i386: use pte_update_defer in ptep_test_and_clear_{dirty,young}
Zachary Amsden [Sun, 6 May 2007 21:49:20 +0000 (14:49 -0700)]
If you actually clear the bit, you need to:

+         pte_update_defer(vma->vm_mm, addr, ptep);

The reason is, when updating PTEs, the hypervisor must be notified.  Using
atomic operations to do this is fine for all hypervisors I am aware of.
However, for hypervisors which shadow page tables, if these PTE
modifications are not trapped, you need a post-modification call to fulfill
the update of the shadow page table.

Acked-by: Zachary Amsden <zach@vmware.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/asm-i386/pgtable.h

index 995e8b3..e16359f 100644 (file)
@@ -297,22 +297,24 @@ do {                                                                      \
 } while (0)
 
 #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_DIRTY
-static inline int ptep_test_and_clear_dirty(struct vm_area_struct *vma,
-                                           unsigned long addr, pte_t *ptep)
-{
-       if (!pte_dirty(*ptep))
-               return 0;
-       return test_and_clear_bit(_PAGE_BIT_DIRTY, &ptep->pte_low);
-}
+#define ptep_test_and_clear_dirty(vma, addr, ptep) ({                  \
+       int ret = 0;                                                    \
+       if (pte_dirty(*ptep))                                           \
+               ret = test_and_clear_bit(_PAGE_BIT_DIRTY, &ptep->pte_low); \
+       if (ret)                                                        \
+               pte_update_defer(vma->vm_mm, addr, ptep);               \
+       ret;                                                            \
+})
 
 #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
-static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
-                                           unsigned long addr, pte_t *ptep)
-{
-       if (!pte_young(*ptep))
-               return 0;
-       return test_and_clear_bit(_PAGE_BIT_ACCESSED, &ptep->pte_low);
-}
+#define ptep_test_and_clear_young(vma, addr, ptep) ({                  \
+       int ret = 0;                                                    \
+       if (pte_young(*ptep))                                           \
+               ret = test_and_clear_bit(_PAGE_BIT_ACCESSED, &ptep->pte_low); \
+       if (ret)                                                        \
+               pte_update_defer(vma->vm_mm, addr, ptep);               \
+       ret;                                                            \
+})
 
 /*
  * Rules for using ptep_establish: the pte MUST be a user pte, and
@@ -330,10 +332,8 @@ do {                                                                       \
 ({                                                                     \
        int __dirty;                                                    \
        __dirty = ptep_test_and_clear_dirty((vma), (address), (ptep));  \
-       if (__dirty) {                                                  \
-               pte_update_defer((vma)->vm_mm, (address), (ptep));      \
+       if (__dirty)                                                    \
                flush_tlb_page(vma, address);                           \
-       }                                                               \
        __dirty;                                                        \
 })
 
@@ -342,10 +342,8 @@ do {                                                                       \
 ({                                                                     \
        int __young;                                                    \
        __young = ptep_test_and_clear_young((vma), (address), (ptep));  \
-       if (__young) {                                                  \
-               pte_update_defer((vma)->vm_mm, (address), (ptep));      \
+       if (__young)                                                    \
                flush_tlb_page(vma, address);                           \
-       }                                                               \
        __young;                                                        \
 })