From: Imre Palik <[email protected]> perf doesn't seem to honour the number of fixed counters specified by cpuid leaf 0xa. It always assume that Intel CPUs have at least 3 fixed counters.
So if some of the fixed counters are masked out by the hypervisor, it still tries to check/set them. This patch makes perf behave nicer when the kernel is running under a hypervisor that doesn't expose all the counters. This patch contains some ideas from Matt Wilson. Signed-off-by: Imre Palik <[email protected]> Cc: Matt Wilson <[email protected]> Cc: David Woodhouse <[email protected]> --- arch/x86/events/intel/core.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index a3a9eb8..e06d071 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -3607,10 +3607,14 @@ __init int intel_pmu_init(void) /* * Quirk: v2 perfmon does not report fixed-purpose events, so - * assume at least 3 events: + * assume at least 3 events, when not running in a hypervisor: */ - if (version > 1) - x86_pmu.num_counters_fixed = max((int)edx.split.num_counters_fixed, 3); + if (version > 1) { + if (static_cpu_has(X86_FEATURE_HYPERVISOR)) + x86_pmu.num_counters_fixed = edx.split.num_counters_fixed; + else + x86_pmu.num_counters_fixed = max((int)edx.split.num_counters_fixed, 3); + } if (boot_cpu_has(X86_FEATURE_PDCM)) { u64 capabilities; -- 2.10.1
