[v1] perf/x86/intel: Remove anythread_deprecated bit from perf_capabilities

[PATCH] perf/x86/intel: Remove anythread_deprecated bit from perf_capabilities

Posted by Dapeng Mi 2 months ago

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@vger.kernel.org
Reported-by: Namhyung Kim <namhyung@kernel.org>
Fixes: cadbaa039b99 ("perf/x86/intel: Make anythread filter support conditional")
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
---
 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

Re: [PATCH] perf/x86/intel: Remove anythread_deprecated bit from perf_capabilities

Posted by Namhyung Kim 1 month, 3 weeks ago

On Wed, Apr 15, 2026 at 10:10:10AM +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.
> 
> Cc: stable@vger.kernel.org
> Reported-by: Namhyung Kim <namhyung@kernel.org>
> Fixes: cadbaa039b99 ("perf/x86/intel: Make anythread filter support conditional")
> Acked-by: Namhyung Kim <namhyung@kernel.org>
> Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
> ---
>  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)

Do we need to check the version here as well?

Thanks,
Namhyung


>  		x86_pmu.format_attrs = intel_arch_formats_attr;
>

Re: [PATCH] perf/x86/intel: Remove anythread_deprecated bit from perf_capabilities

Posted by Mi, Dapeng 1 month, 3 weeks ago

On 4/21/2026 5:23 AM, Namhyung Kim wrote:
> On Wed, Apr 15, 2026 at 10:10:10AM +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.
>>
>> Cc: stable@vger.kernel.org
>> Reported-by: Namhyung Kim <namhyung@kernel.org>
>> Fixes: cadbaa039b99 ("perf/x86/intel: Make anythread filter support conditional")
>> Acked-by: Namhyung Kim <namhyung@kernel.org>
>> Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
>> ---
>>  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)
> Do we need to check the version here as well?

hmm, it should be enough to only check the CPUID
"edx.split.anythread_deprecated" bit  in practice. But if we want to follow
the SDM 100%, the version check should be added here.

I would add an version check here. Thanks.


>
> Thanks,
> Namhyung
>
>
>>  		x86_pmu.format_attrs = intel_arch_formats_attr;
>>

Re: [PATCH] perf/x86/intel: Remove anythread_deprecated bit from perf_capabilities

Posted by Chen, Zide 1 month, 3 weeks ago


On 4/20/2026 5:51 PM, Mi, Dapeng wrote:
> 
> On 4/21/2026 5:23 AM, Namhyung Kim wrote:
>> On Wed, Apr 15, 2026 at 10:10:10AM +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.
>>>
>>> Cc: stable@vger.kernel.org
>>> Reported-by: Namhyung Kim <namhyung@kernel.org>
>>> Fixes: cadbaa039b99 ("perf/x86/intel: Make anythread filter support conditional")
>>> Acked-by: Namhyung Kim <namhyung@kernel.org>
>>> Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
>>> ---
>>>  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)
>> Do we need to check the version here as well?
> 
> hmm, it should be enough to only check the CPUID
> "edx.split.anythread_deprecated" bit  in practice. But if we want to follow
> the SDM 100%, the version check should be added here.
> 
> I would add an version check here. Thanks.

How about merging pr_cont(" AnyThread deprecated, ") to here? No need to
repeat "if (version >= 5 && edx.split.anythread_deprecated)" twice in
one single API.


>>
>> Thanks,
>> Namhyung
>>
>>
>>>  		x86_pmu.format_attrs = intel_arch_formats_attr;
>>>

Re: [PATCH] perf/x86/intel: Remove anythread_deprecated bit from perf_capabilities

Posted by Mi, Dapeng 1 month, 3 weeks ago

On 4/22/2026 5:58 AM, Chen, Zide wrote:
>
> On 4/20/2026 5:51 PM, Mi, Dapeng wrote:
>> On 4/21/2026 5:23 AM, Namhyung Kim wrote:
>>> On Wed, Apr 15, 2026 at 10:10:10AM +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.
>>>>
>>>> Cc: stable@vger.kernel.org
>>>> Reported-by: Namhyung Kim <namhyung@kernel.org>
>>>> Fixes: cadbaa039b99 ("perf/x86/intel: Make anythread filter support conditional")
>>>> Acked-by: Namhyung Kim <namhyung@kernel.org>
>>>> Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
>>>> ---
>>>>  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)
>>> Do we need to check the version here as well?
>> hmm, it should be enough to only check the CPUID
>> "edx.split.anythread_deprecated" bit  in practice. But if we want to follow
>> the SDM 100%, the version check should be added here.
>>
>> I would add an version check here. Thanks.
> How about merging pr_cont(" AnyThread deprecated, ") to here? No need to
> repeat "if (version >= 5 && edx.split.anythread_deprecated)" twice in
> one single API.

OK. Although it would change the perfmon print message order slightly, on
one should care about the message order. Thanks.


>
>
>>> Thanks,
>>> Namhyung
>>>
>>>
>>>>  		x86_pmu.format_attrs = intel_arch_formats_attr;
>>>>  
>