RE: TDX #VE in SYSCALL gap (was: [RFD] x86: Curing the exception and syscall trainwreck in hardware)

[Luck, Tony]

> > Or malicious hypervisor action, and that's a problem.
> >
> > Suppose the hypervisor remaps a GPA used in the SYSCALL gap (e.g. the
> > actual SYSCALL text or the first memory it accesses -- I don't have a
> > TDX spec so I don't know the details).

Is it feasible to defend against a malicious (or buggy) hypervisor?

Obviously, we can't leave holes that guests can exploit. But the hypervisor
can crash the system no matter how clever TDX is.

-Tony