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perf/x86/intel: Honour the CPUID for number of fixed counters in hypervisors

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perf doesn't seem to honour the number of fixed counters specified by CPUID
leaf 0xa. It always assumes 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 <imrep@amazon.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Alexander Kozyrev <alexander.kozyrev@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Artyom Kuanbekov <artyom.kuanbekov@intel.com>
Cc: David Carrillo-Cisneros <davidcc@google.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Wilson <msw@amazon.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1477037939-15605-1-git-send-email-imrep.amz@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Imre Palik 2016-10-21 01:18:59 -07:00 committed by Ingo Molnar
parent 5aab90ce1e
commit f92b760414
1 changed files with 7 additions and 3 deletions
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10
arch/x86/events/intel/core.c
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@ -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) {
int assume = 3 * !boot_cpu_has(X86_FEATURE_HYPERVISOR);
x86_pmu.num_counters_fixed =
max((int)edx.split.num_counters_fixed, assume);
}
if (boot_cpu_has(X86_FEATURE_PDCM)) {
u64 capabilities;