[PATCH 4/5] virtio-net: Update virtio-net curr_queue_pairs in vdpa backends

["Eugenio Pérez" <eperezma@redhat.com>]

It was returned as error before. Instead of it, simply update the
corresponding field so qemu can send it in the migration data.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 hw/net/virtio-net.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index dd0d056fde..63a8332cd0 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -1412,19 +1412,14 @@ static int virtio_net_handle_mq(VirtIONet *n, uint8_t cmd,
         return VIRTIO_NET_ERR;
     }
 
-    /* Avoid changing the number of queue_pairs for vdpa device in
-     * userspace handler. A future fix is needed to handle the mq
-     * change in userspace handler with vhost-vdpa. Let's disable
-     * the mq handling from userspace for now and only allow get
-     * done through the kernel. Ripples may be seen when falling
-     * back to userspace, but without doing it qemu process would
-     * crash on a recursive entry to virtio_net_set_status().
-     */
+    n->curr_queue_pairs = queue_pairs;
     if (nc->peer && nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) {
-        return VIRTIO_NET_ERR;
+        /*
+         * Avoid updating the backend for a vdpa device: We're only interested
+         * in updating the device model queues.
+         */
+        return VIRTIO_NET_OK;
     }
-
-    n->curr_queue_pairs = queue_pairs;
     /* stop the backend before changing the number of queue_pairs to avoid handling a
      * disabled queue */
     virtio_net_set_status(vdev, vdev->status);
-- 
2.31.1