Commit 80a5ce11 authored Oct 01, 2020 by Kan Liang Committed by Peter Zijlstra Oct 03, 2020

perf/x86/intel: Check perf metrics feature for each CPU

It might be possible that different CPUs have different CPU metrics on a
platform. In this case, writing the GLOBAL_CTRL_EN_PERF_METRICS bit to
the GLOBAL_CTRL register of a CPU, which doesn't support the TopDown
perf metrics feature, causes MSR access error.

Current TopDown perf metrics feature is enumerated using the boot CPU's
PERF_CAPABILITIES MSR. The MSR only indicates the boot CPU supports this
feature.

Check the PERF_CAPABILITIES MSR for each CPU. If any CPU doesn't support
the perf metrics feature, disable the feature globally.

Fixes: 59a854e2 ("perf/x86/intel: Support TopDown metrics on Ice Lake")
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201001211711.25708-1-kan.liang@linux.intel.com

parent 010cb002

arch/x86/events/intel/core.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -4083,6 +4083,17 @@ static void intel_pmu_cpu_starting(int cpu)
		if (x86_pmu.counter_freezing)
		enable_counter_freeze();

		/* Disable perf metrics if any added CPU doesn't support it. */
		if (x86_pmu.intel_cap.perf_metrics) {
		union perf_capabilities perf_cap;

		rdmsrl(MSR_IA32_PERF_CAPABILITIES, perf_cap.capabilities);
		if (!perf_cap.perf_metrics) {
		x86_pmu.intel_cap.perf_metrics = 0;
		x86_pmu.intel_ctrl &= ~(1ULL << GLOBAL_CTRL_EN_PERF_METRICS);
		}
		}

		if (!cpuc->shared_regs)
		return;

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