3 files changed, 27 insertions, 6 deletions

diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 53bc653ed5ca..3b7a1ddcc0bc 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -95,7 +95,6 @@ static inline void play_dead(void)
 {
         /* This must be done before dead CPU ack */
         cpu_exit_clear();
-        wbinvd();
         mb();
         /* Ack it */
         __get_cpu_var(cpu_state) = CPU_DEAD;
@@ -104,8 +103,8 @@ static inline void play_dead(void)
          * With physical CPU hotplug, we should halt the cpu
          */
         local_irq_disable();
-        while (1)
-                halt();
+        /* mask all interrupts, flush any and all caches, and halt */
+        wbinvd_halt();
 }
 #else
 static inline void play_dead(void)
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 3fb62a7d9a16..71553b664e2a 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -93,14 +93,13 @@ DECLARE_PER_CPU(int, cpu_state);
 static inline void play_dead(void)
 {
         idle_task_exit();
-        wbinvd();
         mb();
         /* Ack it */
         __get_cpu_var(cpu_state) = CPU_DEAD;
 
         local_irq_disable();
-        while (1)
-                halt();
+        /* mask all interrupts, flush any and all caches, and halt */
+        wbinvd_halt();
 }
 #else
 static inline void play_dead(void)
diff --git a/include/asm-x86/processor.h b/include/asm-x86/processor.h
index 5f58da401b43..4df3e2f6fb56 100644
--- a/include/asm-x86/processor.h
+++ b/include/asm-x86/processor.h
@@ -728,6 +728,29 @@ extern unsigned long		boot_option_idle_override;
 extern unsigned long            idle_halt;
 extern unsigned long            idle_nomwait;
 
+/*
+ * on systems with caches, caches must be flashed as the absolute
+ * last instruction before going into a suspended halt.  Otherwise,
+ * dirty data can linger in the cache and become stale on resume,
+ * leading to strange errors.
+ *
+ * perform a variety of operations to guarantee that the compiler
+ * will not reorder instructions.  wbinvd itself is serializing
+ * so the processor will not reorder.
+ *
+ * Systems without cache can just go into halt.
+ */
+static inline void wbinvd_halt(void)
+{
+        mb();
+        /* check for clflush to determine if wbinvd is legal */
+        if (cpu_has_clflush)
+                asm volatile("cli; wbinvd; 1: hlt; jmp 1b" : : : "memory");
+        else
+                while (1)
+                        halt();
+}
+
 extern void enable_sep_cpu(void);
 extern int sysenter_setup(void);