linux-kernel - Re: [PATCH v4 1/3] Drivers: hv: vmbus: Disable Suspend-to-Idle for VMBus

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Message-ID: <Z2HQkTfB18nvZn8a@liuwe-devbox-debian-v2>
Date: Tue, 17 Dec 2024 19:27:13 +0000
From: Wei Liu <wei.liu@...nel.org>
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,
	stable@...r.kernel.org,
	Saurabh Sengar <ssengar@...ux.microsoft.com>
Subject: Re: [PATCH v4 1/3] Drivers: hv: vmbus: Disable Suspend-to-Idle for
 VMBus

On Mon, Dec 16, 2024 at 08:17:07PM -0800, Erni Sri Satya Vennela wrote:
> This change is specific to Hyper-V VM user.
> 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.
> 
> Fixes: 1a06d017fb3f ("Drivers: hv: vmbus: Fix Suspend-to-Idle for Generation-2 VM")
> Cc: stable@...r.kernel.org
> Signed-off-by: Saurabh Sengar <ssengar@...ux.microsoft.com>
> Signed-off-by: Erni Sri Satya Vennela <ernis@...ux.microsoft.com>>
> ---
> Changes in v4:
> * No change
> 
> Changes in v3:
> * Add "Cc: stable@...r.kernel.org" in sign-off area.
> 
> Changes in v2:
> * Add "#define vmbus_freeze NULL" when CONFIG_PM_SLEEP is not 
>   enabled.
> ---
>  drivers/hv/vmbus_drv.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 6d89d37b069a..4df6b12bf6a1 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.
> + */

The indentation is off. I can fix it for you if the series gets
sufficient reviews. Please fix it yourself if you end up posting another
round.

Thanks,
Wei.

> +	return -EOPNOTSUPP;
> +}
> +
>  /*
>   * vmbus_suspend - Suspend a vmbus device
>   */
> @@ -938,6 +951,7 @@ static int vmbus_resume(struct device *child_device)
>  	return drv->resume(dev);
>  }
>  #else
> +#define vmbus_freeze NULL
>  #define vmbus_suspend NULL
>  #define vmbus_resume NULL
>  #endif /* CONFIG_PM_SLEEP */
> @@ -969,7 +983,7 @@ 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
>