From 4d976a0a9f641cad0f59283c8f6e594ce94f4be9 Mon Sep 17 00:00:00 2001
From: "kaf24@firebug.cl.cam.ac.uk" <kaf24@firebug.cl.cam.ac.uk>
Date: Mon, 15 Aug 2005 07:45:42 +0000
Subject: [PATCH] Fix special backptr values on x86/64 to avoid spurious wrpt
 emulations. Signed-off-by: Keir Fraser <keir@xensource.com> Signed-off-by:
 Jun Nakajima <jun.nakajima@intel.com>

---
 xen/include/asm-x86/mm.h | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/xen/include/asm-x86/mm.h b/xen/include/asm-x86/mm.h
index 3c378a28df..9147b631bd 100644
--- a/xen/include/asm-x86/mm.h
+++ b/xen/include/asm-x86/mm.h
@@ -90,12 +90,9 @@ struct pfn_info
 #define PGT_va_shift        32
 #define PGT_va_mask         ((unsigned long)((1U<<28)-1)<<PGT_va_shift)
  /* Is the back pointer still mutable (i.e. not fixed yet)? */
- /* Use PML4 slot for HYPERVISOR_VIRT_START.  
-    18 = L4_PAGETABLE_SHIFT - L2_PAGETABLE_SHIFT */
-#define PGT_va_mutable      ((unsigned long)(256U<<18)<<PGT_va_shift)
+#define PGT_va_mutable      ((unsigned long)((1U<<28)-1)<<PGT_va_shift)
  /* Is the back pointer unknown (e.g., p.t. is mapped at multiple VAs)? */
- /* Use PML4 slot for HYPERVISOR_VIRT_START + 1 */
-#define PGT_va_unknown      ((unsigned long)(257U<<18)<<PGT_va_shift)
+#define PGT_va_unknown      ((unsigned long)((1U<<28)-2)<<PGT_va_shift)
 #endif
 
  /* 16-bit count of uses of this frame as its current type. */
-- 
2.30.2