diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c
index 0a7dde135db1..3a194eb3ce8a 100644
--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -4,6 +4,7 @@
  *  Copyright (C) 2007, 2008 Rusty Russell IBM Corporation
  */
 
+#include <asm/barrier.h>
 #include <linux/err.h>
 #include <linux/hw_random.h>
 #include <linux/scatterlist.h>
@@ -37,13 +38,13 @@ struct virtrng_info {
 static void random_recv_done(struct virtqueue *vq)
 {
 	struct virtrng_info *vi = vq->vdev->priv;
+	unsigned int len;
 
 	/* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */
-	if (!virtqueue_get_buf(vi->vq, &vi->data_avail))
+	if (!virtqueue_get_buf(vi->vq, &len))
 		return;
 
-	vi->data_idx = 0;
-
+	smp_store_release(&vi->data_avail, len);
 	complete(&vi->have_data);
 }
 
@@ -52,7 +53,6 @@ static void request_entropy(struct virtrng_info *vi)
 	struct scatterlist sg;
 
 	reinit_completion(&vi->have_data);
-	vi->data_avail = 0;
 	vi->data_idx = 0;
 
 	sg_init_one(&sg, vi->data, sizeof(vi->data));
@@ -88,7 +88,7 @@ static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait)
 	read = 0;
 
 	/* copy available data */
-	if (vi->data_avail) {
+	if (smp_load_acquire(&vi->data_avail)) {
 		chunk = copy_data(vi, buf, size);
 		size -= chunk;
 		read += chunk;