linux-hardening - Re: [PATCH 2/2] perf/x86/rapl: Fix the energy-pkg event for AMD CPUs

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Date: Fri, 3 May 2024 15:37:01 +0530
From: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
To: Ingo Molnar <mingo@...nel.org>
Cc: tglx@...utronix.de, bp@...en8.de, dave.hansen@...ux.intel.com,
 x86@...nel.org, peterz@...radead.org, mingo@...hat.com,
 ananth.narayan@....com, gautham.shenoy@....com,
 linux-perf-users@...r.kernel.org, linux-hardening@...r.kernel.org,
 linux-kernel@...r.kernel.org, sandipan.das@....com,
 alexander.shishkin@...ux.intel.com, irogers@...gle.com,
 gustavoars@...nel.org, kprateek.nayak@....com, ravi.bangoria@....com
Subject: Re: [PATCH 2/2] perf/x86/rapl: Fix the energy-pkg event for AMD CPUs

Hi Ingo,

On 5/3/2024 3:24 PM, Ingo Molnar wrote:
> 
> * Dhananjay Ugwekar <Dhananjay.Ugwekar@....com> wrote:
> 
>> After commit ("x86/cpu/topology: Add support for the AMD 0x80000026 leaf"),
>> on AMD processors that support extended CPUID leaf 0x80000026, the
>> topology_die_cpumask() and topology_logical_die_id() macros, no longer 
>> return the package cpumask and package id, instead they return the CCD 
>> (Core Complex Die) mask and id respectively. This leads to the energy-pkg 
>> event scope to be modified to CCD instead of package.
>>
>> Replacing these macros with their package counterparts fixes the
>> energy-pkg event for AMD CPUs.
>>
>> However due to the difference between the scope of energy-pkg event for 
>> Intel and AMD CPUs, we have to replace these macros conditionally only for
>> AMD CPUs.
>>
>> On a 12 CCD 1 Package AMD Zen4 Genoa machine:
>>
>> Before:
>> $ cat /sys/devices/power/cpumask
>> 0,8,16,24,32,40,48,56,64,72,80,88.
>>
>> The expected cpumask here is supposed to be just "0", as it is a package 
>> scope event, only one CPU will be collecting the event for all the CPUs in 
>> the package.
>>
>> After:
>> $ cat /sys/devices/power/cpumask
>> 0
>>
>> Signed-off-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
>> Fixes: 63edbaa48a57 ("x86/cpu/topology: Add support for the AMD 0x80000026 leaf")
>> ---
>>  arch/x86/events/rapl.c | 30 ++++++++++++++++++++++++++----
>>  1 file changed, 26 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/x86/events/rapl.c b/arch/x86/events/rapl.c
>> index 46e673585560..d77bf7959a43 100644
>> --- a/arch/x86/events/rapl.c
>> +++ b/arch/x86/events/rapl.c
>> @@ -102,6 +102,10 @@ static struct perf_pmu_events_attr event_attr_##v = {				\
>>  	.event_str	= str,							\
>>  };
>>  
>> +#define rapl_pmu_is_pkg_scope()				\
>> +	(boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||	\
>> +	 boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
>> +
>>  struct rapl_pmu {
>>  	raw_spinlock_t		lock;
>>  	int			n_active;
>> @@ -139,9 +143,21 @@ static unsigned int rapl_cntr_mask;
>>  static u64 rapl_timer_ms;
>>  static struct perf_msr *rapl_msrs;
>>  
>> +static inline unsigned int get_rapl_pmu_idx(int cpu)
>> +{
>> +	return rapl_pmu_is_pkg_scope() ? topology_logical_package_id(cpu) :
>> +					 topology_logical_die_id(cpu);
>> +}
>> +
>> +static inline cpumask_t *get_rapl_pmu_cpumask(int cpu)
>> +{
>> +	return rapl_pmu_is_pkg_scope() ? topology_core_cpumask(cpu) :
>> +					 topology_die_cpumask(cpu);
>> +}
> 
> Note that this breaks the build with this config:
> 
>   https://download.01.org/0day-ci/archive/20240503/202405030828.RgFuznL9-lkp@intel.com/config
> 
> I've removed the commit from perf/core for now.

Sure, will fix this in v2.

Regards,
Dhananjay

> 
> Thanks,
> 
> 	Ingo