virtio: remove event notifier cleanup call on de-assign

The virtio_bus_set_host_notifier function no longer calls
event_notifier_cleanup when a event notifier is removed.

The commit updates the code to match the new behavior and calls
virtio_bus_cleanup_host_notifier after the notifier was de-assign
and no longer in use.

This change is a preparation to allow executing the
virtio_bus_set_host_notifier function in a memory region
transaction.

Signed-off-by: Gal Hammer <ghammer@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Tested-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/block/dataplane/virtio-blk.c

@@ -192,6 +192,7 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
             fprintf(stderr, "virtio-blk failed to set host notifier (%d)\n", r);
             while (i--) {
                 virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
+                virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
             }
             goto fail_guest_notifiers;
         }
@@ -267,6 +268,7 @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev)
 
     for (i = 0; i < nvqs; i++) {
         virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
+        virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
     }
 
     /* Clean up guest notifier (irq) */

hw/scsi/virtio-scsi-dataplane.c

@@ -175,6 +175,7 @@ fail_vrings:
     aio_context_release(s->ctx);
     for (i = 0; i < vs->conf.num_queues + 2; i++) {
         virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
+        virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
     }
     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 fail_guest_notifiers:
@@ -213,6 +214,7 @@ void virtio_scsi_dataplane_stop(VirtIODevice *vdev)
 
     for (i = 0; i < vs->conf.num_queues + 2; i++) {
         virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
+        virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
     }
 
     /* Clean up guest notifier (irq) */

hw/virtio/vhost.c

@@ -1418,6 +1418,7 @@ fail_vq:
             error_report("vhost VQ %d notifier cleanup error: %d", i, -r);
         }
         assert (e >= 0);
+        virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i);
     }
     virtio_device_release_ioeventfd(vdev);
 fail:
@@ -1441,6 +1442,7 @@ void vhost_dev_disable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
             error_report("vhost VQ %d notifier cleanup failed: %d", i, -r);
         }
         assert (r >= 0);
+        virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i);
     }
     virtio_device_release_ioeventfd(vdev);
 }

hw/virtio/virtio-bus.c

@@ -283,20 +283,26 @@ int virtio_bus_set_host_notifier(VirtioBusState *bus, int n, bool assign)
         r = k->ioeventfd_assign(proxy, notifier, n, true);
         if (r < 0) {
             error_report("%s: unable to assign ioeventfd: %d", __func__, r);
-            goto cleanup_event_notifier;
+            virtio_bus_cleanup_host_notifier(bus, n);
         }
-        return 0;
     } else {
         k->ioeventfd_assign(proxy, notifier, n, false);
     }
 
-cleanup_event_notifier:
+    return r;
+}
+
+void virtio_bus_cleanup_host_notifier(VirtioBusState *bus, int n)
+{
+    VirtIODevice *vdev = virtio_bus_get_device(bus);
+    VirtQueue *vq = virtio_get_queue(vdev, n);
+    EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
+
     /* Test and clear notifier after disabling event,
      * in case poll callback didn't have time to run.
      */
     virtio_queue_host_notifier_read(notifier);
     event_notifier_cleanup(notifier);
-    return r;
 }
 
 static char *virtio_bus_get_dev_path(DeviceState *dev)

hw/virtio/virtio.c

@@ -2608,6 +2608,7 @@ assign_error:
         event_notifier_set_handler(&vq->host_notifier, NULL);
         r = virtio_bus_set_host_notifier(qbus, n, false);
         assert(r >= 0);
+        virtio_bus_cleanup_host_notifier(qbus, n);
     }
     return err;
 }
@@ -2634,6 +2635,7 @@ static void virtio_device_stop_ioeventfd_impl(VirtIODevice *vdev)
         event_notifier_set_handler(&vq->host_notifier, NULL);
         r = virtio_bus_set_host_notifier(qbus, n, false);
         assert(r >= 0);
+        virtio_bus_cleanup_host_notifier(qbus, n);
     }
 }
 

include/hw/virtio/virtio-bus.h

@@ -148,5 +148,7 @@ int virtio_bus_grab_ioeventfd(VirtioBusState *bus);
 void virtio_bus_release_ioeventfd(VirtioBusState *bus);
 /* Switch from/to the generic ioeventfd handler */
 int virtio_bus_set_host_notifier(VirtioBusState *bus, int n, bool assign);
+/* Tell the bus that the ioeventfd handler is no longer required. */
+void virtio_bus_cleanup_host_notifier(VirtioBusState *bus, int n);
 
 #endif /* VIRTIO_BUS_H */