From 79202ba9ff8cf570a75596f42e011167734d1c4b Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Tue, 26 May 2009 08:10:00 +0200 Subject: [PATCH] perf_counter, x86: Fix APIC NMI programming My Nehalem box locks up in certain situations (with an always-asserted NMI causing a lockup) if the PMU LVT entry is programmed between NMI and IRQ mode with a high frequency. Standardize exlusively on NMIs instead. [ Impact: fix lockup ] Cc: Peter Zijlstra Cc: Mike Galbraith Cc: Paul Mackerras Cc: Corey Ashford Cc: Marcelo Tosatti Cc: Arnaldo Carvalho de Melo Cc: Thomas Gleixner Cc: John Kacur LKML-Reference: Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_counter.c | 16 +++------------- 1 file changed, 3 insertions(+), 13 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index 189bf9d7cdab..ece3813c7a3c 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -285,14 +285,10 @@ static int __hw_perf_counter_init(struct perf_counter *counter) hwc->config |= ARCH_PERFMON_EVENTSEL_OS; /* - * If privileged enough, allow NMI events: + * Use NMI events all the time: */ - hwc->nmi = 0; - if (hw_event->nmi) { - if (sysctl_perf_counter_priv && !capable(CAP_SYS_ADMIN)) - return -EACCES; - hwc->nmi = 1; - } + hwc->nmi = 1; + hw_event->nmi = 1; if (!hwc->irq_period) hwc->irq_period = x86_pmu.max_period; @@ -553,9 +549,6 @@ fixed_mode_idx(struct perf_counter *counter, struct hw_perf_counter *hwc) if (!x86_pmu.num_counters_fixed) return -1; - if (unlikely(hwc->nmi)) - return -1; - event = hwc->config & ARCH_PERFMON_EVENT_MASK; if (unlikely(event == x86_pmu.event_map(PERF_COUNT_INSTRUCTIONS))) @@ -806,9 +799,6 @@ static int amd_pmu_handle_irq(struct pt_regs *regs, int nmi) counter = cpuc->counters[idx]; hwc = &counter->hw; - if (counter->hw_event.nmi != nmi) - continue; - val = x86_perf_counter_update(counter, hwc, idx); if (val & (1ULL << (x86_pmu.counter_bits - 1))) continue;