From: Liu, Jinsong <jinsong.liu@intel.com>
Date: Fri, 11 Mar 2011 17:18:01 +0000 (+0000)
Subject: x86: Fix cache flush bug of cpu offline
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=61799a138af63113b21594fe7e3a9de56f15815a;p=xen.git

x86: Fix cache flush bug of cpu offline

Current xen cpu offline logic flush cache too early, which potentially
break cache coherency.  wbinvd should be the last ops before cpu going
into dead, otherwise cache may be dirty, i.e, something like setting
an A bit on page tables. Pointed out by Arjan van de Ven.

Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com>
---

diff --git a/xen/arch/x86/acpi/cpu_idle.c b/xen/arch/x86/acpi/cpu_idle.c
index a01a27f4ad..6fa94cab62 100644
--- a/xen/arch/x86/acpi/cpu_idle.c
+++ b/xen/arch/x86/acpi/cpu_idle.c
@@ -561,11 +561,14 @@ static void acpi_dead_idle(void)
     if ( (cx = &power->states[power->count-1]) == NULL )
         goto default_halt;
 
+    /*
+     * cache must be flashed as the last ops before cpu going into dead,
+     * otherwise, cpu may dead with dirty data breaking cache coherency,
+     * leading to strange errors.
+     */
+    wbinvd();
     for ( ; ; )
     {
-        if ( !power->flags.bm_check && cx->type == ACPI_STATE_C3 )
-            ACPI_FLUSH_CPU_CACHE();
-
         switch ( cx->entry_method )
         {
             case ACPI_CSTATE_EM_FFH:
@@ -579,6 +582,7 @@ static void acpi_dead_idle(void)
     }
 
 default_halt:
+    wbinvd();
     for ( ; ; )
         halt();
 }
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 09da6221af..a024e198e9 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -93,6 +93,12 @@ static void default_idle(void)
 
 static void default_dead_idle(void)
 {
+    /*
+     * cache must be flashed as the last ops before cpu going into dead,
+     * otherwise, cpu may dead with dirty data breaking cache coherency,
+     * leading to strange errors.
+     */
+    wbinvd();
     for ( ; ; )
         halt();
 }
@@ -100,7 +106,6 @@ static void default_dead_idle(void)
 static void play_dead(void)
 {
     local_irq_disable();
-    wbinvd();
 
     /*
      * NOTE: After cpu_exit_clear, per-cpu variables are no longer accessible,