Index: head/usr.sbin/bhyve/pci_virtio_console.c
===================================================================
--- head/usr.sbin/bhyve/pci_virtio_console.c
+++ head/usr.sbin/bhyve/pci_virtio_console.c
@@ -607,7 +607,7 @@
 
 	if (!port->vsp_rx_ready) {
 		port->vsp_rx_ready = 1;
-		vq->vq_used->vu_flags |= VRING_USED_F_NO_NOTIFY;
+		vq_kick_disable(vq);
 	}
 }
 
Index: head/usr.sbin/bhyve/pci_virtio_net.c
===================================================================
--- head/usr.sbin/bhyve/pci_virtio_net.c
+++ head/usr.sbin/bhyve/pci_virtio_net.c
@@ -39,7 +39,6 @@
 #include <sys/select.h>
 #include <sys/uio.h>
 #include <sys/ioctl.h>
-#include <machine/atomic.h>
 #include <net/ethernet.h>
 #ifndef NETMAP_WITH_LIBS
 #define NETMAP_WITH_LIBS
@@ -585,7 +584,7 @@
 	 */
 	if (sc->vsc_rx_ready == 0) {
 		sc->vsc_rx_ready = 1;
-		vq->vq_used->vu_flags |= VRING_USED_F_NO_NOTIFY;
+		vq_kick_disable(vq);
 	}
 }
 
@@ -631,7 +630,7 @@
 
 	/* Signal the tx thread for processing */
 	pthread_mutex_lock(&sc->tx_mtx);
-	vq->vq_used->vu_flags |= VRING_USED_F_NO_NOTIFY;
+	vq_kick_disable(vq);
 	if (sc->tx_in_progress == 0)
 		pthread_cond_signal(&sc->tx_cond);
 	pthread_mutex_unlock(&sc->tx_mtx);
@@ -660,8 +659,7 @@
 	for (;;) {
 		/* note - tx mutex is locked here */
 		while (sc->resetting || !vq_has_descs(vq)) {
-			vq->vq_used->vu_flags &= ~VRING_USED_F_NO_NOTIFY;
-			mb();
+			vq_kick_enable(vq);
 			if (!sc->resetting && vq_has_descs(vq))
 				break;
 
@@ -669,7 +667,7 @@
 			error = pthread_cond_wait(&sc->tx_cond, &sc->tx_mtx);
 			assert(error == 0);
 		}
-		vq->vq_used->vu_flags |= VRING_USED_F_NO_NOTIFY;
+		vq_kick_disable(vq);
 		sc->tx_in_progress = 1;
 		pthread_mutex_unlock(&sc->tx_mtx);
 
Index: head/usr.sbin/bhyve/pci_virtio_scsi.c
===================================================================
--- head/usr.sbin/bhyve/pci_virtio_scsi.c
+++ head/usr.sbin/bhyve/pci_virtio_scsi.c
@@ -581,7 +581,7 @@
 pci_vtscsi_eventq_notify(void *vsc, struct vqueue_info *vq)
 {
 
-	vq->vq_used->vu_flags |= VRING_USED_F_NO_NOTIFY;
+	vq_kick_disable(vq);
 }
 
 static void
Index: head/usr.sbin/bhyve/virtio.h
===================================================================
--- head/usr.sbin/bhyve/virtio.h
+++ head/usr.sbin/bhyve/virtio.h
@@ -31,6 +31,8 @@
 #ifndef	_VIRTIO_H_
 #define	_VIRTIO_H_
 
+#include <machine/atomic.h>
+
 /*
  * These are derived from several virtio specifications.
  *
@@ -445,6 +447,26 @@
 		pci_lintr_assert(vs->vs_pi);
 		VS_UNLOCK(vs);
 	}
+}
+
+static inline void
+vq_kick_enable(struct vqueue_info *vq)
+{
+
+	vq->vq_used->vu_flags &= ~VRING_USED_F_NO_NOTIFY;
+	/*
+	 * Full memory barrier to make sure the store to vu_flags
+	 * happens before the load from va_idx, which results from
+	 * a subsequent call to vq_has_descs().
+	 */
+	atomic_thread_fence_seq_cst();
+}
+
+static inline void
+vq_kick_disable(struct vqueue_info *vq)
+{
+
+	vq->vq_used->vu_flags |= VRING_USED_F_NO_NOTIFY;
 }
 
 struct iovec;
Index: head/usr.sbin/bhyve/virtio.c
===================================================================
--- head/usr.sbin/bhyve/virtio.c
+++ head/usr.sbin/bhyve/virtio.c
@@ -428,7 +428,8 @@
 
 	/*
 	 * Ensure the used descriptor is visible before updating the index.
-	 * This is necessary on ISAs with memory ordering less strict than x86.
+	 * This is necessary on ISAs with memory ordering less strict than x86
+	 * (and even on x86 to act as a compiler barrier).
 	 */
 	atomic_thread_fence_rel();
 	vuh->vu_idx = uidx;