diff --git a/drivers/hv/hv_utils_transport.h b/drivers/hv/hv_utils_transport.h
index 06254a1..d98f522 100644
--- a/drivers/hv/hv_utils_transport.h
+++ b/drivers/hv/hv_utils_transport.h
@@ -36,6 +36,7 @@
 	struct list_head list;              /* hvt_list */
 	int (*on_msg)(void *, int);         /* callback on new user message */
 	void (*on_reset)(void);             /* callback when userspace drops */
+	void (*on_read)(void);              /* callback on message read */
 	u8 *outmsg;                         /* message to the userspace */
 	int outmsg_len;                     /* its length */
 	wait_queue_head_t outmsg_q;         /* poll/read wait queue */
@@ -46,7 +47,8 @@
 					       u32 cn_idx, u32 cn_val,
 					       int (*on_msg)(void *, int),
 					       void (*on_reset)(void));
-int hvutil_transport_send(struct hvutil_transport *hvt, void *msg, int len);
+int hvutil_transport_send(struct hvutil_transport *hvt, void *msg, int len,
+			  void (*on_read_cb)(void));
 void hvutil_transport_destroy(struct hvutil_transport *hvt);
 
 #endif /* _HV_UTILS_TRANSPORT_H */