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From: Ingo Molnar <mingo@kernel.org>
To: Sandipan Das <sandipan.das@amd.com>
Cc: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
	x86@kernel.org, peterz@infradead.org, acme@kernel.org,
	namhyung@kernel.org, mark.rutland@arm.com,
	alexander.shishkin@linux.intel.com, jolsa@kernel.org,
	adrian.hunter@intel.com, tglx@linutronix.de, bp@alien8.de,
	seanjc@google.com, pbonzini@redhat.com, eranian@google.com,
	irogers@google.com, ravi.bangoria@amd.com,
	ananth.narayan@amd.com
Subject: Re: [PATCH v4 1/2] x86/cpufeatures: Add dedicated feature word for CPUID leaf 0x80000022[EAX]
Date: Tue, 19 Mar 2024 14:00:26 +0100	[thread overview]
Message-ID: <ZfmMah58YSyYGywo@gmail.com> (raw)
In-Reply-To: <ZflmU+H2Lt2I0VOq@gmail.com>


* Ingo Molnar <mingo@kernel.org> wrote:

> > +/* AMD-defined performance monitoring features, CPUID level 0x80000022 (EAX), word 21 */
> > +#define X86_FEATURE_PERFMON_V2		(21*32+ 0) /* AMD Performance Monitoring Version 2 */
> > +#define X86_FEATURE_AMD_LBR_V2		(21*32+ 1) /* AMD Last Branch Record Extension Version 2 */
> 
> Thank you! I presume you tested both patches on the relevant system 
> with the X86_FEATURE_AMD_LBR_PMC_FREEZE bug?

Also, Boris reminds me that we really want to do what I suggested 
originally and use a new synthethic word here, not a new vendor word, to 
keep all the bits better compressed in cpuinfo.x86_capability[] - so one 
more iteration will be needed.

Thanks,

	Ingo

  parent reply	other threads:[~2024-03-19 13:00 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-19  8:18 [PATCH v4 0/2] perf/x86/amd: Fix for LBR Freeze Sandipan Das
2024-03-19  8:18 ` [PATCH v4 1/2] x86/cpufeatures: Add dedicated feature word for CPUID leaf 0x80000022[EAX] Sandipan Das
2024-03-19 10:17   ` Ingo Molnar
2024-03-19 10:36     ` Sandipan Das
2024-03-19 13:00     ` Ingo Molnar [this message]
2024-03-19  8:18 ` [PATCH v4 2/2] perf/x86/amd/lbr: Use freeze based on availability Sandipan Das

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