On Mon, 15 Mar 2021 12:55:42 +0000,
Shameerali Kolothum Thodi [off-list ref] wrote:

quoted

-----Original Message-----
From: Marc Zyngier [mailto:maz@kernel.org]
Sent: 05 March 2021 18:53
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Alexandru Elisei <redacted>; Andre Przywara
[off-list ref]; Andrew Scull [off-list ref]; Catalin
Marinas [off-list ref]; Christoffer Dall
[off-list ref]; Howard Zhang [off-list ref]; Jia
He [off-list ref]; Mark Rutland [off-list ref]; Quentin
Perret [off-list ref]; Shameerali Kolothum Thodi
[off-list ref]; Suzuki K Poulose
[off-list ref]; Will Deacon [off-list ref]; James Morse
[off-list ref]; Julien Thierry [off-list ref];
kernel-team@android.com; linux-arm-kernel@lists.infradead.org;
kvmarm@lists.cs.columbia.edu; kvm@vger.kernel.org
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
[off-list ref]
Tested-by: Shameer Kolothum <redacted>
Signed-off-by: Marc Zyngier <maz@kernel.org>

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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