Drivers: hv: vmbus: Implement the protocol for tearing down vmbus state

Implement the protocol for tearing down the monitor state established with
the host.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Tested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

4 files changed, 33 insertions, 1 deletions

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 865a3afa1d86..4b9d89ab44d3 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -422,6 +422,30 @@ static void init_vp_index(struct vmbus_channel *channel, const uuid_le *type_gui
 }
 
 /*
+ * vmbus_unload_response - Handler for the unload response.
+ */
+static void vmbus_unload_response(struct vmbus_channel_message_header *hdr)
+{
+        /*
+         * This is a global event; just wakeup the waiting thread.
+         * Once we successfully unload, we can cleanup the monitor state.
+         */
+        complete(&vmbus_connection.unload_event);
+}
+
+void vmbus_initiate_unload(void)
+{
+        struct vmbus_channel_message_header hdr;
+
+        init_completion(&vmbus_connection.unload_event);
+        memset(&hdr, 0, sizeof(struct vmbus_channel_message_header));
+        hdr.msgtype = CHANNELMSG_UNLOAD;
+        vmbus_post_msg(&hdr, sizeof(struct vmbus_channel_message_header));
+
+        wait_for_completion(&vmbus_connection.unload_event);
+}
+
+/*
  * vmbus_onoffer - Handler for channel offers from vmbus in parent partition.
  *
  */
@@ -717,6 +741,7 @@ struct vmbus_channel_message_table_entry
         {CHANNELMSG_INITIATE_CONTACT,           0, NULL},
         {CHANNELMSG_VERSION_RESPONSE,           1, vmbus_onversion_response},
         {CHANNELMSG_UNLOAD,                     0, NULL},
+        {CHANNELMSG_UNLOAD_RESPONSE,            1, vmbus_unload_response},
 };
 
 /*
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index b27220a425f4..acd50e9d666a 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -227,6 +227,11 @@ cleanup:
 
 void vmbus_disconnect(void)
 {
+        /*
+         * First send the unload request to the host.
+         */
+        vmbus_initiate_unload();
+
         if (vmbus_connection.work_queue) {
                 drain_workqueue(vmbus_connection.work_queue);
                 destroy_workqueue(vmbus_connection.work_queue);
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 138d6634c79d..cddc0c9f6bf9 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -647,6 +647,7 @@ struct vmbus_connection {
 
         atomic_t next_gpadl_handle;
 
+        struct completion  unload_event;
         /*
          * Represents channel interrupts. Each bit position represents a
          * channel.  When a channel sends an interrupt via VMBUS, it finds its
@@ -741,6 +742,7 @@ void hv_vss_onchannelcallback(void *);
 int hv_fcopy_init(struct hv_util_service *);
 void hv_fcopy_deinit(void);
 void hv_fcopy_onchannelcallback(void *);
+void vmbus_initiate_unload(void);
 
 static inline void hv_poll_channel(struct vmbus_channel *channel,
                                    void (*cb)(void *))
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 7870a906365e..2b56260b0eb4 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1106,6 +1106,7 @@ static void __exit vmbus_exit(void)
 
         vmbus_connection.conn_state = DISCONNECTED;
         hv_synic_clockevents_cleanup();
+        vmbus_disconnect();
         hv_remove_vmbus_irq();
         vmbus_free_channels();
         if (ms_hyperv.features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
@@ -1118,7 +1119,6 @@ static void __exit vmbus_exit(void)
                 smp_call_function_single(cpu, hv_synic_cleanup, NULL, 1);
         acpi_bus_unregister_driver(&vmbus_acpi_driver);
         hv_cpu_hotplug_quirk(false);
-        vmbus_disconnect();
 }