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Date:   Thu, 18 Feb 2021 15:26:18 +0000
From:   Mark Rutland <mark.rutland@arm.com>
To:     Hector Martin <marcan@marcan.st>
Cc:     Arnd Bergmann <arnd@kernel.org>, Rob Herring <robh@kernel.org>,
        Tony Lindgren <tony@atomide.com>,
        Marc Zyngier <maz@kernel.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        linux-kernel@vger.kernel.org,
        Krzysztof Kozlowski <krzk@kernel.org>,
        devicetree@vger.kernel.org, Alexander Graf <graf@amazon.com>,
        Olof Johansson <olof@lixom.net>,
        Mohamed Mediouni <mohamed.mediouni@caramail.com>,
        Stan Skowronek <stan@corellium.com>,
        Will Deacon <will@kernel.org>,
        linux-arm-kernel@lists.infradead.org,
        Mark Kettenis <mark.kettenis@xs4all.nl>
Subject: Re: [PATCH v2 08/25] arm64: Always keep DAIF.[IF] in sync
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On Thu, Feb 18, 2021 at 11:42:01PM +0900, Hector Martin wrote:
> On 18/02/2021 23.22, Mark Rutland wrote:
> > I think that for consistency we always want to keep IRQ and FIQ in-sync,
> > even when using GIC priorities. So when handling a pseudo-NMI we should
> > unmask DAIF.DA and leave DAIF.IF masked.
> 
> In that case there's one more, in daifflags.h:local_daif_restore():
> 
> 			/*
> 			 * If interrupts are disabled but we can take
> 			 * asynchronous errors, we can take NMIs
> 			 */
> 			flags &= PSR_I_BIT;
> 			pmr = GIC_PRIO_IRQOFF;

Good spot, yes!

I did a quick scan with `git grep 'PSR_[IF]_BIT' -- arch/arm64`, and
AFAICT that's the last one.

> > > And a minor related one: should init_gic_priority_masking() WARN if FIQ is
> > > masked too? This probably goes with the above.
> > 
> > I think it should, yes.
> 
> Done for v3 then. Thanks!

Cool!

Mark.