diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 79c4aa7..898eac9 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -392,6 +392,10 @@
 	CHANNELMSG_VERSION_RESPONSE		= 15,
 	CHANNELMSG_UNLOAD			= 16,
 	CHANNELMSG_UNLOAD_RESPONSE		= 17,
+	CHANNELMSG_18				= 18,
+	CHANNELMSG_19				= 19,
+	CHANNELMSG_20				= 20,
+	CHANNELMSG_TL_CONNECT_REQUEST		= 21,
 	CHANNELMSG_COUNT
 };
 
@@ -562,6 +566,13 @@
 	u64 monitor_page2;
 } __packed;
 
+/* Hyper-V socket: guest's connect()-ing to host */
+struct vmbus_channel_tl_connect_request {
+	struct vmbus_channel_message_header header;
+	uuid_le guest_endpoint_id;
+	uuid_le host_service_id;
+} __packed;
+
 struct vmbus_channel_version_response {
 	struct vmbus_channel_message_header header;
 	u8 version_supported;
@@ -1283,4 +1294,6 @@
 
 extern __u32 vmbus_proto_version;
 
+int vmbus_send_tl_connect_request(const uuid_le *shv_guest_servie_id,
+				  const uuid_le *shv_host_servie_id);
 #endif /* _HYPERV_H */