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Subject[PATCH 0/7] KVM: x86: expose CVE-2017-5715 ("Spectre variant 2") mitigations to guest
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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.

Thanks,

Paolo

Paolo Bonzini (5):
KVM: x86: add SPEC_CTRL and IBPB_SUPPORT accessors
x86/msr: add definitions for indirect branch predictor MSRs
kvm: vmx: pass MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD down to the guest
kvm: svm: pass MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD down to guest
KVM: x86: add SPEC_CTRL and IBPB_SUPPORT to MSR and CPUID lists

Tim Chen (1):
kvm: vmx: Set IBPB when running a different VCPU

Tom Lendacky (1):
x86/svm: Set IBPB when running a different VCPU

arch/x86/include/asm/msr-index.h | 5 ++++
arch/x86/kvm/cpuid.c | 27 +++++++++++++----
arch/x86/kvm/cpuid.h | 22 ++++++++++++++
arch/x86/kvm/svm.c | 65 +++++++++++++++++++++++++++++++++++++++-
arch/x86/kvm/vmx.c | 41 +++++++++++++++++++++++++
arch/x86/kvm/x86.c | 1 +
6 files changed, 154 insertions(+), 7 deletions(-)

--
1.8.3.1

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