linux-kernel - Re: [PATCH 4/6] x86: KVM: Enable AVX-VNNI-INT8 CPUID and expose it to guest

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Message-ID: <Y0+6tJ7MiZWbYK5l@zn.tnic>
Date:   Wed, 19 Oct 2022 10:52:04 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Jiaxi Chen <jiaxi.chen@...ux.intel.com>
Cc:     kvm@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
        dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
        seanjc@...gle.com, pbonzini@...hat.com, ndesaulniers@...gle.com,
        alexandre.belloni@...tlin.com, peterz@...radead.org,
        jpoimboe@...nel.org, chang.seok.bae@...el.com,
        pawan.kumar.gupta@...ux.intel.com, babu.moger@....com,
        jmattson@...gle.com, sandipan.das@....com, tony.luck@...el.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com, fenghua.yu@...el.com,
        keescook@...omium.org, jane.malalane@...rix.com, nathan@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/6] x86: KVM: Enable AVX-VNNI-INT8 CPUID and expose it
 to guest

On Wed, Oct 19, 2022 at 04:47:32PM +0800, Jiaxi Chen wrote:
> AVX-VNNI-INT8 is a new set of instructions in the latest Intel platform
> Sierra Forest. It multiplies the individual bytes of two unsigned or
> unsigned source operands, then add and accumulate the results into the
> destination dword element size operand. This instruction allows for the
> platform to have superior AI capabilities.
> 
> The bit definition:
> CPUID.(EAX=7,ECX=1):EDX[bit 4]
> 
> This patch enables this CPUID in the kernel feature bits and expose it to
> guest OS. Since the CPUID involves a bit of EDX (EAX=7,ECX=1) which has not
> been enumerated yet, this patch adds CPUID_7_1_EDX to CPUID subleaves. At
> the same time, word 20 is newly-defined in CPU features for CPUID level

For all your commit messages:

Avoid having "This patch" or "This commit" in the commit message. It is
tautologically useless.

Also, do

$ git grep 'This patch' Documentation/process

for more details.

For this particular one, use scattered.c instead of adding a new leaf.

Thx.

-- 
Regards/Gruss,
    Boris.

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