[PATCH for-stable-5.10 2/2] KVM: arm64: Workaround firmware wrongly advertising GICv2-on-v3 compatibility

[Shameerali Kolothum Thodi]

> -----Original Message-----
> From: Marc Zyngier [mailto:maz at kernel.org]
> Sent: 25 March 2021 09:33
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi at huawei.com>
> Cc: kvmarm at lists.cs.columbia.edu; kvm at vger.kernel.org;
> linux-arm-kernel at lists.infradead.org; stable at vger.kernel.org;
> pbonzini at redhat.com; Linuxarm <linuxarm at huawei.com>
> Subject: Re: [PATCH for-stable-5.10 2/2] KVM: arm64: Workaround firmware
> wrongly advertising GICv2-on-v3 compatibility
> 
> On 2021-03-25 09:14, Shameer Kolothum wrote:
> > From: Marc Zyngier <maz at kernel.org>
> >
> > commit 9739f6ef053f104a997165701c6e15582c4307ee upstream.
> >
> > 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.
> >
> > Cc: stable at vger.kernel.org #5.10
> > Reported-by: Shameerali Kolothum Thodi
> > <shameerali.kolothum.thodi at huawei.com>
> > Tested-by: Shameer Kolothum <shameerali.kolothum.thodi at huawei.com>
> > Signed-off-by: Marc Zyngier <maz at kernel.org>
> > Message-Id: <20210305185254.3730990-8-maz at kernel.org>
> > Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
> > Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi at huawei.com>
> 
> Please hold on on that.
> 
> This patch causes a regression, and needs a fix that is currently queued for 5.12
> [1]. Once this hits upstream, please add the fix to the series and post it as a
> whole.

Ok. Yes, I noted that. But was thinking if this goes through first and then we can have a 
stable tag for that one, we can manage it. Anyway, will wait now.

Thanks,
Shameer
 
> Thanks,
> 
>          M.
> 
> [1] https://lore.kernel.org/r/20210323162301.2049595-1-maz@kernel.org
> --
> Jazz is not dead. It just smells funny...