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

[Sean Christopherson]

On Tue, Sep 14, 2021, Peter Gonda wrote:
> Copying an ASID into new vCPUs will not work for SEV-ES since the vCPUs
> VMSAs need to be setup and measured before SEV_LAUNCH_FINISH. Return an
> error if a users tries to KVM_CAP_VM_COPY_ENC_CONTEXT_FROM from an
> SEV-ES guest.

What happens if userspace does KVM_CAP_VM_COPY_ENC_CONTEXT_FROM before the source
has created vCPUs, i.e. before it has done SEV_LAUNCH_FINISH?

Might be worth noting that the destination cannot be an SEV guest, and therefore
can't be an SEV-ES guest either.

> Fixes: 54526d1fd593 ("KVM: x86: Support KVM VMs sharing SEV context")

Cc: stable@xxxxxxxxxxxxxxx