void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
{
	int r;

	if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
		return;
	vq->used_flags |= VRING_USED_F_NO_NOTIFY;
	if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
		r = vhost_update_used_flags(vq);
		if (r)
			vq_err(vq, "Failed to enable notification at %p: %d\n",
			       &vq->used->flags, r);
	}
}
void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
{
	int r;

	if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
		return;
	vq->used_flags |= VRING_USED_F_NO_NOTIFY;
	if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
		r = vhost_update_used_flags(vq);
		if (r)
			vq_err(vq, "Failed to enable notification at %p: %d\n",
			       &vq->used->flags, r);
	}
}