diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 92f78df0f685..a017011ad1f5 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -563,6 +563,9 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
 		r = copy_to_user(argp, &v->vdpa->ngroups,
 				 sizeof(v->vdpa->ngroups));
 		break;
+	case VHOST_VDPA_GET_AS_NUM:
+		r = copy_to_user(argp, &v->vdpa->nas, sizeof(v->vdpa->nas));
+		break;
 	case VHOST_SET_LOG_BASE:
 	case VHOST_SET_LOG_FD:
 		r = -ENOIOCTLCMD;
diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
index 61317c61d768..51322008901a 100644
--- a/include/uapi/linux/vhost.h
+++ b/include/uapi/linux/vhost.h
@@ -154,4 +154,6 @@
 /* Get the number of virtqueue groups. */
 #define VHOST_VDPA_GET_GROUP_NUM	_IOR(VHOST_VIRTIO, 0x81, __u32)
 
+/* Get the number of address spaces. */
+#define VHOST_VDPA_GET_AS_NUM		_IOR(VHOST_VIRTIO, 0x7A, unsigned int)
 #endif