1 files changed, 16 insertions, 16 deletions

diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c
index 424fc8de68e4..02f072830237 100644
--- a/arch/x86/kernel/cpu/perf_event_p4.c
+++ b/arch/x86/kernel/cpu/perf_event_p4.c
@@ -465,15 +465,21 @@ out:
         return rc;
 }
 
-static inline void p4_pmu_clear_cccr_ovf(struct hw_perf_event *hwc)
+static inline int p4_pmu_clear_cccr_ovf(struct hw_perf_event *hwc)
 {
-        unsigned long dummy;
+        int overflow = 0;
+        u32 low, high;
 
-        rdmsrl(hwc->config_base + hwc->idx, dummy);
-        if (dummy & P4_CCCR_OVF) {
+        rdmsr(hwc->config_base + hwc->idx, low, high);
+
+        /* we need to check high bit for unflagged overflows */
+        if ((low & P4_CCCR_OVF) || (high & (1 << 31))) {
+                overflow = 1;
                 (void)checking_wrmsrl(hwc->config_base + hwc->idx,
-                        ((u64)dummy) & ~P4_CCCR_OVF);
+                        ((u64)low) & ~P4_CCCR_OVF);
         }
+
+        return overflow;
 }
 
 static inline void p4_pmu_disable_event(struct perf_event *event)
@@ -584,21 +590,15 @@ static int p4_pmu_handle_irq(struct pt_regs *regs)
 
                 WARN_ON_ONCE(hwc->idx != idx);
 
-                /*
-                 * FIXME: Redundant call, actually not needed
-                 * but just to check if we're screwed
-                 */
-                p4_pmu_clear_cccr_ovf(hwc);
+                /* it might be unflagged overflow */
+                handled = p4_pmu_clear_cccr_ovf(hwc);
 
                 val = x86_perf_event_update(event);
-                if (val & (1ULL << (x86_pmu.cntval_bits - 1)))
+                if (!handled && (val & (1ULL << (x86_pmu.cntval_bits - 1))))
                         continue;
 
-                /*
-                 * event overflow
-                 */
-                handled         = 1;
-                data.period     = event->hw.last_period;
+                /* event overflow for sure */
+                data.period = event->hw.last_period;
 
                 if (!x86_perf_event_set_period(event))
                         continue;