diff options
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event_intel_lbr.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c index 3d537252f011..94e5b506caa6 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c @@ -135,7 +135,7 @@ static void intel_pmu_lbr_filter(struct cpu_hw_events *cpuc); static void __intel_pmu_lbr_enable(bool pmi) { struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); - u64 debugctl, lbr_select = 0; + u64 debugctl, lbr_select = 0, orig_debugctl; /* * No need to reprogram LBR_SELECT in a PMI, as it @@ -147,6 +147,7 @@ static void __intel_pmu_lbr_enable(bool pmi) } rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl); + orig_debugctl = debugctl; debugctl |= DEBUGCTLMSR_LBR; /* * LBR callstack does not work well with FREEZE_LBRS_ON_PMI. @@ -155,7 +156,8 @@ static void __intel_pmu_lbr_enable(bool pmi) */ if (!(lbr_select & LBR_CALL_STACK)) debugctl |= DEBUGCTLMSR_FREEZE_LBRS_ON_PMI; - wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl); + if (orig_debugctl != debugctl) + wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl); } static void __intel_pmu_lbr_disable(void) |