linux-hardening - Re: [PATCH v3 02/10] perf/x86/rapl: Fix the energy-pkg event for AMD CPUs

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Message-ID: <b1e53de4-444a-4f1f-ac83-5dceba59b06d@amd.com>
Date: Tue, 2 Jul 2024 15:09:21 +0530
From: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: mingo@...hat.com, acme@...nel.org, namhyung@...nel.org,
 mark.rutland@....com, alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
 irogers@...gle.com, adrian.hunter@...el.com, kan.liang@...ux.intel.com,
 tglx@...utronix.de, bp@...en8.de, dave.hansen@...ux.intel.com,
 x86@...nel.org, kees@...nel.org, gustavoars@...nel.org, rui.zhang@...el.com,
 oleksandr@...alenko.name, linux-perf-users@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org,
 ananth.narayan@....com, gautham.shenoy@....com, kprateek.nayak@....com,
 ravi.bangoria@....com, sandipan.das@....com, linux-pm@...r.kernel.org
Subject: Re: [PATCH v3 02/10] perf/x86/rapl: Fix the energy-pkg event for AMD
 CPUs

Hello Peter,

On 7/1/2024 6:29 PM, Peter Zijlstra wrote:
> On Mon, Jun 24, 2024 at 05:58:59AM +0000, Dhananjay Ugwekar wrote:
>  	
>> diff --git a/arch/x86/events/rapl.c b/arch/x86/events/rapl.c
>> index b985ca79cf97..73be25e1f4b4 100644
>> --- a/arch/x86/events/rapl.c
>> +++ b/arch/x86/events/rapl.c
>> @@ -103,6 +103,10 @@ 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;
>> @@ -140,9 +144,21 @@ 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 const struct cpumask *get_rapl_pmu_cpumask(int cpu)
>> +{
>> +	return rapl_pmu_is_pkg_scope() ? topology_core_cpumask(cpu) :
>> +					 topology_die_cpumask(cpu);
>> +}
> 
> This wants a comment. The next time someone looks at this we're going to
> be confused.

Yes, will add a comment.

> 
>> @@ -677,6 +696,9 @@ static int __init init_rapl_pmus(void)
>>  {
>>  	int nr_rapl_pmu = topology_max_packages() * topology_max_dies_per_package();
>>  
>> +	if (rapl_pmu_is_pkg_scope())
>> +		nr_rapl_pmu = topology_max_packages();
>> +
> 
> How about:
> 
> 	int nr_rapl_pmu = topology_max_packages();
> 	if (!rapl_pmu_is_pkg_scope())
> 		nr_rapl_pmu *= topology_max_dies_per_package();
> 
> hmm?

Sure, I'm okay with this as well, will modify in next version.

Thanks,
Dhananjay