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Diffstat (limited to 'arch/x86/kernel/cpu/perf_event_p4.c')
-rw-r--r--arch/x86/kernel/cpu/perf_event_p4.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c
index f7a0993c1e7..ff751a9f182 100644
--- a/arch/x86/kernel/cpu/perf_event_p4.c
+++ b/arch/x86/kernel/cpu/perf_event_p4.c
@@ -770,9 +770,14 @@ static inline int p4_pmu_clear_cccr_ovf(struct hw_perf_event *hwc)
return 1;
}
- /* it might be unflagged overflow */
- rdmsrl(hwc->event_base + hwc->idx, v);
- if (!(v & ARCH_P4_CNTRVAL_MASK))
+ /*
+ * In some circumstances the overflow might issue an NMI but did
+ * not set P4_CCCR_OVF bit. Because a counter holds a negative value
+ * we simply check for high bit being set, if it's cleared it means
+ * the counter has reached zero value and continued counting before
+ * real NMI signal was received:
+ */
+ if (!(v & ARCH_P4_UNFLAGGED_BIT))
return 1;
return 0;