Jeremy Fitzhardinge
2010-Jul-20 19:55 UTC
[Xen-devel] [PATCH] x86/hugetlb: use set_pmd for huge pte operations
From: Dave McCracken <dave.mccracken@oracle.com>
On x86, a huge pte is logically a pte, but structurally a pmd. Among
other issues, pmds and ptes overload some flags for multiple uses (PAT
vs PSE), so it is necessary to know which structural level a pagetable
entry is in order interpret it properly.
When huge pages are used within a paravirtualized system, it is therefore
appropriate to use the pmd set of function to operate on them, so that
the hypervisor can correctly validate the update.
Signed-off-by: Dave McCracken <dave.mccracken@oracle.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
diff --git a/arch/x86/include/asm/hugetlb.h b/arch/x86/include/asm/hugetlb.h
index 439a9ac..4cfd4de 100644
--- a/arch/x86/include/asm/hugetlb.h
+++ b/arch/x86/include/asm/hugetlb.h
@@ -36,16 +36,24 @@ static inline void hugetlb_free_pgd_range(struct mmu_gather
*tlb,
free_pgd_range(tlb, addr, end, floor, ceiling);
}
+static inline pte_t huge_ptep_get(pte_t *ptep)
+{
+ return *ptep;
+}
+
static inline void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte)
{
- set_pte_at(mm, addr, ptep, pte);
+ set_pmd((pmd_t *)ptep, __pmd(pte_val(pte)));
}
static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
- return ptep_get_and_clear(mm, addr, ptep);
+ pte_t pte = huge_ptep_get(ptep);
+
+ set_huge_pte_at(mm, addr, ptep, __pte(0));
+ return pte;
}
static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
@@ -66,19 +74,25 @@ static inline pte_t huge_pte_wrprotect(pte_t pte)
static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
- ptep_set_wrprotect(mm, addr, ptep);
+ pte_t pte = huge_ptep_get(ptep);
+
+ pte = pte_wrprotect(pte);
+ set_huge_pte_at(mm, addr, ptep, pte);
}
static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep,
pte_t pte, int dirty)
{
- return ptep_set_access_flags(vma, addr, ptep, pte, dirty);
-}
+ pte_t oldpte = huge_ptep_get(ptep);
+ int changed = !pte_same(oldpte, pte);
-static inline pte_t huge_ptep_get(pte_t *ptep)
-{
- return *ptep;
+ if (changed && dirty) {
+ set_huge_pte_at(vma->vm_mm, addr, ptep, pte);
+ flush_tlb_page(vma, addr);
+ }
+
+ return changed;
}
static inline int arch_prepare_hugepage(struct page *page)
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel