Merge branch 'x86-idle-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[pandora-kernel.git] / arch / x86 / kernel / smpboot.c

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index bc2cc44..0116552 100644 (file)
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -62,6 +62,7 @@
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
 #include <asm/mtrr.h>
+#include <asm/mwait.h>
 #include <asm/vmi.h>
 #include <asm/apic.h>
 #include <asm/setup.h>
@@ -1395,11 +1396,88 @@ void play_dead_common(void)
        local_irq_disable();
 }
 
+/*
+ * We need to flush the caches before going to sleep, lest we have
+ * dirty data in our caches when we come back up.
+ */
+static inline void mwait_play_dead(void)
+{
+       unsigned int eax, ebx, ecx, edx;
+       unsigned int highest_cstate = 0;
+       unsigned int highest_subcstate = 0;
+       int i;
+       void *mwait_ptr;
+
+       if (!cpu_has(&current_cpu_data, X86_FEATURE_MWAIT))
+               return;
+       if (!cpu_has(&current_cpu_data, X86_FEATURE_CLFLSH))
+               return;
+       if (current_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
+               return;
+
+       eax = CPUID_MWAIT_LEAF;
+       ecx = 0;
+       native_cpuid(&eax, &ebx, &ecx, &edx);
+
+       /*
+        * eax will be 0 if EDX enumeration is not valid.
+        * Initialized below to cstate, sub_cstate value when EDX is valid.
+        */
+       if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED)) {
+               eax = 0;
+       } else {
+               edx >>= MWAIT_SUBSTATE_SIZE;
+               for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
+                       if (edx & MWAIT_SUBSTATE_MASK) {
+                               highest_cstate = i;
+                               highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
+                       }
+               }
+               eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
+                       (highest_subcstate - 1);
+       }
+
+       /*
+        * This should be a memory location in a cache line which is
+        * unlikely to be touched by other processors.  The actual
+        * content is immaterial as it is not actually modified in any way.
+        */
+       mwait_ptr = &current_thread_info()->flags;
+
+       wbinvd();
+
+       while (1) {
+               /*
+                * The CLFLUSH is a workaround for erratum AAI65 for
+                * the Xeon 7400 series.  It's not clear it is actually
+                * needed, but it should be harmless in either case.
+                * The WBINVD is insufficient due to the spurious-wakeup
+                * case where we return around the loop.
+                */
+               clflush(mwait_ptr);
+               __monitor(mwait_ptr, 0, 0);
+               mb();
+               __mwait(eax, 0);
+       }
+}
+
+static inline void hlt_play_dead(void)
+{
+       if (current_cpu_data.x86 >= 4)
+               wbinvd();
+
+       while (1) {
+               native_halt();
+       }
+}
+
 void native_play_dead(void)
 {
        play_dead_common();
        tboot_shutdown(TB_SHUTDOWN_WFS);
-       wbinvd_halt();
+
+       mwait_play_dead();      /* Only returns on failure */
+       hlt_play_dead();
 }
 
 #else /* ... !CONFIG_HOTPLUG_CPU */