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

[Dave McCracken <dcm@xxxxxxxx>]

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@xxxxxxxxxx>

--------


--- 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);

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