Drivers: hv: Add a check to deal with spurious interrupts

We establish the handler before we have fully initialized the VMBUS state.
Deal with spurious interrupts.

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>

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index e066d418be97..797142c07fa0 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -454,6 +454,12 @@ static irqreturn_t vmbus_isr(int irq, void *dev_id)
         union hv_synic_event_flags *event;
         bool handled = false;
 
+        page_addr = hv_context.synic_event_page[cpu];
+        if (page_addr == NULL)
+                return IRQ_NONE;
+
+        event = (union hv_synic_event_flags *)page_addr +
+                                         VMBUS_MESSAGE_SINT;
         /*
          * Check for events before checking for messages. This is the order
          * in which events and messages are checked in Windows guests on
@@ -463,10 +469,6 @@ static irqreturn_t vmbus_isr(int irq, void *dev_id)
         if ((vmbus_proto_version == VERSION_WS2008) ||
                 (vmbus_proto_version == VERSION_WIN7)) {
 
-                page_addr = hv_context.synic_event_page[cpu];
-                event = (union hv_synic_event_flags *)page_addr +
-                                         VMBUS_MESSAGE_SINT;
-
                 /* Since we are a child, we only need to check bit 0 */
                 if (sync_test_and_clear_bit(0,
                         (unsigned long *) &event->flags32[0])) {