idle, x86: Allow off-lined CPU to enter deeper C states

Currently when a CPU is off-lined it enters either MWAIT-based idle or,
if MWAIT is not desired or supported, HLT-based idle (which places the
processor in C1 state). This patch allows processors without MWAIT
support to stay in states deeper than C1.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@amd.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 66d250c00d11..93a2a0932b51 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -50,6 +50,7 @@
 #include <linux/tboot.h>
 #include <linux/stackprotector.h>
 #include <linux/gfp.h>
+#include <linux/cpuidle.h>
 
 #include <asm/acpi.h>
 #include <asm/desc.h>
@@ -1422,7 +1423,8 @@ void native_play_dead(void)
         tboot_shutdown(TB_SHUTDOWN_WFS);
 
         mwait_play_dead();      /* Only returns on failure */
-        hlt_play_dead();
+        if (cpuidle_play_dead())
+                hlt_play_dead();
 }
 
 #else /* ... !CONFIG_HOTPLUG_CPU */