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SubjectRe: [PATCH 6/9] KVM: SVM: WARN if KVM attempts emulation on #UD or #GP for SEV guests
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On 20/01/2022 01:07, Sean Christopherson wrote:
> WARN if KVM attempts to emulate in response to #UD or #GP for SEV guests,
> i.e. if KVM intercepts #UD or #GP, as emulation on any fault except #NPF
> is impossible since KVM cannot read guest private memory to get the code
> stream, and the CPU's DecodeAssists feature only provides the instruction
> bytes on #NPF.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/kvm/svm/svm.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 994224ae2731..ed2ca875b84b 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -4267,6 +4267,9 @@ static bool svm_can_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type,
> if (!sev_guest(vcpu->kvm))
> return true;
>
> + /* #UD and #GP should never be intercepted for SEV guests. */
> + WARN_ON_ONCE(emul_type & (EMULTYPE_TRAP_UD | EMULTYPE_VMWARE_GP));

What about EMULTYPE_TRAP_UD_FORCED?

Otherwise
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>


> +
> /*
> * Emulation is impossible for SEV-ES guests as KVM doesn't have access
> * to guest register state.

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