linux-kernel - Re: [PATCH 0/3] Disable Suspend-to-Idle in Hyper-V and Fix Hibernation Interruptions

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Message-ID: <20240926034508.GA25516@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net>
Date: Wed, 25 Sep 2024 20:45:08 -0700
From: Erni Sri Satya Vennela <ernis@...ux.microsoft.com>
To: "Srivatsa S. Bhat" <srivatsa@...il.mit.edu>
Cc: kys@...rosoft.com, haiyangz@...rosoft.com, wei.liu@...nel.org,
	decui@...rosoft.com, jikos@...nel.org, bentiss@...nel.org,
	dmitry.torokhov@...il.com, linux-hyperv@...r.kernel.org,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	ernis@...rosoft.com, rafael@...nel.org, pavel@....cz,
	lenb@...nel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH 0/3] Disable Suspend-to-Idle in Hyper-V and Fix
 Hibernation Interruptions

On Tue, Sep 24, 2024 at 03:26:14AM +0000, Srivatsa S. Bhat wrote:
> Hi Vennela,
> 
> [+linux-pm, Rafael, Pavel, Len]
> 
> Let's CC the linux-pm mailing list for discussions related to power
> management features (such as suspend/resume and hibernation).
> 
> On Thu, Sep 12, 2024 at 02:27:47PM -0700, Erni Sri Satya Vennela wrote:
> > It has been reported that Hyper-V VM users can unintentionally abort
> > hibernation by mouse or keyboard movements. To address this issue,
> > we have decided to remove the wakeup events for the Hyper-V keyboard
> > and mouse driver.
> 
> >From the description of the problem, it doesn't occur to me that this
> is specific to Hyper-V. I was wondering if VMs on other hypervisor
> platforms wouldn't face the same issue? I'd like to recommend
> exploring how this problem has been solved for other platforms, so
> that we can reuse the same approach here. (If it turns out that
> removing keyboard and mouse wakeup events is the way to go, then
> great; otherwise, we can learn and apply the recommended solution).
> 
This is how the keyboard and mouse devices can be disabled manually and
is the proper way to address this issue.
>echo disabled > /sys/bus/vmbus/drivers/hid_hyperv/$HV_MOUSE/power/wakeup
>echo disabled > 
>/sys/bus/vmbus/drivers/hyperv_keyboard/$HV_KEYBOARD/power/wakeup
>systemctl hibernate
But based on customer feedback we are totally eliminating them as wakeup
events.

Initially, they were registered as wakeup events to wakeup from
Suspend-to-Idle state. Since there is no real user of this operation,
we are disabling them to ensure they do not interfere with hibernation
process.
> > However, this change introduces another problem: 
> > Suspend-to-Idle brings the system down with no method to wake it back up.
> > 
> > Given that there are no real users of Suspend-to-Idle in Hyper-V,
> > we have decided to disable this feature for VMBus. This results in:
> > 
> > $echo freeze > /sys/power/state
> > > bash: echo: write error: Operation not supported
> > 
> > The keyboard and mouse were previously registered as wakeup sources to
> > interrupt the freeze operation in a VM. Since the freeze operation itself
> > is no longer supported, we are disabling them as wakeup events.
> > 
> > This patchset ensures that the system remains stable and prevents
> > unintended interruptions during hibernation.
> > 
> > Erni Sri Satya Vennela (3):
> >   Drivers: hv: vmbus: Disable Suspend-to-Idle for VMBus
> >   Revert "Input: hyperv-keyboard - register as a wakeup source"
> >   Revert "HID: hyperv: register as a wakeup source"
> > 
> >  drivers/hid/hid-hyperv.c              |  6 ------
> >  drivers/hv/vmbus_drv.c                | 15 ++++++++++++++-
> >  drivers/input/serio/hyperv-keyboard.c | 12 ------------
> >  3 files changed, 14 insertions(+), 19 deletions(-)
> > 
> > -- 
> > 2.34.1
> > 
> > 
> 
> Regards,
> Srivatsa
> Microsoft Linux Systems Group