Re: [PATCH] Add KVM_EXIT_SHUTDOWN metadata for SEV-ES

[Paolo Bonzini]

On 3/21/22 16:42, Peter Gonda wrote:
> On Mon, Mar 21, 2022 at 9:27 AM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
> > On 3/21/22 16:02, Peter Gonda wrote:
> > > SEV-ES guests can request termination using the GHCB's MSR protocol. See
> > > AMD's GHCB spec section '4.1.13 Termination Request'. Currently when a
> > > guest does this the userspace VMM sees an KVM_EXIT_UNKNOWN (-EVINAL)
> > > return code from KVM_RUN. By adding a KVM_EXIT_SHUTDOWN_ENTRY to kvm_run
> > > struct the userspace VMM can clearly see the guest has requested a SEV-ES
> > > termination including the termination reason code set and reason code.
> > >
> > > Signed-off-by: Peter Gonda <pgonda@xxxxxxxxxx>
> > > Cc: Borislav Petkov <bp@xxxxxxxxx>
> > > Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
> > > Cc: Brijesh Singh <brijesh.singh@xxxxxxx>
> > > Cc: Joerg Roedel <jroedel@xxxxxxx>
> > > Cc: Marc Orr <marcorr@xxxxxxxxxx>
> > > Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
> > > Cc: kvm@xxxxxxxxxxxxxxx
> > > Cc: linux-kernel@xxxxxxxxxxxxxxx
> >
> > Looks good, but it has to also add a capability.
>
> Thanks for the quick review! Just so I understand. I should add
> KVM_CAP_SEV_TERM or something, then if that has been enabled do the
> new functionality, else keep the old functionality?

No, much simpler; just something for which KVM_CHECK_EXTENSION returns 
1, so that userspace knows that there is a "shutdown" member to be 
filled by KVM_EXIT_SHUTDOWN.  e.g. KVM_CAP_EXIT_SHUTDOWN_REASON.

Paolo