[PATCH 1/3] Drivers: hv: vmbus: Disable Suspend-to-Idle for VMBus

[Erni Sri Satya Vennela <ernis@linux.microsoft.com>]

If the Virtual Machine Connection window is focused,
a Hyper-V VM user can unintentionally touch the keyboard/mouse
when the VM is hibernating or resuming, and consequently the
hibernation or resume operation can be aborted unexpectedly.
Fix the issue by no longer registering the keyboard/mouse as
wakeup devices (see the other two patches for the
changes to drivers/input/serio/hyperv-keyboard.c and
drivers/hid/hid-hyperv.c).

The keyboard/mouse were registered as wakeup devices because the
VM needs to be woken up from the Suspend-to-Idle state after
a user runs "echo freeze > /sys/power/state". It seems like
the Suspend-to-Idle feature has no real users in practice, so
let's no longer support that by returning -EOPNOTSUPP if a
user tries to use that.

Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Signed-off-by: Erni Sri Satya Vennela <ernis@linux.microsoft.com>
---
 drivers/hv/vmbus_drv.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 965d2a4efb7e..4efd8856392f 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -900,6 +900,19 @@ static void vmbus_shutdown(struct device *child_device)
 }
 
 #ifdef CONFIG_PM_SLEEP
+/*
+ * vmbus_freeze - Suspend-to-Idle
+ */
+static int vmbus_freeze(struct device *child_device)
+{
+/*
+ * Do not support Suspend-to-Idle ("echo freeze > /sys/power/state") as
+ * that would require registering the Hyper-V synthetic mouse/keyboard
+ * devices as wakeup devices, which can abort hibernation/resume unexpectedly.
+ */
+	return -EOPNOTSUPP;
+}
+
 /*
  * vmbus_suspend - Suspend a vmbus device
  */
@@ -969,7 +982,7 @@ static void vmbus_device_release(struct device *device)
  */
 
 static const struct dev_pm_ops vmbus_pm = {
-	.suspend_noirq	= NULL,
+	.suspend_noirq  = vmbus_freeze,
 	.resume_noirq	= NULL,
 	.freeze_noirq	= vmbus_suspend,
 	.thaw_noirq	= vmbus_resume,
-- 
2.34.1