Re: [PATCH] KVM: SEV: Disable KVM_CAP_VM_COPY_ENC_CONTEXT_FROM for SEV-ES

[Paolo Bonzini]

On 14/09/21 20:49, Sean Christopherson wrote:
> On Tue, Sep 14, 2021, Peter Gonda wrote:
> > I do not think so. You cannot call KVM_SEV_LAUNCH_UPDATE_VMSA on the mirror
> > because svm_mem_enc_op() blocks calls from the mirror. So either you have to
> > update vmsa from the mirror or have the original VM read through its mirror's
> > vCPUs when calling KVM_SEV_LAUNCH_UPDATE_VMSA. Not sure which way is better
> > but I don't see a way to do this without updating KVM.
>
> Ah, right, I forgot all of the SEV ioctls are blocked on the mirror.  Put something
> to that effect into the changelog to squash any argument about whether or not this
> is the correct KVM behavior.

Indeed, at least KVM_SEV_LAUNCH_UPDATE_VMSA would have to be allowed in 
the mirror VM.  Do you think anything else would be necessary?

Paolo