linux-kernel - [015/129] perf, x86, Pentium4: Clear the P4_CCCR_FORCE

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Date:	Sat, 18 Sep 2010 12:11:53 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Lin Ming <ming.m.lin@...el.com>,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: [015/129] perf, x86, Pentium4: Clear the P4_CCCR_FORCE_OVF flag

2.6.35-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Lin Ming <ming.m.lin@...el.com>

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@...s.utk.edu>
Signed-off-by: Lin Ming <ming.m.lin@...el.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@...nvz.org>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 arch/x86/kernel/cpu/perf_event_p4.c |    2 ++
 1 file changed, 2 insertions(+)

--- 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_even
 		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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