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SubjectRe: [PATCH 0/4] KVM: x86: Require EFER.NX support unless EPT is on
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On 15/06/21 18:45, Sean Christopherson wrote:
> KVM has silently required EFER.NX support for shadow paging for well over
> a year, and for NPT for roughly the same amount of time. Attempting to
> run any VM with shadow paging on a system without NX support will fail due
> to invalid state, while enabling nx_huge_pages with NPT and no NX will
> explode due to setting a reserved bit in the page tables.
>
> I really, really wanted to require NX across the board, because the lack
> of bug reports for the shadow paging change strongly suggests no one is
> running KVM on a CPU that truly doesn't have NX. But, Intel CPUs let
> firmware disable NX via MISC_ENABLES, so it's plausible that there are
> users running KVM with EPT and no NX.
>
> Sean Christopherson (4):
> KVM: VMX: Refuse to load kvm_intel if EPT and NX are disabled
> KVM: SVM: Refuse to load kvm_amd if NX support is not available
> KVM: x86: WARN and reject loading KVM if NX is supported but not
> enabled
> KVM: x86: Simplify logic to handle lack of host NX support
>
> arch/x86/kvm/cpuid.c | 13 +++++--------
> arch/x86/kvm/svm/svm.c | 13 ++++++++++---
> arch/x86/kvm/vmx/vmx.c | 6 ++++++
> arch/x86/kvm/x86.c | 3 +++
> 4 files changed, 24 insertions(+), 11 deletions(-)
>

Queued 1-3, thanks.

Paolo

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