Index: sys/dev/virtio/scsi/virtio_scsi.h
===================================================================
--- sys/dev/virtio/scsi/virtio_scsi.h
+++ sys/dev/virtio/scsi/virtio_scsi.h
@@ -37,6 +37,10 @@
 #define VIRTIO_SCSI_F_HOTPLUG	0x0002	/* Host should enable hot plug/unplug
 					 * of new LUNs and targets.
 					 */
+#define VIRTIO_SCSI_F_CHANGE	0x0004	/* Host will report changes to LUN
+					 * parameters via a
+					 * VIRTIO_SCSI_T_PARAM_CHANGE.
+					 */
 
 #define VIRTIO_SCSI_CDB_SIZE	32
 #define VIRTIO_SCSI_SENSE_SIZE	96
@@ -140,6 +144,7 @@
 #define VIRTIO_SCSI_T_NO_EVENT                 0
 #define VIRTIO_SCSI_T_TRANSPORT_RESET          1
 #define VIRTIO_SCSI_T_ASYNC_NOTIFY             2
+#define VIRTIO_SCSI_T_PARAM_CHANGE             3
 
 /* Reasons of transport reset event */
 #define VIRTIO_SCSI_EVT_RESET_HARD             0
Index: sys/dev/virtio/scsi/virtio_scsi.c
===================================================================
--- sys/dev/virtio/scsi/virtio_scsi.c
+++ sys/dev/virtio/scsi/virtio_scsi.c
@@ -206,6 +206,7 @@
 static struct virtio_feature_desc vtscsi_feature_desc[] = {
 	{ VIRTIO_SCSI_F_INOUT,		"InOut"		},
 	{ VIRTIO_SCSI_F_HOTPLUG,	"Hotplug"	},
+	{ VIRTIO_SCSI_F_CHANGE,		"Change"	},
 
 	{ 0, NULL }
 };
@@ -1758,6 +1759,30 @@
 }
 
 static void
+vtscsi_param_change_event(struct vtscsi_softc *sc,
+    struct virtio_scsi_event *event)
+{
+	target_id_t target_id;
+	lun_id_t lun_id;
+	uint8_t asc, ascq;
+
+	vtscsi_get_request_lun(event->lun, &target_id, &lun_id);
+
+	asc = event->reason & 0xff;
+	ascq = event->reason >> 8;
+	/*
+	 * ASC	ASCQ	Description
+	 * 0x2A	0x00	PARAMETERS CHANGED
+	 * 0x2A	0x01	MODE PARAMETERS CHANGED
+	 * 0x2A	0x09	CAPACITY DATA HAS CHANGED
+	 */
+	if (asc == 0x2a && (ascq == 0x00 || ascq == 0x01 || ascq == 0x09)) {
+		/* Disk capacity has changed. */
+		vtscsi_announce(sc, AC_INQ_CHANGED, target_id, lun_id);
+	}
+}
+
+static void
 vtscsi_handle_event(struct vtscsi_softc *sc, struct virtio_scsi_event *event)
 {
 	int error;
@@ -1767,6 +1792,9 @@
 		case VIRTIO_SCSI_T_TRANSPORT_RESET:
 			vtscsi_transport_reset_event(sc, event);
 			break;
+		case VIRTIO_SCSI_T_PARAM_CHANGE:
+			vtscsi_param_change_event(sc, event);
+			break;
 		default:
 			device_printf(sc->vtscsi_dev,
 			    "unhandled event: %d\n", event->event);
Index: sys/dev/virtio/scsi/virtio_scsivar.h
===================================================================
--- sys/dev/virtio/scsi/virtio_scsivar.h
+++ sys/dev/virtio/scsi/virtio_scsivar.h
@@ -141,6 +141,7 @@
 /* Features desired/implemented by this driver. */
 #define VTSCSI_FEATURES \
     (VIRTIO_SCSI_F_HOTPLUG		| \
+     VIRTIO_SCSI_F_CHANGE		| \
      VIRTIO_RING_F_INDIRECT_DESC)
 
 #define VTSCSI_MTX(_sc)			&(_sc)->vtscsi_mtx