[virtio] Use host-specified MTU when available

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/drivers/net/virtio-net.c b/src/drivers/net/virtio-net.c
index 40367b89da2ad806db443c3963ccc8cdf2a4ceaf..4151532e686d02799dced454f6a41fde7f013250 100644 (file)
--- a/src/drivers/net/virtio-net.c
+++ b/src/drivers/net/virtio-net.c
@@ -77,13 +77,8 @@ enum {
        QUEUE_NB
 };
 
-enum {
-       /** Max number of pending rx packets */
-       NUM_RX_BUF = 8,
-
-       /** Max Ethernet frame length, including FCS and VLAN tag */
-       RX_BUF_SIZE = 1522,
-};
+/** Max number of pending rx packets */
+#define NUM_RX_BUF 8
 
 struct virtnet_nic {
        /** Base pio register address */
@@ -160,12 +155,13 @@ static void virtnet_enqueue_iob ( struct net_device *netdev,
  */
 static void virtnet_refill_rx_virtqueue ( struct net_device *netdev ) {
        struct virtnet_nic *virtnet = netdev->priv;
+       size_t len = ( netdev->max_pkt_len + 4 /* VLAN */ );
 
        while ( virtnet->rx_num_iobufs < NUM_RX_BUF ) {
                struct io_buffer *iobuf;
 
                /* Try to allocate a buffer, stop for now if out of memory */
-               iobuf = alloc_iob ( RX_BUF_SIZE );
+               iobuf = alloc_iob ( len );
                if ( ! iobuf )
                        break;
 
@@ -173,7 +169,7 @@ static void virtnet_refill_rx_virtqueue ( struct net_device *netdev ) {
                list_add ( &iobuf->list, &virtnet->rx_iobufs );
 
                /* Mark packet length until we know the actual size */
-               iob_put ( iobuf, RX_BUF_SIZE );
+               iob_put ( iobuf, len );
 
                virtnet_enqueue_iob ( netdev, RX_INDEX, iobuf );
                virtnet->rx_num_iobufs++;
@@ -237,7 +233,8 @@ static int virtnet_open_legacy ( struct net_device *netdev ) {
 
        /* Driver is ready */
        features = vp_get_features ( ioaddr );
-       vp_set_features ( ioaddr, features & ( 1 << VIRTIO_NET_F_MAC ) );
+       vp_set_features ( ioaddr, features & ( ( 1 << VIRTIO_NET_F_MAC ) |
+                                              ( 1 << VIRTIO_NET_F_MTU ) ) );
        vp_set_status ( ioaddr, VIRTIO_CONFIG_S_DRIVER | VIRTIO_CONFIG_S_DRIVER_OK );
        return 0;
 }
@@ -260,6 +257,7 @@ static int virtnet_open_modern ( struct net_device *netdev ) {
        }
        vpm_set_features ( &virtnet->vdev, features & (
                ( 1ULL << VIRTIO_NET_F_MAC ) |
+               ( 1ULL << VIRTIO_NET_F_MTU ) |
                ( 1ULL << VIRTIO_F_VERSION_1 ) |
                ( 1ULL << VIRTIO_F_ANY_LAYOUT ) ) );
        vpm_add_status ( &virtnet->vdev, VIRTIO_CONFIG_S_FEATURES_OK );
@@ -389,7 +387,7 @@ static void virtnet_process_rx_packets ( struct net_device *netdev ) {
                virtnet->rx_num_iobufs--;
 
                /* Update iobuf length */
-               iob_unput ( iobuf, RX_BUF_SIZE );
+               iob_unput ( iobuf, iob_len ( iobuf ) );
                iob_put ( iobuf, len - sizeof ( struct virtio_net_hdr ) );
 
                DBGC2 ( virtnet, "VIRTIO-NET %p rx complete iobuf %p len %zd\n",
@@ -461,6 +459,7 @@ static int virtnet_probe_legacy ( struct pci_device *pci ) {
        struct net_device *netdev;
        struct virtnet_nic *virtnet;
        u32 features;
+       u16 mtu;
        int rc;
 
        /* Allocate and hook up net device */
@@ -480,7 +479,7 @@ static int virtnet_probe_legacy ( struct pci_device *pci ) {
        adjust_pci_device ( pci );
        vp_reset ( ioaddr );
 
-       /* Load MAC address */
+       /* Load MAC address and MTU */
        features = vp_get_features ( ioaddr );
        if ( features & ( 1 << VIRTIO_NET_F_MAC ) ) {
                vp_get ( ioaddr, offsetof ( struct virtio_net_config, mac ),
@@ -488,6 +487,12 @@ static int virtnet_probe_legacy ( struct pci_device *pci ) {
                DBGC ( virtnet, "VIRTIO-NET %p mac=%s\n", virtnet,
                       eth_ntoa ( netdev->hw_addr ) );
        }
+       if ( features & ( 1ULL << VIRTIO_NET_F_MTU ) ) {
+               vp_get ( ioaddr, offsetof ( struct virtio_net_config, mtu ),
+                        &mtu, sizeof ( mtu ) );
+               DBGC ( virtnet, "VIRTIO-NET %p mtu=%d\n", virtnet, mtu );
+               netdev->max_pkt_len = ( mtu + ETH_HLEN );
+       }
 
        /* Register network device */
        if ( ( rc = register_netdev ( netdev ) ) != 0 )
@@ -517,6 +522,7 @@ static int virtnet_probe_modern ( struct pci_device *pci, int *found_dev ) {
        struct net_device *netdev;
        struct virtnet_nic *virtnet;
        u64 features;
+       u16 mtu;
        int rc, common, isr, notify, config, device;
 
        common = virtio_pci_find_capability ( pci, VIRTIO_PCI_CAP_COMMON_CFG );
@@ -583,7 +589,7 @@ static int virtnet_probe_modern ( struct pci_device *pci, int *found_dev ) {
        vpm_add_status ( &virtnet->vdev, VIRTIO_CONFIG_S_ACKNOWLEDGE );
        vpm_add_status ( &virtnet->vdev, VIRTIO_CONFIG_S_DRIVER );
 
-       /* Load MAC address */
+       /* Load MAC address and MTU */
        if ( device ) {
                features = vpm_get_features ( &virtnet->vdev );
                if ( features & ( 1ULL << VIRTIO_NET_F_MAC ) ) {
@@ -593,6 +599,14 @@ static int virtnet_probe_modern ( struct pci_device *pci, int *found_dev ) {
                        DBGC ( virtnet, "VIRTIO-NET %p mac=%s\n", virtnet,
                               eth_ntoa ( netdev->hw_addr ) );
                }
+               if ( features & ( 1ULL << VIRTIO_NET_F_MTU ) ) {
+                       vpm_get ( &virtnet->vdev,
+                                 offsetof ( struct virtio_net_config, mtu ),
+                                 &mtu, sizeof ( mtu ) );
+                       DBGC ( virtnet, "VIRTIO-NET %p mtu=%d\n", virtnet,
+                              mtu );
+                       netdev->max_pkt_len = ( mtu + ETH_HLEN );
+               }
        }
 
        /* We need a valid MAC address */

diff --git a/src/drivers/net/virtio-net.h b/src/drivers/net/virtio-net.h
index c2b4a17cc414661451519eb2155d8cc617b911bb..ff58d3ef101e51238da0c1455106435aab606a93 100644 (file)
--- a/src/drivers/net/virtio-net.h
+++ b/src/drivers/net/virtio-net.h
@@ -4,6 +4,7 @@
 /* The feature bitmap for virtio net */
 #define VIRTIO_NET_F_CSUM       0       /* Host handles pkts w/ partial csum */
 #define VIRTIO_NET_F_GUEST_CSUM 1       /* Guest handles pkts w/ partial csum */
+#define VIRTIO_NET_F_MTU        3       /* Initial MTU advice */
 #define VIRTIO_NET_F_MAC        5       /* Host has given MAC address. */
 #define VIRTIO_NET_F_GSO        6       /* Host handles pkts w/ any GSO type */
 #define VIRTIO_NET_F_GUEST_TSO4 7       /* Guest can handle TSOv4 in. */
@@ -25,6 +26,15 @@ struct virtio_net_config
 {
    /* The config defining mac address (if VIRTIO_NET_F_MAC) */
    u8 mac[6];
+   /* See VIRTIO_NET_F_STATUS and VIRTIO_NET_S_* above */
+   u16 status;
+   /* Maximum number of each of transmit and receive queues;
+    * see VIRTIO_NET_F_MQ and VIRTIO_NET_CTRL_MQ.
+    * Legal values are between 1 and 0x8000
+    */
+   u16 max_virtqueue_pairs;
+   /* Default maximum transmit unit advice */
+   u16 mtu;
 } __attribute__((packed));
 
 /* This is the first element of the scatter-gather list.  If you don't