linux-kernel - Re: [PATCH v2 1/2] x86/cpufeatures: Add the Virtual SPEC

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Date:   Wed, 30 Dec 2020 08:15:41 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Babu Moger <babu.moger@....com>
Cc:     pbonzini@...hat.com, tglx@...utronix.de, mingo@...hat.com,
        fenghua.yu@...el.com, tony.luck@...el.com, wanpengli@...cent.com,
        kvm@...r.kernel.org, thomas.lendacky@....com, peterz@...radead.org,
        seanjc@...gle.com, joro@...tes.org, x86@...nel.org,
        kyung.min.park@...el.com, linux-kernel@...r.kernel.org,
        krish.sadhukhan@...cle.com, hpa@...or.com, mgross@...ux.intel.com,
        vkuznets@...hat.com, kim.phillips@....com, wei.huang2@....com,
        jmattson@...gle.com
Subject: Re: [PATCH v2 1/2] x86/cpufeatures: Add the Virtual SPEC_CTRL feature

On Tue, Dec 22, 2020 at 04:31:32PM -0600, Babu Moger wrote:
> Newer AMD processors have a feature to virtualize the use of the
> SPEC_CTRL MSR. Presence of this feature is indicated via CPUID
> function 0x8000000A_EDX[20]: GuestSpecCtrl. When preset, the SPEC_CTRL
> MSR is automatically virtualized.
> 
> Signed-off-by: Babu Moger <babu.moger@....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 dad350d42ecf..aee4a924ecd7 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -335,6 +335,7 @@
>  #define X86_FEATURE_AVIC		(15*32+13) /* Virtual Interrupt Controller */
>  #define X86_FEATURE_V_VMSAVE_VMLOAD	(15*32+15) /* Virtual VMSAVE VMLOAD */
>  #define X86_FEATURE_VGIF		(15*32+16) /* Virtual GIF */
> +#define X86_FEATURE_V_SPEC_CTRL 	(15*32+20) /* Virtual SPEC_CTRL */
>  
>  /* Intel-defined CPU features, CPUID level 0x00000007:0 (ECX), word 16 */
>  #define X86_FEATURE_AVX512VBMI		(16*32+ 1) /* AVX512 Vector Bit Manipulation instructions*/


I'm guessing this will go through the kvm tree so:

Acked-by: Borislav Petkov <bp@...e.de>

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette