Re: xen: IPI interrupts not resumed early enough on suspend/resume

From: Thomas Gleixner
Date: Mon Oct 03 2011 - 14:42:36 EST

On Mon, 3 Oct 2011, Ian Campbell wrote:
> I can see a few options for how I might go about solving this in a
> non-hacky way, which approach do you think would be preferable:

The question is whether you need to disable the IPI interrupt at
all. If not, we have a flag for that.

> * Add "IRQF_RESUME_EARLY", driven from syscore_resume, and use it
> for these interrupts.

That's the preferable solution, as we could use that for PPC as well,
unless we can move stuff around, so we disable stuff later.

> * register syscore ops for the Xen event channel subsystem to
> unmask the IPIs earlier (would probably look a lot like the code
> removed by 676dc3cf5bc3).

I'd like to avoid that.

> * add syscore_ops to Xen smp subsystem to unmask the specific IPIs
> (which it binds at start of day) earlier.
> * push dpm_(suspend|resume)_noirq down into stop machine region

Where is stomp machine used?

> * use something other than stop_machine to quiesce system and move
> to cpu0 for suspend (doesn't seem sensible to reproduce that
> functionality).

We already shut down the nonboot cpus on suspend. We could do that
_before_ we disable devices and the interrupts.

Raphael ?


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