[PATCH] perf/x86/intel: Remove anythread_deprecated bit from perf_capabilities
From: Dapeng Mi
Date: Tue Apr 14 2026 - 22:15:25 EST
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.
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Fixes: cadbaa039b99 ("perf/x86/intel: Make anythread filter support conditional")
Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Signed-off-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
---
arch/x86/events/intel/core.c | 9 +++------
arch/x86/events/perf_event.h | 2 +-
2 files changed, 4 insertions(+), 7 deletions(-)
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 793335c3ce78..450c63165a22 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -7612,11 +7612,8 @@ __init int intel_pmu_init(void)
x86_add_quirk(intel_arch_events_quirk); /* Install first, so it runs last */
- if (version >= 5) {
- x86_pmu.intel_cap.anythread_deprecated = edx.split.anythread_deprecated;
- if (x86_pmu.intel_cap.anythread_deprecated)
- pr_cont(" AnyThread deprecated, ");
- }
+ if (version >= 5 && edx.split.anythread_deprecated)
+ pr_cont(" AnyThread deprecated, ");
/* The perf side of core PMU is ready to support the mediated vPMU. */
x86_get_pmu(smp_processor_id())->capabilities |= PERF_PMU_CAP_MEDIATED_VPMU;
@@ -8467,7 +8464,7 @@ __init int intel_pmu_init(void)
&x86_pmu.intel_ctrl);
/* AnyThread may be deprecated on arch perfmon v5 or later */
- if (x86_pmu.intel_cap.anythread_deprecated)
+ if (edx.split.anythread_deprecated)
x86_pmu.format_attrs = intel_arch_formats_attr;
intel_pmu_check_event_constraints_all(NULL);
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index fad87d3c8b2c..01217c663dff 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -660,7 +660,7 @@ union perf_capabilities {
u64 perf_metrics:1;
u64 pebs_output_pt_available:1;
u64 pebs_timing_info:1;
- u64 anythread_deprecated:1;
+ u64 __reserved:1;
u64 rdpmc_metrics_clear:1;
};
u64 capabilities;
--
2.34.1