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

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Message-ID: <ZvIxVn1NKWuJ4u2k@csail.mit.edu>
Date: Tue, 24 Sep 2024 03:26:14 +0000
From: "Srivatsa S. Bhat" <srivatsa@...il.mit.edu>
To: Erni Sri Satya Vennela <ernis@...ux.microsoft.com>
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

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).

> 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