Drivers: hv: vmbus: Support handling messages on multiple CPUs

Starting with Windows 2012 R2, message inteerupts can be delivered
on any VCPU in the guest. Support this functionality.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 6cd12f1..64713ff 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -45,7 +45,6 @@
 
 static struct acpi_device  *hv_acpi_dev;
 
-static struct tasklet_struct msg_dpc;
 static struct completion probe_event;
 
 
@@ -712,7 +711,7 @@
 	vmbus_signal_eom(msg);
 }
 
-static void vmbus_on_msg_dpc(unsigned long data)
+void vmbus_on_msg_dpc(unsigned long data)
 {
 	int cpu = smp_processor_id();
 	void *page_addr = hv_context.synic_message_page[cpu];
@@ -800,7 +799,7 @@
 		if (msg->header.message_type == HVMSG_TIMER_EXPIRED)
 			hv_process_timer_expiration(msg, cpu);
 		else
-			tasklet_schedule(&msg_dpc);
+			tasklet_schedule(hv_context.msg_dpc[cpu]);
 	}
 }
 
@@ -824,8 +823,6 @@
 		return ret;
 	}
 
-	tasklet_init(&msg_dpc, vmbus_on_msg_dpc, 0);
-
 	ret = bus_register(&hv_bus);
 	if (ret)
 		goto err_cleanup;
@@ -1321,7 +1318,8 @@
 	hv_synic_clockevents_cleanup();
 	vmbus_disconnect();
 	hv_remove_vmbus_irq();
-	tasklet_kill(&msg_dpc);
+	for_each_online_cpu(cpu)
+		tasklet_kill(hv_context.msg_dpc[cpu]);
 	vmbus_free_channels();
 	if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
 		unregister_die_notifier(&hyperv_die_block);