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    SubjectRe: [RFC PATCH v4 00/19] Core scheduling v4
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    On 3/17/20 2:17 PM, Thomas Gleixner wrote:

    >> The interrupt handler will be run with PTE inverted. So I don't think
    >> there's a leak via L1TF in this scenario.
    >
    > How so?
    >
    > Host memory is attackable, when one of the sibling SMT threads runs in
    > host OS (hypervisor) context and the other in guest context.
    >
    > HT1 is in guest mode and attacking (has control over PTEs). HT2 is
    > running in host mode and executes an interrupt handler. The host PTE
    > inversion does not matter in this scenario at all.
    >
    > So HT1 can very well see data which is brought into the shared L1 by
    > HT2.
    >
    > The only way to mitigate that aside of disabling HT is disabling EPT.
    >

    I had a brain lapse. Yes, PTE inversion is for mitigating against malicious
    user space code, not for malicious guest.

    Thanks for the correction.

    Tim

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