On Thu, Jan 20, 2022, Liam Merwick wrote: > 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@xxxxxxxxxx> > > --- > > 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? Hmm, yeah, it's worth adding, there's no additional cost. I was thinking it was a modifier to EMULTYPE_TRAP_UD, but it's a replacement specifically to bypass the EmulateOnUD check (which I should have remembered since I added the type...).
