[PATCH 1/2] arm64: smp: Fix pseudo NMI issues w/ broken Mediatek FW

[Catalin Marinas]

On Thu, Oct 05, 2023 at 08:34:56AM -0700, Doug Anderson wrote:
> On Thu, Oct 5, 2023 at 3:27 AM Mark Rutland <mark.rutland at arm.com> wrote:
> > On Wed, Oct 04, 2023 at 07:04:12AM -0700, Doug Anderson wrote:
> > > On Wed, Oct 4, 2023 at 3:15 AM Marc Zyngier <maz at kernel.org> wrote:
> > > > On Wed, 04 Oct 2023 10:59:50 +0100,
> > > > Mark Rutland <mark.rutland at arm.com> wrote:
> > > > > Given you haven't seen any issues, I suspect those are getting reset to fixed
> > > > > values that happens to work out for us, but it is a bit worrisome more
> > > > > generally (e.g. the LPI case above).
> > > >
> > > > It is likely that these SoCs don't even have an ITS.
> > >
> > > Right. That was what we decided [1] when Marc pointed this out earlier.
> > >
> > > Overall: we know that this firmware behavior is not good but we're
> > > stuck with it. :( At the very least, any new devices coming out will
> > > have this fixed. Presumably if old devices are working OK enough today
> > > (as long as you don't enable pseudo-NMI) then they can be made to keep
> > > working?
> > >
> > > So circling back: what patch should we actually land?
> >
> > For now I'd prefer we took the patch I sent in:
> >
> >   https://lore.kernel.org/linux-arm-kernel/ZRr8r7XMoyDKaitd@FVFF77S0Q05N.cambridge.arm.com/
> >
> > ... as that leaves us no worse than before this series, and it's pretty simple.
> 
> Sounds good to me!
> 
> Catalin / Will: Please yell if there's anything you need me to do.
> Otherwise I'll assume you'll pick up Mark's patch instead of my patch
> #1 and then you'll pick up my patch #2.

I applied both to the arm64 for-next/backtrace-ipi branch. Thanks.

-- 
Catalin