Re: [PATCH v2 1/5] virtio-net: setup vhost_dev and notifiers for cvq only when feature is negotiated

[Jason Wang]

在 2022/4/27 16:30, Si-Wei Liu 写道:

When the control virtqueue feature is absent or not negotiated,
vhost_net_start() still tries to set up vhost_dev and install
vhost notifiers for the control virtqueue, which results in
erroneous ioctl calls with incorrect queue index sending down
to driver. Do that only when needed.

Fixes: 22288fe ("virtio-net: vhost control virtqueue support")
Signed-off-by: Si-Wei Liu <si-wei....@oracle.com>

Acked-by: Jason Wang <jasow...@redhat.com>

---
  hw/net/virtio-net.c | 3 ++-
  1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 1067e72..ffb3475 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -245,7 +245,8 @@ static void virtio_net_vhost_status(VirtIONet *n, uint8_t 
status)
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      NetClientState *nc = qemu_get_queue(n->nic);
      int queue_pairs = n->multiqueue ? n->max_queue_pairs : 1;
-    int cvq = n->max_ncs - n->max_queue_pairs;
+    int cvq = virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ) ?
+              n->max_ncs - n->max_queue_pairs : 0;

if (!get_vhost_net(nc->peer)) {

          return;