2 files changed, 21 insertions, 7 deletions

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 06bbcbd66e9c..4f5af8447d54 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -302,16 +302,30 @@ static inline pte_t pte_mkspecial(pte_t pte)
 
 extern pteval_t __supported_pte_mask;
 
+/*
+ * Mask out unsupported bits in a present pgprot.  Non-present pgprots
+ * can use those bits for other purposes, so leave them be.
+ */
+static inline pgprotval_t massage_pgprot(pgprot_t pgprot)
+{
+        pgprotval_t protval = pgprot_val(pgprot);
+
+        if (protval & _PAGE_PRESENT)
+                protval &= __supported_pte_mask;
+
+        return protval;
+}
+
 static inline pte_t pfn_pte(unsigned long page_nr, pgprot_t pgprot)
 {
-        return __pte((((phys_addr_t)page_nr << PAGE_SHIFT) |
-                      pgprot_val(pgprot)) & __supported_pte_mask);
+        return __pte(((phys_addr_t)page_nr << PAGE_SHIFT) |
+                     massage_pgprot(pgprot));
 }
 
 static inline pmd_t pfn_pmd(unsigned long page_nr, pgprot_t pgprot)
 {
-        return __pmd((((phys_addr_t)page_nr << PAGE_SHIFT) |
-                      pgprot_val(pgprot)) & __supported_pte_mask);
+        return __pmd(((phys_addr_t)page_nr << PAGE_SHIFT) |
+                     massage_pgprot(pgprot));
 }
 
 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
@@ -323,7 +337,7 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
          * the newprot (if present):
          */
         val &= _PAGE_CHG_MASK;
-        val |= pgprot_val(newprot) & (~_PAGE_CHG_MASK) & __supported_pte_mask;
+        val |= massage_pgprot(newprot) & ~_PAGE_CHG_MASK;
 
         return __pte(val);
 }
@@ -339,7 +353,7 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
 
 #define pte_pgprot(x) __pgprot(pte_flags(x) & PTE_FLAGS_MASK)
 
-#define canon_pgprot(p) __pgprot(pgprot_val(p) & __supported_pte_mask)
+#define canon_pgprot(p) __pgprot(massage_pgprot(p))
 
 static inline int is_new_memtype_allowed(unsigned long flags,
                                                 unsigned long new_flags)
diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index 7ef617ef1df3..4bd990ee43df 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -137,7 +137,7 @@ static inline pte_t mfn_pte(unsigned long page_nr, pgprot_t pgprot)
         pte_t pte;
 
         pte.pte = ((phys_addr_t)page_nr << PAGE_SHIFT) |
-                (pgprot_val(pgprot) & __supported_pte_mask);
+                        massage_pgprot(pgprot);
 
         return pte;
 }