linux-kernel - Re: [PATCHv4 1/8] x86/cpu: Add CPUID feature bit for VNMI

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Message-ID: <CALMp9eTrz2SkK=CjTSc9NdHvP4qsP+UWukFadbqv+BA+KdtMMg@mail.gmail.com>
Date:   Wed, 31 Aug 2022 16:42:03 -0700
From:   Jim Mattson <jmattson@...gle.com>
To:     Santosh Shukla <santosh.shukla@....com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Tom Lendacky <thomas.lendacky@....com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, mlevitsk@...hat.com,
        mail@...iej.szmigiero.name
Subject: Re: [PATCHv4 1/8] x86/cpu: Add CPUID feature bit for VNMI

On Mon, Aug 29, 2022 at 3:09 AM Santosh Shukla <santosh.shukla@....com> wrote:
>
> VNMI feature allows the hypervisor to inject NMI into the guest w/o
> using Event injection mechanism, The benefit of using VNMI over the
> event Injection that does not require tracking the Guest's NMI state and
> intercepting the IRET for the NMI completion. VNMI achieves that by
> exposing 3 capability bits in VMCB intr_cntrl which helps with
> virtualizing NMI injection and NMI_Masking.
>
> The presence of this feature is indicated via the CPUID function
> 0x8000000A_EDX[25].
>
> Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>
> Signed-off-by: Santosh Shukla <santosh.shukla@....com>
> ---
>  arch/x86/include/asm/cpufeatures.h | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> index ef4775c6db01..33e3603be09e 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -356,6 +356,7 @@
>  #define X86_FEATURE_VGIF               (15*32+16) /* Virtual GIF */
>  #define X86_FEATURE_X2AVIC             (15*32+18) /* Virtual x2apic */
>  #define X86_FEATURE_V_SPEC_CTRL                (15*32+20) /* Virtual SPEC_CTRL */
> +#define X86_FEATURE_V_NMI              (15*32+25) /* Virtual NMI */
>  #define X86_FEATURE_SVME_ADDR_CHK      (15*32+28) /* "" SVME addr check */

Why is it "V_NMI," but "VGIF"?

Reviewed-by: Jim Mattson <jmattson@...gle.com>