[PATCH] x86: fix mwait_play_dead() faulting on mwait-incapable cpus

[Avi Kivity <avi@redhat.com>]

A logic error in mwait_play_dead() causes the kernel to use mwait
even on cpus which don't support it, such as KVM virtual cpus.

Introduced by 349c004e3d31fd.

Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=36222

Reported-by: Török Edwin <edwintorok@gmail.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
---
 arch/x86/kernel/smpboot.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index eefd967..33a0c11 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1332,7 +1332,7 @@ static inline void mwait_play_dead(void)
 	void *mwait_ptr;
 	struct cpuinfo_x86 *c = __this_cpu_ptr(&cpu_info);
 
-	if (!this_cpu_has(X86_FEATURE_MWAIT) && mwait_usable(c))
+	if (!(this_cpu_has(X86_FEATURE_MWAIT) && mwait_usable(c)))
 		return;
 	if (!this_cpu_has(X86_FEATURE_CLFLSH))
 		return;
-- 
1.7.5.3