[PATCH] arm64/irq: use NMI to send stop IPI

[Pingfan Liu]

On Tue, Dec 8, 2020 at 10:04 PM Marc Zyngier <maz at kernel.org> wrote:
>
> On 2020-12-08 13:14, Pingfan Liu wrote:
> > Like other arches, both 'kexec -l' and 'kexec -p' expect to use NMI to
> > interrupt other cpus in order to capture cpus tightly to a known state.
> >
> > So for both of the cases, try to use NMI IPI if irqchip supports NMI.
>
> There are at least 2 other competing series doing the same thing,
> and (ab)using NMIs for dubious purposes (kexec, kgdb...)
>
I think kexec has a good justification, but start with (2) at present.
> (1) Please work with others instead of reinventing things from scratch,
>      with similar problems
>
I will.
> (2) No additional NMI patches will make it until we have resolved the
> issues
>      described in [1], which is likely to take some time
>
After serval days of chasing this issue, I have a raw idea about it.
What about re-structure the code like
DEFINE_IDTENTRY_SYSVEC_SIMPLE(sysvec_reschedule_ipi) ?

I will send a series soon afterward.

Thanks,
Pingfan

> Thanks,
>
>          M.
>
> [1]
> https://lore.kernel.org/linux-arm-kernel/87lfewnmdz.fsf@nanos.tec.linutronix.de/
> --
> Jazz is not dead. It just smells funny...