virtio-net: support longer header

virtio-1 devices always use num_buffers in the header, even if
mergeable rx buffers have not been negotiated.
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>

hw/net/virtio-net.c

@@ -367,15 +367,21 @@ static int peer_has_ufo(VirtIONet *n)
     return n->has_ufo;
 }
 
-static void virtio_net_set_mrg_rx_bufs(VirtIONet *n, int mergeable_rx_bufs)
+static void virtio_net_set_mrg_rx_bufs(VirtIONet *n, int mergeable_rx_bufs,
+                                       int version_1)
 {
     int i;
     NetClientState *nc;
 
     n->mergeable_rx_bufs = mergeable_rx_bufs;
 
-    n->guest_hdr_len = n->mergeable_rx_bufs ?
-        sizeof(struct virtio_net_hdr_mrg_rxbuf) : sizeof(struct virtio_net_hdr);
+    if (version_1) {
+        n->guest_hdr_len = sizeof(struct virtio_net_hdr_mrg_rxbuf);
+    } else {
+        n->guest_hdr_len = n->mergeable_rx_bufs ?
+            sizeof(struct virtio_net_hdr_mrg_rxbuf) :
+            sizeof(struct virtio_net_hdr);
+    }
 
     for (i = 0; i < n->max_queues; i++) {
         nc = qemu_get_subqueue(n->nic, i);
@@ -522,7 +528,9 @@ static void virtio_net_set_features(VirtIODevice *vdev, uint64_t features)
 
     virtio_net_set_mrg_rx_bufs(n,
                                __virtio_has_feature(features,
-                                                    VIRTIO_NET_F_MRG_RXBUF));
+                                                    VIRTIO_NET_F_MRG_RXBUF),
+                               __virtio_has_feature(features,
+                                                    VIRTIO_F_VERSION_1));
 
     if (n->has_vnet_hdr) {
         n->curr_guest_offloads =
@@ -1375,7 +1383,8 @@ static int virtio_net_load_device(VirtIODevice *vdev, QEMUFile *f,
     qemu_get_buffer(f, n->mac, ETH_ALEN);
     n->vqs[0].tx_waiting = qemu_get_be32(f);
 
-    virtio_net_set_mrg_rx_bufs(n, qemu_get_be32(f));
+    virtio_net_set_mrg_rx_bufs(n, qemu_get_be32(f),
+                               virtio_has_feature(vdev, VIRTIO_F_VERSION_1));
 
     if (version_id >= 3)
         n->status = qemu_get_be16(f);
@@ -1627,7 +1636,7 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp)
 
     n->vqs[0].tx_waiting = 0;
     n->tx_burst = n->net_conf.txburst;
-    virtio_net_set_mrg_rx_bufs(n, 0);
+    virtio_net_set_mrg_rx_bufs(n, 0, 0);
     n->promisc = 1; /* for compatibility */
 
     n->mac_table.macs = g_malloc0(MAC_TABLE_ENTRIES * ETH_ALEN);