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From: "Mi, Dapeng" <dapeng1.mi@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	Ian Rogers <irogers@google.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Andi Kleen <ak@linux.intel.com>,
	Eranian Stephane <eranian@google.com>,
	linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
	Dapeng Mi <dapeng1.mi@intel.com>, Zide Chen <zide.chen@intel.com>,
	Falcon Thomas <thomas.falcon@intel.com>,
	Xudong Hao <xudong.hao@intel.com>,
	stable@vger.kernel.org
Subject: Re: [Patch v3 1/8] perf/x86/intel: Remove anythread_deprecated bit from perf_capabilities
Date: Mon, 15 Jun 2026 08:59:29 +0800	[thread overview]
Message-ID: <96a18944-bc0d-47dd-b435-e9aa63b93c43@linux.intel.com> (raw)
In-Reply-To: <20260612094648.GB42921@noisy.programming.kicks-ass.net>


On 6/12/2026 5:46 PM, Peter Zijlstra wrote:
> On Fri, Jun 12, 2026 at 05:01:07PM +0800, Dapeng Mi wrote:
>> AnyThread mode deprecation is enumerated by CPUID.0AH:EDX[15] instead of
>> PERF_CAPABILITIES MSR. It's not a good practice to define a bit to
>> represent "anythread deprecation" in perf_capabilities. It leads to the
>> anythread_deprecated bit could be overwritten by the real value of
>> PERF_CAPABILITIES MSR, just like the below code in update_pmu_cap() does.
>>
>> ```
>> if (!intel_pmu_broken_perf_cap()) {
>> 	/* Perf Metric (Bit 15) and PEBS via PT (Bit 16) are hybrid enumeration */
>> 	rdmsrq(MSR_IA32_PERF_CAPABILITIES, hybrid(pmu, intel_cap).capabilities);
>> }
>> ```
>>
>> It leads to the anythread_deprecated bit is cleared to 0 and the "any"
>> attribute is incorrectly shown in the /sys/devices/cpu/format/ folder on
>> these support Perfmon v6 platforms, like Clearwater Forest.
>>
>> ```
>> $grep . /sys/devices/cpu/format/*
>> /sys/devices/cpu/format/acr_mask:config2:0-63
>> /sys/devices/cpu/format/any:config:21
>> /sys/devices/cpu/format/cmask:config:24-31
>> ```
>>
>> So remove the anythread_deprecated bit from perf_capabilities structure
>> and directly depends on CPUID.0AH:EDX[15] to judge if anythread is
>> deprecated.
> Again, no markdown please. I've stripped it from these patches.

My bad. Thanks a lot.

BTW, Peter, have you pull these patches? I didn't see them in perf/core or
perf/urgent branches. Sashiko reports a defect about "Patch 5/8:
perf/x86/intel: Validate the return value of intel_pmu_init_hybrid()". If
not, I would post a v4 patchset to fix the defect. Thanks.



  reply	other threads:[~2026-06-15  0:59 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-12  9:01 [Patch v3 0/8] perf/x86: Miscellaneous PMU bug fixes Dapeng Mi
2026-06-12  9:01 ` [Patch v3 1/8] perf/x86/intel: Remove anythread_deprecated bit from perf_capabilities Dapeng Mi
2026-06-12  9:46   ` Peter Zijlstra
2026-06-15  0:59     ` Mi, Dapeng [this message]
2026-06-15  3:28       ` Mi, Dapeng
2026-06-12  9:01 ` [Patch v3 2/8] perf/x86/intel: Keep cap_user_rdpmc in sync with RDPMC user-disable state Dapeng Mi
2026-06-12  9:01 ` [Patch v3 3/8] perf/x86/intel: Fallback to sw branch type decoding if no hw decoding Dapeng Mi
2026-06-12  9:21   ` sashiko-bot
2026-06-15  1:00     ` Mi, Dapeng
2026-06-15  1:03       ` Mi, Dapeng
2026-06-12  9:01 ` [Patch v3 4/8] perf/x86/intel: Fix kernel address leakages in LBR stack Dapeng Mi
2026-06-12  9:18   ` sashiko-bot
2026-06-15  1:01     ` Mi, Dapeng
2026-06-12  9:01 ` [Patch v3 5/8] perf/x86/intel: Validate the return value of intel_pmu_init_hybrid() Dapeng Mi
2026-06-12  9:31   ` sashiko-bot
2026-06-15  1:08     ` Mi, Dapeng
2026-06-12  9:01 ` [Patch v3 6/8] perf/x86/intel: Drop fixed-counter PEBS constraints for baseline PEBS Dapeng Mi
2026-06-12  9:01 ` [Patch v3 7/8] perf/core: Fix kernel register info leak via hardware skid Dapeng Mi
2026-06-12  9:01 ` [Patch v3 8/8] perf/core: Check kernel access when kernel callchains are requested Dapeng Mi

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