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    SubjectRe: [PATCH v2 3/10] KVM: MMU: fix direct sp's access corruptted
    On 06/28/2010 01:02 PM, Xiao Guangrong wrote:
    > Avi Kivity wrote:
    >> Instead of adding a new bit, can you encode the protection in the direct
    >> sp's access bits? So we'll have one sp for read-only or
    >> writeable-but-not-dirty small pages, and another sp for
    >> writeable-and-dirty small pages.
    > It looks like it can't solve all problems, it fix the access corrupted,
    > but will cause D bit losed:
    > mapping A and mapping B both are writable-and-dirty, when mapping A write
    > #PF occurs, the mapping is writable, then we can't set B's D bit anymore.

    If B is writeable-and-dirty, then it's D bit is already set, and we
    don't need to do anything.

    If B is writeable-and-clean, then we'll have an spte pointing to a
    read-only sp, so we'll get a write fault on access and an opportunity to
    set the D bit.

    > Anyway, i think we should re-intall the mapping when the state is changed. :-(

    When the gpte is changed from read-only to writeable or from clean to
    dirty, we need to update the spte, yes. But that's true for other sptes
    as well, not just large gptes.

    error compiling committee.c: too many arguments to function

     \ /
      Last update: 2010-06-28 13:15    [W:0.029 / U:29.136 seconds]
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