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
*/
|