linux-kernel - Re: [PATCH 0/3] selftests: Remove duplicate CPUID wrappers

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Message-ID: <81df8c0e-fde6-f3b8-f988-b539f193635b@linuxfoundation.org>
Date:   Fri, 4 Feb 2022 16:39:38 -0700
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     Reinette Chatre <reinette.chatre@...el.com>, shuah@...nel.org,
        linux-kselftest@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ram Pai <linuxram@...ibm.com>,
        Sandipan Das <sandipan@...ux.ibm.com>,
        Florian Weimer <fweimer@...hat.com>,
        "Desnes A. Nunes do Rosario" <desnesn@...ux.vnet.ibm.com>,
        Ingo Molnar <mingo@...nel.org>,
        Thiago Jung Bauermann <bauerman@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Michal Suchanek <msuchanek@...e.de>, linux-mm@...ck.org,
        "Chang S . Bae" <chang.seok.bae@...el.com>,
        Borislav Petkov <bp@...e.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Andy Lutomirski <luto@...nel.org>,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH 0/3] selftests: Remove duplicate CPUID wrappers

On 2/4/22 12:17 PM, Reinette Chatre wrote:
> A few tests that require running CPUID do so with a private
> implementation of a wrapper for CPUID. This duplication of
> the CPUID wrapper should be avoided but having one is also
> unnecessary because of the existence of a macro that can
> be used instead.
> 
> This series replaces private CPUID wrappers with calls
> to the __cpuid_count() macro from cpuid.h as made available
> by gcc and clang/llvm.
> 
> Cc: Dave Hansen <dave.hansen@...ux.intel.com>
> Cc: Ram Pai <linuxram@...ibm.com>
> Cc: Sandipan Das <sandipan@...ux.ibm.com>
> Cc: Florian Weimer <fweimer@...hat.com>
> Cc: "Desnes A. Nunes do Rosario" <desnesn@...ux.vnet.ibm.com>
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: Thiago Jung Bauermann <bauerman@...ux.ibm.com>
> Cc: Michael Ellerman <mpe@...erman.id.au>
> Cc: Michal Suchanek <msuchanek@...e.de>
> Cc: linux-mm@...ck.org
> Cc: Chang S. Bae <chang.seok.bae@...el.com>
> Cc: Borislav Petkov <bp@...e.de>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: "H. Peter Anvin" <hpa@...or.com>
> Cc: x86@...nel.org
> Cc: Andy Lutomirski <luto@...nel.org>
> 
> Reinette Chatre (3):
>    selftests/vm/pkeys: Use existing __cpuid_count() macro
>    selftests/x86/amx: Use existing __cpuid_count() macro
>    selftests/x86/corrupt_xstate_header: Use existing __cpuid_count()
>      macro
> 
>   tools/testing/selftests/vm/pkey-x86.h         | 22 +++---------------
>   tools/testing/selftests/x86/amx.c             | 23 +++++--------------
>   .../selftests/x86/corrupt_xstate_header.c     | 17 ++------------
>   3 files changed, 11 insertions(+), 51 deletions(-)
> 

I am all for this cleanup. However, I am not finding __cpuid_count()
marco on my system with gcc:

gcc --version
gcc (Ubuntu 11.2.0-7ubuntu2) 11.2.0

My concern is regression on older gcc versions.

thanks,
-- Shuah