The following commit has been merged into the perf/core branch of tip: Commit-ID: baf0f4a6733095d7443a07e5db5525376c1c9bd5 Gitweb: https://git.kernel.org/tip/baf0f4a6733095d7443a07e5db5525376c1c9bd5 Author: Sandipan Das <sandipan.das@xxxxxxx> AuthorDate: Thu, 21 Apr 2022 11:16:56 +05:30 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Fri, 29 Apr 2022 11:06:27 +02:00 perf/x86/amd/core: Detect available counters If AMD Performance Monitoring Version 2 (PerfMonV2) is supported, use CPUID leaf 0x80000022 EBX to detect the number of Core PMCs. This offers more flexibility if the counts change in later processor families. Signed-off-by: Sandipan Das <sandipan.das@xxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/68a6d9688df189267db26530378870edd34f7b06.1650515382.git.sandipan.das@xxxxxxx --- arch/x86/events/amd/core.c | 6 ++++++ arch/x86/include/asm/perf_event.h | 17 +++++++++++++++++ 2 files changed, 23 insertions(+) diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c index b70dfa0..52fd794 100644 --- a/arch/x86/events/amd/core.c +++ b/arch/x86/events/amd/core.c @@ -1186,6 +1186,7 @@ static const struct attribute_group *amd_attr_update[] = { static int __init amd_core_pmu_init(void) { + union cpuid_0x80000022_ebx ebx; u64 even_ctr_mask = 0ULL; int i; @@ -1206,9 +1207,14 @@ static int __init amd_core_pmu_init(void) /* Check for Performance Monitoring v2 support */ if (boot_cpu_has(X86_FEATURE_PERFMON_V2)) { + ebx.full = cpuid_ebx(EXT_PERFMON_DEBUG_FEATURES); + /* Update PMU version for later usage */ x86_pmu.version = 2; + /* Find the number of available Core PMCs */ + x86_pmu.num_counters = ebx.split.num_core_pmc; + amd_pmu_global_cntr_mask = (1ULL << x86_pmu.num_counters) - 1; } diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h index 8199fc5..c6cc07f 100644 --- a/arch/x86/include/asm/perf_event.h +++ b/arch/x86/include/asm/perf_event.h @@ -186,6 +186,18 @@ union cpuid28_ecx { unsigned int full; }; +/* + * AMD "Extended Performance Monitoring and Debug" CPUID + * detection/enumeration details: + */ +union cpuid_0x80000022_ebx { + struct { + /* Number of Core Performance Counters */ + unsigned int num_core_pmc:4; + } split; + unsigned int full; +}; + struct x86_pmu_capability { int version; int num_counters_gp; @@ -368,6 +380,11 @@ struct pebs_xmm { }; /* + * AMD Extended Performance Monitoring and Debug cpuid feature detection + */ +#define EXT_PERFMON_DEBUG_FEATURES 0x80000022 + +/* * IBS cpuid feature detection */
![]() |