Drivers: hv: Save and export negotiated vmbus version

Export the negotiated vmbus version as this may be useful for
individual drivers.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/connection.c

@@ -30,6 +30,7 @@
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/hyperv.h>
+#include <linux/export.h>
 #include <asm/hyperv.h>
 #include "hyperv_vmbus.h"
 
@@ -54,6 +55,12 @@ struct vmbus_connection vmbus_connection = {
 
 #define VERSION_INVAL -1
 
+/*
+ * Negotiated protocol version with the host.
+ */
+__u32 vmbus_proto_version;
+EXPORT_SYMBOL_GPL(vmbus_proto_version);
+
 static __u32 vmbus_get_next_version(__u32 current_version)
 {
 	switch (current_version) {
@@ -215,6 +222,8 @@ int vmbus_connect(void)
 	if (version == VERSION_INVAL)
 		goto cleanup;
 
+	vmbus_proto_version = version;
+	pr_info("Negotiated host information %d\n", version);
 	kfree(msginfo);
 	return 0;
 

include/linux/hyperv.h

@@ -1204,5 +1204,11 @@ int hv_kvp_init(struct hv_util_service *);
 void hv_kvp_deinit(void);
 void hv_kvp_onchannelcallback(void *);
 
+/*
+ * Negotiated version with the Host.
+ */
+
+extern __u32 vmbus_proto_version;
+
 #endif /* __KERNEL__ */
 #endif /* _HYPERV_H */