Re: [kvm-unit-tests PATCH v4 1/2] x86: Skip perf related tests when platform cannot support

[Sean Christopherson <seanjc@google.com>]

On Tue, Jun 28, 2022, Yang Weijiang wrote:
> Add helpers to check whether MSR_CORE_PERF_GLOBAL_CTRL and rdpmc
> are supported in KVM. When pmu is disabled with enable_pmu=0,
> reading MSR_CORE_PERF_GLOBAL_CTRL or executing rdpmc leads to #GP,
> so skip related tests in this case to avoid test failure.
> 
> Opportunistically replace some "printf" with "report_skip" to make
> the output log clean.

Ooof, these end up dominating the patch.  Can you split them to a separate prep
patch?  Thanks!

> Suggested-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
> 
> v4:
> - Use supported_fn() to make the code nicer. [Sean]
> - Replace some of the printf with report_skip to make the results clean. [Sean]

Put the versioning info below the three dashes so that it doesn't show up in the
final changelog.

> ---

<version info goes here>

>  lib/x86/processor.h | 10 ++++++++++
>  x86/vmx_tests.c     | 40 +++++++++++++++++++++++++++-------------
>  2 files changed, 37 insertions(+), 13 deletions(-)
> 
> diff --git a/lib/x86/processor.h b/lib/x86/processor.h
> index 9a0dad6..7b6ee92 100644
> --- a/lib/x86/processor.h
> +++ b/lib/x86/processor.h
> @@ -690,4 +690,14 @@ static inline bool cpuid_osxsave(void)
>  	return cpuid(1).c & (1 << (X86_FEATURE_OSXSAVE % 32));
>  }
>  
> +static inline u8 pmu_version(void)
> +{
> +	return cpuid(10).a & 0xff;
> +}
> +
> +static inline bool cpu_has_perf_global_ctrl(void)
> +{
> +	return pmu_version() > 1;
> +}
> +
>  #endif
> diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
> index 4d581e7..3a14cb2 100644
> --- a/x86/vmx_tests.c
> +++ b/x86/vmx_tests.c
> @@ -852,6 +852,10 @@ static bool monitor_supported(void)
>  	return this_cpu_has(X86_FEATURE_MWAIT);
>  }
>  
> +static inline bool pmu_supported(void) {

Curly brace goes on a new line.

> +	return !!pmu_version();
> +}

Why not put this in processor.h?  And maybe call it cpu_has_pmu()?