Index: head/sys/dev/hyperv/include/vmbus.h
===================================================================
--- head/sys/dev/hyperv/include/vmbus.h
+++ head/sys/dev/hyperv/include/vmbus.h
@@ -173,5 +173,7 @@
 		vmbus_chan_guid_inst(const struct vmbus_channel *chan);
 int		vmbus_chan_prplist_nelem(int br_size, int prpcnt_max,
 		    int dlen_max);
+bool		vmbus_chan_rx_empty(const struct vmbus_channel *chan);
+bool		vmbus_chan_tx_empty(const struct vmbus_channel *chan);
 
 #endif	/* !_VMBUS_H_ */
Index: head/sys/dev/hyperv/vmbus/vmbus_brvar.h
===================================================================
--- head/sys/dev/hyperv/vmbus/vmbus_brvar.h
+++ head/sys/dev/hyperv/vmbus/vmbus_brvar.h
@@ -83,6 +83,20 @@
 	return (tbr->txbr_dsize - sizeof(uint64_t) - 1);
 }
 
+static __inline bool
+vmbus_txbr_empty(const struct vmbus_txbr *tbr)
+{
+
+	return (tbr->txbr_windex == tbr->txbr_rindex ? true : false);
+}
+
+static __inline bool
+vmbus_rxbr_empty(const struct vmbus_rxbr *rbr)
+{
+
+	return (rbr->rxbr_windex == rbr->rxbr_rindex ? true : false);
+}
+
 static __inline int
 vmbus_br_nelem(int br_size, int elem_size)
 {
Index: head/sys/dev/hyperv/vmbus/vmbus_chan.c
===================================================================
--- head/sys/dev/hyperv/vmbus/vmbus_chan.c
+++ head/sys/dev/hyperv/vmbus/vmbus_chan.c
@@ -1692,3 +1692,17 @@
 
 	return (vmbus_br_nelem(br_size, elem_size));
 }
+
+bool
+vmbus_chan_tx_empty(const struct vmbus_channel *chan)
+{
+
+	return (vmbus_txbr_empty(&chan->ch_txbr));
+}
+
+bool
+vmbus_chan_rx_empty(const struct vmbus_channel *chan)
+{
+
+	return (vmbus_rxbr_empty(&chan->ch_rxbr));
+}