linux-kernel - Re: [PATCH 0/3] irqchip: GIC kexec/kdump improvement and workarounds

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Message-ID: <20180314165708.daoui66waxvicciq@lakrids.cambridge.arm.com>
Date:   Wed, 14 Mar 2018 16:57:09 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     Marc Zyngier <marc.zyngier@....com>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Jason Cooper <jason@...edaemon.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Grzegorz Jaszczyk <jaz@...ihalf.com>
Subject: Re: [PATCH 0/3] irqchip: GIC kexec/kdump improvement and workarounds

On Tue, Mar 13, 2018 at 06:35:07PM +0000, Marc Zyngier wrote:
> On 13/03/18 17:51, Mark Rutland wrote:
> > On Tue, Mar 13, 2018 at 05:21:00PM +0000, Marc Zyngier wrote:
> >> As kexec and kdump are getting used a bit more intensively, I've been
> >> made aware of a number of shortcomings.
> >>
> >> The main gripe is from folks trying to launch a kdump kernel from
> >> within an interrupt handler. If using EOImode==1, things work as
> >> expected. If using EOImode==0 (such as in a guest), the secondary
> >> kernel hangs as the previous interrupt hasn't been EOI'd, and the
> >> active priority is still set. The first two patches are addressing
> >> this situation for both GICv2 and GICv3 by reseting the APRs to their
> >> default value.
> > 
> > As a more general thing, if irqchip drivers have state that needs to be
> > reset in their init code, can we live all this irqchip reset to the
> > crashdump kernel, and kill machine_kexec_mask_interrupts() entirely?
> 
> We could, once we know for sure that all the potential irqchips have
> been fixed. Or we could just remove it immediately, and see what breaks.

I would be very tempted to do the latter.

Thanks,
Mark.