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    SubjectRe: Redoing eXclusive Page Frame Ownership (XPFO) with isolated CPUs in mind (for KVM to isolate its guests per CPU)
    On Mon, Aug 20, 2018 at 09:52:19PM +0000, Woodhouse, David wrote:
    > On Mon, 2018-08-20 at 14:48 -0700, Linus Torvalds wrote:
    > >
    > > Of course, after the long (and entirely unrelated) discussion about
    > > the TLB flushing bug we had, I'm starting to worry about my own
    > > competence, and maybe I'm missing something really fundamental, and
    > > the XPFO patches do something else than what I think they do, or my
    > > "hey, let's use our Meltdown code" idea has some fundamental weakness
    > > that I'm missing.
    >
    > The interesting part is taking the user (and other) pages out of the
    > kernel's 1:1 physmap.
    >
    > It's the *kernel* we don't want being able to access those pages,
    > because of the multitude of unfixable cache load gadgets.

    I am missing why we need this since the kernel can't access
    (SMAP) unless we go through to the copy/to/from interface
    or execute any of the user pages. Is it because of the dependency
    on the availability of those features?

    Balbir Singh.

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