[Linux PATCH] Fix to hugepages to work around new PWT handling

[Dave McCracken <dcm@mccr.org>]

Recent changes to Linux include code to set new flags in the pte,
including _PAGE_PAT and _PAGE_PWT.  That change conflicts with hugepage
using the pte macros to set up its pmd entries.  This patch resolves
that problem.

An additional fix here is to make sure the _PAGE_PRESENT bit is set
before hugepages does a mk_pte(), since Xen depends on that bit to
trigger the pfn->mfn translation.

Signed-off-by: Dave McCracken <dave.mccracken@oracle.com>

--------


--- stable-2.6.32.x//arch/x86/include/asm/hugetlb.h	2010-06-04 12:19:31.000000000 -0500
+++ 2.6.32-hfix//arch/x86/include/asm/hugetlb.h	2010-06-08 12:23:53.000000000 -0500
@@ -44,7 +44,7 @@ static inline pte_t huge_ptep_get(pte_t
 static inline void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
 				   pte_t *ptep, pte_t pte)
 {
-	set_pmd((pmd_t *)ptep, __pmd(pte_val(pte)));
+	set_pmd((pmd_t *)ptep, native_make_pmd(native_pte_val(pte)));
 }
 
 static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
--- stable-2.6.32.x//mm/hugetlb.c	2010-06-04 12:19:36.000000000 -0500
+++ 2.6.32-hfix//mm/hugetlb.c	2010-06-07 07:11:34.000000000 -0500
@@ -1732,12 +1732,14 @@ static pte_t make_huge_pte(struct vm_are
 				int writable)
 {
 	pte_t entry;
+	pgprot_t pgprot;
 
+	pgprot = __pgprot(pgprot_val(vma->vm_page_prot) | _PAGE_PRESENT);
 	if (writable) {
 		entry =
-		    pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
+		    pte_mkwrite(pte_mkdirty(mk_pte(page, pgprot)));
 	} else {
-		entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
+		entry = huge_pte_wrprotect(mk_pte(page, pgprot));
 	}
 	entry = pte_mkyoung(entry);
 	entry = pte_mkhuge(entry);