[RFC PATCH v4 16/20] vhost: Check for device VRING_USED_F_NO_NOTIFY at shadow virtqueue kick

[Eugenio Pérez]

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 hw/virtio/vhost-shadow-virtqueue.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/hw/virtio/vhost-shadow-virtqueue.c 
b/hw/virtio/vhost-shadow-virtqueue.c
index df7e6fa3ec..775f8d36a0 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -173,6 +173,15 @@ static void vhost_svq_add(VhostShadowVirtqueue *svq, 
VirtQueueElement *elem)
     svq->ring_id_maps[qemu_head] = elem;
 }
 
+static void vhost_svq_kick(VhostShadowVirtqueue *svq)
+{
+    /* Make sure we are reading updated device flag */
+    smp_mb();
+    if (!(svq->vring.used->flags & VRING_USED_F_NO_NOTIFY)) {
+        event_notifier_set(&svq->kick_notifier);
+    }
+}
+
 /* Handle guest->device notifications */
 static void vhost_handle_guest_kick(EventNotifier *n)
 {
@@ -197,7 +206,7 @@ static void vhost_handle_guest_kick(EventNotifier *n)
             }
 
             vhost_svq_add(svq, elem);
-            event_notifier_set(&svq->kick_notifier);
+            vhost_svq_kick(svq);
         }
 
         virtio_queue_set_notification(svq->vq, true);
-- 
2.27.0