diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index eb95daa3e5a52314e6d9a857ddcd5591b395c654..55e5aa662ad59d4b72c44db743198876654f2d2d 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -2233,6 +2233,8 @@ int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
 		return -EFAULT;
 	}
 	if (unlikely(vq->log_used)) {
+		/* Make sure used idx is seen before log. */
+		smp_wmb();
 		/* Log used index update. */
 		log_write(vq->log_base,
 			  vq->log_addr + offsetof(struct vring_used, idx),