Re: [Xen-devel] [PATCH] xen: Suspend ticks on all CPUs during suspend

[Boris Ostrovsky]

On 04/27/2015 06:33 AM, David Vrabel wrote:
> On 08/04/15 19:53, Boris Ostrovsky wrote:
> > Commit 77e32c89a711 ("clockevents: Manage device's state separately for
> > the core") decouples clockevent device's modes from states. With this
> > change when a Xen guest tries to resume, it won't be calling its
> > set_mode op which needs to be done on each VCPU in order to make the
> > hypervisor aware that we are in oneshot mode.
> >
> > This happens because clockevents_tick_resume() (which is an intermediate
> > step of resuming ticks on a processor) no longer calls clockevents_set_state()
> > and because during suspend clockevent devices on all VCPUs (except for the
> > one doing the suspend) are left in ONESHOT state. As result, during resume
> > the clockevents state machine will assume that device is already where it
> > should be and doesn't need to be updated.
> >
> > To avoid this problem we should suspend ticks on all VCPUs during
> > suspend.
> Sorry for the delay in reviewing this.
>
> > diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
> > index bf19407..2fd9fe8 100644
> > --- a/drivers/xen/manage.c
> > +++ b/drivers/xen/manage.c
> > @@ -131,6 +131,8 @@ static void do_suspend(void)
> >   		goto out_resume;
> >   	}
> >   
> > +	xen_arch_suspend();
> > +
> >   	si.cancelled = 1;
> xen_arch_resume() is only called when !si.cancelled but you call
> xen_arch_suspend() unconditionally.


Good point. Let me see if I can move this to xen_arch_post_suspend, when 
we know whether the suspend has been canceled.

-boris
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