Messages in this thread | | | Date | Mon, 11 Oct 2021 09:49:15 -0700 | Subject | Re: [PATCH v8 06/11] x86/traps: Add #VE support for TDX guest | From | Andi Kleen <> |
| |
> Minor clarification: it eliminates the chance of a #VE during the syscall gap > _if the VMM is benign_. If the VMM is malicious, it can unmap and remap the > syscall page to induce an EPT Violation #VE due to the page not being accepted.
This has been addressed. The TDX module will support a mode that forbids unmapping pages permanently, and Linux is going to check/enforce that this mode is enabled. The patch for the check is not included in the posted patches yet though.
> > This question? > > Can the hypervisor cause an already-accepted secure-EPT page to transition to > the unaccepted state? > > Yep. I wrote the above before following the link, I should have guessed which > question it was :-) > > IIRC, the proposed middle ground was to add a TDCALL and/or TDPARAMS setting that > would allow the guest to opt-out of EPT Violation #VE due to page not accepted,
It's a TDPARAMS setting
-Andi
| |