From: Andi Kleen <ak@suse.de>
Date: Wed, 15 Aug 2007 10:38:58 +0000 (+0200)
Subject: i386: Handle P6s without performance counters in nmi watchdog
X-Git-Tag: v2.6.22.5~3
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c2c1d493fa0ee16491bffd6682cf4f479b8792c2;p=thirdparty%2Fkernel%2Fstable.git

i386: Handle P6s without performance counters in nmi watchdog

I got an oops while booting a 32bit kernel on KVM because it doesn't
implement performance counters used by the NMI watchdog. Handle this
case.


Cc: Avi Kivity <avi@qumranet.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/arch/i386/kernel/cpu/perfctr-watchdog.c b/arch/i386/kernel/cpu/perfctr-watchdog.c
index 4d26d514c56f9..996f6f89ce8e8 100644
--- a/arch/i386/kernel/cpu/perfctr-watchdog.c
+++ b/arch/i386/kernel/cpu/perfctr-watchdog.c
@@ -346,7 +346,9 @@ static int setup_p6_watchdog(unsigned nmi_hz)
 	perfctr_msr = MSR_P6_PERFCTR0;
 	evntsel_msr = MSR_P6_EVNTSEL0;
 
-	wrmsrl(perfctr_msr, 0UL);
+	/* KVM doesn't implement this MSR */
+	if (wrmsr_safe(perfctr_msr, 0, 0) < 0)
+		return 0;
 
 	evntsel = P6_EVNTSEL_INT
 		| P6_EVNTSEL_OS