From: Jason Wang <jasowang@redhat.com>

Add the check of vhost_set_iotlb_callback
before calling

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Cindy Lu <lulu@redhat.com>
---
 hw/virtio/vhost.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 5fd25fe520..10304b583e 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -1686,8 +1686,9 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
         }
     }
 
-    if (vhost_dev_has_iommu(hdev)) {
-        hdev->vhost_ops->vhost_set_iotlb_callback(hdev, true);
+    if (vhost_dev_has_iommu(hdev) &&
+        hdev->vhost_ops->vhost_set_iotlb_callback) {
+            hdev->vhost_ops->vhost_set_iotlb_callback(hdev, true);
 
         /* Update used ring information for IOTLB to work correctly,
          * vhost-kernel code requires for this.*/
@@ -1730,7 +1731,9 @@ void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev)
     }
 
     if (vhost_dev_has_iommu(hdev)) {
-        hdev->vhost_ops->vhost_set_iotlb_callback(hdev, false);
+        if (hdev->vhost_ops->vhost_set_iotlb_callback) {
+            hdev->vhost_ops->vhost_set_iotlb_callback(hdev, false);
+        }
         memory_listener_unregister(&hdev->iommu_listener);
     }
     vhost_log_put(hdev, true);
-- 
2.21.1