diff --git a/libc/kernel/uapi/linux/vhost.h b/libc/kernel/uapi/linux/vhost.h
index 0349fa7..a844ec8 100644
--- a/libc/kernel/uapi/linux/vhost.h
+++ b/libc/kernel/uapi/linux/vhost.h
@@ -44,6 +44,7 @@
 #define VHOST_SET_VRING_BUSYLOOP_TIMEOUT _IOW(VHOST_VIRTIO, 0x23, struct vhost_vring_state)
 #define VHOST_GET_VRING_BUSYLOOP_TIMEOUT _IOW(VHOST_VIRTIO, 0x24, struct vhost_vring_state)
 #define VHOST_BACKEND_F_IOTLB_MSG_V2 0x1
+#define VHOST_BACKEND_F_IOTLB_BATCH 0x2
 #define VHOST_SET_BACKEND_FEATURES _IOW(VHOST_VIRTIO, 0x25, __u64)
 #define VHOST_GET_BACKEND_FEATURES _IOR(VHOST_VIRTIO, 0x26, __u64)
 #define VHOST_NET_SET_BACKEND _IOW(VHOST_VIRTIO, 0x30, struct vhost_vring_file)