Re: [PATCH v2 0/3] TDX attestation support and GHCI fixup

[Paolo Bonzini]

On Fri, Jun 20, 2025 at 2:48 PM Xiaoyao Li <xiaoyao.li@xxxxxxxxx> wrote:
> > The interface I chose is that KVM always exits, but it initializes the
> > output values such that userspace can leave them untouched for unknown
> > TDVMCALLs or unknown leaves. So there is no need for this.
> >
> > Querying kernel support of other services can be added later, but
> > unless the GHCI adds more input or output fields to TdVmCallInfo there
> > is no need to limit the userspace exit to leaf 1.
>
> I meant the case where KVM is going to support another optional TDVMCALL
> leaf in the future, e.g., SetEventNotifyInterrupt. At that time,
> userspace needs to differentiate between old KVM which only supports
> <GetQuote> and new KVM which supports both <GetQuote> and
> <SetEventNotifyInterrupt>.

Yeah, I see what you mean now. Userspace cannot know which TDVMCALL
will exit, other than GET_QUOTE which we know is in the first part.

By the way I'm tempted to implement SetupEventNotifyInterrupt as well,
it's just a handful of lines of code.

Paolo