Drivers: hv: vmbus: enable VMBus protocol version 5.0

With VMBus protocol 5.0, we're able to better support new features, e.g.
running two or more VMBus drivers simultaneously in a single VM -- note:
we can't simply load the current VMBus driver twice, instead, a secondary
VMBus driver must be implemented.

This patch adds the support for the new VMBus protocol, which is available
on new Windows hosts, by:

1) We still use SINT2 for compatibility;
2) We must use Connection ID 4 for the Initiate Contact Message, and for
subsequent messages, we must use the Message Connection ID field in
the host-returned VersionResponse Message.

Notes for developers of the secondary VMBus driver:
1) Must use VMBus protocol 5.0 as well;
2) Must use a different SINT number that is not in use.
3) Must use Connection ID 4 for the Initiate Contact Message, and for
subsequent messages, must use the Message Connection ID field in
the host-returned VersionResponse Message.
4) It's possible that the primary VMBus driver using protocol version 4.0
can work with a secondary VMBus driver using protocol version 5.0, but it's
recommended that both should use 5.0 for new Hyper-V features in the future.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 24 insertions, 2 deletions

diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 192ed8fbc403..11b5612dc066 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -163,6 +163,7 @@ static inline u32 hv_get_bytes_to_write(const struct hv_ring_buffer_info *rbi)
  * 2 . 4  (Windows 8)
  * 3 . 0  (Windows 8 R2)
  * 4 . 0  (Windows 10)
+ * 5 . 0  (Newer Windows 10)
  */
 
 #define VERSION_WS2008  ((0 << 16) | (13))
@@ -170,10 +171,11 @@ static inline u32 hv_get_bytes_to_write(const struct hv_ring_buffer_info *rbi)
 #define VERSION_WIN8    ((2 << 16) | (4))
 #define VERSION_WIN8_1    ((3 << 16) | (0))
 #define VERSION_WIN10	((4 << 16) | (0))
+#define VERSION_WIN10_V5 ((5 << 16) | (0))
 
 #define VERSION_INVAL -1
 
-#define VERSION_CURRENT VERSION_WIN10
+#define VERSION_CURRENT VERSION_WIN10_V5
 
 /* Make maximum size of pipe payload of 16K */
 #define MAX_PIPE_DATA_PAYLOAD		(sizeof(u8) * 16384)
@@ -570,7 +572,14 @@ struct vmbus_channel_initiate_contact {
 	struct vmbus_channel_message_header header;
 	u32 vmbus_version_requested;
 	u32 target_vcpu; /* The VCPU the host should respond to */
-	u64 interrupt_page;
+	union {
+		u64 interrupt_page;
+		struct {
+			u8	msg_sint;
+			u8	padding1[3];
+			u32	padding2;
+		};
+	};
 	u64 monitor_page1;
 	u64 monitor_page2;
 } __packed;
@@ -585,6 +594,19 @@ struct vmbus_channel_tl_connect_request {
 struct vmbus_channel_version_response {
 	struct vmbus_channel_message_header header;
 	u8 version_supported;
+
+	u8 connection_state;
+	u16 padding;
+
+	/*
+	 * On new hosts that support VMBus protocol 5.0, we must use
+	 * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
+	 * and for subsequent messages, we must use the Message Connection ID
+	 * field in the host-returned Version Response Message.
+	 *
+	 * On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
+	 */
+	u32 msg_conn_id;
 } __packed;
 
 enum vmbus_channel_state {