1 files changed, 42 insertions, 2 deletions

diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 72855182b191..ced041899456 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -63,6 +63,9 @@ static __u32 vmbus_get_next_version(__u32 current_version)
         case (VERSION_WIN10):
                 return VERSION_WIN8_1;
 
+        case (VERSION_WIN10_V5):
+                return VERSION_WIN10;
+
         case (VERSION_WS2008):
         default:
                 return VERSION_INVAL;
@@ -80,9 +83,29 @@ static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
 
         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
 
+        memset(msg, 0, sizeof(*msg));
         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
         msg->vmbus_version_requested = version;
-        msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
+
+        /*
+         * VMBus protocol 5.0 (VERSION_WIN10_V5) requires that 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. And, with
+         * VERSION_WIN10_V5, we don't use msg->interrupt_page, but we tell
+         * the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
+         * compatibility.
+         *
+         * On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
+         */
+        if (version >= VERSION_WIN10_V5) {
+                msg->msg_sint = VMBUS_MESSAGE_SINT;
+                vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
+        } else {
+                msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
+                vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
+        }
+
         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
         msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
         /*
@@ -137,6 +160,10 @@ static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
         /* Check if successful */
         if (msginfo->response.version_response.version_supported) {
                 vmbus_connection.conn_state = CONNECTED;
+
+                if (version >= VERSION_WIN10_V5)
+                        vmbus_connection.msg_conn_id =
+                                msginfo->response.version_response.msg_conn_id;
         } else {
                 return -ECONNREFUSED;
         }
@@ -354,13 +381,14 @@ void vmbus_on_event(unsigned long data)
  */
 int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
 {
+        struct vmbus_channel_message_header *hdr;
         union hv_connection_id conn_id;
         int ret = 0;
         int retries = 0;
         u32 usec = 1;
 
         conn_id.asu32 = 0;
-        conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
+        conn_id.u.id = vmbus_connection.msg_conn_id;
 
         /*
          * hv_post_message() can have transient failures because of
@@ -373,6 +401,18 @@ int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
                 switch (ret) {
                 case HV_STATUS_INVALID_CONNECTION_ID:
                         /*
+                         * See vmbus_negotiate_version(): VMBus protocol 5.0
+                         * requires that we must use
+                         * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
+                         * Contact message, but on old hosts that only
+                         * support VMBus protocol 4.0 or lower, here we get
+                         * HV_STATUS_INVALID_CONNECTION_ID and we should
+                         * return an error immediately without retrying.
+                         */
+                        hdr = buffer;
+                        if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
+                                return -EINVAL;
+                        /*
                          * We could get this if we send messages too
                          * frequently.
                          */