linux-kernel - Re: [PATCH] KVM: x86: Remove the best->function == 0x7 assignment

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Date:   Wed, 24 Feb 2021 10:04:19 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Yejune Deng <yejune.deng@...il.com>
Cc:     pbonzini@...hat.com, vkuznets@...hat.com, wanpengli@...cent.com,
        jmattson@...gle.com, joro@...tes.org, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, x86@...nel.org, hpa@...or.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: x86: Remove the best->function == 0x7 assignment

Hmm, the shortlog should provide a higher level overview of the change.  Stating
the literal code change doesn't provide much context.  Maybe:

  KVM: x86: Remove an unnecessary best->function check

On Wed, Feb 24, 2021, Yejune Deng wrote:
> In kvm_update_cpuid_runtime(), there is no need the best->function
> == 0x7 assignment, because there is e->function == function in

s/assignment/check, here and in the shortlog.

> cpuid_entry2_find().
> 
> Signed-off-by: Yejune Deng <yejune.deng@...il.com>

With the shortlog and changelog cleaned up:

Reviewed-by: Sean Christopherson <seanjc@...gle.com>

> ---
>  arch/x86/kvm/cpuid.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index c8f2592ccc99..eb7a01b1907b 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -120,7 +120,7 @@ void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
>  	}
>  
>  	best = kvm_find_cpuid_entry(vcpu, 7, 0);
> -	if (best && boot_cpu_has(X86_FEATURE_PKU) && best->function == 0x7)
> +	if (best && boot_cpu_has(X86_FEATURE_PKU))
>  		cpuid_entry_change(best, X86_FEATURE_OSPKE,
>  				   kvm_read_cr4_bits(vcpu, X86_CR4_PKE));
>  
> -- 
> 2.29.0
>