linux-kernel - Re: [PATCH v4 1/6] x86: KVM: Advertise CMPccXADD CPUID to user space

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Message-ID: <Y3fQRy3aqRbrkkZH@zn.tnic>
Date:   Fri, 18 Nov 2022 19:34:47 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Jiaxi Chen <jiaxi.chen@...ux.intel.com>, 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, nathan@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/6] x86: KVM: Advertise CMPccXADD CPUID to user space

On Fri, Nov 18, 2022 at 08:47:55AM -0800, Dave Hansen wrote:
> Also, do we *want* this showing up in /proc/cpuinfo?

Yeah, I was wondering about that. Currently, we try to add feature bits
to /proc/cpuinfo only when the kernel has done any enablement for them.
For other needs, people should use tools/arch/x86/kcpuid/

If we say that adding those bits so that guests can export them doesn't
count as a real enablement, then sure we can hide them initially.

I wanna say yes here...

-- 
Regards/Gruss,
    Boris.

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