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    SubjectRe: [patch 1/2] x86_64 page fault NMI-safe
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    On Wed, Jul 14, 2010 at 11:46 AM, Ingo Molnar <mingo@elte.hu> wrote:
    >>  NMI entry:
    >
    > I think at this point [NMI re-entry] we've corrupted the top of the NMI kernel
    > stack already, due to entering via the IST stack mechanism, which is
    > non-nesting and which enters at the same point - right?

    Yeah, you're right, but we could easily fix that up. We know we don't
    need any stack for the nested case, so all we would need to do is to
    just subtract a small bit off %rsp, and copy the three words or so to
    create a "new" stack for the non-nested case.

    > We could solve that by copying that small stack frame off before entering the
    > 'generic' NMI routine - but it all feels a bit pulled in by the hair.

    Why? It's much cleaner than making the _real_ codepaths much worse.

    Linus
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