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

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.

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