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SubjectRe: [PATCH 0/7] KVM: x86: expose CVE-2017-5715 ("Spectre variant 2") mitigations to guest
On Mon, 8 Jan 2018, Paolo Bonzini wrote:

> This series allows guests to use the MSR_IA32_SPEC_CTRL and
> MSR_IA32_PRED_CMD model specific registers that were added as mitigations
> for CVE-2017-5715.
>
> These are only the KVM specific parts of the fix. It does *not* yet
> include any protection for reading host memory from the guest, because
> that would be done in the same way as the rest of Linux. So there is no
> IBRS *usage* here, no retpolines, no stuffing of the return stack buffer.
> (KVM already includes a fix to clear all registers on vmexit, which is
> enough to block Google Project Zero's PoC exploit).
>
> However, I am including the changes to use IBPB (indirect branch
> predictor barrier) if available. That occurs only when there is a VCPU
> switch on a physical CPU, thus it has a small impact on performance.
>
> The patches are a bit hackish because the relevant cpufeatures have
> not been included yet, and because I wanted to make the patches easier
> to backport to distro kernels if desired, but I would still like to
> have them in 4.16.
>
> Please review.

CC'ing x86@kernel.org on this would have been asked too much, right?





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