On Tue, Jan 19, 2021 at 12:38:23PM -0800, [email protected] wrote:
> @@ -5228,7 +5231,7 @@ __init int intel_pmu_init(void)
> * Check whether the Architectural PerfMon supports
> * Branch Misses Retired hw_event or not.
> */
> - cpuid(10, &eax.full, &ebx.full, &unused, &edx.full);
> + cpuid(10, &eax.full, &ebx.full, &fixed_mask, &edx.full);
> if (eax.split.mask_length < ARCH_PERFMON_EVENTS_COUNT)
> return -ENODEV;
>
> @@ -5255,8 +5258,16 @@ __init int intel_pmu_init(void)
> if (version > 1) {
> int assume = 3 * !boot_cpu_has(X86_FEATURE_HYPERVISOR);
>
> - x86_pmu.num_counters_fixed =
> - max((int)edx.split.num_counters_fixed, assume);
> + if (!fixed_mask) {
> + x86_pmu.num_counters_fixed =
> + max((int)edx.split.num_counters_fixed, assume);
> + } else {
> + /*
> + * The fixed-purpose counters are enumerated in the ECX
> + * since V5 perfmon.
> + */
But that's not what the code implements.
> + x86_pmu.num_counters_fixed = fls(fixed_mask);
> + }
> }
What you were looking for is something like this:
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index fe940082d49a..9ad42cb59606 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4817,6 +4817,13 @@ __init int intel_pmu_init(void)
x86_pmu.num_counters_fixed =
max((int)edx.split.num_counters_fixed, assume);
+
+ if (version >= 5) {
+ /*
+ * V5 and later provide a fixed counter mask.
+ */
+ x86_pmu.num_counters_fixed = fls(fixed_mask);
+ }
}
if (boot_cpu_has(X86_FEATURE_PDCM)) {
