> On Mar 30, 2021, at 8:14 AM, Sean Christopherson <sea...@google.com> wrote: > > On Mon, Mar 29, 2021, Andy Lutomirski wrote: >> >>>> On Mar 29, 2021, at 7:04 PM, Andi Kleen <a...@linux.intel.com> 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.
Normally in non-root mode means that every XSETBV results in a VM exit and, IIUC, there’s a buglet in that this happens even if CPL==3. Does something special happen in TDX or does the exit get reflected back to the guest as a #VE?
