virtio: update queue size on guest write

Some guests read back queue size after writing it.
Update the size immediatly upon write otherwise
they get confused.

In particular this is the case for seabios.

Reported-by: Roman Kagan <rkagan@virtuozzo.com>
Suggested-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index c6b47a9c7385195a9e9bed074040cd554b1f2b66..e5c759e19eb57cfff1051ca03e843c4add27eefb 100644 (file)
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -1256,6 +1256,8 @@ static void virtio_pci_common_write(void *opaque, hwaddr addr,
         break;
     case VIRTIO_PCI_COMMON_Q_SIZE:
         proxy->vqs[vdev->queue_sel].num = val;
+        virtio_queue_set_num(vdev, vdev->queue_sel,
+                             proxy->vqs[vdev->queue_sel].num);
         break;
     case VIRTIO_PCI_COMMON_Q_MSIX:
         msix_vector_unuse(&proxy->pci_dev,