From: Keir Fraser <keir@xen.org>
Date: Fri, 11 Mar 2011 17:27:25 +0000 (+0000)
Subject: x86: Clean up wbinvd usage in cpu offline paths.
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=baabb96f5c637561f68a9dd8038b6a903b2a7493;p=xen.git

x86: Clean up wbinvd usage in cpu offline paths.

No need to wbinvd before HLT (entering C1) as the processor continues
to participate in the full cache coherency protocol in this sleep
state.

Signed-off-by: Keir Fraser <keir@xen.org>
---

diff --git a/xen/arch/x86/acpi/cpu_idle.c b/xen/arch/x86/acpi/cpu_idle.c
index 3f947841d0..a2368d39b1 100644
--- a/xen/arch/x86/acpi/cpu_idle.c
+++ b/xen/arch/x86/acpi/cpu_idle.c
@@ -567,8 +567,8 @@ static void acpi_dead_idle(void)
     if ( cx->entry_method == ACPI_CSTATE_EM_FFH )
     {
         /*
-         * cache must be flashed as the last ops before cpu going into dead,
-         * otherwise, cpu may dead with dirty data breaking cache coherency,
+         * Cache must be flushed as the last operation before sleeping.
+         * Otherwise, CPU may still hold dirty data, breaking cache coherency,
          * leading to strange errors.
          */
         wbinvd();
@@ -593,7 +593,6 @@ 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 a024e198e9..b859cd576f 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -93,12 +93,6 @@ 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();
 }