Re: [RFC PATCH 3/4] KVM: TDX: Exit to userspace for GetTdVmCallInfo

[Edgecombe, Rick P]

On Wed, 2025-06-11 at 07:54 -0700, Sean Christopherson wrote:
> > Let's see what Paolo and Sean will say.
> 
> Kicking this to userspace seems premature.  AIUI, no "optional" VMCALL
> features
> are defined at this time, i.e. there's nothing to enumerate.  And there's no
> guarantee that there will ever be capabilties that require enumeration from 
> *userspace*.  E.g. if fancy feature XYZ requires enumeration, but that feature
> requires explicit KVM support, then forcing userspace will be messy.
> 
> So I don't see why KVM should anything other than return '0' to the guest (or
> whatever value says "there's nothing here").

GetQuote is not part of the "Base" TDVMCALLs and so has a bit in
GetTdVmCallInfo. We could move it to base?

Paolo seemed keen on GetTdVmCallInfo exiting to userspace, but this was before
the spec overhaul.