diff --git a/linux-2.6.8.1-xen-sparse/include/asm-xen/asm-i386/system.h b/linux-2.6.8.1-xen-sparse/include/asm-xen/asm-i386/system.h
index 822c57f29a..133f1eaf49 100644
--- a/linux-2.6.8.1-xen-sparse/include/asm-xen/asm-i386/system.h
+++ b/linux-2.6.8.1-xen-sparse/include/asm-xen/asm-i386/system.h
@@ -122,9 +122,13 @@ static inline unsigned long _get_base(char * addr)
 
 #endif	/* __KERNEL__ */
 
-#define wbinvd() \
-	BUG();
-//	__asm__ __volatile__ ("wbinvd": : :"memory");
+static inline void wbinvd(void)
+{
+    mmu_update_t u;
+    u.ptr = MMU_EXTENDED_COMMAND;
+    u.val = MMUEXT_FLUSH_CACHE;
+    (void)HYPERVISOR_mmu_update(&u, 1, NULL);
+}
 
 static inline unsigned long get_limit(unsigned long segment)
 {
diff --git a/xen/arch/x86/memory.c b/xen/arch/x86/memory.c
index 5d95bea71e..35a248a50d 100644
--- a/xen/arch/x86/memory.c
+++ b/xen/arch/x86/memory.c
@@ -905,6 +905,18 @@ static int do_extended_command(unsigned long ptr, unsigned long val)
         __flush_tlb_one(ptr);
         break;
 
+    case MMUEXT_FLUSH_CACHE:
+        if ( unlikely(!IS_CAPABLE_PHYSDEV(d)) )
+        {
+            MEM_LOG("Non-physdev domain tried to FLUSH_CACHE.\n");
+            okay = 0;
+        }
+        else
+        {
+            wbinvd();
+        }
+        break;
+
     case MMUEXT_SET_LDT:
     {
         unsigned long ents = val >> MMUEXT_CMD_SHIFT;
diff --git a/xen/include/hypervisor-ifs/dom0_ops.h b/xen/include/hypervisor-ifs/dom0_ops.h
index 7dec0af739..ebac7397bd 100644
--- a/xen/include/hypervisor-ifs/dom0_ops.h
+++ b/xen/include/hypervisor-ifs/dom0_ops.h
@@ -19,7 +19,7 @@
  * This makes sure that old versions of dom0 tools will stop working in a
  * well-defined way (rather than crashing the machine, for instance).
  */
-#define DOM0_INTERFACE_VERSION   0xAAAA0012
+#define DOM0_INTERFACE_VERSION   0xAAAA0013
 
 #define MAX_DOMAIN_NAME    16
 
diff --git a/xen/include/hypervisor-ifs/hypervisor-if.h b/xen/include/hypervisor-ifs/hypervisor-if.h
index 36528bfda4..2b9f8c7166 100644
--- a/xen/include/hypervisor-ifs/hypervisor-if.h
+++ b/xen/include/hypervisor-ifs/hypervisor-if.h
@@ -117,6 +117,9 @@
  *   val[7:0] == MMUEXT_INVLPG:
  *   ptr[:2]  -- Linear address to be flushed from the TLB.
  * 
+ *   val[7:0] == MMUEXT_FLUSH_CACHE:
+ *   No additional arguments. Writes back and flushes cache contents.
+ * 
  *   val[7:0] == MMUEXT_SET_LDT:
  *   ptr[:2]  -- Linear address of LDT base (NB. must be page-aligned).
  *   val[:8]  -- Number of entries in LDT.
@@ -143,15 +146,16 @@
 #define MMU_MACHPHYS_UPDATE      2 /* ptr = MA of frame to modify entry for  */
 #define MMU_EXTENDED_COMMAND     3 /* least 8 bits of val demux further      */
 #define MMUEXT_PIN_TABLE         0 /* ptr = MA of frame to pin               */
-#define MMUEXT_UNPIN_TABLE       4 /* ptr = MA of frame to unpin             */
-#define MMUEXT_NEW_BASEPTR       5 /* ptr = MA of new pagetable base         */
-#define MMUEXT_TLB_FLUSH         6 /* ptr = NULL                             */
-#define MMUEXT_INVLPG            7 /* ptr = VA to invalidate                 */
-#define MMUEXT_SET_LDT           8 /* ptr = VA of table; val = # entries     */
+#define MMUEXT_UNPIN_TABLE       1 /* ptr = MA of frame to unpin             */
+#define MMUEXT_NEW_BASEPTR       2 /* ptr = MA of new pagetable base         */
+#define MMUEXT_TLB_FLUSH         3 /* ptr = NULL                             */
+#define MMUEXT_INVLPG            4 /* ptr = VA to invalidate                 */
+#define MMUEXT_FLUSH_CACHE       5
+#define MMUEXT_SET_LDT           6 /* ptr = VA of table; val = # entries     */
+#define MMUEXT_SET_FOREIGNDOM    7 /* val[31:16] = dom                       */
+#define MMUEXT_CLEAR_FOREIGNDOM  8
 #define MMUEXT_TRANSFER_PAGE     9 /* ptr = MA of frame; val[31:16] = dom    */
-#define MMUEXT_SET_FOREIGNDOM   10 /* val[31:16] = dom                       */
-#define MMUEXT_CLEAR_FOREIGNDOM 11
-#define MMUEXT_REASSIGN_PAGE    12
+#define MMUEXT_REASSIGN_PAGE    10
 #define MMUEXT_CMD_MASK        255
 #define MMUEXT_CMD_SHIFT         8