linux-kernel - Re: [PATCH] KVM: nVMX: Remove outdated comments in nested_vmx_setup_ctls

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Message-ID: <Y5tmFKPj8ZX2GgUY@google.com>
Date:   Thu, 15 Dec 2022 18:23:16 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Yu Zhang <yu.c.zhang@...ux.intel.com>
Cc:     pbonzini@...hat.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: nVMX: Remove outdated comments in
 nested_vmx_setup_ctls_msrs().

On Thu, Dec 15, 2022, Yu Zhang wrote:
> nested_vmx_setup_ctls_msrs() initializes the vmcs_conf.nested,
> which stores the global VMX MSR configurations when nested is
> supported, regardless of any particular CPUID settings for one
> VM.
> 
> Commit 6defc591846d ("KVM: nVMX: include conditional controls
> in /dev/kvm KVM_GET_MSRS") added the some feature flags for
> secondary proc-based controls, so that those features can be
> available in KVM_GET_MSRS. Yet this commit did not remove the
> obsolete comments in nested_vmx_setup_ctls_msrs().
> 
> Just fix the comments, and no functional change intended.
> 
> Fixes: 6defc591846d ("KVM: nVMX: include conditional controls in /dev/kvm KVM_GET_MSRS")
> Reported-by: Sean Christopherson <seanjc@...gle.com>

I appreciate the nod, but you found this, not me :-)

> Signed-off-by: Yu Zhang <yu.c.zhang@...ux.intel.com>
> ---
>  arch/x86/kvm/vmx/nested.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index b6f4411b613e..76cca5d5aa6b 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -6854,11 +6854,7 @@ void nested_vmx_setup_ctls_msrs(struct vmcs_config *vmcs_conf, u32 ept_caps)
>  	msrs->procbased_ctls_low &=
>  		~(CPU_BASED_CR3_LOAD_EXITING | CPU_BASED_CR3_STORE_EXITING);
>  
> -	/*
> -	 * secondary cpu-based controls.  Do not include those that
> -	 * depend on CPUID bits, they are added later by
> -	 * vmx_vcpu_after_set_cpuid.
> -	 */
> +	/* secondary cpu-based controls */

Eh, just drop the comment.  Pretty obvious this is for secondary execution controls.

>  	msrs->secondary_ctls_low = 0;
>  
>  	msrs->secondary_ctls_high = vmcs_conf->cpu_based_2nd_exec_ctrl;
> -- 
> 2.17.1
>