Re: [PATCH v3 1/1] x86/tdx: Handle MWAIT, MONITOR and WBINVD

[Sean Christopherson]

On Mon, Mar 29, 2021, Andy Lutomirski wrote:
> 
> > On Mar 29, 2021, at 7:04 PM, Andi Kleen <ak@xxxxxxxxxxxxxxx> wrote:
> > 
> > 
> >> 
> >>> No, if these instructions take a #VE then they were executed at CPL=0.  MONITOR
> >>> and MWAIT will #UD without VM-Exit->#VE.  Same for WBINVD, s/#UD/#GP.
> >> 
> >> Dare I ask about XSETBV?
> > 
> > XGETBV does not cause a #VE, it just works normally. The guest has full
> > AVX capabilities.
> > 
> 
> X *SET* BV

Heh, XSETBV also works normally, relative to the features enumerated in CPUID.
XSAVES/XRSTORS support is fixed to '1' in the virtual CPU model.  A subset of
the features managed by XSAVE can be hidden by the VMM, but attempting to enable
unsupported features will #GP (either from hardware or injected by TDX Module),
not #VE.