Re: [PATCHv7 10/14] x86/mm: Avoid load_unaligned_zeropad() stepping into unaccepted memory

Kirill A. Shutemov
2022-08-13T21:10:29Z

On Sat, Aug 13, 2022 at 09:11:52AM -0700, Andy Lutomirski wrote:
> Now if the TD module could deliver an unrecoverable #MC instead of an
> impossible-to-handle #VE, maybe we could at least get a nice debug trace
> out? Of course it’s not so easy to do anything with a debug trace that
> doesn’t break confidentiality.

It is not impossible-to-handle #VE, it is no #VE for the guest and exit to
the host that cannot be recovered. Yes, it is not friednly for debugging.

Our plan was to allow SEPT_VE_DISABLE=0 for debug TD. It helps with
debugging stepping on unaccepted memory as allows #VE in the guest which
leads to panic() and nice traceback.

Would it be enough?

--
Kiryl Shutsemau / Kirill A. Shutemov