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 3f947841d0a1321ae916b76161681f3af4fd08c3..a2368d39b1732fa9ebdb865791a7141e222e4db2 100644 (file)
--- 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 a024e198e90b4bacdf1ee975c0becbb8ee2aaf37..b859cd576fac6a9756af2e40bc2e791bf630bbc3 100644 (file)
--- 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();
 }