perf, x86, Pentium4: Clear the P4_CCCR_FORCE_OVF flag

Lin Ming · Ingo Molnar · commit 8d330919927e · 2010-08-25T15:15:33.000+02:00
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 &lt;vweaver1@eecs.utk.edu&gt;
Signed-off-by: Lin Ming &lt;ming.m.lin@intel.com&gt;
Signed-off-by: Cyrill Gorcunov &lt;gorcunov@openvz.org&gt;
Cc: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: &lt;stable@kernel.org&gt;
Signed-off-by: Ingo Molnar &lt;mingo@elte.hu&gt;
diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c
@@ -497,6 +497,8 @@ 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 | P4_CCCR_RESERVED));
+
+		event->hw.config &= ~P4_CCCR_FORCE_OVF;
 	}
 
 	rc = x86_setup_perfctr(event);

Original file line number	Diff line number	Diff line change
`@@ -497,6 +497,8 @@ static int p4_hw_config(struct perf_event *event)`
`497`	`497`	`event->hw.config \|= event->attr.config &`
`498`	`498`	`(p4_config_pack_escr(P4_ESCR_MASK_HT) \|`
`499`	`499`	`p4_config_pack_cccr(P4_CCCR_MASK_HT \| P4_CCCR_RESERVED));`
	`500`	`+`
	`501`	`+ event->hw.config &= ~P4_CCCR_FORCE_OVF;`
`500`	`502`	`}`
`501`	`503`
`502`	`504`	`rc = x86_setup_perfctr(event);`