Re: x86/vmx: Don't spuriously crash the domain when INIT is received

[Jason Andryuk <jandryuk@xxxxxxxxx>]

On Fri, Feb 25, 2022 at 12:12 PM Andrew Cooper
<Andrew.Cooper3@xxxxxxxxxx> wrote:
>
> On 25/02/2022 13:19, Jan Beulich wrote:
> > But I don't think I see the full picture here yet, unless your
> > mentioning of TXT was actually implying that TXT was active at the
> > point of the crash (which I don't think was said anywhere).
>
> This did cause confusion during debugging.  As far as we can tell, TXT
> is not active, but the observed behaviour certainly looks like TXT is
> active.

It's curious since the CPU, i5-1135G7, is listed as *not* supporting
TXT.  However, it does support Boot Guard, and both Boot Guard and TXT
use Authenticated Code Modules (ACMs) to implement their
functionality.  There is the below quote from the Measured Launched
Environment Developer’s Guide:
http://kib.kiev.ua/x86docs/Intel/TXT/315168-014.pdf

"Both Server TXT and Boot Guard (BtG) technologies require Startup ACM to be
executed at platform reset. Intel ® CPUs can support only single such ACM and
therefore combining of BtG ACM with a Startup ACM is inevitable for platforms
supporting both technologies. This combining requirement triggered the
whole set of
upgrades targeted to better alignment of both technologies, and their
mutual benefits."

So I'm just speculating, but it seems there is TXT-ish stuff going on
when it resumes.

Regards,
Jason