Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

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

/*
 *  drivers/net/veth.c
 *
 *  Copyright (C) 2007 OpenVZ http://openvz.org, SWsoft Inc
 *
 * Author: Pavel Emelianov <xemul@openvz.org>
 * Ethtool interface from: Eric W. Biederman <ebiederm@xmission.com>
 *
 */

#include <linux/netdevice.h>
#include <linux/slab.h>
#include <linux/ethtool.h>
#include <linux/etherdevice.h>
#include <linux/u64_stats_sync.h>

#include <net/rtnetlink.h>
#include <net/dst.h>
#include <net/xfrm.h>
#include <net/xdp.h>
#include <linux/veth.h>
#include <linux/module.h>
#include <linux/bpf.h>
#include <linux/filter.h>
#include <linux/ptr_ring.h>
#include <linux/bpf_trace.h>
#include <linux/net_tstamp.h>

#define DRV_NAME        "veth"
#define DRV_VERSION     "1.0"

#define VETH_XDP_FLAG           BIT(0)
#define VETH_RING_SIZE          256
#define VETH_XDP_HEADROOM       (XDP_PACKET_HEADROOM + NET_IP_ALIGN)

/* Separating two types of XDP xmit */
#define VETH_XDP_TX             BIT(0)
#define VETH_XDP_REDIR          BIT(1)

struct veth_rq_stats {
        u64                     xdp_packets;
        u64                     xdp_bytes;
        u64                     xdp_drops;
        struct u64_stats_sync   syncp;
};

struct veth_rq {
        struct napi_struct      xdp_napi;
        struct net_device       *dev;
        struct bpf_prog __rcu   *xdp_prog;
        struct xdp_mem_info     xdp_mem;
        struct veth_rq_stats    stats;
        bool                    rx_notify_masked;
        struct ptr_ring         xdp_ring;
        struct xdp_rxq_info     xdp_rxq;
};

struct veth_priv {
        struct net_device __rcu *peer;
        atomic64_t              dropped;
        struct bpf_prog         *_xdp_prog;
        struct veth_rq          *rq;
        unsigned int            requested_headroom;
};

/*
 * ethtool interface
 */

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

#define VETH_RQ_STAT(m) offsetof(struct veth_rq_stats, m)

static const struct veth_q_stat_desc veth_rq_stats_desc[] = {
        { "xdp_packets",        VETH_RQ_STAT(xdp_packets) },
        { "xdp_bytes",          VETH_RQ_STAT(xdp_bytes) },
        { "xdp_drops",          VETH_RQ_STAT(xdp_drops) },
};

#define VETH_RQ_STATS_LEN       ARRAY_SIZE(veth_rq_stats_desc)

static struct {
        const char string[ETH_GSTRING_LEN];
} ethtool_stats_keys[] = {
        { "peer_ifindex" },
};

static int veth_get_link_ksettings(struct net_device *dev,
                                   struct ethtool_link_ksettings *cmd)
{
        cmd->base.speed         = SPEED_10000;
        cmd->base.duplex        = DUPLEX_FULL;
        cmd->base.port          = PORT_TP;
        cmd->base.autoneg       = AUTONEG_DISABLE;
        return 0;
}

static void veth_get_drvinfo(struct net_device *dev, struct ethtool_drvinfo *info)
{
        strlcpy(info->driver, DRV_NAME, sizeof(info->driver));
        strlcpy(info->version, DRV_VERSION, sizeof(info->version));
}

static void veth_get_strings(struct net_device *dev, u32 stringset, u8 *buf)
{
        char *p = (char *)buf;
        int i, j;

        switch(stringset) {
        case ETH_SS_STATS:
                memcpy(p, &ethtool_stats_keys, sizeof(ethtool_stats_keys));
                p += sizeof(ethtool_stats_keys);
                for (i = 0; i < dev->real_num_rx_queues; i++) {
                        for (j = 0; j < VETH_RQ_STATS_LEN; j++) {
                                snprintf(p, ETH_GSTRING_LEN,
                                         "rx_queue_%u_%.11s",
                                         i, veth_rq_stats_desc[j].desc);
                                p += ETH_GSTRING_LEN;
                        }
                }
                break;
        }
}

static int veth_get_sset_count(struct net_device *dev, int sset)
{
        switch (sset) {
        case ETH_SS_STATS:
                return ARRAY_SIZE(ethtool_stats_keys) +
                       VETH_RQ_STATS_LEN * dev->real_num_rx_queues;
        default:
                return -EOPNOTSUPP;
        }
}

static void veth_get_ethtool_stats(struct net_device *dev,
                struct ethtool_stats *stats, u64 *data)
{
        struct veth_priv *priv = netdev_priv(dev);
        struct net_device *peer = rtnl_dereference(priv->peer);
        int i, j, idx;

        data[0] = peer ? peer->ifindex : 0;
        idx = 1;
        for (i = 0; i < dev->real_num_rx_queues; i++) {
                const struct veth_rq_stats *rq_stats = &priv->rq[i].stats;
                const void *stats_base = (void *)rq_stats;
                unsigned int start;
                size_t offset;

                do {
                        start = u64_stats_fetch_begin_irq(&rq_stats->syncp);
                        for (j = 0; j < VETH_RQ_STATS_LEN; j++) {
                                offset = veth_rq_stats_desc[j].offset;
                                data[idx + j] = *(u64 *)(stats_base + offset);
                        }
                } while (u64_stats_fetch_retry_irq(&rq_stats->syncp, start));
                idx += VETH_RQ_STATS_LEN;
        }
}

static int veth_get_ts_info(struct net_device *dev,
                            struct ethtool_ts_info *info)
{
        info->so_timestamping =
                SOF_TIMESTAMPING_TX_SOFTWARE |
                SOF_TIMESTAMPING_RX_SOFTWARE |
                SOF_TIMESTAMPING_SOFTWARE;
        info->phc_index = -1;

        return 0;
}

static const struct ethtool_ops veth_ethtool_ops = {
        .get_drvinfo            = veth_get_drvinfo,
        .get_link               = ethtool_op_get_link,
        .get_strings            = veth_get_strings,
        .get_sset_count         = veth_get_sset_count,
        .get_ethtool_stats      = veth_get_ethtool_stats,
        .get_link_ksettings     = veth_get_link_ksettings,
        .get_ts_info            = veth_get_ts_info,
};

/* general routines */

static bool veth_is_xdp_frame(void *ptr)
{
        return (unsigned long)ptr & VETH_XDP_FLAG;
}

static void *veth_ptr_to_xdp(void *ptr)
{
        return (void *)((unsigned long)ptr & ~VETH_XDP_FLAG);
}

static void *veth_xdp_to_ptr(void *ptr)
{
        return (void *)((unsigned long)ptr | VETH_XDP_FLAG);
}

static void veth_ptr_free(void *ptr)
{
        if (veth_is_xdp_frame(ptr))
                xdp_return_frame(veth_ptr_to_xdp(ptr));
        else
                kfree_skb(ptr);
}

static void __veth_xdp_flush(struct veth_rq *rq)
{
        /* Write ptr_ring before reading rx_notify_masked */
        smp_mb();
        if (!rq->rx_notify_masked) {
                rq->rx_notify_masked = true;
                napi_schedule(&rq->xdp_napi);
        }
}

static int veth_xdp_rx(struct veth_rq *rq, struct sk_buff *skb)
{
        if (unlikely(ptr_ring_produce(&rq->xdp_ring, skb))) {
                dev_kfree_skb_any(skb);
                return NET_RX_DROP;
        }

        return NET_RX_SUCCESS;
}

static int veth_forward_skb(struct net_device *dev, struct sk_buff *skb,
                            struct veth_rq *rq, bool xdp)
{
        return __dev_forward_skb(dev, skb) ?: xdp ?
                veth_xdp_rx(rq, skb) :
                netif_rx(skb);
}

static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct veth_priv *rcv_priv, *priv = netdev_priv(dev);
        struct veth_rq *rq = NULL;
        struct net_device *rcv;
        int length = skb->len;
        bool rcv_xdp = false;
        int rxq;

        rcu_read_lock();
        rcv = rcu_dereference(priv->peer);
        if (unlikely(!rcv)) {
                kfree_skb(skb);
                goto drop;
        }

        rcv_priv = netdev_priv(rcv);
        rxq = skb_get_queue_mapping(skb);
        if (rxq < rcv->real_num_rx_queues) {
                rq = &rcv_priv->rq[rxq];
                rcv_xdp = rcu_access_pointer(rq->xdp_prog);
                if (rcv_xdp)
                        skb_record_rx_queue(skb, rxq);
        }

        skb_tx_timestamp(skb);
        if (likely(veth_forward_skb(rcv, skb, rq, rcv_xdp) == NET_RX_SUCCESS)) {
                if (!rcv_xdp) {
                        struct pcpu_lstats *stats = this_cpu_ptr(dev->lstats);

                        u64_stats_update_begin(&stats->syncp);
                        stats->bytes += length;
                        stats->packets++;
                        u64_stats_update_end(&stats->syncp);
                }
        } else {
drop:
                atomic64_inc(&priv->dropped);
        }

        if (rcv_xdp)
                __veth_xdp_flush(rq);

        rcu_read_unlock();

        return NETDEV_TX_OK;
}

static u64 veth_stats_tx(struct pcpu_lstats *result, struct net_device *dev)
{
        struct veth_priv *priv = netdev_priv(dev);
        int cpu;

        result->packets = 0;
        result->bytes = 0;
        for_each_possible_cpu(cpu) {
                struct pcpu_lstats *stats = per_cpu_ptr(dev->lstats, cpu);
                u64 packets, bytes;
                unsigned int start;

                do {
                        start = u64_stats_fetch_begin_irq(&stats->syncp);
                        packets = stats->packets;
                        bytes = stats->bytes;
                } while (u64_stats_fetch_retry_irq(&stats->syncp, start));
                result->packets += packets;
                result->bytes += bytes;
        }
        return atomic64_read(&priv->dropped);
}

static void veth_stats_rx(struct veth_rq_stats *result, struct net_device *dev)
{
        struct veth_priv *priv = netdev_priv(dev);
        int i;

        result->xdp_packets = 0;
        result->xdp_bytes = 0;
        result->xdp_drops = 0;
        for (i = 0; i < dev->num_rx_queues; i++) {
                struct veth_rq_stats *stats = &priv->rq[i].stats;
                u64 packets, bytes, drops;
                unsigned int start;

                do {
                        start = u64_stats_fetch_begin_irq(&stats->syncp);
                        packets = stats->xdp_packets;
                        bytes = stats->xdp_bytes;
                        drops = stats->xdp_drops;
                } while (u64_stats_fetch_retry_irq(&stats->syncp, start));
                result->xdp_packets += packets;
                result->xdp_bytes += bytes;
                result->xdp_drops += drops;
        }
}

static void veth_get_stats64(struct net_device *dev,
                             struct rtnl_link_stats64 *tot)
{
        struct veth_priv *priv = netdev_priv(dev);
        struct net_device *peer;
        struct veth_rq_stats rx;
        struct pcpu_lstats tx;

        tot->tx_dropped = veth_stats_tx(&tx, dev);
        tot->tx_bytes = tx.bytes;
        tot->tx_packets = tx.packets;

        veth_stats_rx(&rx, dev);
        tot->rx_dropped = rx.xdp_drops;
        tot->rx_bytes = rx.xdp_bytes;
        tot->rx_packets = rx.xdp_packets;

        rcu_read_lock();
        peer = rcu_dereference(priv->peer);
        if (peer) {
                tot->rx_dropped += veth_stats_tx(&tx, peer);
                tot->rx_bytes += tx.bytes;
                tot->rx_packets += tx.packets;

                veth_stats_rx(&rx, peer);
                tot->tx_bytes += rx.xdp_bytes;
                tot->tx_packets += rx.xdp_packets;
        }
        rcu_read_unlock();
}

/* fake multicast ability */
static void veth_set_multicast_list(struct net_device *dev)
{
}

static struct sk_buff *veth_build_skb(void *head, int headroom, int len,
                                      int buflen)
{
        struct sk_buff *skb;

        if (!buflen) {
                buflen = SKB_DATA_ALIGN(headroom + len) +
                         SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
        }
        skb = build_skb(head, buflen);
        if (!skb)
                return NULL;

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

        return skb;
}

static int veth_select_rxq(struct net_device *dev)
{
        return smp_processor_id() % dev->real_num_rx_queues;
}

static int veth_xdp_xmit(struct net_device *dev, int n,
                         struct xdp_frame **frames, u32 flags)
{
        struct veth_priv *rcv_priv, *priv = netdev_priv(dev);
        struct net_device *rcv;
        int i, ret, drops = n;
        unsigned int max_len;
        struct veth_rq *rq;

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

        rcv = rcu_dereference(priv->peer);
        if (unlikely(!rcv)) {
                ret = -ENXIO;
                goto drop;
        }

        rcv_priv = netdev_priv(rcv);
        rq = &rcv_priv->rq[veth_select_rxq(rcv)];
        /* Non-NULL xdp_prog ensures that xdp_ring is initialized on receive
         * side. This means an XDP program is loaded on the peer and the peer
         * device is up.
         */
        if (!rcu_access_pointer(rq->xdp_prog)) {
                ret = -ENXIO;
                goto drop;
        }

        drops = 0;
        max_len = rcv->mtu + rcv->hard_header_len + VLAN_HLEN;

        spin_lock(&rq->xdp_ring.producer_lock);
        for (i = 0; i < n; i++) {
                struct xdp_frame *frame = frames[i];
                void *ptr = veth_xdp_to_ptr(frame);

                if (unlikely(frame->len > max_len ||
                             __ptr_ring_produce(&rq->xdp_ring, ptr))) {
                        xdp_return_frame_rx_napi(frame);
                        drops++;
                }
        }
        spin_unlock(&rq->xdp_ring.producer_lock);

        if (flags & XDP_XMIT_FLUSH)
                __veth_xdp_flush(rq);

        if (likely(!drops))
                return n;

        ret = n - drops;
drop:
        atomic64_add(drops, &priv->dropped);

        return ret;
}

static void veth_xdp_flush(struct net_device *dev)
{
        struct veth_priv *rcv_priv, *priv = netdev_priv(dev);
        struct net_device *rcv;
        struct veth_rq *rq;

        rcu_read_lock();
        rcv = rcu_dereference(priv->peer);
        if (unlikely(!rcv))
                goto out;

        rcv_priv = netdev_priv(rcv);
        rq = &rcv_priv->rq[veth_select_rxq(rcv)];
        /* xdp_ring is initialized on receive side? */
        if (unlikely(!rcu_access_pointer(rq->xdp_prog)))
                goto out;

        __veth_xdp_flush(rq);
out:
        rcu_read_unlock();
}

static int veth_xdp_tx(struct net_device *dev, struct xdp_buff *xdp)
{
        struct xdp_frame *frame = convert_to_xdp_frame(xdp);

        if (unlikely(!frame))
                return -EOVERFLOW;

        return veth_xdp_xmit(dev, 1, &frame, 0);
}

static struct sk_buff *veth_xdp_rcv_one(struct veth_rq *rq,
                                        struct xdp_frame *frame,
                                        unsigned int *xdp_xmit)
{
        void *hard_start = frame->data - frame->headroom;
        void *head = hard_start - sizeof(struct xdp_frame);
        int len = frame->len, delta = 0;
        struct xdp_frame orig_frame;
        struct bpf_prog *xdp_prog;
        unsigned int headroom;
        struct sk_buff *skb;

        rcu_read_lock();
        xdp_prog = rcu_dereference(rq->xdp_prog);
        if (likely(xdp_prog)) {
                struct xdp_buff xdp;
                u32 act;

                xdp.data_hard_start = hard_start;
                xdp.data = frame->data;
                xdp.data_end = frame->data + frame->len;
                xdp.data_meta = frame->data - frame->metasize;
                xdp.rxq = &rq->xdp_rxq;

                act = bpf_prog_run_xdp(xdp_prog, &xdp);

                switch (act) {
                case XDP_PASS:
                        delta = frame->data - xdp.data;
                        len = xdp.data_end - xdp.data;
                        break;
                case XDP_TX:
                        orig_frame = *frame;
                        xdp.data_hard_start = head;
                        xdp.rxq->mem = frame->mem;
                        if (unlikely(veth_xdp_tx(rq->dev, &xdp) < 0)) {
                                trace_xdp_exception(rq->dev, xdp_prog, act);
                                frame = &orig_frame;
                                goto err_xdp;
                        }
                        *xdp_xmit |= VETH_XDP_TX;
                        rcu_read_unlock();
                        goto xdp_xmit;
                case XDP_REDIRECT:
                        orig_frame = *frame;
                        xdp.data_hard_start = head;
                        xdp.rxq->mem = frame->mem;
                        if (xdp_do_redirect(rq->dev, &xdp, xdp_prog)) {
                                frame = &orig_frame;
                                goto err_xdp;
                        }
                        *xdp_xmit |= VETH_XDP_REDIR;
                        rcu_read_unlock();
                        goto xdp_xmit;
                default:
                        bpf_warn_invalid_xdp_action(act);
                        /* fall through */
                case XDP_ABORTED:
                        trace_xdp_exception(rq->dev, xdp_prog, act);
                        /* fall through */
                case XDP_DROP:
                        goto err_xdp;
                }
        }
        rcu_read_unlock();

        headroom = sizeof(struct xdp_frame) + frame->headroom - delta;
        skb = veth_build_skb(head, headroom, len, 0);
        if (!skb) {
                xdp_return_frame(frame);
                goto err;
        }

        xdp_scrub_frame(frame);
        skb->protocol = eth_type_trans(skb, rq->dev);
err:
        return skb;
err_xdp:
        rcu_read_unlock();
        xdp_return_frame(frame);
xdp_xmit:
        return NULL;
}

static struct sk_buff *veth_xdp_rcv_skb(struct veth_rq *rq, struct sk_buff *skb,
                                        unsigned int *xdp_xmit)
{
        u32 pktlen, headroom, act, metalen;
        void *orig_data, *orig_data_end;
        struct bpf_prog *xdp_prog;
        int mac_len, delta, off;
        struct xdp_buff xdp;

        skb_orphan(skb);

        rcu_read_lock();
        xdp_prog = rcu_dereference(rq->xdp_prog);
        if (unlikely(!xdp_prog)) {
                rcu_read_unlock();
                goto out;
        }

        mac_len = skb->data - skb_mac_header(skb);
        pktlen = skb->len + mac_len;
        headroom = skb_headroom(skb) - mac_len;

        if (skb_shared(skb) || skb_head_is_locked(skb) ||
            skb_is_nonlinear(skb) || headroom < XDP_PACKET_HEADROOM) {
                struct sk_buff *nskb;
                int size, head_off;
                void *head, *start;
                struct page *page;

                size = SKB_DATA_ALIGN(VETH_XDP_HEADROOM + pktlen) +
                       SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
                if (size > PAGE_SIZE)
                        goto drop;

                page = alloc_page(GFP_ATOMIC | __GFP_NOWARN);
                if (!page)
                        goto drop;

                head = page_address(page);
                start = head + VETH_XDP_HEADROOM;
                if (skb_copy_bits(skb, -mac_len, start, pktlen)) {
                        page_frag_free(head);
                        goto drop;
                }

                nskb = veth_build_skb(head,
                                      VETH_XDP_HEADROOM + mac_len, skb->len,
                                      PAGE_SIZE);
                if (!nskb) {
                        page_frag_free(head);
                        goto drop;
                }

                skb_copy_header(nskb, skb);
                head_off = skb_headroom(nskb) - skb_headroom(skb);
                skb_headers_offset_update(nskb, head_off);
                consume_skb(skb);
                skb = nskb;
        }

        xdp.data_hard_start = skb->head;
        xdp.data = skb_mac_header(skb);
        xdp.data_end = xdp.data + pktlen;
        xdp.data_meta = xdp.data;
        xdp.rxq = &rq->xdp_rxq;
        orig_data = xdp.data;
        orig_data_end = xdp.data_end;

        act = bpf_prog_run_xdp(xdp_prog, &xdp);

        switch (act) {
        case XDP_PASS:
                break;
        case XDP_TX:
                get_page(virt_to_page(xdp.data));
                consume_skb(skb);
                xdp.rxq->mem = rq->xdp_mem;
                if (unlikely(veth_xdp_tx(rq->dev, &xdp) < 0)) {
                        trace_xdp_exception(rq->dev, xdp_prog, act);
                        goto err_xdp;
                }
                *xdp_xmit |= VETH_XDP_TX;
                rcu_read_unlock();
                goto xdp_xmit;
        case XDP_REDIRECT:
                get_page(virt_to_page(xdp.data));
                consume_skb(skb);
                xdp.rxq->mem = rq->xdp_mem;
                if (xdp_do_redirect(rq->dev, &xdp, xdp_prog))
                        goto err_xdp;
                *xdp_xmit |= VETH_XDP_REDIR;
                rcu_read_unlock();
                goto xdp_xmit;
        default:
                bpf_warn_invalid_xdp_action(act);
                /* fall through */
        case XDP_ABORTED:
                trace_xdp_exception(rq->dev, xdp_prog, act);
                /* fall through */
        case XDP_DROP:
                goto drop;
        }
        rcu_read_unlock();

        delta = orig_data - xdp.data;
        off = mac_len + delta;
        if (off > 0)
                __skb_push(skb, off);
        else if (off < 0)
                __skb_pull(skb, -off);
        skb->mac_header -= delta;
        off = xdp.data_end - orig_data_end;
        if (off != 0)
                __skb_put(skb, off);
        skb->protocol = eth_type_trans(skb, rq->dev);

        metalen = xdp.data - xdp.data_meta;
        if (metalen)
                skb_metadata_set(skb, metalen);
out:
        return skb;
drop:
        rcu_read_unlock();
        kfree_skb(skb);
        return NULL;
err_xdp:
        rcu_read_unlock();
        page_frag_free(xdp.data);
xdp_xmit:
        return NULL;
}

static int veth_xdp_rcv(struct veth_rq *rq, int budget, unsigned int *xdp_xmit)
{
        int i, done = 0, drops = 0, bytes = 0;

        for (i = 0; i < budget; i++) {
                void *ptr = __ptr_ring_consume(&rq->xdp_ring);
                unsigned int xdp_xmit_one = 0;
                struct sk_buff *skb;

                if (!ptr)
                        break;

                if (veth_is_xdp_frame(ptr)) {
                        struct xdp_frame *frame = veth_ptr_to_xdp(ptr);

                        bytes += frame->len;
                        skb = veth_xdp_rcv_one(rq, frame, &xdp_xmit_one);
                } else {
                        skb = ptr;
                        bytes += skb->len;
                        skb = veth_xdp_rcv_skb(rq, skb, &xdp_xmit_one);
                }
                *xdp_xmit |= xdp_xmit_one;

                if (skb)
                        napi_gro_receive(&rq->xdp_napi, skb);
                else if (!xdp_xmit_one)
                        drops++;

                done++;
        }

        u64_stats_update_begin(&rq->stats.syncp);
        rq->stats.xdp_packets += done;
        rq->stats.xdp_bytes += bytes;
        rq->stats.xdp_drops += drops;
        u64_stats_update_end(&rq->stats.syncp);

        return done;
}

static int veth_poll(struct napi_struct *napi, int budget)
{
        struct veth_rq *rq =
                container_of(napi, struct veth_rq, xdp_napi);
        unsigned int xdp_xmit = 0;
        int done;

        xdp_set_return_frame_no_direct();
        done = veth_xdp_rcv(rq, budget, &xdp_xmit);

        if (done < budget && napi_complete_done(napi, done)) {
                /* Write rx_notify_masked before reading ptr_ring */
                smp_store_mb(rq->rx_notify_masked, false);
                if (unlikely(!__ptr_ring_empty(&rq->xdp_ring))) {
                        rq->rx_notify_masked = true;
                        napi_schedule(&rq->xdp_napi);
                }
        }

        if (xdp_xmit & VETH_XDP_TX)
                veth_xdp_flush(rq->dev);
        if (xdp_xmit & VETH_XDP_REDIR)
                xdp_do_flush_map();
        xdp_clear_return_frame_no_direct();

        return done;
}

static int veth_napi_add(struct net_device *dev)
{
        struct veth_priv *priv = netdev_priv(dev);
        int err, i;

        for (i = 0; i < dev->real_num_rx_queues; i++) {
                struct veth_rq *rq = &priv->rq[i];

                err = ptr_ring_init(&rq->xdp_ring, VETH_RING_SIZE, GFP_KERNEL);
                if (err)
                        goto err_xdp_ring;
        }

        for (i = 0; i < dev->real_num_rx_queues; i++) {
                struct veth_rq *rq = &priv->rq[i];

                netif_napi_add(dev, &rq->xdp_napi, veth_poll, NAPI_POLL_WEIGHT);
                napi_enable(&rq->xdp_napi);
        }

        return 0;
err_xdp_ring:
        for (i--; i >= 0; i--)
                ptr_ring_cleanup(&priv->rq[i].xdp_ring, veth_ptr_free);

        return err;
}

static void veth_napi_del(struct net_device *dev)
{
        struct veth_priv *priv = netdev_priv(dev);
        int i;

        for (i = 0; i < dev->real_num_rx_queues; i++) {
                struct veth_rq *rq = &priv->rq[i];

                napi_disable(&rq->xdp_napi);
                napi_hash_del(&rq->xdp_napi);
        }
        synchronize_net();

        for (i = 0; i < dev->real_num_rx_queues; i++) {
                struct veth_rq *rq = &priv->rq[i];

                netif_napi_del(&rq->xdp_napi);
                rq->rx_notify_masked = false;
                ptr_ring_cleanup(&rq->xdp_ring, veth_ptr_free);
        }
}

static int veth_enable_xdp(struct net_device *dev)
{
        struct veth_priv *priv = netdev_priv(dev);
        int err, i;

        if (!xdp_rxq_info_is_reg(&priv->rq[0].xdp_rxq)) {
                for (i = 0; i < dev->real_num_rx_queues; i++) {
                        struct veth_rq *rq = &priv->rq[i];

                        err = xdp_rxq_info_reg(&rq->xdp_rxq, dev, i);
                        if (err < 0)
                                goto err_rxq_reg;

                        err = xdp_rxq_info_reg_mem_model(&rq->xdp_rxq,
                                                         MEM_TYPE_PAGE_SHARED,
                                                         NULL);
                        if (err < 0)
                                goto err_reg_mem;

                        /* Save original mem info as it can be overwritten */
                        rq->xdp_mem = rq->xdp_rxq.mem;
                }

                err = veth_napi_add(dev);
                if (err)
                        goto err_rxq_reg;
        }

        for (i = 0; i < dev->real_num_rx_queues; i++)
                rcu_assign_pointer(priv->rq[i].xdp_prog, priv->_xdp_prog);

        return 0;
err_reg_mem:
        xdp_rxq_info_unreg(&priv->rq[i].xdp_rxq);
err_rxq_reg:
        for (i--; i >= 0; i--)
                xdp_rxq_info_unreg(&priv->rq[i].xdp_rxq);

        return err;
}

static void veth_disable_xdp(struct net_device *dev)
{
        struct veth_priv *priv = netdev_priv(dev);
        int i;

        for (i = 0; i < dev->real_num_rx_queues; i++)
                rcu_assign_pointer(priv->rq[i].xdp_prog, NULL);
        veth_napi_del(dev);
        for (i = 0; i < dev->real_num_rx_queues; i++) {
                struct veth_rq *rq = &priv->rq[i];

                rq->xdp_rxq.mem = rq->xdp_mem;
                xdp_rxq_info_unreg(&rq->xdp_rxq);
        }
}

static int veth_open(struct net_device *dev)
{
        struct veth_priv *priv = netdev_priv(dev);
        struct net_device *peer = rtnl_dereference(priv->peer);
        int err;

        if (!peer)
                return -ENOTCONN;

        if (priv->_xdp_prog) {
                err = veth_enable_xdp(dev);
                if (err)
                        return err;
        }

        if (peer->flags & IFF_UP) {
                netif_carrier_on(dev);
                netif_carrier_on(peer);
        }

        return 0;
}

static int veth_close(struct net_device *dev)
{
        struct veth_priv *priv = netdev_priv(dev);
        struct net_device *peer = rtnl_dereference(priv->peer);

        netif_carrier_off(dev);
        if (peer)
                netif_carrier_off(peer);

        if (priv->_xdp_prog)
                veth_disable_xdp(dev);

        return 0;
}

static int is_valid_veth_mtu(int mtu)
{
        return mtu >= ETH_MIN_MTU && mtu <= ETH_MAX_MTU;
}

static int veth_alloc_queues(struct net_device *dev)
{
        struct veth_priv *priv = netdev_priv(dev);
        int i;

        priv->rq = kcalloc(dev->num_rx_queues, sizeof(*priv->rq), GFP_KERNEL);
        if (!priv->rq)
                return -ENOMEM;

        for (i = 0; i < dev->num_rx_queues; i++) {
                priv->rq[i].dev = dev;
                u64_stats_init(&priv->rq[i].stats.syncp);
        }

        return 0;
}

static void veth_free_queues(struct net_device *dev)
{
        struct veth_priv *priv = netdev_priv(dev);

        kfree(priv->rq);
}

static int veth_dev_init(struct net_device *dev)
{
        int err;

        dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
        if (!dev->lstats)
                return -ENOMEM;

        err = veth_alloc_queues(dev);
        if (err) {
                free_percpu(dev->lstats);
                return err;
        }

        return 0;
}

static void veth_dev_free(struct net_device *dev)
{
        veth_free_queues(dev);
        free_percpu(dev->lstats);
}

#ifdef CONFIG_NET_POLL_CONTROLLER
static void veth_poll_controller(struct net_device *dev)
{
        /* veth only receives frames when its peer sends one
         * Since it has nothing to do with disabling irqs, we are guaranteed
         * never to have pending data when we poll for it so
         * there is nothing to do here.
         *
         * We need this though so netpoll recognizes us as an interface that
         * supports polling, which enables bridge devices in virt setups to
         * still use netconsole
         */
}
#endif  /* CONFIG_NET_POLL_CONTROLLER */

static int veth_get_iflink(const struct net_device *dev)
{
        struct veth_priv *priv = netdev_priv(dev);
        struct net_device *peer;
        int iflink;

        rcu_read_lock();
        peer = rcu_dereference(priv->peer);
        iflink = peer ? peer->ifindex : 0;
        rcu_read_unlock();

        return iflink;
}

static netdev_features_t veth_fix_features(struct net_device *dev,
                                           netdev_features_t features)
{
        struct veth_priv *priv = netdev_priv(dev);
        struct net_device *peer;

        peer = rtnl_dereference(priv->peer);
        if (peer) {
                struct veth_priv *peer_priv = netdev_priv(peer);

                if (peer_priv->_xdp_prog)
                        features &= ~NETIF_F_GSO_SOFTWARE;
        }

        return features;
}

static void veth_set_rx_headroom(struct net_device *dev, int new_hr)
{
        struct veth_priv *peer_priv, *priv = netdev_priv(dev);
        struct net_device *peer;

        if (new_hr < 0)
                new_hr = 0;

        rcu_read_lock();
        peer = rcu_dereference(priv->peer);
        if (unlikely(!peer))
                goto out;

        peer_priv = netdev_priv(peer);
        priv->requested_headroom = new_hr;
        new_hr = max(priv->requested_headroom, peer_priv->requested_headroom);
        dev->needed_headroom = new_hr;
        peer->needed_headroom = new_hr;

out:
        rcu_read_unlock();
}

static int veth_xdp_set(struct net_device *dev, struct bpf_prog *prog,
                        struct netlink_ext_ack *extack)
{
        struct veth_priv *priv = netdev_priv(dev);
        struct bpf_prog *old_prog;
        struct net_device *peer;
        unsigned int max_mtu;
        int err;

        old_prog = priv->_xdp_prog;
        priv->_xdp_prog = prog;
        peer = rtnl_dereference(priv->peer);

        if (prog) {
                if (!peer) {
                        NL_SET_ERR_MSG_MOD(extack, "Cannot set XDP when peer is detached");
                        err = -ENOTCONN;
                        goto err;
                }

                max_mtu = PAGE_SIZE - VETH_XDP_HEADROOM -
                          peer->hard_header_len -
                          SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
                if (peer->mtu > max_mtu) {
                        NL_SET_ERR_MSG_MOD(extack, "Peer MTU is too large to set XDP");
                        err = -ERANGE;
                        goto err;
                }

                if (dev->real_num_rx_queues < peer->real_num_tx_queues) {
                        NL_SET_ERR_MSG_MOD(extack, "XDP expects number of rx queues not less than peer tx queues");
                        err = -ENOSPC;
                        goto err;
                }

                if (dev->flags & IFF_UP) {
                        err = veth_enable_xdp(dev);
                        if (err) {
                                NL_SET_ERR_MSG_MOD(extack, "Setup for XDP failed");
                                goto err;
                        }
                }

                if (!old_prog) {
                        peer->hw_features &= ~NETIF_F_GSO_SOFTWARE;
                        peer->max_mtu = max_mtu;
                }
        }

        if (old_prog) {
                if (!prog) {
                        if (dev->flags & IFF_UP)
                                veth_disable_xdp(dev);

                        if (peer) {
                                peer->hw_features |= NETIF_F_GSO_SOFTWARE;
                                peer->max_mtu = ETH_MAX_MTU;
                        }
                }
                bpf_prog_put(old_prog);
        }

        if ((!!old_prog ^ !!prog) && peer)
                netdev_update_features(peer);

        return 0;
err:
        priv->_xdp_prog = old_prog;

        return err;
}

static u32 veth_xdp_query(struct net_device *dev)
{
        struct veth_priv *priv = netdev_priv(dev);
        const struct bpf_prog *xdp_prog;

        xdp_prog = priv->_xdp_prog;
        if (xdp_prog)
                return xdp_prog->aux->id;

        return 0;
}

static int veth_xdp(struct net_device *dev, struct netdev_bpf *xdp)
{
        switch (xdp->command) {
        case XDP_SETUP_PROG:
                return veth_xdp_set(dev, xdp->prog, xdp->extack);
        case XDP_QUERY_PROG:
                xdp->prog_id = veth_xdp_query(dev);
                return 0;
        default:
                return -EINVAL;
        }
}

static const struct net_device_ops veth_netdev_ops = {
        .ndo_init            = veth_dev_init,
        .ndo_open            = veth_open,
        .ndo_stop            = veth_close,
        .ndo_start_xmit      = veth_xmit,
        .ndo_get_stats64     = veth_get_stats64,
        .ndo_set_rx_mode     = veth_set_multicast_list,
        .ndo_set_mac_address = eth_mac_addr,
#ifdef CONFIG_NET_POLL_CONTROLLER
        .ndo_poll_controller    = veth_poll_controller,
#endif
        .ndo_get_iflink         = veth_get_iflink,
        .ndo_fix_features       = veth_fix_features,
        .ndo_features_check     = passthru_features_check,
        .ndo_set_rx_headroom    = veth_set_rx_headroom,
        .ndo_bpf                = veth_xdp,
        .ndo_xdp_xmit           = veth_xdp_xmit,
};

#define VETH_FEATURES (NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_HW_CSUM | \
                       NETIF_F_RXCSUM | NETIF_F_SCTP_CRC | NETIF_F_HIGHDMA | \
                       NETIF_F_GSO_SOFTWARE | NETIF_F_GSO_ENCAP_ALL | \
                       NETIF_F_HW_VLAN_CTAG_TX | NETIF_F_HW_VLAN_CTAG_RX | \
                       NETIF_F_HW_VLAN_STAG_TX | NETIF_F_HW_VLAN_STAG_RX )

static void veth_setup(struct net_device *dev)
{
        ether_setup(dev);

        dev->priv_flags &= ~IFF_TX_SKB_SHARING;
        dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
        dev->priv_flags |= IFF_NO_QUEUE;
        dev->priv_flags |= IFF_PHONY_HEADROOM;

        dev->netdev_ops = &veth_netdev_ops;
        dev->ethtool_ops = &veth_ethtool_ops;
        dev->features |= NETIF_F_LLTX;
        dev->features |= VETH_FEATURES;
        dev->vlan_features = dev->features &
                             ~(NETIF_F_HW_VLAN_CTAG_TX |
                               NETIF_F_HW_VLAN_STAG_TX |
                               NETIF_F_HW_VLAN_CTAG_RX |
                               NETIF_F_HW_VLAN_STAG_RX);
        dev->needs_free_netdev = true;
        dev->priv_destructor = veth_dev_free;
        dev->max_mtu = ETH_MAX_MTU;

        dev->hw_features = VETH_FEATURES;
        dev->hw_enc_features = VETH_FEATURES;
        dev->mpls_features = NETIF_F_HW_CSUM | NETIF_F_GSO_SOFTWARE;
}

/*
 * netlink interface
 */

static int veth_validate(struct nlattr *tb[], struct nlattr *data[],
                         struct netlink_ext_ack *extack)
{
        if (tb[IFLA_ADDRESS]) {
                if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
                        return -EINVAL;
                if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
                        return -EADDRNOTAVAIL;
        }
        if (tb[IFLA_MTU]) {
                if (!is_valid_veth_mtu(nla_get_u32(tb[IFLA_MTU])))
                        return -EINVAL;
        }
        return 0;
}

static struct rtnl_link_ops veth_link_ops;

static int veth_newlink(struct net *src_net, struct net_device *dev,
                        struct nlattr *tb[], struct nlattr *data[],
                        struct netlink_ext_ack *extack)
{
        int err;
        struct net_device *peer;
        struct veth_priv *priv;
        char ifname[IFNAMSIZ];
        struct nlattr *peer_tb[IFLA_MAX + 1], **tbp;
        unsigned char name_assign_type;
        struct ifinfomsg *ifmp;
        struct net *net;

        /*
         * create and register peer first
         */
        if (data != NULL && data[VETH_INFO_PEER] != NULL) {
                struct nlattr *nla_peer;

                nla_peer = data[VETH_INFO_PEER];
                ifmp = nla_data(nla_peer);
                err = rtnl_nla_parse_ifla(peer_tb,
                                          nla_data(nla_peer) + sizeof(struct ifinfomsg),
                                          nla_len(nla_peer) - sizeof(struct ifinfomsg),
                                          NULL);
                if (err < 0)
                        return err;

                err = veth_validate(peer_tb, NULL, extack);
                if (err < 0)
                        return err;

                tbp = peer_tb;
        } else {
                ifmp = NULL;
                tbp = tb;
        }

        if (ifmp && tbp[IFLA_IFNAME]) {
                nla_strlcpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ);
                name_assign_type = NET_NAME_USER;
        } else {
                snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");
                name_assign_type = NET_NAME_ENUM;
        }

        net = rtnl_link_get_net(src_net, tbp);
        if (IS_ERR(net))
                return PTR_ERR(net);

        peer = rtnl_create_link(net, ifname, name_assign_type,
                                &veth_link_ops, tbp, extack);
        if (IS_ERR(peer)) {
                put_net(net);
                return PTR_ERR(peer);
        }

        if (!ifmp || !tbp[IFLA_ADDRESS])
                eth_hw_addr_random(peer);

        if (ifmp && (dev->ifindex != 0))
                peer->ifindex = ifmp->ifi_index;

        peer->gso_max_size = dev->gso_max_size;
        peer->gso_max_segs = dev->gso_max_segs;

        err = register_netdevice(peer);
        put_net(net);
        net = NULL;
        if (err < 0)
                goto err_register_peer;

        netif_carrier_off(peer);

        err = rtnl_configure_link(peer, ifmp);
        if (err < 0)
                goto err_configure_peer;

        /*
         * register dev last
         *
         * note, that since we've registered new device the dev's name
         * should be re-allocated
         */

        if (tb[IFLA_ADDRESS] == NULL)
                eth_hw_addr_random(dev);

        if (tb[IFLA_IFNAME])
                nla_strlcpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
        else
                snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");

        err = register_netdevice(dev);
        if (err < 0)
                goto err_register_dev;

        netif_carrier_off(dev);

        /*
         * tie the deviced together
         */

        priv = netdev_priv(dev);
        rcu_assign_pointer(priv->peer, peer);

        priv = netdev_priv(peer);
        rcu_assign_pointer(priv->peer, dev);

        return 0;

err_register_dev:
        /* nothing to do */
err_configure_peer:
        unregister_netdevice(peer);
        return err;

err_register_peer:
        free_netdev(peer);
        return err;
}

static void veth_dellink(struct net_device *dev, struct list_head *head)
{
        struct veth_priv *priv;
        struct net_device *peer;

        priv = netdev_priv(dev);
        peer = rtnl_dereference(priv->peer);

        /* Note : dellink() is called from default_device_exit_batch(),
         * before a rcu_synchronize() point. The devices are guaranteed
         * not being freed before one RCU grace period.
         */
        RCU_INIT_POINTER(priv->peer, NULL);
        unregister_netdevice_queue(dev, head);

        if (peer) {
                priv = netdev_priv(peer);
                RCU_INIT_POINTER(priv->peer, NULL);
                unregister_netdevice_queue(peer, head);
        }
}

static const struct nla_policy veth_policy[VETH_INFO_MAX + 1] = {
        [VETH_INFO_PEER]        = { .len = sizeof(struct ifinfomsg) },
};

static struct net *veth_get_link_net(const struct net_device *dev)
{
        struct veth_priv *priv = netdev_priv(dev);
        struct net_device *peer = rtnl_dereference(priv->peer);

        return peer ? dev_net(peer) : dev_net(dev);
}

static struct rtnl_link_ops veth_link_ops = {
        .kind           = DRV_NAME,
        .priv_size      = sizeof(struct veth_priv),
        .setup          = veth_setup,
        .validate       = veth_validate,
        .newlink        = veth_newlink,
        .dellink        = veth_dellink,
        .policy         = veth_policy,
        .maxtype        = VETH_INFO_MAX,
        .get_link_net   = veth_get_link_net,
};

/*
 * init/fini
 */

static __init int veth_init(void)
{
        return rtnl_link_register(&veth_link_ops);
}

static __exit void veth_exit(void)
{
        rtnl_link_unregister(&veth_link_ops);
}

module_init(veth_init);
module_exit(veth_exit);

MODULE_DESCRIPTION("Virtual Ethernet Tunnel");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS_RTNL_LINK(DRV_NAME);