Re: [PATCH 1/2] xenbus: Use .freeze/.thaw to handle xenbus devices

["Yann Sionneau" <yann.sionneau@xxxxxxxxxx>]

Hi Jason,

On 11/19/25 23:46, Jason Andryuk wrote:
> The goal is to fix s2idle and S3 for Xen PV devices.  A domain resuming
> from s3 or s2idle disconnects its PV devices during resume.  The
> backends are not expecting this and do not reconnect.
> 
> b3e96c0c7562 ("xen: use freeze/restore/thaw PM events for suspend/
> resume/chkpt") changed xen_suspend()/do_suspend() from
> PMSG_SUSPEND/PMSG_RESUME to PMSG_FREEZE/PMSG_THAW/PMSG_RESTORE, but the
> suspend/resume callbacks remained.
> 
> .freeze/restore are used with hiberation where Linux restarts in a new
> place in the future.  .suspend/resume are useful for runtime power
> management for the duration of a boot.
> 
> The current behavior of the callbacks works for an xl save/restore or
> live migration where the domain is restored/migrated to a new location
> and connecting to a not-already-connected backend.
> 
> Change xenbus_pm_ops to use .freeze/thaw/restore and drop the
> .suspend/resume hook.  This matches the use in drivers/xen/manage.c for
> save/restore and live migration.  With .suspend/resume empty, PV devices
> are left connected during s2idle and s3, so PV devices are not changed
> and work after resume.
> 
> Signed-off-by: Jason Andryuk <jason.andryuk@xxxxxxx>
> ---
>   drivers/xen/xenbus/xenbus_probe_frontend.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c 
> b/drivers/xen/xenbus/xenbus_probe_frontend.c
> index 6d1819269cbe..199917b6f77c 100644
> --- a/drivers/xen/xenbus/xenbus_probe_frontend.c
> +++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
> @@ -148,11 +148,9 @@ static void xenbus_frontend_dev_shutdown(struct device 
> *_dev)
>   }
>   
>   static const struct dev_pm_ops xenbus_pm_ops = {
> -     .suspend        = xenbus_dev_suspend,
> -     .resume         = xenbus_frontend_dev_resume,
>       .freeze         = xenbus_dev_suspend,
>       .thaw           = xenbus_dev_cancel,
> -     .restore        = xenbus_dev_resume,
> +     .restore        = xenbus_frontend_dev_resume,
>   };
>   
>   static struct xen_bus_type xenbus_frontend = {

I've tried putting Debian 13 to sleep with your patch (echo freeze > 
/sys/power/state) and could not wake up the guest.
Isn't it also mandatory to apply this patch 
https://github.com/QubesOS/qubes-linux-kernel/blob/main/xen-events-Add-wakeup-support-to-xen-pirq.patch
 
?

With both patches applied, I get the wake up to work.

Regards,

-- 


--
Yann Sionneau | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech