Re: [PATCH] KVM: arm64: Bump KVM_VCPU_MAX_FEATURES

[Marc Zyngier <maz@kernel.org>]

On Wed, 27 Nov 2024 15:24:32 +0000,
Steven Price <steven.price@arm.com> wrote:
> 
> On 27/11/2024 15:16, Marc Zyngier wrote:
> > On Wed, 27 Nov 2024 14:56:31 +0000,
> > Steven Price <steven.price@arm.com> wrote:
> >>
> >> When the KVM_ARM_VCPU_HAS_EL2 define was added, the value of
> >> KVM_VCPU_MAX_FEATURES wasn't incremented, so that feature has never been
> >> in the KVM_VCPU_VALID_FEATURES bit mask. This means the HAS_EL2 feature
> >> will never be exposed to user space even if the system supports it.
> >>
> >> Fixes: 89b0e7de3451 ("KVM: arm64: nv: Introduce nested virtualization VCPU feature")
> >> Signed-off-by: Steven Price <steven.price@arm.com>
> >> ---
> >> I might be missing something, and it's possible that
> >> KVM_ARM_VCPU_HAS_EL2 is deliberately not exposed yet.
> > 
> > This is on purpose. I'm not planning to enable EL2 support until it is
> > ready.
> 
> I did suspect that's the case - but it might have been better to knobble
> it in system_supported_vcpu_features()/kvm_vcpu_init_check_features()
> rather than 'hiding' it in the MAX_FEATURES. But hindsight is a
> wonderful thing ;)
> 
> >> However I'm
> >> working on v6 of the host CCA series and as part of that want to add a
> >> new feature but and bump KVM_VCPU_MAX_FEATURES up to 9.
> > 
> > Well, I guess that defines some ordering then! :D
> 
> Indeed - I'll try to remember to include note about this "dependency" in
> my cover letter. We're likely to need a few more rounds for CCA to be
> ready, so hopefully NV will naturally be there in time :D

Any minute now, according to those impersonating a French physicist...

	M.

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