linux-kernel - Re: [PATCH v2 2/5] KVM: selftests: Add timing_info bit support in vmx_pmu_caps

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aMH1xwsK1eTjJh71@google.com>
Date: Wed, 10 Sep 2025 15:03:51 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Dapeng Mi <dapeng1.mi@...ux.intel.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Jim Mattson <jmattson@...gle.com>, Mingwei Zhang <mizhang@...gle.com>, 
	Zide Chen <zide.chen@...el.com>, Das Sandipan <Sandipan.Das@....com>, 
	Shukla Manali <Manali.Shukla@....com>, Yi Lai <yi1.lai@...el.com>, 
	Dapeng Mi <dapeng1.mi@...el.com>
Subject: Re: [PATCH v2 2/5] KVM: selftests: Add timing_info bit support in vmx_pmu_caps_test

On Fri, Jul 18, 2025, Dapeng Mi wrote:
> A new bit PERF_CAPABILITIES[17] called "PEBS_TIMING_INFO" bit is added
> to indicated if PEBS supports to record timing information in a new
> "Retried Latency" field.
> 
> Since KVM requires user can only set host consistent PEBS capabilities,
> otherwise the PERF_CAPABILITIES setting would fail, so add
> pebs_timing_info bit into "immutable_caps" to block host inconsistent
> PEBS configuration and cause errors.

Please explain the removal of anythread_deprecated.  AFAICT, something like this
is accurate:

Opportunistically drop the anythread_deprecated bit.  It isn't and likely
never was a PERF_CAPABILITIES flag, the test's definition snuck in when
the union was copy+pasted from the kernel's definition.

> Signed-off-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
> Tested-by: Yi Lai <yi1.lai@...el.com>
> ---
>  tools/testing/selftests/kvm/x86/vmx_pmu_caps_test.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/kvm/x86/vmx_pmu_caps_test.c b/tools/testing/selftests/kvm/x86/vmx_pmu_caps_test.c
> index a1f5ff45d518..f8deea220156 100644
> --- a/tools/testing/selftests/kvm/x86/vmx_pmu_caps_test.c
> +++ b/tools/testing/selftests/kvm/x86/vmx_pmu_caps_test.c
> @@ -29,7 +29,7 @@ static union perf_capabilities {
>  		u64 pebs_baseline:1;
>  		u64	perf_metrics:1;
>  		u64	pebs_output_pt_available:1;
> -		u64	anythread_deprecated:1;
> +		u64	pebs_timing_info:1;
>  	};
>  	u64	capabilities;
>  } host_cap;
> @@ -44,6 +44,7 @@ static const union perf_capabilities immutable_caps = {
>  	.pebs_arch_reg = 1,
>  	.pebs_format = -1,
>  	.pebs_baseline = 1,
> +	.pebs_timing_info = 1,
>  };
>  
>  static const union perf_capabilities format_caps = {
> -- 
> 2.34.1
>