virtio: don't call device on !vm_running

On vm stop, virtio changes vm_running state
too soon, so callbacks can get envoked with
vm_running = false;

Cc: qemu-stable@nongnu.org
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

hw/virtio/virtio.c

@@ -1108,7 +1108,10 @@ static void virtio_vmstate_change(void *opaque, int running, RunState state)
     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     bool backend_run = running && (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK);
-    vdev->vm_running = running;
+
+    if (running) {
+        vdev->vm_running = running;
+    }
 
     if (backend_run) {
         virtio_set_status(vdev, vdev->status);
@@ -1121,6 +1124,10 @@ static void virtio_vmstate_change(void *opaque, int running, RunState state)
     if (!backend_run) {
         virtio_set_status(vdev, vdev->status);
     }
+
+    if (!running) {
+        vdev->vm_running = running;
+    }
 }
 
 void virtio_init(VirtIODevice *vdev, const char *name,