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    Subject[PATCH 2 of 4] x86: revert "defer cr3 reload when doing pud_clear()"
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    Revert "defer cr3 reload when doing pud_clear()" since I'm going to
    replace it.

    Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
    ---
    include/asm-x86/pgalloc_32.h | 7 -------
    include/asm-x86/pgtable-3level.h | 21 ++++++---------------
    2 files changed, 6 insertions(+), 22 deletions(-)

    diff --git a/include/asm-x86/pgalloc_32.h b/include/asm-x86/pgalloc_32.h
    --- a/include/asm-x86/pgalloc_32.h
    +++ b/include/asm-x86/pgalloc_32.h
    @@ -74,13 +74,6 @@ static inline void pmd_free(pmd_t *pmd)

    static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
    {
    - /* This is called just after the pmd has been detached from
    - the pgd, which requires a full tlb flush to be recognized
    - by the CPU. Rather than incurring multiple tlb flushes
    - while the address space is being pulled down, make the tlb
    - gathering machinery do a full flush when we're done. */
    - tlb->fullmm = 1;
    -
    paravirt_release_pd(__pa(pmd) >> PAGE_SHIFT);
    tlb_remove_page(tlb, virt_to_page(pmd));
    }
    diff --git a/include/asm-x86/pgtable-3level.h b/include/asm-x86/pgtable-3level.h
    --- a/include/asm-x86/pgtable-3level.h
    +++ b/include/asm-x86/pgtable-3level.h
    @@ -96,23 +96,14 @@ static inline void pud_clear(pud_t *pudp
    set_pud(pudp, __pud(0));

    /*
    - * In principle we need to do a cr3 reload here to make sure
    - * the processor recognizes the changed pgd. In practice, all
    - * the places where pud_clear() gets called are followed by
    - * full tlb flushes anyway, so we can defer the cost here.
    + * Pentium-II erratum A13: in PAE mode we explicitly have to flush
    + * the TLB via cr3 if the top-level pgd is changed...
    *
    - * Specifically:
    - *
    - * mm/memory.c:free_pmd_range() - immediately after the
    - * pud_clear() it does a pmd_free_tlb(). We change the
    - * mmu_gather structure to do a full tlb flush (which has the
    - * effect of reloading cr3) when the pagetable free is
    - * complete.
    - *
    - * arch/x86/mm/hugetlbpage.c:huge_pmd_unshare() - the call to
    - * this is followed by a flush_tlb_range, which on x86 does a
    - * full tlb flush.
    + * XXX I don't think we need to worry about this here, since
    + * when clearing the pud, the calling code needs to flush the
    + * tlb anyway. But do it now for safety's sake. - jsgf
    */
    + write_cr3(read_cr3());
    }

    #define pud_page(pud) \



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