Re: (Proposal) New TDX Global Metadata To Report FIXED0 and FIXED1 CPUID Bits

[Edgecombe, Rick P]

On Tue, 2024-12-10 at 11:22 +0800, Xiaoyao Li wrote:
> > The solution in this proposal decreases the work the VMM has to do, but in
> > the
> > long term won't remove hand coding completely. As long as we are designing
> > something, what kind of bar should we target?
> 
> For this specific #VE reduction case, I think userspace doesn't need to 
> do any hand coding. Userspace just treats the bits related to #VE 
> reduction as configurable as reported by TDX module/KVM. And userspace 
> doesn't care if the value seen by TD guest is matched with what gets 
> configured by it because they are out of control of userspace.

Besides a specific problem, here reduced #VE is also an example of increasing
complexity for TD CPUID. If we have more things like it, it could make this
interface too rigid. But another way to address it would be to get this
interface *and* understanding of "no more CPUID config complexity". And that may
be a good idea anyway.