[PATCH 18/78] virtio-mmio: update queue size on guest write

[Michael Roth]

From: Denis Plotnikov <dplotnikov@virtuozzo.com>

Some guests read back queue size after writing it.
Always update the on size write otherwise they might be confused.

Cc: qemu-stable@nongnu.org
Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
Message-Id: <20191224081446.17003-1-dplotnikov@virtuozzo.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit 1049f4c62c4070618cc5defc9963c6a17ae7a5ae)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 hw/virtio/virtio-mmio.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c
index 94d934c44b..1e40a74869 100644
--- a/hw/virtio/virtio-mmio.c
+++ b/hw/virtio/virtio-mmio.c
@@ -295,8 +295,9 @@ static void virtio_mmio_write(void *opaque, hwaddr offset, 
uint64_t value,
         break;
     case VIRTIO_MMIO_QUEUE_NUM:
         trace_virtio_mmio_queue_write(value, VIRTQUEUE_MAX_SIZE);
+        virtio_queue_set_num(vdev, vdev->queue_sel, value);
+
         if (proxy->legacy) {
-            virtio_queue_set_num(vdev, vdev->queue_sel, value);
             virtio_queue_update_rings(vdev, vdev->queue_sel);
         } else {
             proxy->vqs[vdev->queue_sel].num = value;
-- 
2.17.1