From 133aa6cbaf169f375a70d0ed8df7bc2ab583cc34 Mon Sep 17 00:00:00 2001
From: Lin Ming <ming.m.lin@intel.com>
Date: Wed, 25 Aug 2010 21:06:32 +0000
Subject: perf, x86, Pentium4: Clear the P4_CCCR_FORCE_OVF flag

commit 8d330919927ea31fa083b5a80084dc991da813a0 upstream.

If on Pentium4 CPUs the FORCE_OVF flag is set then an NMI happens
on every event, which can generate a flood of NMIs. Clear it.

Reported-by: Vince Weaver <vweaver1@eecs.utk.edu>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
 arch/x86/kernel/cpu/perf_event_p4.c | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'arch')

diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c
index 0ffe19e9373a..a187365d98b4 100644
--- a/arch/x86/kernel/cpu/perf_event_p4.c
+++ b/arch/x86/kernel/cpu/perf_event_p4.c
@@ -457,6 +457,8 @@ static int p4_hw_config(struct perf_event *event)
 		event->hw.config |= event->attr.config &
 			(p4_config_pack_escr(P4_ESCR_MASK_HT) |
 			 p4_config_pack_cccr(P4_CCCR_MASK_HT));
+
+		event->hw.config &= ~P4_CCCR_FORCE_OVF;
 	}
 
 	rc = x86_setup_perfctr(event);
-- 
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