From: Dexuan Cui <decui@microsoft.com> Sent: Tuesday, November 19, 2019 11:14 PM

During the suspend process and resume process, if there is any keyboard
event, there is a small chance the suspend and the resume process can be
aborted because of hv_kbd_on_receive() -> pm_wakeup_hard_event().

This behavior can be avoided by disabling the Hyper-V keyboard device as
a wakeup source:

echo disabled > /sys/bus/vmbus/drivers/hyperv_keyboard/XXX/power/wakeup
(XXX is the device's GUID).

I'd like to see a more descriptive commit message, along the lines of:

Add suspend() and resume() functions so the Hyper-V virtual keyboard
can participate in VM hibernation.

Note that the keyboard is a "wakeup" device that could abort an in-progress
hibernation if there is keyboard event.  No attempt is made to suppress this
behavior.  If desired, a sysadmin can disable the keyboard as a wakeup device
using standard mechanisms such as:

echo disabled > /sys/bus/vmbus/drivers/hyperv_keyboard/XXX/power/wakeup
(where XXX is the device's GUID)

Signed-off-by: Dexuan Cui <decui@microsoft.com>
---

This patch is basically a pure Hyper-V specific change. I suggest it should
go through the Hyper-V tree:
https://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux.git/log/?h=hyperv-next

Changes in v2:
  Removed the "struct notifier_block pm_nb;" after the discussion
with Dmitry Torokhov:

https://lore.kernel.org/lkml/PU1P153MB016914A7C827CA35D7FEB66ABF8B0@PU1P153MB0169.APCP153.PROD.OUTLOOK.COM/T/#m8948c711301220a36a1a413eead74cd2fb6dcac1 (local)> 

 drivers/input/serio/hyperv-keyboard.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

Notwithstanding the suggestion on the commit message,

Reviewed-by:  Michael Kelley <redacted>