linux-kernel - Re: [PATCH 0/5] KVM: x86: Use kernel x86 cpuid utilities in KVM selftests

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Date:   Thu, 22 Apr 2021 09:02:09 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Ricardo Koller <ricarkol@...gle.com>
Cc:     kvm@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com
Subject: Re: [PATCH 0/5] KVM: x86: Use kernel x86 cpuid utilities in KVM
 selftests

On 22/04/21 02:56, Ricardo Koller wrote:
> The kernel has a set of utilities and definitions to deal with x86 cpu
> features.  The x86 KVM selftests don't use them, and instead have
> evolved to use differing and ad-hoc methods for checking features. The
> advantage of the kernel feature definitions is that they use a format
> that embeds the info needed to extract them from cpuid (function, index,
> and register to use).
> 
> The first 3 patches massage the related cpuid header files in the kernel
> side, then copy them into tools/ so they can be included by selftests.
> The last 2 patches replace the tests checking for cpu features to use
> the definitions and utilities introduced from the kernel.

I queued the first, but I am not sure about the rest.

An alternative is to copy over the code from kvm-unit-tests which 
encodes the leaf/subleaf/register/bit values into the X86_FEATURE_* 
value.  Sharing code with kvm-unit-tests is probably simpler than adding 
#ifdef __KERNEL__ and keeping the headers in sync.

Paolo

> Thanks,
> Ricardo
> 
> Ricardo Koller (5):
>    KVM: x86: Move reverse CPUID helpers to separate header file
>    x86/cpu: Expose CPUID regs, leaf and index definitions to tools
>    tools headers x86: Copy cpuid helpers from the kernel
>    KVM: selftests: Introduce utilities for checking x86 features
>    KVM: selftests: Use kernel x86 cpuid features format
> 
>   arch/x86/events/intel/pt.c                    |   1 +
>   arch/x86/include/asm/cpufeature.h             |  23 +-
>   arch/x86/include/asm/processor.h              |  11 -
>   arch/x86/kernel/cpu/scattered.c               |   2 +-
>   arch/x86/kernel/cpuid.c                       |   2 +-
>   arch/x86/kvm/cpuid.h                          | 177 +-----------
>   arch/x86/kvm/reverse_cpuid.h                  | 185 +++++++++++++
>   tools/arch/x86/include/asm/cpufeature.h       | 257 ++++++++++++++++++
>   tools/arch/x86/include/asm/cpufeatures.h      |   3 +
>   .../selftests/kvm/include/x86_64/cpuid.h      |  61 +++++
>   .../selftests/kvm/include/x86_64/processor.h  |  16 --
>   .../kvm/include/x86_64/reverse_cpuid.h        | 185 +++++++++++++
>   .../selftests/kvm/include/x86_64/svm_util.h   |  11 +-
>   tools/testing/selftests/kvm/lib/x86_64/svm.c  |   6 +-
>   tools/testing/selftests/kvm/lib/x86_64/vmx.c  |   5 +-
>   tools/testing/selftests/kvm/steal_time.c      |   5 +-
>   .../kvm/x86_64/cr4_cpuid_sync_test.c          |  23 +-
>   .../selftests/kvm/x86_64/set_sregs_test.c     |  25 +-
>   .../selftests/kvm/x86_64/vmx_pmu_msrs_test.c  |   8 +-
>   .../kvm/x86_64/vmx_set_nested_state_test.c    |   5 +-
>   .../selftests/kvm/x86_64/xss_msr_test.c       |  10 +-
>   21 files changed, 749 insertions(+), 272 deletions(-)
>   create mode 100644 arch/x86/kvm/reverse_cpuid.h
>   create mode 100644 tools/arch/x86/include/asm/cpufeature.h
>   create mode 100644 tools/testing/selftests/kvm/include/x86_64/cpuid.h
>   create mode 100644 tools/testing/selftests/kvm/include/x86_64/reverse_cpuid.h
>