pae: nx support

Index: xen/include/asm-x86/x86_32/page-2level.h
===================================================================
@@ -46,6 +46,8 @@ typedef l2_pgentry_t root_pgentry_t;
  *  12-bit flags = (pte[11:0])
  */
 
+#define _PAGE_NX                0U
+
 /* Extract flags into 12-bit integer, or turn 12-bit flags into a pte mask. */
 #define get_pte_flags(x) ((int)(x) & 0xFFF)
 #define put_pte_flags(x) ((intpte_t)((x) & 0xFFF))

Index: xen/include/asm-x86/x86_32/page-3level.h
===================================================================
@@ -59,6 +59,8 @@ typedef l3_pgentry_t root_pgentry_t;
  *  32-bit flags = (pte[63:44],pte[11:0])
  */
 
+#define _PAGE_NX (cpu_has_nx ? (1<<31) : 0)
+
 /* Extract flags into 32-bit integer, or turn 32-bit flags into a pte mask. */
 #define get_pte_flags(x) (((int)((x) >> 32) & ~0xFFF) | ((int)(x) & 0xFFF))
 #define put_pte_flags(x) (((intpte_t)((x) & ~0xFFF) << 40) | ((x) & 0xFFF))

Index: xen/include/asm-x86/x86_32/page.h
===================================================================
@@ -7,8 +7,6 @@
 #define VADDR_BITS              32
 #define VADDR_MASK              (~0UL)
 
-#define _PAGE_NX                0U
-
 #include <xen/config.h>
 #ifdef CONFIG_X86_PAE
 # include <asm/x86_32/page-3level.h>