);
                }
                virtnet_xdp_put_sq(vi, sq);
        }

        return received;
}

static void virtnet_disable_queue_pair(struct virtnet_info *vi, int qp_index)
{
        virtnet_napi_tx_disable(&vi->sq[qp_index].napi);
        napi_disable(&vi->rq[qp_index].napi);
        xdp_rxq_info_unreg(&vi->rq[qp_index].xdp_rxq);
}

static int virtnet_enable_queue_pair(struct virtnet_info *vi, int qp_index)
{
        struct net_device *dev = vi->dev;
        int err;

        err = xdp_rxq_info_reg(&vi->rq[qp_index].xdp_rxq, dev, qp_index,
                               vi->rq[qp_index].napi.napi_id);
        if (err < 0)
                return err;

        err = xdp_rxq_info_reg_mem_model(&vi->rq[qp_index].xdp_rxq,
                                         MEM_TYPE_PAGE_SHARED, NULL);
        if (err < 0)
                goto err_xdp_reg_mem_model;

        virtnet_napi_enable(vi->rq[qp_index].vq, &vi->rq[qp_index].napi);
        virtnet_napi_tx_enable(vi, vi->sq[qp_index].vq, &vi->sq[qp_index].napi);

        return 0;

err_xdp_reg_mem_model:
        xdp_rxq_info_unreg(&vi->rq[qp_index].xdp_rxq);
        return err;
}

static int virtnet_open(struct net_device *dev)
{
        struct virtnet_info *vi = netdev_priv(dev);
        int i, err;

        enable_delayed_refill(vi);

        for (i = 0; i < vi->max_queue_pairs; i++) {
                if (i < vi->curr_queue_pairs)
                        /* Make sure we have some buffers: if oom use wq. */
                        if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL))
                                schedule_delayed_work(&vi->refill, 0);

                err = virtnet_enable_queue_pair(vi, i);
                if (err < 0)
                        goto err_enable_qp;
        }

        return 0;

err_enable_qp:
        disable_delayed_refill(vi);
        cancel_delayed_work_sync(&vi->refill);

        for (i--; i >= 0; i--)
                virtnet_disable_queue_pair(vi, i);
        return err;
}

static int virtnet_poll_tx(struct napi_struct *napi, int budget)
{
        struct send_queue *sq = container_of(napi, struct send_queue, napi);
        struct virtnet_info *vi = sq->vq->vdev->priv;
        unsigned int index = vq2txq(sq->vq);
        struct netdev_queue *txq;
        int opaque;
        bool done;

        if (unlikely(is_xdp_raw_buffer_queue(vi, index))) {
                /* We don't need to enable cb for XDP */
                napi_complete_done(napi, 0);
                return 0;
        }

        txq = netdev_get_tx_queue(vi->dev, index);
        __netif_tx_lock(txq, raw_smp_processor_id());
        virtqueue_disable_cb(sq->vq);
        free_old_xmit_skbs(sq, true);

        if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS)
                netif_tx_wake_queue(txq);

        opaque = virtqueue_enable_cb_prepare(sq->vq);

        done = napi_complete_done(napi, 0);

        if (!done)
                virtqueue_disable_cb(sq->vq);

        __netif_tx_unlock(txq);

        if (done) {
                if (unlikely(virtqueue_poll(sq->vq, opaque))) {
                        if (napi_schedule_prep(napi)) {
                                __netif_tx_lock(txq, raw_smp_processor_id());
                                virtqueue_disable_cb(sq->vq);
                                __netif_tx_unlock(txq);
                                __napi_schedule(napi);
                        }
                }
        }

        return 0;
}

static int xmit_skb(struct send_queue *sq, struct sk_buff *skb)
{
        struct virtio_net_hdr_mrg_rxbuf *hdr;
        const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;
        struct virtnet_info *vi = sq->vq->vdev->priv;
        int num_sg;
        unsigned hdr_len = vi->hdr_len;
        bool can_push;

        pr_debug("%s: xmit %p %pM\n", vi->dev->name, skb, dest);

        can_push = vi->any_header_sg &&
                !((unsigned long)skb->data & (__alignof__(*hdr) - 1)) &&
                !skb_header_cloned(skb) && skb_headroom(skb) >= hdr_len;
        /* Even if we can, don't push here yet as this would skew
         * csum_start offset below. */
        if (can_push)
                hdr = (struct virtio_net_hdr_mrg_rxbuf *)(skb->data - hdr_len);
        else
                hdr = &skb_vnet_common_hdr(skb)->mrg_hdr;

        if (virtio_net_hdr_from_skb(skb, &hdr->hdr,
                                    virtio_is_little_endian(vi->vdev), false,
                                    0))
                return -EPROTO;

        if (vi->mergeable_rx_bufs)
                hdr->num_buffers = 0;

        sg_init_table(sq->sg, skb_shinfo(skb)->nr_frags + (can_push ? 1 : 2));
        if (can_push) {
                __skb_push(skb, hdr_len);
                num_sg = skb_to_sgvec(skb, sq->sg, 0, skb->len);
                if (unlikely(num_sg < 0))
                        return num_sg;
                /* Pull header back to avoid skew in tx bytes calculations. */
                __skb_pull(skb, hdr_len);
        } else {
                sg_set_buf(sq->sg, hdr, hdr_len);
                num_sg = skb_to_sgvec(skb, sq->sg + 1, 0, skb->len);
                if (unlikely(num_sg < 0))
                        return num_sg;
                num_sg++;
        }
        return virtqueue_add_outbuf(sq->vq, sq->sg, num_sg, skb, GFP_ATOMIC);
}

static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct virtnet_info *vi = netdev_priv(dev);
        int qnum = skb_get_queue_mapping(skb);
        struct send_queue *sq = &vi->sq[qnum];
        int err;
        struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum);
        bool kick = !netdev_xmit_more();
        bool use_napi = sq->napi.weight;

        /* Free up any pending old buffers before queueing new ones. */
        do {
                if (use_napi)
                        virtqueue_disable_cb(sq->vq);

                free_old_xmit_skbs(sq, false);

        } while (use_napi && kick &&
               unlikely(!virtqueue_enable_cb_delayed(sq->vq)));

        /* timestamp packet in software */
        skb_tx_timestamp(skb);

        /* Try to transmit */
        err = xmit_skb(sq, skb);

        /* This should not happen! */
        if (unlikely(err)) {
                dev->stats.tx_fifo_errors++;
                if (net_ratelimit())
                        dev_warn(&dev->dev,
                                 "Unexpected TXQ (%d) queue failure: %d\n",
                                 qnum, err);
                dev->stats.tx_dropped++;
                dev_kfree_skb_any(skb);
                return NETDEV_TX_OK;
        }

        /* Don't wait up for transmitted skbs to be freed. */
        if (!use_napi) {
                skb_orphan(skb);
                nf_reset_ct(skb);
        }

        check_sq_full_and_disable(vi, dev, sq);

        if (kick || netif_xmit_stopped(txq)) {
                if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) {
                        u64_stats_update_begin(&sq->stats.syncp);
                        sq->stats.kicks++;
                        u64_stats_update_end(&sq->stats.syncp);
                }
        }

        return NETDEV_TX_OK;
}

static int virtnet_rx_resize(struct virtnet_info *vi,
                             struct receive_queue *rq, u32 ring_num)
{
        bool running = netif_running(vi->dev);
        int err, qindex;

        qindex = rq - vi->rq;

        if (running)
                napi_disable(&rq->napi);

        err = virtqueue_resize(rq->vq, ring_num, virtnet_rq_free_unused_buf);
        if (err)
                netdev_err(vi->dev, "resize rx fail: rx queue index: %d err: %d\n", qindex, err);

        if (!try_fill_recv(vi, rq, GFP_KERNEL))
                schedule_delayed_work(&vi->refill, 0);

        if (running)
                virtnet_napi_enable(rq->vq, &rq->napi);
        return err;
}

static int virtnet_tx_resize(struct virtnet_info *vi,
                             struct send_queue *sq, u32 ring_num)
{
        bool running = netif_running(vi->dev);
        struct netdev_queue *txq;
        int err, qindex;

        qindex = sq - vi->sq;

        if (running)
                virtnet_napi_tx_disable(&sq->napi);

        txq = netdev_get_tx_queue(vi->dev, qindex);

        /* 1. wait all ximt complete
         * 2. fix the race of netif_stop_subqueue() vs netif_start_subqueue()
         */
        __netif_tx_lock_bh(txq);

        /* Prevent rx poll from accessing sq. */
        sq->reset = true;

        /* Prevent the upper layer from trying to send packets. */
        netif_stop_subqueue(vi->dev, qindex);

        __netif_tx_unlock_bh(txq);

        err = virtqueue_resize(sq->vq, ring_num, virtnet_sq_free_unused_buf);
        if (err)
                netdev_err(vi->dev, "resize tx fail: tx queue index: %d err: %d\n", qindex, err);

        __netif_tx_lock_bh(txq);
        sq->reset = false;
        netif_tx_wake_queue(txq);
        __netif_tx_unlock_bh(txq);

        if (running)
                virtnet_napi_tx_enable(vi, sq->vq, &sq->napi);
        return err;
}

/*
 * Send command via the control virtqueue and check status.  Commands
 * supported by the hypervisor, as indicated by feature bits, should
 * never fail unless improperly formatted.
 */
static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
                                 struct scatterlist *out)
{
        struct scatterlist *sgs[4], hdr, stat;
        unsigned out_num = 0, tmp;
        int ret;

        /* Caller should know better */
        BUG_ON(!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ));

        vi->ctrl->status = ~0;
        vi->ctrl->hdr.class = class;
        vi->ctrl->hdr.cmd = cmd;
        /* Add header */
        sg_init_one(&hdr, &vi->ctrl->hdr, sizeof(vi->ctrl->hdr));
        sgs[out_num++] = &hdr;

        if (out)
                sgs[out_num++] = out;

        /* Add return status. */
        sg_init_one(&stat, &vi->ctrl->status, sizeof(vi->ctrl->status));
        sgs[out_num] = &stat;

        BUG_ON(out_num + 1 > ARRAY_SIZE(sgs));
        ret = virtqueue_add_sgs(vi->cvq, sgs, out_num, 1, vi, GFP_ATOMIC);
        if (ret < 0) {
                dev_warn(&vi->vdev->dev,
                         "Failed to add sgs for command vq: %d\n.", ret);
                return false;
        }

        if (unlikely(!virtqueue_kick(vi->cvq)))
                return vi->ctrl->status == VIRTIO_NET_OK;

        /* Spin for a response, the kick causes an ioport write, trapping
         * into the hypervisor, so the request should be handled immediately.
         */
        while (!virtqueue_get_buf(vi->cvq, &tmp) &&
               !virtqueue_is_broken(vi->cvq))
                cpu_relax();

        return vi->ctrl->status == VIRTIO_NET_OK;
}

static int virtnet_set_mac_address(struct net_device *dev, void *p)
{
        struct virtnet_info *vi = netdev_priv(dev);
        struct virtio_device *vdev = vi->vdev;
        int ret;
        struct sockaddr *addr;
        struct scatterlist sg;

        if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STANDBY))
                return -EOPNOTSUPP;

        addr = kmemdup(p, sizeof(*addr), GFP_KERNEL);
        if (!addr)
                return -ENOMEM;

        ret = eth_prepare_mac_addr_change(dev, addr);
        if (ret)
                goto out;

        if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR)) {
                sg_init_one(&sg, addr->sa_data, dev->addr_len);
                if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
                                          VIRTIO_NET_CTRL_MAC_ADDR_SET, &sg)) {
                        dev_warn(&vdev->dev,
                                 "Failed to set mac address by vq command.\n");
                        ret = -EINVAL;
                        goto out;
                }
        } else if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC) &&
                   !virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) {
                unsigned int i;

                /* Naturally, this has an atomicity problem. */
                for (i = 0; i < dev->addr_len; i++)
                        virtio_cwrite8(vdev,
                                       offsetof(struct virtio_net_config, mac) +
                                       i, addr->sa_data[i]);
        }

        eth_commit_mac_addr_change(dev, p);
        ret = 0;

out:
        kfree(addr);
        return ret;
}

static void virtnet_stats(struct net_device *dev,
                          struct rtnl_link_stats64 *tot)
{
        struct virtnet_info *vi = netdev_priv(dev);
        unsigned int start;
        int i;

        for (i = 0; i < vi->max_queue_pairs; i++) {
                u64 tpackets, tbytes, terrors, rpackets, rbytes, rdrops;
                struct receive_queue *rq = &vi->rq[i];
                struct send_queue *sq = &vi->sq[i];

                do {
                        start = u64_stats_fetch_begin(&sq->stats.syncp);
                        tpackets = sq->stats.packets;
                        tbytes   = sq->stats.bytes;
                        terrors  = sq->stats.tx_timeouts;
                } while (u64_stats_fetch_retry(&sq->stats.syncp, start));

                do {
                        start = u64_stats_fetch_begin(&rq->stats.syncp);
                        rpackets = rq->stats.packets;
                        rbytes   = rq->stats.bytes;
                        rdrops   = rq->stats.drops;
                } while (u64_stats_fetch_retry(&rq->stats.syncp, start));

                tot->rx_packets += rpackets;
                tot->tx_packets += tpackets;
                tot->rx_bytes   += rbytes;
                tot->tx_bytes   += tbytes;
                tot->rx_dropped += rdrops;
                tot->tx_errors  += terrors;
        }

        tot->tx_dropped = dev->stats.tx_dropped;
        tot->tx_fifo_errors = dev->stats.tx_fifo_errors;
        tot->rx_length_errors = dev->stats.rx_length_errors;
        tot->rx_frame_errors = dev->stats.rx_frame_errors;
}

static void virtnet_ack_link_announce(struct virtnet_info *vi)
{
        rtnl_lock();
        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_ANNOUNCE,
                                  VIRTIO_NET_CTRL_ANNOUNCE_ACK, NULL))
                dev_warn(&vi->dev->dev, "Failed to ack link announce.\n");
        rtnl_unlock();
}

static int _virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs)
{
        struct scatterlist sg;
        struct net_device *dev = vi->dev;

        if (!vi->has_cvq || !virtio_has_feature(vi->vdev, VIRTIO_NET_F_MQ))
                return 0;

        vi->ctrl->mq.virtqueue_pairs = cpu_to_virtio16(vi->vdev, queue_pairs);
        sg_init_one(&sg, &vi->ctrl->mq, sizeof(vi->ctrl->mq));

        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MQ,
                                  VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET, &sg)) {
                dev_warn(&dev->dev, "Fail to set num of queue pairs to %d\n",
                         queue_pairs);
                return -EINVAL;
        } else {
                vi->curr_queue_pairs = queue_pairs;
                /* virtnet_open() will refill when device is going to up. */
                if (dev->flags & IFF_UP)
                        schedule_delayed_work(&vi->refill, 0);
        }

        return 0;
}

static int virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs)
{
        int err;

        rtnl_lock();
        err = _virtnet_set_queues(vi, queue_pairs);
        rtnl_unlock();
        return err;
}

static int virtnet_close(struct net_device *dev)
{
        struct virtnet_info *vi = netdev_priv(dev);
        int i;

        /* Make sure NAPI doesn't schedule refill work */
        disable_delayed_refill(vi);
        /* Make sure refill_work doesn't re-enable napi! */
        cancel_delayed_work_sync(&vi->refill);

        for (i = 0; i < vi->max_queue_pairs; i++)
                virtnet_disable_queue_pair(vi, i);

        return 0;
}

static void virtnet_set_rx_mode(struct net_device *dev)
{
        struct virtnet_info *vi = netdev_priv(dev);
        struct scatterlist sg[2];
        struct virtio_net_ctrl_mac *mac_data;
        struct netdev_hw_addr *ha;
        int uc_count;
        int mc_count;
        void *buf;
        int i;

        /* We can't dynamically set ndo_set_rx_mode, so return gracefully */
        if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_RX))
                return;

        vi->ctrl->promisc = ((dev->flags & IFF_PROMISC) != 0);
        vi->ctrl->allmulti = ((dev->flags & IFF_ALLMULTI) != 0);

        sg_init_one(sg, &vi->ctrl->promisc, sizeof(vi->ctrl->promisc));

        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_RX,
                                  VIRTIO_NET_CTRL_RX_PROMISC, sg))
                dev_warn(&dev->dev, "Failed to %sable promisc mode.\n",
                         vi->ctrl->promisc ? "en" : "dis");

        sg_init_one(sg, &vi->ctrl->allmulti, sizeof(vi->ctrl->allmulti));

        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_RX,
                                  VIRTIO_NET_CTRL_RX_ALLMULTI, sg))
                dev_warn(&dev->dev, "Failed to %sable allmulti mode.\n",
                         vi->ctrl->allmulti ? "en" : "dis");

        uc_count = netdev_uc_count(dev);
        mc_count = netdev_mc_count(dev);
        /* MAC filter - use one buffer for both lists */
        buf = kzalloc(((uc_count + mc_count) * ETH_ALEN) +
                      (2 * sizeof(mac_data->entries)), GFP_ATOMIC);
        mac_data = buf;
        if (!buf)
                return;

        sg_init_table(sg, 2);

        /* Store the unicast list and count in the front of the buffer */
        mac_data->entries = cpu_to_virtio32(vi->vdev, uc_count);
        i = 0;
        netdev_for_each_uc_addr(ha, dev)
                memcpy(&mac_data->macs[i++][0], ha->addr, ETH_ALEN);

        sg_set_buf(&sg[0], mac_data,
                   sizeof(mac_data->entries) + (uc_count * ETH_ALEN));

        /* multicast list and count fill the end */
        mac_data = (void *)&mac_data->macs[uc_count][0];

        mac_data->entries = cpu_to_virtio32(vi->vdev, mc_count);
        i = 0;
        netdev_for_each_mc_addr(ha, dev)
                memcpy(&mac_data->macs[i++][0], ha->addr, ETH_ALEN);

        sg_set_buf(&sg[1], mac_data,
                   sizeof(mac_data->entries) + (mc_count * ETH_ALEN));

        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
                                  VIRTIO_NET_CTRL_MAC_TABLE_SET, sg))
                dev_warn(&dev->dev, "Failed to set MAC filter table.\n");

        kfree(buf);
}

static int virtnet_vlan_rx_add_vid(struct net_device *dev,
                                   __be16 proto, u16 vid)
{
        struct virtnet_info *vi = netdev_priv(dev);
        struct scatterlist sg;

        vi->ctrl->vid = cpu_to_virtio16(vi->vdev, vid);
        sg_init_one(&sg, &vi->ctrl->vid, sizeof(vi->ctrl->vid));

        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_VLAN,
                                  VIRTIO_NET_CTRL_VLAN_ADD, &sg))
                dev_warn(&dev->dev, "Failed to add VLAN ID %d.\n", vid);
        return 0;
}

static int virtnet_vlan_rx_kill_vid(struct net_device *dev,
                                    __be16 proto, u16 vid)
{
        struct virtnet_info *vi = netdev_priv(dev);
        struct scatterlist sg;

        vi->ctrl->vid = cpu_to_virtio16(vi->vdev, vid);
        sg_init_one(&sg, &vi->ctrl->vid, sizeof(vi->ctrl->vid));

        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_VLAN,
                                  VIRTIO_NET_CTRL_VLAN_DEL, &sg))
                dev_warn(&dev->dev, "Failed to kill VLAN ID %d.\n", vid);
        return 0;
}

static void virtnet_clean_affinity(struct virtnet_info *vi)
{
        int i;

        if (vi->affinity_hint_set) {
                for (i = 0; i < vi->max_queue_pairs; i++) {
                        virtqueue_set_affinity(vi->rq[i].vq, NULL);
                        virtqueue_set_affinity(vi->sq[i].vq, NULL);
                }

                vi->affinity_hint_set = false;
        }
}

static void virtnet_set_affinity(struct virtnet_info *vi)
{
        cpumask_var_t mask;
        int stragglers;
        int group_size;
        int i, j, cpu;
        int num_cpu;
        int stride;

        if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {
                virtnet_clean_affinity(vi);
                return;
        }

        num_cpu = num_online_cpus();
        stride = max_t(int, num_cpu / vi->curr_queue_pairs, 1);
        stragglers = num_cpu >= vi->curr_queue_pairs ?
                        num_cpu % vi->curr_queue_pairs :
                        0;
        cpu = cpumask_first(cpu_online_mask);

        for (i = 0; i < vi->curr_queue_pairs; i++) {
                group_size = stride + (i < stragglers ? 1 : 0);

                for (j = 0; j < group_size; j++) {
                        cpumask_set_cpu(cpu, mask);
                        cpu = cpumask_next_wrap(cpu, cpu_online_mask,
                                                nr_cpu_ids, false);
                }
                virtqueue_set_affinity(vi->rq[i].vq, mask);
                virtqueue_set_affinity(vi->sq[i].vq, mask);
                __netif_set_xps_queue(vi->dev, cpumask_bits(mask), i, XPS_CPUS);
                cpumask_clear(mask);
        }

        vi->affinity_hint_set = true;
        free_cpumask_var(mask);
}

static int virtnet_cpu_online(unsigned int cpu, struct hlist_node *node)
{
        struct virtnet_info *vi = hlist_entry_safe(node, struct virtnet_info,
                                                   node);
        virtnet_set_affinity(vi);
        return 0;
}

static int virtnet_cpu_dead(unsigned int cpu, struct hlist_node *node)
{
        struct virtnet_info *vi = hlist_entry_safe(node, struct virtnet_info,
                                                   node_dead);
        virtnet_set_affinity(vi);
        return 0;
}

static int virtnet_cpu_down_prep(unsigned int cpu, struct hlist_node *node)
{
        struct virtnet_info *vi = hlist_entry_safe(node, struct virtnet_info,
                                                   node);

        virtnet_clean_affinity(vi);
        return 0;
}

static enum cpuhp_state virtionet_online;

static int virtnet_cpu_notif_add(struct virtnet_info *vi)
{
        int ret;

        ret = cpuhp_state_add_instance_nocalls(virtionet_online, &vi->node);
        if (ret)
                return ret;
        ret = cpuhp_state_add_instance_nocalls(CPUHP_VIRT_NET_DEAD,
                                               &vi->node_dead);
        if (!ret)
                return ret;
        cpuhp_state_remove_instance_nocalls(virtionet_online, &vi->node);
        return ret;
}

static void virtnet_cpu_notif_remove(struct virtnet_info *vi)
{
        cpuhp_state_remove_instance_nocalls(virtionet_online, &vi->node);
        cpuhp_state_remove_instance_nocalls(CPUHP_VIRT_NET_DEAD,
                                            &vi->node_dead);
}

static void virtnet_get_ringparam(struct net_device *dev,
                                  struct ethtool_ringparam *ring,
                                  struct kernel_ethtool_ringparam *kernel_ring,
                                  struct netlink_ext_ack *extack)
{
        struct virtnet_info *vi = netdev_priv(dev);

        ring->rx_max_pending = vi->rq[0].vq->num_max;
        ring->tx_max_pending = vi->sq[0].vq->num_max;
        ring->rx_pending = virtqueue_get_vring_size(vi->rq[0].vq);
        ring->tx_pending = virtqueue_get_vring_size(vi->sq[0].vq);
}

static int virtnet_set_ringparam(struct net_device *dev,
                                 struct ethtool_ringparam *ring,
                                 struct kernel_ethtool_ringparam *kernel_ring,
                                 struct netlink_ext_ack *extack)
{
        struct virtnet_info *vi = netdev_priv(dev);
        u32 rx_pending, tx_pending;
        struct receive_queue *rq;
        struct send_queue *sq;
        int i, err;

        if (ring->rx_mini_pending || ring->rx_jumbo_pending)
                return -EINVAL;

        rx_pending = virtqueue_get_vring_size(vi->rq[0].vq);
        tx_pending = virtqueue_get_vring_size(vi->sq[0].vq);

        if (ring->rx_pending == rx_pending &&
            ring->tx_pending == tx_pending)
                return 0;

        if (ring->rx_pending > vi->rq[0].vq->num_max)
                return -EINVAL;

        if (ring->tx_pending > vi->sq[0].vq->num_max)
                return -EINVAL;

        for (i = 0; i < vi->max_queue_pairs; i++) {
                rq = vi->rq + i;
                sq = vi->sq + i;

                if (ring->tx_pending != tx_pending) {
                        err = virtnet_tx_resize(vi, sq, ring->tx_pending);
                        if (err)
                                return err;
                }

                if (ring->rx_pending != rx_pending) {
                        err = virtnet_rx_resize(vi, rq, ring->rx_pending);
                        if (err)
                                return err;
                }
        }

        return 0;
}

static bool virtnet_commit_rss_command(struct virtnet_info *vi)
{
        struct net_device *dev = vi->dev;
        struct scatterlist sgs[4];
        unsigned int sg_buf_size;

        /* prepare sgs */
        sg_init_table(sgs, 4);

        sg_buf_size = offsetof(struct virtio_net_ctrl_rss, indirection_table);
        sg_set_buf(&sgs[0], &vi->ctrl->rss, sg_buf_size);

        sg_buf_size = sizeof(uint16_t) * (vi->ctrl->rss.indirection_table_mask + 1);
        sg_set_buf(&sgs[1], vi->ctrl->rss.indirection_table, sg_buf_size);

        sg_buf_size = offsetof(struct virtio_net_ctrl_rss, key)
                        - offsetof(struct virtio_net_ctrl_rss, max_tx_vq);
        sg_set_buf(&sgs[2], &vi->ctrl->rss.max_tx_vq, sg_buf_size);

        sg_buf_size = vi->rss_key_size;
        sg_set_buf(&sgs[3], vi->ctrl->rss.key, sg_buf_size);

        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MQ,
                                  vi->has_rss ? VIRTIO_NET_CTRL_MQ_RSS_CONFIG
                                  : VIRTIO_NET_CTRL_MQ_HASH_CONFIG, sgs)) {
                dev_warn(&dev->dev, "VIRTIONET issue with committing RSS sgs\n");
                return false;
        }
        return true;
}

static void virtnet_init_default_rss(struct virtnet_info *vi)
{
        u32 indir_val = 0;
        int i = 0;

        vi->ctrl->rss.hash_types = vi->rss_hash_types_supported;
        vi->rss_hash_types_saved = vi->rss_hash_types_supported;
        vi->ctrl->rss.indirection_table_mask = vi->rss_indir_table_size
                                                ? vi->rss_indir_table_size - 1 : 0;
        vi->ctrl->rss.unclassified_queue = 0;

        for (; i < vi->rss_indir_table_size; ++i) {
                indir_val = ethtool_rxfh_indir_default(i, vi->curr_queue_pairs);
                vi->ctrl->rss.indirection_table[i] = indir_val;
        }

        vi->ctrl->rss.max_tx_vq = vi->has_rss ? vi->curr_queue_pairs : 0;
        vi->ctrl->rss.hash_key_length = vi->rss_key_size;

        netdev_rss_key_fill(vi->ctrl->rss.key, vi->rss_key_size);
}

static void virtnet_get_hashflow(const struct virtnet_info *vi, struct ethtool_rxnfc *info)
{
        info->data = 0;
        switch (info->flow_type) {
        case TCP_V4_FLOW:
                if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_TCPv4) {
                        info->data = RXH_IP_SRC | RXH_IP_DST |
                                                 RXH_L4_B_0_1 | RXH_L4_B_2_3;
                } else if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv4) {
                        info->data = RXH_IP_SRC | RXH_IP_DST;
                }
                break;
        case TCP_V6_FLOW:
                if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_TCPv6) {
                        info->data = RXH_IP_SRC | RXH_IP_DST |
                                                 RXH_L4_B_0_1 | RXH_L4_B_2_3;
                } else if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv6) {
                        info->data = RXH_IP_SRC | RXH_IP_DST;
                }
                break;
        case UDP_V4_FLOW:
                if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_UDPv4) {
                        info->data = RXH_IP_SRC | RXH_IP_DST |
                                                 RXH_L4_B_0_1 | RXH_L4_B_2_3;
                } else if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv4) {
                        info->data = RXH_IP_SRC | RXH_IP_DST;
                }
                break;
        case UDP_V6_FLOW:
                if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_UDPv6) {
                        info->data = RXH_IP_SRC | RXH_IP_DST |
                                                 RXH_L4_B_0_1 | RXH_L4_B_2_3;
                } else if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv6) {
                        info->data = RXH_IP_SRC | RXH_IP_DST;
                }
                break;
        case IPV4_FLOW:
                if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv4)
                        info->data = RXH_IP_SRC | RXH_IP_DST;

                break;
        case IPV6_FLOW:
                if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv6)
                        info->data = RXH_IP_SRC | RXH_IP_DST;

                break;
        default:
                info->data = 0;
                break;
        }
}

static bool virtnet_set_hashflow(struct virtnet_info *vi, struct ethtool_rxnfc *info)
{
        u32 new_hashtypes = vi->rss_hash_types_saved;
        bool is_disable = info->data & RXH_DISCARD;
        bool is_l4 = info->data == (RXH_IP_SRC | RXH_IP_DST | RXH_L4_B_0_1 | RXH_L4_B_2_3);

        /* supports only 'sd', 'sdfn' and 'r' */
        if (!((info->data == (RXH_IP_SRC | RXH_IP_DST)) | is_l4 | is_disable))
                return false;

        switch (info->flow_type) {
        case TCP_V4_FLOW:
                new_hashtypes &= ~(VIRTIO_NET_RSS_HASH_TYPE_IPv4 | VIRTIO_NET_RSS_HASH_TYPE_TCPv4);
                if (!is_disable)
                        new_hashtypes |= VIRTIO_NET_RSS_HASH_TYPE_IPv4
                                | (is_l4 ? VIRTIO_NET_RSS_HASH_TYPE_TCPv4 : 0);
                break;
        case UDP_V4_FLOW:
                new_hashtypes &= ~(VIRTIO_NET_RSS_HASH_TYPE_IPv4 | VIRTIO_NET_RSS_HASH_TYPE_UDPv4);
                if (!is_disable)
                        new_hashtypes |= VIRTIO_NET_RSS_HASH_TYPE_IPv4
                                | (is_l4 ? VIRTIO_NET_RSS_HASH_TYPE_UDPv4 : 0);
                break;
        case IPV4_FLOW:
                new_hashtypes &= ~VIRTIO_NET_RSS_HASH_TYPE_IPv4;
                if (!is_disable)
                        new_hashtypes = VIRTIO_NET_RSS_HASH_TYPE_IPv4;
                break;
        case TCP_V6_FLOW:
                new_hashtypes &= ~(VIRTIO_NET_RSS_HASH_TYPE_IPv6 | VIRTIO_NET_RSS_HASH_TYPE_TCPv6);
                if (!is_disable)
                        new_hashtypes |= VIRTIO_NET_RSS_HASH_TYPE_IPv6
                                | (is_l4 ? VIRTIO_NET_RSS_HASH_TYPE_TCPv6 : 0);
                break;
        case UDP_V6_FLOW:
                new_hashtypes &= ~(VIRTIO_NET_RSS_HASH_TYPE_IPv6 | VIRTIO_NET_RSS_HASH_TYPE_UDPv6);
                if (!is_disable)
                        new_hashtypes |= VIRTIO_NET_RSS_HASH_TYPE_IPv6
                                | (is_l4 ? VIRTIO_NET_RSS_HASH_TYPE_UDPv6 : 0);
                break;
        case IPV6_FLOW:
                new_hashtypes &= ~VIRTIO_NET_RSS_HASH_TYPE_IPv6;
                if (!is_disable)
                        new_hashtypes = VIRTIO_NET_RSS_HASH_TYPE_IPv6;
                break;
        default:
                /* unsupported flow */
                return false;
        }

        /* if unsupported hashtype was set */
        if (new_hashtypes != (new_hashtypes & vi->rss_hash_types_supported))
                return false;

        if (new_hashtypes != vi->rss_hash_types_saved) {
                vi->rss_hash_types_saved = new_hashtypes;
                vi->ctrl->rss.hash_types = vi->rss_hash_types_saved;
                if (vi->dev->features & NETIF_F_RXHASH)
                        return virtnet_commit_rss_command(vi);
        }

        return true;
}

static void virtnet_get_drvinfo(struct net_device *dev,
                                struct ethtool_drvinfo *info)
{
        struct virtnet_info *vi = netdev_priv(dev);
        struct virtio_device *vdev = vi->vdev;

        strscpy(info->driver, KBUILD_MODNAME, sizeof(info->driver));
        strscpy(info->version, VIRTNET_DRIVER_VERSION, sizeof(info->version));
        strscpy(info->bus_info, virtio_bus_name(vdev), sizeof(info->bus_info));

}

/* TODO: Eliminate OOO packets during switching */
static int virtnet_set_channels(struct net_device *dev,
                                struct ethtool_channels *channels)
{
        struct virtnet_info *vi = netdev_priv(dev);
        u16 queue_pairs = channels->combined_count;
        int err;

        /* We don't support separate rx/tx channels.
         * We don't allow setting 'other' channels.
         */
        if (channels->rx_count || channels->tx_count || channels->other_count)
                return -EINVAL;

        if (queue_pairs > vi->max_queue_pairs || queue_pairs == 0)
                return -EINVAL;

        /* For now we don't support modifying channels while XDP is loaded
         * also when XDP is loaded all RX queues have XDP programs so we only
         * need to check a single RX queue.
         */
        if (vi->rq[0].xdp_prog)
                return -EINVAL;

        cpus_read_lock();
        err = _virtnet_set_queues(vi, queue_pairs);
        if (err) {
                cpus_read_unlock();
                goto err;
        }
        virtnet_set_affinity(vi);
        cpus_read_unlock();

        netif_set_real_num_tx_queues(dev, queue_pairs);
        netif_set_real_num_rx_queues(dev, queue_pairs);
 err:
        return err;
}

static void virtnet_get_strings(struct net_device *dev, u32 stringset, u8 *data)
{
        struct virtnet_info *vi = netdev_priv(dev);
        unsigned int i, j;
        u8 *p = data;

        switch (stringset) {
        case ETH_SS_STATS:
                for (i = 0; i < vi->curr_queue_pairs; i++) {
                        for (j = 0; j < VIRTNET_RQ_STATS_LEN; j++)
                                ethtool_sprintf(&p, "rx_queue_%u_%s", i,
                                                virtnet_rq_stats_desc[j].desc);
                }

                for (i = 0; i < vi->curr_queue_pairs; i++) {
                        for (j = 0; j < VIRTNET_SQ_STATS_LEN; j++)
                                ethtool_sprintf(&p, "tx_queue_%u_%s", i,
                                                virtnet_sq_stats_desc[j].desc);
                }
                break;
        }
}

static int virtnet_get_sset_count(struct net_device *dev, int sset)
{
        struct virtnet_info *vi = netdev_priv(dev);

        switch (sset) {
        case ETH_SS_STATS:
                return vi->curr_queue_pairs * (VIRTNET_RQ_STATS_LEN +
                                               VIRTNET_SQ_STATS_LEN);
        default:
                return -EOPNOTSUPP;
        }
}

static void virtnet_get_ethtool_stats(struct net_device *dev,
                                      struct ethtool_stats *stats, u64 *data)
{
        struct virtnet_info *vi = netdev_priv(dev);
        unsigned int idx = 0, start, i, j;
        const u8 *stats_base;
        size_t offset;

        for (i = 0; i < vi->curr_queue_pairs; i++) {
                struct receive_queue *rq = &vi->rq[i];

                stats_base = (u8 *)&rq->stats;
                do {
                        start = u64_stats_fetch_begin(&rq->stats.syncp);
                        for (j = 0; j < VIRTNET_RQ_STATS_LEN; j++) {
                                offset = virtnet_rq_stats_desc[j].offset;
                                data[idx + j] = *(u64 *)(stats_base + offset);
                        }
                } while (u64_stats_fetch_retry(&rq->stats.syncp, start));
                idx += VIRTNET_RQ_STATS_LEN;
        }

        for (i = 0; i < vi->curr_queue_pairs; i++) {
                struct send_queue *sq = &vi->sq[i];

                stats_base = (u8 *)&sq->stats;
                do {
                        start = u64_stats_fetch_begin(&sq->stats.syncp);
                        for (j = 0; j < VIRTNET_SQ_STATS_LEN; j++) {
                                offset = virtnet_sq_stats_desc[j].offset;
                                data[idx + j] = *(u64 *)(stats_base + offset);
                        }
                } while (u64_stats_fetch_retry(&sq->stats.syncp, start));
                idx += VIRTNET_SQ_STATS_LEN;
        }
}

static void virtnet_get_channels(struct net_device *dev,
                                 struct ethtool_channels *channels)
{
        struct virtnet_info *vi = netdev_priv(dev);

        channels->combined_count = vi->curr_queue_pairs;
        channels->max_combined = vi->max_queue_pairs;
        channels->max_other = 0;
        channels->rx_count = 0;
        channels->tx_count = 0;
        channels->other_count = 0;
}

static int virtnet_set_link_ksettings(struct net_device *dev,
                                      const struct ethtool_link_ksettings *cmd)
{
        struct virtnet_info *vi = netdev_priv(dev);

        return ethtool_virtdev_set_link_ksettings(dev, cmd,
                                                  &vi->speed, &vi->duplex);
}

static int virtnet_get_link_ksettings(struct net_device *dev,
                                      struct ethtool_link_ksettings *cmd)
{
        struct virtnet_info *vi = netdev_priv(dev);

        cmd->base.speed = vi->speed;
        cmd->base.duplex = vi->duplex;
        cmd->base.port = PORT_OTHER;

        return 0;
}

static int virtnet_send_notf_coal_cmds(struct virtnet_info *vi,
                                       struct ethtool_coalesce *ec)
{
        struct scatterlist sgs_tx, sgs_rx;

        vi->ctrl->coal_tx.tx_usecs = cpu_to_le32(ec->tx_coalesce_usecs);
        vi->ctrl->coal_tx.tx_max_packets = cpu_to_le32(ec->tx_max_coalesced_frames);
        sg_init_one(&sgs_tx, &vi->ctrl->coal_tx, sizeof(vi->ctrl->coal_tx));

        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
                                  VIRTIO_NET_CTRL_NOTF_COAL_TX_SET,
                                  &sgs_tx))
                return -EINVAL;

        /* Save parameters */
        vi->intr_coal_tx.max_usecs = ec->tx_coalesce_usecs;
        vi->intr_coal_tx.max_packets = ec->tx_max_coalesced_frames;

        vi->ctrl->coal_rx.rx_usecs = cpu_to_le32(ec->rx_coalesce_usecs);
        vi->ctrl->coal_rx.rx_max_packets = cpu_to_le32(ec->rx_max_coalesced_frames);
        sg_init_one(&sgs_rx, &vi->ctrl->coal_rx, sizeof(vi->ctrl->coal_rx));

        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
                                  VIRTIO_NET_CTRL_NOTF_COAL_RX_SET,
                                  &sgs_rx))
                return -EINVAL;

        /* Save parameters */
        vi->intr_coal_rx.max_usecs = ec->rx_coalesce_usecs;
        vi->intr_coal_rx.max_packets = ec->rx_max_coalesced_frames;

        return 0;
}

static int virtnet_send_ctrl_coal_vq_cmd(struct virtnet_info *vi,
                                         u16 vqn, u32 max_usecs, u32 max_packets)
{
        struct scatterlist sgs;

        vi->ctrl->coal_vq.vqn = cpu_to_le16(vqn);
        vi->ctrl->coal_vq.coal.max_usecs = cpu_to_le32(max_usecs);
        vi->ctrl->coal_vq.coal.max_packets = cpu_to_le32(max_packets);
        sg_init_one(&sgs, &vi->ctrl->coal_vq, sizeof(vi->ctrl->coal_vq));

        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
                                  VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET,
                                  &sgs))
                return -EINVAL;

        return 0;
}

static int virtnet_send_notf_coal_vq_cmds(struct virtnet_info *vi,
                                          struct ethtool_coalesce *ec,
                                          u16 queue)
{
        int err;

        if (ec->rx_coalesce_usecs || ec->rx_max_coalesced_frames) {
                err = virtnet_send_ctrl_coal_vq_cmd(vi, rxq2vq(queue),
                                                    ec->rx_coalesce_usecs,
                                                    ec->rx_max_coalesced_frames);
                if (err)
                        return err;
                /* Save parameters */
                vi->rq[queue].intr_coal.max_usecs = ec->rx_coalesce_usecs;
                vi->rq[queue].intr_coal.max_packets = ec->rx_max_coalesced_frames;
        }

        if (ec->tx_coalesce_usecs || ec->tx_max_coalesced_frames) {
                err = virtnet_send_ctrl_coal_vq_cmd(vi, txq2vq(queue),
                                                    ec->tx_coalesce_usecs,
                                                    ec->tx_max_coalesced_frames);
                if (err)
                        return err;
                /* Save parameters */
                vi->sq[queue].intr_coal.max_usecs = ec->tx_coalesce_usecs;
                vi->sq[queue].intr_coal.max_packets = ec->tx_max_coalesced_frames;
        }

        return 0;
}

static int virtnet_coal_params_supported(struct ethtool_coalesce *ec)
{
        /* usecs coalescing is supported only if VIRTIO_NET_F_NOTF_COAL
         * feature is negotiated.
         */
        if (ec->rx_coalesce_usecs || ec->tx_coalesce_usecs)
                return -EOPNOTSUPP;

        if (ec->tx_max_coalesced_frames > 1 ||
            ec->rx_max_coalesced_frames != 1)
                return -EINVAL;

        return 0;
}

static int virtnet_should_update_vq_weight(int dev_flags, int weight,
                                           int vq_weight, bool *should_update)
{
        if (weight ^ vq_weight) {
                if (dev_flags & IFF_UP)
                        return -EBUSY;
                *should_update = true;
        }

        return 0;
}

static int virtnet_set_coalesce(struct net_device *dev,
                                struct ethtool_coalesce *ec,
                                struct kernel_ethtool_coalesce *kernel_coal,
                                struct netlink_ext_ack *extack)
{
        struct virtnet_info *vi = netdev_priv(dev);
        int ret, queue_number, napi_weight;
        bool update_napi = false;

        /* Can't change NAPI weight if the link is up */
        napi_weight = ec->tx_max_coalesced_frames ? NAPI_POLL_WEIGHT : 0;
        for (queue_number = 0; queue_number < vi->max_queue_pairs; queue_number++) {
                ret = virtnet_should_update_vq_weight(dev->flags, napi_weight,
                                                      vi->sq[queue_number].napi.weight,
                                                      &update_napi);
                if (ret)
                        return ret;

                if (update_napi) {
                        /* All queues that belong to [queue_number, vi->max_queue_pairs] will be
                         * updated for the sake of simplicity, which might not be necessary
                         */
                        break;
                }
        }

        if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL))
                ret = virtnet_send_notf_coal_cmds(vi, ec);
        else
                ret = virtnet_coal_params_supported(ec);

        if (ret)
                return ret;

        if (update_napi) {
                for (; queue_number < vi->max_queue_pairs; queue_number++)
                        vi->sq[queue_number].napi.weight = napi_weight;
        }

        return ret;
}

static int virtnet_get_coalesce(struct net_device *dev,
                                struct ethtool_coalesce *ec,
                                struct kernel_ethtool_coalesce *kernel_coal,
                                struct netlink_ext_ack *extack)
{
        struct virtnet_info *vi = netdev_priv(dev);

        if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL)) {
                ec->rx_coalesce_usecs = vi->intr_coal_rx.max_usecs;
                ec->tx_coalesce_usecs = vi->intr_coal_tx.max_usecs;
                ec->tx_max_coalesced_frames = vi->intr_coal_tx.max_packets;
                ec->rx_max_coalesced_frames = vi->intr_coal_rx.max_packets;
        } else {
                ec->rx_max_coalesced_frames = 1;

                if (vi->sq[0].napi.weight)
                        ec->tx_max_coalesced_frames = 1;
        }

        return 0;
}

static int virtnet_set_per_queue_coalesce(struct net_device *dev,
                                          u32 queue,
                                          struct ethtool_coalesce *ec)
{
        struct virtnet_info *vi = netdev_priv(dev);
        int ret, napi_weight;
        bool update_napi = false;

        if (queue >= vi->max_queue_pairs)
                return -EINVAL;

        /* Can't change NAPI weight if the link is up */
        napi_weight = ec->tx_max_coalesced_frames ? NAPI_POLL_WEIGHT : 0;
        ret = virtnet_should_update_vq_weight(dev->flags, napi_weight,
                                              vi->sq[queue].napi.weight,
                                              &update_napi);
        if (ret)
                return ret;

        if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL))
                ret = virtnet_send_notf_coal_vq_cmds(vi, ec, queue);
        else
                ret = virtnet_coal_params_supported(ec);

        if (ret)
                return ret;

        if (update_napi)
                vi->sq[queue].napi.weight = napi_weight;

        return 0;
}

static int virtnet_get_per_queue_coalesce(struct net_device *dev,
                                          u32 queue,
                                          struct ethtool_coalesce *ec)
{
        struct virtnet_info *vi = netdev_priv(dev);

        if (queue >= vi->max_queue_pairs)
                return -EINVAL;

        if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL)) {
                ec->rx_coalesce_usecs = vi->rq[queue].intr_coal.max_usecs;
                ec->tx_coalesce_usecs = vi->sq[queue].intr_coal.max_usecs;
                ec->tx_max_coalesced_frames = vi->sq[queue].intr_coal.max_packets;
                ec->rx_max_coalesced_frames = vi->rq[queue].intr_coal.max_packets;
        } else {
                ec->rx_max_coalesced_frames = 1;

                if (vi->sq[0].napi.weight)
                        ec->tx_max_coalesced_frames = 1;
        }

        return 0;
}

static void virtnet_init_settings(struct net_device *dev)
{
        struct virtnet_info *vi = netdev_priv(dev);

        vi->speed = SPEED_UNKNOWN;
        vi->duplex = DUPLEX_UNKNOWN;
}

static void virtnet_update_settings(struct virtnet_info *vi)
{
        u32 speed;
        u8 duplex;

        if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_SPEED_DUPLEX))
                return;

        virtio_cread_le(vi->vdev, struct virtio_net_config, speed, &speed);

        if (ethtool_validate_speed(speed))
                vi->speed = speed;

        virtio_cread_le(vi->vdev, struct virtio_net_config, duplex, &duplex);

        if (ethtool_validate_duplex(duplex))
                vi->duplex = duplex;
}

static u32 virtnet_get_rxfh_key_size(struct net_device *dev)
{
        return ((struct virtnet_info *)netdev_priv(dev))->rss_key_size;
}

static u32 virtnet_get_rxfh_indir_size(struct net_device *dev)
{
        return ((struct virtnet_info *)netdev_priv(dev))->rss_indir_table_size;
}

static int virtnet_get_rxfh(struct net_device *dev, u32 *indir, u8 *key, u8 *hfunc)
{
        struct virtnet_info *vi = netdev_priv(dev);
        int i;

        if (indir) {
                for (i = 0; i < vi->rss_indir_table_size; ++i)
                        indir[i] = vi->ctrl->rss.indirection_table[i];
        }

        if (key)
                memcpy(key, vi->ctrl->rss.key, vi->rss_key_size);

        if (hfunc)
                *hfunc = ETH_RSS_HASH_TOP;

        return 0;
}

static int virtnet_set_rxfh(struct net_device *dev, const u32 *indir, const u8 *key, const u8 hfunc)
{
        struct virtnet_info *vi = netdev_priv(dev);
        int i;

        if (hfunc != ETH_RSS_HASH_NO_CHANGE && hfunc != ETH_RSS_HASH_TOP)
                return -EOPNOTSUPP;

        if (indir) {
                for (i = 0; i < vi->rss_indir_table_size; ++i)
                        vi->ctrl->rss.indirection_table[i] = indir[i];
        }
        if (key)
                memcpy(vi->ctrl->rss.key, key, vi->rss_key_size);

        virtnet_commit_rss_command(vi);

        return 0;
}

static int virtnet_get_rxnfc(struct net_device *dev, struct ethtool_rxnfc *info, u32 *rule_locs)
{
        struct virtnet_info *vi = netdev_priv(dev);
        int rc = 0;

        switch (info->cmd) {
        case ETHTOOL_GRXRINGS:
                info->data = vi->curr_queue_pairs;
                break;
        case ETHTOOL_GRXFH:
                virtnet_get_hashflow(vi, info);
                break;
        default:
                rc = -EOPNOTSUPP;
        }

        return rc;
}

static int virtnet_set_rxnfc(struct net_device *dev, struct ethtool_rxnfc *info)
{
        struct virtnet_info *vi = netdev_priv(dev);
        int rc = 0;

        switch (info->cmd) {
        case ETHTOOL_SRXFH:
                if (!virtnet_set_hashflow(vi, info))
                        rc = -EINVAL;

                break;
        default:
                rc = -EOPNOTSUPP;
        }

        return rc;
}

static const struct ethtool_ops virtnet_ethtool_ops = {
        .supported_coalesce_params = ETHTOOL_COALESCE_MAX_FRAMES |
                ETHTOOL_COALESCE_USECS,
        .get_drvinfo = virtnet_get_drvinfo,
        .get_link = ethtool_op_get_link,
        .get_ringparam = virtnet_get_ringparam,
        .set_ringparam = virtnet_set_ringparam,
        .get_strings = virtnet_get_strings,
        .get_sset_count = virtnet_get_sset_count,
        .get_ethtool_stats = virtnet_get_ethtool_stats,
        .set_channels = virtnet_set_channels,
        .get_channels = virtnet_get_channels,
        .get_ts_info = ethtool_op_get_ts_info,
        .get_link_ksettings = virtnet_get_link_ksettings,
        .set_link_ksettings = virtnet_set_link_ksettings,
        .set_coalesce = virtnet_set_coalesce,
        .get_coalesce = virtnet_get_coalesce,
        .set_per_queue_coalesce = virtnet_set_per_queue_coalesce,
        .get_per_queue_coalesce = virtnet_get_per_queue_coalesce,
        .get_rxfh_key_size = virtnet_get_rxfh_key_size,
        .get_rxfh_indir_size = virtnet_get_rxfh_indir_size,
        .get_rxfh = virtnet_get_rxfh,
        .set_rxfh = virtnet_set_rxfh,
        .get_rxnfc = virtnet_get_rxnfc,
        .set_rxnfc = virtnet_set_rxnfc,
};

static void virtnet_freeze_down(struct virtio_device *vdev)
{
        struct virtnet_info *vi = vdev->priv;

        /* Make sure no work handler is accessing the device */
        flush_work(&vi->config_work);

        netif_tx_lock_bh(vi->dev);
        netif_device_detach(vi->dev);
        netif_tx_unlock_bh(vi->dev);
        if (netif_running(vi->dev))
                virtnet_close(vi->dev);
}

static int init_vqs(struct virtnet_info *vi);

static int virtnet_restore_up(struct virtio_device *vdev)
{
        struct virtnet_info *vi = vdev->priv;
        int err;

        err = init_vqs(vi);
        if (err)
                return err;

        virtio_device_ready(vdev);

        enable_delayed_refill(vi);

        if (netif_running(vi->dev)) {
                err = virtnet_open(vi->dev);
                if (err)
                        return err;
        }

        netif_tx_lock_bh(vi->dev);
        netif_device_attach(vi->dev);
        netif_tx_unlock_bh(vi->dev);
        return err;
}

static int virtnet_set_guest_offloads(struct virtnet_info *vi, u64 offloads)
{
        struct scatterlist sg;
        vi->ctrl->offloads = cpu_to_virtio64(vi->vdev, offloads);

        sg_init_one(&sg, &vi->ctrl->offloads, sizeof(vi->ctrl->offloads));

        if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_GUEST_OFFLOADS,
                                  VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET, &sg)) {
                dev_warn(&vi->dev->dev, "Fail to set guest offload.\n");
                return -EINVAL;
        }

        return 0;
}

static int virtnet_clear_guest_offloads(struct virtnet_info *vi)
{
        u64 offloads = 0;

        if (!vi->guest_offloads)
                return 0;

        return virtnet_set_guest_offloads(vi, offloads);
}

static int virtnet_restore_guest_offloads(struct virtnet_info *vi)
{
        u64 offloads = vi->guest_offloads;

        if (!vi->guest_offloads)
                return 0;

        return virtnet_set_guest_offloads(vi, offloads);
}

static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog,
                           struct netlink_ext_ack *extack)
{
        unsigned int room = SKB_DATA_ALIGN(VIRTIO_XDP_HEADROOM +
                                           sizeof(struct skb_shared_info));
        unsigned int max_sz = PAGE_SIZE - room - ETH_HLEN;
        struct virtnet_info *vi = netdev_priv(dev);
        struct bpf_prog *old_prog;
        u16 xdp_qp = 0, curr_qp;
        int i, err;

        if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS)
            && (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
                virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6) ||
                virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_ECN) ||
                virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_UFO) ||
                virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_CSUM) ||
                virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_USO4) ||
                virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_USO6))) {
                NL_SET_ERR_MSG_MOD(extack, "Can't set XDP while host is implementing GRO_HW/CSUM, disable GRO_HW/CSUM first");
                return -EOPNOTSUPP;
        }

        if (vi->mergeable_rx_bufs && !vi->any_header_sg) {
                NL_SET_ERR_MSG_MOD(extack, "XDP expects header/data in single page, any_header_sg required");
                return -EINVAL;
        }

        if (prog && !prog->aux->xdp_has_frags && dev->mtu > max_sz) {
                NL_SET_ERR_MSG_MOD(extack, "MTU too large to enable XDP without frags");
                netdev_warn(dev, "single-buffer XDP requires MTU less than %u\n", max_sz);
                return -EINVAL;
        }

        curr_qp = vi->curr_queue_pairs - vi->xdp_queue_pairs;
        if (prog)
                xdp_qp = nr_cpu_ids;

        /* XDP requires extra queues for XDP_TX */
        if (curr_qp + xdp_qp > vi->max_queue_pairs) {
                netdev_warn_once(dev, "XDP request %i queues but max is %i. XDP_TX and XDP_REDIRECT will operate in a slower locked tx mode.\n",
                                 curr_qp + xdp_qp, vi->max_queue_pairs);
                xdp_qp = 0;
        }

        old_prog = rtnl_dereference(vi->rq[0].xdp_prog);
        if (!prog && !old_prog)
                return 0;

        if (prog)
                bpf_prog_add(prog, vi->max_queue_pairs - 1);

        /* Make sure NAPI is not using any XDP TX queues for RX. */
        if (netif_running(dev)) {
                for (i = 0; i < vi->max_queue_pairs; i++) {
                        napi_disable(&vi->rq[i].napi);
                        virtnet_napi_tx_disable(&vi->sq[i].napi);
                }
        }

        if (!prog) {
                for (i = 0; i < vi->max_queue_pairs; i++) {
                        rcu_assign_pointer(vi->rq[i].xdp_prog, prog);
                        if (i == 0)
                                virtnet_restore_guest_offloads(vi);
                }
                synchronize_net();
        }

        err = _virtnet_set_queues(vi, curr_qp + xdp_qp);
        if (err)
                goto err;
        netif_set_real_num_rx_queues(dev, curr_qp + xdp_qp);
        vi->xdp_queue_pairs = xdp_qp;

        if (prog) {
                vi->xdp_enabled = true;
                for (i = 0; i < vi->max_queue_pairs; i++) {
                        rcu_assign_pointer(vi->rq[i].xdp_prog, prog);
                        if (i == 0 && !old_prog)
                                virtnet_clear_guest_offloads(vi);
                }
                if (!old_prog)
                        xdp_features_set_redirect_target(dev, true);
        } else {
                xdp_features_clear_redirect_target(dev);
                vi->xdp_enabled = false;
        }

        for (i = 0; i < vi->max_queue_pairs; i++) {
                if (old_prog)
                        bpf_prog_put(old_prog);
                if (netif_running(dev)) {
                        virtnet_napi_enable(vi->rq[i].vq, &vi->rq[i].napi);
                        virtnet_napi_tx_enable(vi, vi->sq[i].vq,
                                               &vi->sq[i].napi);
                }
        }

        return 0;

err:
        if (!prog) {
                virtnet_clear_guest_offloads(vi);
                for (i = 0; i < vi->max_queue_pairs; i++)
                        rcu_assign_pointer(vi->rq[i].xdp_prog, old_prog);
        }

        if (netif_running(dev)) {
                for (i = 0; i < vi->max_queue_pairs; i++) {
                        virtnet_napi_enable(vi->rq[i].vq, &vi->rq[i].napi);
                        virtnet_napi_tx_enable(vi, vi->sq[i].vq,
                                               &vi->sq[i].napi);
                }
        }
        if (prog)
                bpf_prog_sub(prog, vi->max_queue_pairs - 1);
        return err;
}

static int virtnet_xdp(struct net_device *dev, struct netdev_bpf *xdp)
{
        switch (xdp->command) {
        case XDP_SETUP_PROG:
                return virtnet_xdp_set(dev, xdp->prog, xdp->extack);
        default:
                return -EINVAL;
        }
}

static int virtnet_get_phys_port_name(struct net_device *dev, char *buf,
                                      size_t len)
{
        struct virtnet_info *vi = netdev_priv(dev);
        int ret;

        if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_STANDBY))
                return -EOPNOTSUPP;

        ret = snprintf(buf, len, "sby");
        if (ret >= len)
                return -EOPNOTSUPP;

        return 0;
}

static int virtnet_set_features(struct net_device *dev,
                                netdev_features_t features)
{
        struct virtnet_info *vi = netdev_priv(dev);
        u64 offloads;
        int err;

        if ((dev->features ^ features) & NETIF_F_GRO_HW) {
                if (vi->xdp_enabled)
                        return -EBUSY;

                if (features & NETIF_F_GRO_HW)
                        offloads = vi->guest_offloads_capable;
                else
                        offloads = vi->guest_offloads_capable &
                                   ~GUEST_OFFLOAD_GRO_HW_MASK;

                err = virtnet_set_guest_offloads(vi, offloads);
                if (err)
                        return err;
                vi->guest_offloads = offloads;
        }

        if ((dev->features ^ features) & NETIF_F_RXHASH) {
                if (features & NETIF_F_RXHASH)
                        vi->ctrl->rss.hash_types = vi->rss_hash_types_saved;
                else
                        vi->ctrl->rss.hash_types = VIRTIO_NET_HASH_REPORT_NONE;

                if (!virtnet_commit_rss_command(vi))
                        return -EINVAL;
        }

        return 0;
}

static void virtnet_tx_timeout(struct net_device *dev, unsigned int txqueue)
{
        struct virtnet_info *priv = netdev_priv(dev);
        struct send_queue *sq = &priv->sq[txqueue];
        struct netdev_queue *txq = netdev_get_tx_queue(dev, txqueue);

        u64_stats_update_begin(&sq->stats.syncp);
        sq->stats.tx_timeouts++;
        u64_stats_update_end(&sq->stats.syncp);

        netdev_err(dev, "TX timeout on queue: %u, sq: %s, vq: 0x%x, name: %s, %u usecs ago\n",
                   txqueue, sq->name, sq->vq->index, sq->vq->name,
                   jiffies_to_usecs(jiffies - READ_ONCE(txq->trans_start)));
}

static const struct net_device_ops virtnet_netdev = {
        .ndo_open            = virtnet_open,
        .ndo_stop            = virtnet_close,
        .ndo_start_xmit      = start_xmit,
        .ndo_validate_addr   = eth_validate_addr,
        .ndo_set_mac_address = virtnet_set_mac_address,
        .ndo_set_rx_mode     = virtnet_set_rx_mode,
        .ndo_get_stats64     = virtnet_stats,
        .ndo_vlan_rx_add_vid = virtnet_vlan_rx_add_vid,
        .ndo_vlan_rx_kill_vid = virtnet_vlan_rx_kill_vid,
        .ndo_bpf                = virtnet_xdp,
        .ndo_xdp_xmit           = virtnet_xdp_xmit,
        .ndo_features_check     = passthru_features_check,
        .ndo_get_phys_port_name = virtnet_get_phys_port_name,
        .ndo_set_features       = virtnet_set_features,
        .ndo_tx_timeout         = virtnet_tx_timeout,
};

static void virtnet_config_changed_work(struct work_struct *work)
{
        struct virtnet_info *vi =
                container_of(work, struct virtnet_info, config_work);
        u16 v;

        if (virtio_cread_feature(vi->vdev, VIRTIO_NET_F_STATUS,
                                 struct virtio_net_config, status, &v) < 0)
                return;

        if (v & VIRTIO_NET_S_ANNOUNCE) {
                netdev_notify_peers(vi->dev);
                virtnet_ack_link_announce(vi);
        }

        /* Ignore unknown (future) status bits */
        v &= VIRTIO_NET_S_LINK_UP;

        if (vi->status == v)
                return;

        vi->status = v;

        if (vi->status & VIRTIO_NET_S_LINK_UP) {
                virtnet_update_settings(vi);
                netif_carrier_on(vi->dev);
                netif_tx_wake_all_queues(vi->dev);
        } else {
                netif_carrier_off(vi->dev);
                netif_tx_stop_all_queues(vi->dev);
        }
}

static void virtnet_config_changed(struct virtio_device *vdev)
{
        struct virtnet_info *vi = vdev->priv;

        schedule_work(&vi->config_work);
}

static void virtnet_free_queues(struct virtnet_info *vi)
{
        int i;

        for (i = 0; i < vi->max_queue_pairs; i++) {
                __netif_napi_del(&vi->rq[i].napi);
                __netif_napi_del(&vi->sq[i].napi);
        }

        /* We called __netif_napi_del(),
         * we need to respect an RCU grace period before freeing vi->rq
         */
        synchronize_net();

        kfree(vi->rq);
        kfree(vi->sq);
        kfree(vi->ctrl);
}

static void _free_receive_bufs(struct virtnet_info *vi)
{
        struct bpf_prog *old_prog;
        int i;

        for (i = 0; i < vi->max_queue_pairs; i++) {
                while (vi->rq[i].pages)
                        __free_pages(get_a_page(&vi->rq[i], GFP_KERNEL), 0);

                old_prog = rtnl_dereference(vi->rq[i].xdp_prog);
                RCU_INIT_POINTER(vi->rq[i].xdp_prog, NULL);
                if (old_prog)
                        bpf_prog_put(old_prog);
        }
}

static void free_receive_bufs(struct virtnet_info *vi)
{
        rtnl_lock();
        _free_receive_bufs(vi);
        rtnl_unlock();
}

static void free_receive_page_frags(struct virtnet_info *vi)
{
        int i;
        for (i = 0; i < vi->max_queue_pairs; i++)
                if (vi->rq[i].alloc_frag.page) {
                        if (vi->rq[i].do_dma && vi->rq[i].last_dma)
                                virtnet_rq_unmap(&vi->rq[i], vi->rq[i].last_dma, 0);
                        put_page(vi->rq[i].alloc_frag.page);
                }
}

static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf)
{
        if (!is_xdp_frame(buf))
                dev_kfree_skb(buf);
        else
                xdp_return_frame(ptr_to_xdp(buf));
}

static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf)
{
        struct virtnet_info *vi = vq->vdev->priv;
        int i = vq2rxq(vq);

        if (vi->mergeable_rx_bufs)
                put_page(virt_to_head_page(buf));
        else if (vi->big_packets)
                give_pages(&vi->rq[i], buf);
        else
                put_page(virt_to_head_page(buf));
}

static void free_unused_bufs(struct virtnet_info *vi)
{
        void *buf;
        int i;

        for (i = 0; i < vi->max_queue_pairs; i++) {
                struct virtqueue *vq = vi->sq[i].vq;
                while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
                        virtnet_sq_free_unused_buf(vq, buf);
                cond_resched();
        }

        for (i = 0; i < vi->max_queue_pairs; i++) {
                struct receive_queue *rq = &vi->rq[i];

                while ((buf = virtnet_rq_detach_unused_buf(rq)) != NULL)
                        virtnet_rq_free_unused_buf(rq->vq, buf);
                cond_resched();
        }
}

static void virtnet_del_vqs(struct virtnet_info *vi)
{
        struct virtio_device *vdev = vi->vdev;

        virtnet_clean_affinity(vi);

        vdev->config->del_vqs(vdev);

        virtnet_free_queues(vi);
}

/* How large should a single buffer be so a queue full of these can fit at
 * least one full packet?
 * Logic below assumes the mergeable buffer header is used.
 */
static unsigned int mergeable_min_buf_len(struct virtnet_info *vi, struct virtqueue *vq)
{
        const unsigned int hdr_len = vi->hdr_len;
        unsigned int rq_size = virtqueue_get_vring_size(vq);
        unsigned int packet_len = vi->big_packets ? IP_MAX_MTU : vi->dev->max_mtu;
        unsigned int buf_len = hdr_len + ETH_HLEN + VLAN_HLEN + packet_len;
        unsigned int min_buf_len = DIV_ROUND_UP(buf_len, rq_size);

        return max(max(min_buf_len, hdr_len) - hdr_len,
                   (unsigned int)GOOD_PACKET_LEN);
}

static int virtnet_find_vqs(struct virtnet_info *vi)
{
        vq_callback_t **callbacks;
        struct virtqueue **vqs;
        int ret = -ENOMEM;
        int i, total_vqs;
        const char **names;
        bool *ctx;

        /* We expect 1 RX virtqueue followed by 1 TX virtqueue, followed by
         * possible N-1 RX/TX queue pairs used in multiqueue mode, followed by
         * possible control vq.
         */
        total_vqs = vi->max_queue_pairs * 2 +
                    virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ);

        /* Allocate space for find_vqs parameters */
        vqs = kcalloc(total_vqs, sizeof(*vqs), GFP_KERNEL);
        if (!vqs)
                goto err_vq;
        callbacks = kmalloc_array(total_vqs, sizeof(*callbacks), GFP_KERNEL);
        if (!callbacks)
                goto err_callback;
        names = kmalloc_array(total_vqs, sizeof(*names), GFP_KERNEL);
        if (!names)
                goto err_names;
        if (!vi->big_packets || vi->mergeable_rx_bufs) {
                ctx = kcalloc(total_vqs, sizeof(*ctx), GFP_KERNEL);
                if (!ctx)
                        goto err_ctx;
        } else {
                ctx = NULL;
        }

        /* Parameters for control virtqueue, if any */
        if (vi->has_cvq) {
                callbacks[total_vqs - 1] = NULL;
                names[total_vqs - 1] = "control";
        }

        /* Allocate/initialize parameters for send/receive virtqueues */
        for (i = 0; i < vi->max_queue_pairs; i++) {
                callbacks[rxq2vq(i)] = skb_recv_done;
                callbacks[txq2vq(i)] = skb_xmit_done;
                sprintf(vi->rq[i].name, "input.%d", i);
                sprintf(vi->sq[i].name, "output.%d", i);
                names[rxq2vq(i)] = vi->rq[i].name;
                names[txq2vq(i)] = vi->sq[i].name;
                if (ctx)
                        ctx[rxq2vq(i)] = true;
        }

        ret = virtio_find_vqs_ctx(vi->vdev, total_vqs, vqs, callbacks,
                                  names, ctx, NULL);
        if (ret)
                goto err_find;

        if (vi->has_cvq) {
                vi->cvq = vqs[total_vqs - 1];
                if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VLAN))
                        vi->dev->features |= NETIF_F_HW_VLAN_CTAG_FILTER;
        }

        for (i = 0; i < vi->max_queue_pairs; i++) {
                vi->rq[i].vq = vqs[rxq2vq(i)];
                vi->rq[i].min_buf_len = mergeable_min_buf_len(vi, vi->rq[i].vq);
                vi->sq[i].vq = vqs[txq2vq(i)];
        }

        /* run here: ret == 0. */


err_find:
        kfree(ctx);
err_ctx:
        kfree(names);
err_names:
        kfree(callbacks);
err_callback:
        kfree(vqs);
err_vq:
        return ret;
}

static int virtnet_alloc_queues(struct virtnet_info *vi)
{
        int i;

        if (vi->has_cvq) {
                vi->ctrl = kzalloc(sizeof(*vi->ctrl), GFP_KERNEL);
                if (!vi->ctrl)
                        goto err_ctrl;
        } else {
                vi->ctrl = NULL;
        }
        vi->sq = kcalloc(vi->max_queue_pairs, sizeof(*vi->sq), GFP_KERNEL);
        if (!vi->sq)
                goto err_sq;
        vi->rq = kcalloc(vi->max_queue_pairs, sizeof(*vi->rq), GFP_KERNEL);
        if (!vi->rq)
                goto err_rq;

        INIT_DELAYED_WORK(&vi->refill, refill_work);
        for (i = 0; i < vi->max_queue_pairs; i++) {
                vi->rq[i].pages = NULL;
                netif_napi_add_weight(vi->dev, &vi->rq[i].napi, virtnet_poll,
                                      napi_weight);
                netif_napi_add_tx_weight(vi->dev, &vi->sq[i].napi,
                                         virtnet_poll_tx,
                                         napi_tx ? napi_weight : 0);

                sg_init_table(vi->rq[i].sg, ARRAY_SIZE(vi->rq[i].sg));
                ewma_pkt_len_init(&vi->rq[i].mrg_avg_pkt_len);
                sg_init_table(vi->sq[i].sg, ARRAY_SIZE(vi->sq[i].sg));

                u64_stats_init(&vi->rq[i].stats.syncp);
                u64_stats_init(&vi->sq[i].stats.syncp);
        }

        return 0;

err_rq:
        kfree(vi->sq);
err_sq:
        kfree(vi->ctrl);
err_ctrl:
        return -ENOMEM;
}

static int init_vqs(struct virtnet_info *vi)
{
        int ret;

        /* Allocate send & receive queues */
        ret = virtnet_alloc_queues(vi);
        if (ret)
                goto err;

        ret = virtnet_find_vqs(vi);
        if (ret)
                goto err_free;

        virtnet_rq_set_premapped(vi);

        cpus_read_lock();
        virtnet_set_affinity(vi);
        cpus_read_unlock();

        return 0;

err_free:
        virtnet_free_queues(vi);
err:
        return ret;
}

#ifdef CONFIG_SYSFS
static ssize_t mergeable_rx_buffer_size_show(struct netdev_rx_queue *queue,
                char *buf)
{
        struct virtnet_info *vi = netdev_priv(queue->dev);
        unsigned int queue_index = get_netdev_rx_queue_index(queue);
        unsigned int headroom = virtnet_get_headroom(vi);
        unsigned int tailroom = headroom ? sizeof(struct skb_shared_info) : 0;
        struct ewma_pkt_len *avg;

        BUG_ON(queue_index >= vi->max_queue_pairs);
        avg = &vi->rq[queue_index].mrg_avg_pkt_len;
        return sprintf(buf, "%u\n",
                       get_mergeable_buf_len(&vi->rq[queue_index], avg,
                                       SKB_DATA_ALIGN(headroom + tailroom)));
}

static struct rx_queue_attribute mergeable_rx_buffer_size_attribute =
        __ATTR_RO(mergeable_rx_buffer_size);

static struct attribute *virtio_net_mrg_rx_attrs[] = {
        &mergeable_rx_buffer_size_attribute.attr,
        NULL
};

static const struct attribute_group virtio_net_mrg_rx_group = {
        .name = "virtio_net",
        .attrs = virtio_net_mrg_rx_attrs
};
#endif

static bool virtnet_fail_on_feature(struct virtio_device *vdev,
                                    unsigned int fbit,
                                    const char *fname, const char *dname)
{
        if (!virtio_has_feature(vdev, fbit))
                return false;

        dev_err(&vdev->dev, "device advertises feature %s but not %s",
                fname, dname);

        return true;
}

#define VIRTNET_FAIL_ON(vdev, fbit, dbit)                       \
        virtnet_fail_on_feature(vdev, fbit, #fbit, dbit)

static bool virtnet_validate_features(struct virtio_device *vdev)
{
        if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ) &&
            (VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_RX,
                             "VIRTIO_NET_F_CTRL_VQ") ||
             VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_VLAN,
                             "VIRTIO_NET_F_CTRL_VQ") ||
             VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_GUEST_ANNOUNCE,
                             "VIRTIO_NET_F_CTRL_VQ") ||
             VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_MQ, "VIRTIO_NET_F_CTRL_VQ") ||
             VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR,
                             "VIRTIO_NET_F_CTRL_VQ") ||
             VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_RSS,
                             "VIRTIO_NET_F_CTRL_VQ") ||
             VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_HASH_REPORT,
                             "VIRTIO_NET_F_CTRL_VQ") ||
             VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_NOTF_COAL,
                             "VIRTIO_NET_F_CTRL_VQ") ||
             VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_VQ_NOTF_COAL,
                             "VIRTIO_NET_F_CTRL_VQ"))) {
                return false;
        }

        return true;
}

#define MIN_MTU ETH_MIN_MTU
#define MAX_MTU ETH_MAX_MTU

static int virtnet_validate(struct virtio_device *vdev)
{
        if (!vdev->config->get) {
                dev_err(&vdev->dev, "%s failure: config access disabled\n",
                        __func__);
                return -EINVAL;
        }

        if (!virtnet_validate_features(vdev))
                return -EINVAL;

        if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
                int mtu = virtio_cread16(vdev,
                                         offsetof(struct virtio_net_config,
                                                  mtu));
                if (mtu < MIN_MTU)
                        __virtio_clear_bit(vdev, VIRTIO_NET_F_MTU);
        }

        if (virtio_has_feature(vdev, VIRTIO_NET_F_STANDBY) &&
            !virtio_has_feature(vdev, VIRTIO_NET_F_MAC)) {
                dev_warn(&vdev->dev, "device advertises feature VIRTIO_NET_F_STANDBY but not VIRTIO_NET_F_MAC, disabling standby");
                __virtio_clear_bit(vdev, VIRTIO_NET_F_STANDBY);
        }

        return 0;
}

static bool virtnet_check_guest_gso(const struct virtnet_info *vi)
{
        return virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
                virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6) ||
                virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_ECN) ||
                virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_UFO) ||
                (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_USO4) &&
                virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_USO6));
}

static void virtnet_set_big_packets(struct virtnet_info *vi, const int mtu)
{
        bool guest_gso = virtnet_check_guest_gso(vi);

        /* If device can receive ANY guest GSO packets, regardless of mtu,
         * allocate packets of maximum size, otherwise limit it to only
         * mtu size worth only.
         */
        if (mtu > ETH_DATA_LEN || guest_gso) {
                vi->big_packets = true;
                vi->big_packets_num_skbfrags = guest_gso ? MAX_SKB_FRAGS : DIV_ROUND_UP(mtu, PAGE_SIZE);
        }
}

static int virtnet_probe(struct virtio_device *vdev)
{
        int i, err = -ENOMEM;
        struct net_device *dev;
        struct virtnet_info *vi;
        u16 max_queue_pairs;
        int mtu = 0;

        /* Find if host supports multiqueue/rss virtio_net device */
        max_queue_pairs = 1;
        if (virtio_has_feature(vdev, VIRTIO_NET_F_MQ) || virtio_has_feature(vdev, VIRTIO_NET_F_RSS))
                max_queue_pairs =
                     virtio_cread16(vdev, offsetof(struct virtio_net_config, max_virtqueue_pairs));

        /* We need at least 2 queue's */
        if (max_queue_pairs < VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MIN ||
            max_queue_pairs > VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MAX ||
            !virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
                max_queue_pairs = 1;

        /* Allocate ourselves a network device with room for our info */
        dev = alloc_etherdev_mq(sizeof(struct virtnet_info), max_queue_pairs);
        if (!dev)
                return -ENOMEM;

        /* Set up network device as normal. */
        dev->priv_flags |= IFF_UNICAST_FLT | IFF_LIVE_ADDR_CHANGE |
                           IFF_TX_SKB_NO_LINEAR;
        dev->netdev_ops = &virtnet_netdev;
        dev->features = NETIF_F_HIGHDMA;

        dev->ethtool_ops = &virtnet_ethtool_ops;
        SET_NETDEV_DEV(dev, &vdev->dev);

        /* Do we support "hardware" checksums? */
        if (virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
                /* This opens up the world of extra features. */
                dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG;
                if (csum)
                        dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG;

                if (virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
                        dev->hw_features |= NETIF_F_TSO
                                | NETIF_F_TSO_ECN | NETIF_F_TSO6;
                }
                /* Individual feature bits: what can host handle? */
                if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_TSO4))
                        dev->hw_features |= NETIF_F_TSO;
                if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_TSO6))
                        dev->hw_features |= NETIF_F_TSO6;
                if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_ECN))
                        dev->hw_features |= NETIF_F_TSO_ECN;
                if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_USO))
                        dev->hw_features |= NETIF_F_GSO_UDP_L4;

                dev->features |= NETIF_F_GSO_ROBUST;

                if (gso)
                        dev->features |= dev->hw_features & NETIF_F_ALL_TSO;
                /* (!csum && gso) case will be fixed by register_netdev() */
        }
        if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_CSUM))
                dev->features |= NETIF_F_RXCSUM;
        if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
            virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6))
                dev->features |= NETIF_F_GRO_HW;
        if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS))
                dev->hw_features |= NETIF_F_GRO_HW;

        dev->vlan_features = dev->features;
        dev->xdp_features = NETDEV_XDP_ACT_BASIC | NETDEV_XDP_ACT_REDIRECT;

        /* MTU range: 68 - 65535 */
        dev->min_mtu = MIN_MTU;
        dev->max_mtu = MAX_MTU;

        /* Configuration may specify what MAC to use.  Otherwise random. */
        if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC)) {
                u8 addr[ETH_ALEN];

                virtio_cread_bytes(vdev,
                                   offsetof(struct virtio_net_config, mac),
                                   addr, ETH_ALEN);
                eth_hw_addr_set(dev, addr);
        } else {
                eth_hw_addr_random(dev);
                dev_info(&vdev->dev, "Assigned random MAC address %pM\n",
                         dev->dev_addr);
        }

        /* Set up our device-specific information */
        vi = netdev_priv(dev);
        vi->dev = dev;
        vi->vdev = vdev;
        vdev->priv = vi;

        INIT_WORK(&vi->config_work, virtnet_config_changed_work);
        spin_lock_init(&vi->refill_lock);

        if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF)) {
                vi->mergeable_rx_bufs = true;
                dev->xdp_features |= NETDEV_XDP_ACT_RX_SG;
        }

        if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL)) {
                vi->intr_coal_rx.max_usecs = 0;
                vi->intr_coal_tx.max_usecs = 0;
                vi->intr_coal_tx.max_packets = 0;
                vi->intr_coal_rx.max_packets = 0;
        }

        if (virtio_has_feature(vdev, VIRTIO_NET_F_HASH_REPORT))
                vi->has_rss_hash_report = true;

        if (virtio_has_feature(vdev, VIRTIO_NET_F_RSS))
                vi->has_rss = true;

        if (vi->has_rss || vi->has_rss_hash_report) {
                vi->rss_indir_table_size =
                        virtio_cread16(vdev, offsetof(struct virtio_net_config,
                                rss_max_indirection_table_length));
                vi->rss_key_size =
                        virtio_cread8(vdev, offsetof(struct virtio_net_config, rss_max_key_size));

                vi->rss_hash_types_supported =
                    virtio_cread32(vdev, offsetof(struct virtio_net_config, supported_hash_types));
                vi->rss_hash_types_supported &=
                                ~(VIRTIO_NET_RSS_HASH_TYPE_IP_EX |
                                  VIRTIO_NET_RSS_HASH_TYPE_TCP_EX |
                                  VIRTIO_NET_RSS_HASH_TYPE_UDP_EX);

                dev->hw_features |= NETIF_F_RXHASH;
        }

        if (vi->has_rss_hash_report)
                vi->hdr_len = sizeof(struct virtio_net_hdr_v1_hash);
        else if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF) ||
                 virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
                vi->hdr_len = sizeof(struct virtio_net_hdr_mrg_rxbuf);
        else
                vi->hdr_len = sizeof(struct virtio_net_hdr);

        if (virtio_has_feature(vdev, VIRTIO_F_ANY_LAYOUT) ||
            virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
                vi->any_header_sg = true;

        if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
                vi->has_cvq = true;

        if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
                mtu = virtio_cread16(vdev,
                                     offsetof(struct virtio_net_config,
                                              mtu));
                if (mtu < dev->min_mtu) {
                        /* Should never trigger: MTU was previously validated
                         * in virtnet_validate.
                         */
                        dev_err(&vdev->dev,
                                "device MTU appears to have changed it is now %d < %d",
                                mtu, dev->min_mtu);
                        err = -EINVAL;
                        goto free;
                }

                dev->mtu = mtu;
                dev->max_mtu = mtu;
        }

        virtnet_set_big_packets(vi, mtu);

        if (vi->any_header_sg)
                dev->needed_headroom = vi->hdr_len;

        /* Enable multiqueue by default */
        if (num_online_cpus() >= max_queue_pairs)
                vi->curr_queue_pairs = max_queue_pairs;
        else
                vi->curr_queue_pairs = num_online_cpus();
        vi->max_queue_pairs = max_queue_pairs;

        /* Allocate/initialize the rx/tx queues, and invoke find_vqs */
        err = init_vqs(vi);
        if (err)
                goto free;

#ifdef CONFIG_SYSFS
        if (vi->mergeable_rx_bufs)
                dev->sysfs_rx_queue_group = &virtio_net_mrg_rx_group;
#endif
        netif_set_real_num_tx_queues(dev, vi->curr_queue_pairs);
        netif_set_real_num_rx_queues(dev, vi->curr_queue_pairs);

        virtnet_init_settings(dev);

        if (virtio_has_feature(vdev, VIRTIO_NET_F_STANDBY)) {
                vi->failover = net_failover_create(vi->dev);
                if (IS_ERR(vi->failover)) {
                        err = PTR_ERR(vi->failover);
                        goto free_vqs;
                }
        }

        if (vi->has_rss || vi->has_rss_hash_report)
                virtnet_init_default_rss(vi);

        /* serialize netdev register + virtio_device_ready() with ndo_open() */
        rtnl_lock();

        err = register_netdevice(dev);
        if (err) {
                pr_debug("virtio_net: registering device failed\n");
                rtnl_unlock();
                goto free_failover;
        }

        virtio_device_ready(vdev);

        _virtnet_set_queues(vi, vi->curr_queue_pairs);

        /* a random MAC address has been assigned, notify the device.
         * We don't fail probe if VIRTIO_NET_F_CTRL_MAC_ADDR is not there
         * because many devices work fine without getting MAC explicitly
         */
        if (!virtio_has_feature(vdev, VIRTIO_NET_F_MAC) &&
            virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_MAC_ADDR)) {
                struct scatterlist sg;

                sg_init_one(&sg, dev->dev_addr, dev->addr_len);
                if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
                                          VIRTIO_NET_CTRL_MAC_ADDR_SET, &sg)) {
                        pr_debug("virtio_net: setting MAC address failed\n");
                        rtnl_unlock();
                        err = -EINVAL;
                        goto free_unregister_netdev;
                }
        }

        rtnl_unlock();

        err = virtnet_cpu_notif_add(vi);
        if (err) {
                pr_debug("virtio_net: registering cpu notifier failed\n");
                goto free_unregister_netdev;
        }

        /* Assume link up if device can't report link status,
           otherwise get link status from config. */
        netif_carrier_off(dev);
        if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) {
                schedule_work(&vi->config_work);
        } else {
                vi->status = VIRTIO_NET_S_LINK_UP;
                virtnet_update_settings(vi);
                netif_carrier_on(dev);
        }

        for (i = 0; i < ARRAY_SIZE(guest_offloads); i++)
                if (virtio_has_feature(vi->vdev, guest_offloads[i]))
                        set_bit(guest_offloads[i], &vi->guest_offloads);
        vi->guest_offloads_capable = vi->guest_offloads;

        pr_debug("virtnet: registered device %s with %d RX and TX vq's\n",
                 dev->name, max_queue_pairs);

        return 0;

free_unregister_netdev:
        unregister_netdev(dev);
free_failover:
        net_failover_destroy(vi->failover);
free_vqs:
        virtio_reset_device(vdev);
        cancel_delayed_work_sync(&vi->refill);
        free_receive_page_frags(vi);
        virtnet_del_vqs(vi);
free:
        free_netdev(dev);
        return err;
}

static void remove_vq_common(struct virtnet_info *vi)
{
        virtio_reset_device(vi->vdev);

        /* Free unused buffers in both send and recv, if any. */
        free_unused_bufs(vi);

        free_receive_bufs(vi);

        free_receive_page_frags(vi);

        virtnet_del_vqs(vi);
}

static void virtnet_remove(struct virtio_device *vdev)
{
        struct virtnet_info *vi = vdev->priv;

        virtnet_cpu_notif_remove(vi);

        /* Make sure no work handler is accessing the device. */
        flush_work(&vi->config_work);

        unregister_netdev(vi->dev);

        net_failover_destroy(vi->failover);

        remove_vq_common(vi);

        free_netdev(vi->dev);
}

static __maybe_unused int virtnet_freeze(struct virtio_device *vdev)
{
        struct virtnet_info *vi = vdev->priv;

        virtnet_cpu_notif_remove(vi);
        virtnet_freeze_down(vdev);
        remove_vq_common(vi);

        return 0;
}

static __maybe_unused int virtnet_restore(struct virtio_device *vdev)
{
        struct virtnet_info *vi = vdev->priv;
        int err;

        err = virtnet_restore_up(vdev);
        if (err)
                return err;
        virtnet_set_queues(vi, vi->curr_queue_pairs);

        err = virtnet_cpu_notif_add(vi);
        if (err) {
                virtnet_freeze_down(vdev);
                remove_vq_common(vi);
                return err;
        }

        return 0;
}

static struct virtio_device_id id_table[] = {
        { VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },
        { 0 },
};

#define VIRTNET_FEATURES \
        VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM, \
        VIRTIO_NET_F_MAC, \
        VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6, \
        VIRTIO_NET_F_HOST_ECN, VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6, \
        VIRTIO_NET_F_GUEST_ECN, VIRTIO_NET_F_GUEST_UFO, \
        VIRTIO_NET_F_HOST_USO, VIRTIO_NET_F_GUEST_USO4, VIRTIO_NET_F_GUEST_USO6, \
        VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ, \
        VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN, \
        VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, \
        VIRTIO_NET_F_CTRL_MAC_ADDR, \
        VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \
        VIRTIO_NET_F_SPEED_DUPLEX, VIRTIO_NET_F_STANDBY, \
        VIRTIO_NET_F_RSS, VIRTIO_NET_F_HASH_REPORT, VIRTIO_NET_F_NOTF_COAL, \
        VIRTIO_NET_F_VQ_NOTF_COAL, \
        VIRTIO_NET_F_GUEST_HDRLEN

static unsigned int features[] = {
        VIRTNET_FEATURES,
};

static unsigned int features_legacy[] = {
        VIRTNET_FEATURES,
        VIRTIO_NET_F_GSO,
        VIRTIO_F_ANY_LAYOUT,
};

static struct virtio_driver virtio_net_driver = {
        .feature_table = features,
        .feature_table_size = ARRAY_SIZE(features),
        .feature_table_legacy = features_legacy,
        .feature_table_size_legacy = ARRAY_SIZE(features_legacy),
        .driver.name =  KBUILD_MODNAME,
        .driver.owner = THIS_MODULE,
        .id_table =     id_table,
        .validate =     virtnet_validate,
        .probe =        virtnet_probe,
        .remove =       virtnet_remove,
        .config_changed = virtnet_config_changed,
#ifdef CONFIG_PM_SLEEP
        .freeze =       virtnet_freeze,
        .restore =      virtnet_restore,
#endif
};

static __init int virtio_net_driver_init(void)
{
        int ret;

        ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "virtio/net:online",
                                      virtnet_cpu_online,
                                      virtnet_cpu_down_prep);
        if (ret < 0)
                goto out;
        virtionet_online = ret;
        ret = cpuhp_setup_state_multi(CPUHP_VIRT_NET_DEAD, "virtio/net:dead",
                                      NULL, virtnet_cpu_dead);
        if (ret)
                goto err_dead;
        ret = register_virtio_driver(&virtio_net_driver);
        if (ret)
                goto err_virtio;
        return 0;
err_virtio:
        cpuhp_remove_multi_state(CPUHP_VIRT_NET_DEAD);
err_dead:
        cpuhp_remove_multi_state(virtionet_online);
out:
        return ret;
}
module_init(virtio_net_driver_init);

static __exit void virtio_net_driver_exit(void)
{
        unregister_virtio_driver(&virtio_net_driver);
        cpuhp_remove_multi_state(CPUHP_VIRT_NET_DEAD);
        cpuhp_remove_multi_state(virtionet_online);
}
module_exit(virtio_net_driver_exit);

MODULE_DEVICE_TABLE(virtio, id_table);
MODULE_DESCRIPTION("Virtio network driver");
MODULE_LICENSE("GPL");