linux-kernel - Re: [PATCH 1/2] Enumerate AVX Vector Neural Network instructions

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Date:   Tue, 5 Jan 2021 13:14:56 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Yang Zhong <yang.zhong@...el.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
        hpa@...or.com, tony.luck@...el.com, seanjc@...gle.com,
        vkuznets@...hat.com, wanpengli@...cent.com, jmattson@...gle.com,
        joro@...tes.org, kyung.min.park@...el.com, x86@...nel.org
Subject: Re: [PATCH 1/2] Enumerate AVX Vector Neural Network instructions

On Tue, Jan 05, 2021 at 12:47:23PM +0100, Paolo Bonzini wrote:
> On 05/01/21 01:49, Yang Zhong wrote:
> > From: Kyung Min Park <kyung.min.park@...el.com>
> > 
> > Add AVX version of the Vector Neural Network (VNNI) Instructions.
> > 
> > A processor supports AVX VNNI instructions if CPUID.0x07.0x1:EAX[4] is
> > present. The following instructions are available when this feature is
> > present.
> >    1. VPDPBUS: Multiply and Add Unsigned and Signed Bytes
> >    2. VPDPBUSDS: Multiply and Add Unsigned and Signed Bytes with Saturation
> >    3. VPDPWSSD: Multiply and Add Signed Word Integers
> >    4. VPDPWSSDS: Multiply and Add Signed Integers with Saturation
> > 
> > The only in-kernel usage of this is kvm passthrough. The CPU feature
> > flag is shown as "avx_vnni" in /proc/cpuinfo.
> > 
> > This instruction is currently documented in the latest "extensions"
> > manual (ISE). It will appear in the "main" manual (SDM) in the future.
> > 
> > Signed-off-by: Kyung Min Park <kyung.min.park@...el.com>
> > Signed-off-by: Yang Zhong <yang.zhong@...el.com>
> > Reviewed-by: Tony Luck <tony.luck@...el.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 f5ef2d5b9231..d10d9962bd9b 100644
> > --- a/arch/x86/include/asm/cpufeatures.h
> > +++ b/arch/x86/include/asm/cpufeatures.h
> > @@ -293,6 +293,7 @@
> >   #define X86_FEATURE_PER_THREAD_MBA	(11*32+ 7) /* "" Per-thread Memory Bandwidth Allocation */
> >   /* Intel-defined CPU features, CPUID level 0x00000007:1 (EAX), word 12 */
> > +#define X86_FEATURE_AVX_VNNI		(12*32+ 4) /* AVX VNNI instructions */
> >   #define X86_FEATURE_AVX512_BF16		(12*32+ 5) /* AVX512 BFLOAT16 instructions */
> >   /* AMD-defined CPU features, CPUID level 0x80000008 (EBX), word 13 */
> > 
> 
> Boris, is it possible to have a topic branch for this patch?

Just take it through your tree pls.

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

Thx.

-- 
Regards/Gruss,
    Boris.

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