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SubjectRe: [PATCH 0/5] KVM: x86: Handle reserved CR4 bit interception in VMX
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On 30/09/20 06:16, Sean Christopherson wrote:
> This series stems from Lai's RFC patches to intercept LA57 and let the
> guest own FSGSBASE[*]. Discussion and inspection revealed that KVM does
> not handle the case where LA57 is supported in hardware but not exposed to
> the guest. This is actually true for all CR4 bits, but LA57 is currently
> the only bit that can be reserved and also owned by the guest. I have
> a unit test for this that I'll post separately.
>
> Intercepting LA57 was by far the easiest fix for the immedidate bug, and
> is likely the right change in the long term as there's no justification
> for letting the guest own LA57.
>
> The middle three patches adjust VMX's CR4 guest/host mask to intercept
> reserved bits. This required reworking CPUID updates to also refresh said
> mask at the correct time.
>
> The last past is Lai's, which let's the guest own FSGSBASE. This depends
> on the reserved bit handling being in place.
>
> Ran everything through unit tests, and ran the kernel's FSGSBASE selftests
> in a VM.
>
> [*] https://lkml.kernel.org/r/20200928083047.3349-1-jiangshanlai@gmail.com
>
> Lai Jiangshan (2):
> KVM: x86: Intercept LA57 to inject #GP fault when it's reserved
> KVM: x86: Let the guest own CR4.FSGSBASE
>
> Sean Christopherson (3):
> KVM: x86: Invoke vendor's vcpu_after_set_cpuid() after all common
> updates
> KVM: x86: Move call to update_exception_bitmap() into VMX code
> KVM: VMX: Intercept guest reserved CR4 bits to inject #GP fault
>
> arch/x86/kvm/cpuid.c | 6 +++---
> arch/x86/kvm/kvm_cache_regs.h | 2 +-
> arch/x86/kvm/vmx/vmx.c | 18 +++++++++++++-----
> 3 files changed, 17 insertions(+), 9 deletions(-)
>

Queued, thanks.

Paolo

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