vhost: fix invalid downcast

virtio_queue_get_desc_addr returns 64-bit hwaddr while int is usually 32-bit.
If returned hwaddr is not equal to 0 but least-significant 32 bits are
equal to 0 then this code will not actually stop running queue.

Signed-off-by: Yury Kotov <yury-kotov@yandex-team.ru>
Acked-by: Jia He <hejianet@gmail.com>
Cc: qemu-stable@nongnu.org
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit fa4ae4be15fb08b37bec35139688ef563311d0b9)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index d4cb5894a82ea2df69db7c9e4c23007f8c39ddb6..569c4053eae75e82edcacebba4e67bea30b4e931 100644 (file)
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -1073,10 +1073,8 @@ static void vhost_virtqueue_stop(struct vhost_dev *dev,
         .index = vhost_vq_index,
     };
     int r;
-    int a;
 
-    a = virtio_queue_get_desc_addr(vdev, idx);
-    if (a == 0) {
+    if (virtio_queue_get_desc_addr(vdev, idx) == 0) {
         /* Don't stop the virtqueue which might have not been started */
         return;
     }