x86/paravirt: add pte_flags to just get pte flags

Add pte_flags() to extract the flags from a pte.  This is a special
case of pte_val() which is only guaranteed to return the pte's flags
correctly; the page number may be corrupted or missing.

The intent is to allow paravirt implementations to return pte flags
without having to do any translation of the page number (most notably,
Xen).
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/paravirt.c

@@ -403,6 +403,7 @@ struct pv_mmu_ops pv_mmu_ops = {
 #endif /* PAGETABLE_LEVELS >= 3 */
 
 	.pte_val = native_pte_val,
+	.pte_flags = native_pte_val,
 	.pgd_val = native_pgd_val,
 
 	.make_pte = native_make_pte,

arch/x86/xen/enlighten.c

@@ -1101,6 +1101,7 @@ static const struct pv_mmu_ops xen_mmu_ops __initdata = {
 	.set_pmd = xen_set_pmd,
 
 	.pte_val = xen_pte_val,
+	.pte_flags = native_pte_val,
 	.pgd_val = xen_pgd_val,
 
 	.make_pte = xen_make_pte,

drivers/lguest/lg.h

@@ -136,7 +136,6 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user);
  * first step in the migration to the kernel types.  pte_pfn is already defined
  * in the kernel. */
 #define pgd_flags(x)	(pgd_val(x) & ~PAGE_MASK)
-#define pte_flags(x)	(pte_val(x) & ~PAGE_MASK)
 #define pgd_pfn(x)	(pgd_val(x) >> PAGE_SHIFT)
 
 /* interrupts_and_traps.c: */

include/asm-x86/page.h

@@ -160,6 +160,7 @@ static inline pteval_t native_pte_val(pte_t pte)
 #endif
 
 #define pte_val(x)	native_pte_val(x)
+#define pte_flags(x)	native_pte_val(x)
 #define __pte(x)	native_make_pte(x)
 
 #endif	/* CONFIG_PARAVIRT */

include/asm-x86/paravirt.h

@@ -239,6 +239,7 @@ struct pv_mmu_ops {
 				 unsigned long addr, pte_t *ptep);
 
 	pteval_t (*pte_val)(pte_t);
+	pteval_t (*pte_flags)(pte_t);
 	pte_t (*make_pte)(pteval_t pte);
 
 	pgdval_t (*pgd_val)(pgd_t);
@@ -996,6 +997,20 @@ static inline pteval_t pte_val(pte_t pte)
 	return ret;
 }
 
+static inline pteval_t pte_flags(pte_t pte)
+{
+	pteval_t ret;
+
+	if (sizeof(pteval_t) > sizeof(long))
+		ret = PVOP_CALL2(pteval_t, pv_mmu_ops.pte_flags,
+				 pte.pte, (u64)pte.pte >> 32);
+	else
+		ret = PVOP_CALL1(pteval_t, pv_mmu_ops.pte_flags,
+				 pte.pte);
+
+	return ret;
+}
+
 static inline pgd_t __pgd(pgdval_t val)
 {
 	pgdval_t ret;

include/asm-x86/pgtable.h

@@ -164,37 +164,37 @@ extern struct list_head pgd_list;
  */
 static inline int pte_dirty(pte_t pte)
 {
-	return pte_val(pte) & _PAGE_DIRTY;
+	return pte_flags(pte) & _PAGE_DIRTY;
 }
 
 static inline int pte_young(pte_t pte)
 {
-	return pte_val(pte) & _PAGE_ACCESSED;
+	return pte_flags(pte) & _PAGE_ACCESSED;
 }
 
 static inline int pte_write(pte_t pte)
 {
-	return pte_val(pte) & _PAGE_RW;
+	return pte_flags(pte) & _PAGE_RW;
 }
 
 static inline int pte_file(pte_t pte)
 {
-	return pte_val(pte) & _PAGE_FILE;
+	return pte_flags(pte) & _PAGE_FILE;
 }
 
 static inline int pte_huge(pte_t pte)
 {
-	return pte_val(pte) & _PAGE_PSE;
+	return pte_flags(pte) & _PAGE_PSE;
 }
 
 static inline int pte_global(pte_t pte)
 {
-	return pte_val(pte) & _PAGE_GLOBAL;
+	return pte_flags(pte) & _PAGE_GLOBAL;
 }
 
 static inline int pte_exec(pte_t pte)
 {
-	return !(pte_val(pte) & _PAGE_NX);
+	return !(pte_flags(pte) & _PAGE_NX);
 }
 
 static inline int pte_special(pte_t pte)
@@ -305,7 +305,7 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
 	return __pgprot(preservebits | addbits);
 }
 
-#define pte_pgprot(x) __pgprot(pte_val(x) & ~PTE_MASK)
+#define pte_pgprot(x) __pgprot(pte_flags(x) & ~PTE_MASK)
 
 #define canon_pgprot(p) __pgprot(pgprot_val(p) & __supported_pte_mask)