Drivers: hv: Cleanup vmbus_set_event() to support win7 and beyond

On win7 (ws2008 R2) and beyond, we have the notion of having dedicated interrupts on
a per-channel basis. When a channel has a dedicated interrupt assigned, there is no need
to set the interrupt bit in the shared page. Implement this optimization.
Signed-off-by: NK. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: NHaiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/connection.c

@@ -383,10 +383,13 @@ int vmbus_post_msg(void *buffer, size_t buflen)
 int vmbus_set_event(struct vmbus_channel *channel)
 {
 	u32 child_relid = channel->offermsg.child_relid;
-	/* Each u32 represents 32 channels */
-	sync_set_bit(child_relid & 31,
-		(unsigned long *)vmbus_connection.send_int_page +
-		(child_relid >> 5));
 
-	return hv_signal_event(hv_context.signal_event_param);
+	if (!channel->is_dedicated_interrupt) {
+		/* Each u32 represents 32 channels */
+		sync_set_bit(child_relid & 31,
+			(unsigned long *)vmbus_connection.send_int_page +
+			(child_relid >> 5));
+	}
+
+	return hv_signal_event(channel->sig_event);
 }