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From: Marc Zyngier <marc.zyngier@arm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Jason Cooper <jason@lakedaemon.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	Grzegorz Jaszczyk <jaz@semihalf.com>
Subject: Re: [PATCH 0/3] irqchip: GIC kexec/kdump improvement and workarounds
Date: Tue, 13 Mar 2018 18:35:07 +0000	[thread overview]
Message-ID: <72c7a6d2-a4c4-26b2-2982-c1d1ffb39b81@arm.com> (raw)
In-Reply-To: <20180313175156.gmncij4rnqcdl5ie@lakrids.cambridge.arm.com>

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.

> That would avoid some work (including pointer chasing on potentially
> corrupt memory) in the kernel that crashed, making it more likely that
> we get to the crashkernel intact...

Seems perfectly sensible to me.

	M.
-- 
Jazz is not dead. It just smells funny...

WARNING: multiple messages have this Message-ID (diff)
From: marc.zyngier@arm.com (Marc Zyngier)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 0/3] irqchip: GIC kexec/kdump improvement and workarounds
Date: Tue, 13 Mar 2018 18:35:07 +0000	[thread overview]
Message-ID: <72c7a6d2-a4c4-26b2-2982-c1d1ffb39b81@arm.com> (raw)
In-Reply-To: <20180313175156.gmncij4rnqcdl5ie@lakrids.cambridge.arm.com>

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.

> That would avoid some work (including pointer chasing on potentially
> corrupt memory) in the kernel that crashed, making it more likely that
> we get to the crashkernel intact...

Seems perfectly sensible to me.

	M.
-- 
Jazz is not dead. It just smells funny...

  reply	other threads:[~2018-03-13 18:35 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-13 17:21 [PATCH 0/3] irqchip: GIC kexec/kdump improvement and workarounds Marc Zyngier
2018-03-13 17:21 ` Marc Zyngier
2018-03-13 17:21 ` [PATCH 1/3] irqchip/gic-v2: Reset APRn registers at boot time Marc Zyngier
2018-03-13 17:21   ` Marc Zyngier
2018-03-13 17:21 ` [PATCH 2/3] irqchip/gic-v3: Reset APgRn " Marc Zyngier
2018-03-13 17:21   ` Marc Zyngier
2018-03-13 17:21 ` [PATCH 3/3] irqchip/gic-v3: Allow LPIs to be disabled from the command line Marc Zyngier
2018-03-13 17:21   ` Marc Zyngier
2018-03-15 14:58   ` Shanker Donthineni
2018-03-15 14:58     ` Shanker Donthineni
2018-03-15 15:59     ` Marc Zyngier
2018-03-15 15:59       ` Marc Zyngier
2018-03-13 17:51 ` [PATCH 0/3] irqchip: GIC kexec/kdump improvement and workarounds Mark Rutland
2018-03-13 17:51   ` Mark Rutland
2018-03-13 18:35   ` Marc Zyngier [this message]
2018-03-13 18:35     ` Marc Zyngier
2018-03-14 16:57     ` Mark Rutland
2018-03-14 16:57       ` Mark Rutland
2018-03-14 17:11       ` Thomas Gleixner
2018-03-14 17:11         ` Thomas Gleixner
2018-03-14 17:42         ` Marc Zyngier
2018-03-14 17:42           ` Marc Zyngier
2018-03-14 19:35           ` Thomas Gleixner
2018-03-14 19:35             ` Thomas Gleixner

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