linux-kernel - Re: [PATCH 2/2] KVM: arm64: pkvm: Don't mask already zeroed FEAT

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Date:   Tue, 10 May 2022 10:45:30 +0100
From:   Fuad Tabba <tabba@...gle.com>
To:     Oliver Upton <oupton@...gle.com>
Cc:     kvmarm@...ts.cs.columbia.edu, kvm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        maz@...nel.org, james.morse@....com, alexandru.elisei@....com,
        suzuki.poulose@....com, qperret@...gle.com, will@...nel.org
Subject: Re: [PATCH 2/2] KVM: arm64: pkvm: Don't mask already zeroed FEAT_SVE

Hi Oliver,


On Mon, May 9, 2022 at 5:26 PM Oliver Upton <oupton@...gle.com> wrote:
>
> FEAT_SVE is already masked by the fixed configuration for
> ID_AA64PFR0_EL1; don't try and mask it at runtime.
>
> No functional change intended.
>
> Signed-off-by: Oliver Upton <oupton@...gle.com>
> ---

Reviewed-by: Fuad Tabba <tabba@...gle.com>

Cheers,
/fuad


>  arch/arm64/kvm/hyp/nvhe/sys_regs.c | 3 ---
>  1 file changed, 3 deletions(-)
>
> diff --git a/arch/arm64/kvm/hyp/nvhe/sys_regs.c b/arch/arm64/kvm/hyp/nvhe/sys_regs.c
> index 33f5181af330..3f5d7bd171c5 100644
> --- a/arch/arm64/kvm/hyp/nvhe/sys_regs.c
> +++ b/arch/arm64/kvm/hyp/nvhe/sys_regs.c
> @@ -90,9 +90,6 @@ static u64 get_pvm_id_aa64pfr0(const struct kvm_vcpu *vcpu)
>         u64 set_mask = 0;
>         u64 allow_mask = PVM_ID_AA64PFR0_ALLOW;
>
> -       if (!vcpu_has_sve(vcpu))
> -               allow_mask &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_SVE);
> -
>         set_mask |= get_restricted_features_unsigned(id_aa64pfr0_el1_sys_val,
>                 PVM_ID_AA64PFR0_RESTRICT_UNSIGNED);
>
> --
> 2.36.0.512.ge40c2bad7a-goog
>