From: Lin Ming <ming.m.lin@intel.com>
Date: Wed, 25 Aug 2010 21:06:32 +0000 (+0000)
Subject: perf, x86, Pentium4: Clear the P4_CCCR_FORCE_OVF flag
X-Git-Tag: v2.6.35.5~115
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=133aa6cbaf169f375a70d0ed8df7bc2ab583cc34;p=thirdparty%2Fkernel%2Fstable.git

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>
---

diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c
index 0ffe19e9373ad..a187365d98b4e 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);