Re: [PATCH 5/8] KVM: nSVM: implement ondemand allocation of the nested state

Maxim Levitsky
2020-08-20T11:55:31Z

On Thu, 2020-08-20 at 11:58 +0200, Paolo Bonzini wrote:
> On 20/08/20 11:13, Maxim Levitsky wrote:
> > @@ -3912,6 +3914,14 @@ static int svm_pre_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
> > vmcb_gpa = GET_SMSTATE(u64, smstate, 0x7ee0);
> >
> > if (guest) {
> > + /*
> > + * This can happen if SVM was not enabled prior to #SMI,
> > + * but guest corrupted the #SMI state and marked it as
> > + * enabled it there
> > + */
> > + if (!svm->nested.initialized)
> > + return 1;
> > +
> > if (kvm_vcpu_map(&svm->vcpu, gpa_to_gfn(vmcb_gpa), &map) == -EINVAL)
> > return 1;
>
> This can also happen if you live migrate while in SMM (EFER.SVME=0).
> You need to check for the SVME bit in the SMM state save area, and:
>
> 1) triple fault if it is clear
>
> 2) call svm_allocate_nested if it is set.
>
> Paolo
>
Makes sense, will do.

Best regards,
Maxim Levitsky