Re: [RFC PATCH V6 01/14] x86/sev: Add a #HV exception handler

[Peter Zijlstra]

On Tue, May 30, 2023 at 02:16:55PM +0200, Gupta, Pankaj wrote:
> 
> > > Add a #HV exception handler that uses IST stack.
> > > 
> > 
> > Urgh.. that is entirely insufficient. Like it doesn't even begin to
> > start to cover things.
> > 
> > The whole existing VC IST stack abuse is already a nightmare and you're
> > duplicating that.. without any explanation for why this would be needed
> > and how it is correct.
> > 
> > Please try again.
> 
> #HV handler handles both #NMI & #MCE in the guest and nested #HV is never
> raised by the hypervisor. 

I thought all this confidental computing nonsense was about not trusting
the hypervisor, so how come we're now relying on the hypervisor being
sane?