x86: invalidate caches before going into suspend

When a CPU core is shut down, all of its caches need to be flushed
to prevent stale data from causing errors if the core is resumed.
Current Linux suspend code performs an assignment after the flush,
which can add dirty data back to the cache.  On some AMD platforms,
additional speculative reads have caused crashes on resume because
of this dirty data.

Relocate the cache flush to be the very last thing done before
halting.  Tie into an assembly line so the compile will not
reorder it.  Add some documentation explaining what is going
on and why we're doing this.

Signed-off-by: Mark Langsdorf <mark.langsdorf@amd.com>
Acked-by: Mark Borden <mark.borden@amd.com>
Acked-by: Michael Hohmuth <michael.hohmuth@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 3 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)