linux-kernel - Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512

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Message-ID: <20161031095312.dzv3rj2fqgjjsy7w@pd.tnic>
Date:   Mon, 31 Oct 2016 10:53:12 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Luc, Piotr" <Piotr.Luc@...el.com>
Cc:     "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "he.chen@...ux.intel.com" <he.chen@...ux.intel.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "Kang, Luwei" <luwei.kang@...el.com>,
        "rkrcmar@...hat.com" <rkrcmar@...hat.com>
Subject: Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS
 features to kvm guest

On Mon, Oct 31, 2016 at 09:15:43AM +0000, Luc, Piotr wrote:
> I think that in v4.9-rc2 the CPUID[7,0].edx bits can be masked out by
> applying noxsave to cmdline. Using directly cpu_count will result in
> passing the bits in edx to a guest directly while the xsaveopt and rest
> of AVX512 features bits will be cleared. 

Errr, I can't parse that reading it backwards and forwards. Please
elaborate.

-- 
Regards/Gruss,
    Boris.

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