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    SubjectRe: Avoid speculative indirect calls in kernel
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    On 04/01/2018 18:13, Dave Hansen wrote:
    > On 01/04/2018 08:25 AM, Andrea Arcangeli wrote:
    >> It's only where SPEC_CTRL is missing and only IBPB_SUPPORT is
    >> available, that ibrs 0 ibpb 2 is the only option to fix variant#2 for
    >> good.
    >
    > Could you help us decode what "ibrs 0 ibpb 2" means to you?

    IBRS 0 = disabled
    IBRS 1 = only kernel sets IBRS=1
    IBRS 2 = indirect branch prediction fully disabled, or do the right
    thing on future processors

    IBPB 0 = disabled
    IBPB 1 = on context switch
    IBPB 2 = on every kernel or hypervisor entry

    Thanks,

    Paolo

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