Subject: Re: [PATCH 7/8] KVM: arm64: Workaround firmware wrongly advertising GICv2-on-v3 compatibility

From: Marc Zyngier <[email-masked]>
Date: Mon, 15 Mar 2021 14:36:33 +0000

On Mon, 15 Mar 2021 12:55:42 +0000,
Shameerali Kolothum Thodi <[email-masked]> wrote:
> 
> 
> 
> > -----Original Message-----
> > From: Marc Zyngier [mailto:[email-masked]]
> > Sent: 05 March 2021 18:53
> > To: Paolo Bonzini <[email-masked]>
> > Cc: Alexandru Elisei <[email-masked]>; Andre Przywara
> > <[email-masked]>; Andrew Scull <[email-masked]>; Catalin
> > Marinas <[email-masked]>; Christoffer Dall
> > <[email-masked]>; Howard Zhang <[email-masked]>; Jia
> > He <[email-masked]>; Mark Rutland <[email-masked]>; Quentin
> > Perret <[email-masked]>; Shameerali Kolothum Thodi
> > <[email-masked]>; Suzuki K Poulose
> > <[email-masked]>; Will Deacon <[email-masked]>; James Morse
> > <[email-masked]>; Julien Thierry <[email-masked]>;
> > [email-masked]; [email-masked];
> > [email-masked]; [email-masked]
> > Subject: [PATCH 7/8] KVM: arm64: Workaround firmware wrongly advertising
> > GICv2-on-v3 compatibility
> > 
> > It looks like we have broken firmware out there that wrongly advertises
> > a GICv2 compatibility interface, despite the CPUs not being able to deal
> > with it.
> > 
> > To work around this, check that the CPU initialising KVM is actually able
> > to switch to MMIO instead of system registers, and use that as a
> > precondition to enable GICv2 compatibility in KVM.
> > 
> > Note that the detection happens on a single CPU. If the firmware is
> > lying *and* that the CPUs are asymetric, all hope is lost anyway.
> > 
> > Reported-by: Shameerali Kolothum Thodi
> > <[email-masked]>
> > Tested-by: Shameer Kolothum <[email-masked]>
> > Signed-off-by: Marc Zyngier <[email-masked]>
> 
> Is it possible to add stable tag for this? Looks like we do have
> systems out there and reports issues.

It is already merged. Which kernel versions do you need that for? In
any case, please submit the backports, and I'll review them.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

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