Re: [RFC PATCH v3 12/36] i386/tdx: Add property sept-ve-disable for tdx-guest object

[Xiaoyao Li]

On 3/22/2022 5:02 PM, Gerd Hoffmann wrote:
> On Thu, Mar 17, 2022 at 09:58:49PM +0800, Xiaoyao Li wrote:
> > Add sept-ve-disable property for tdx-guest object. It's used to
> > configure bit 28 of TD attributes.
>
> What is this?

It seems this bit doesn't show up in the public spec yet.

Bit 28 (SEPT_VE_DISABLE): Disable EPT violation conversion to #VE ON 
guest TD ACCESS of PENDING pages.

The TDX architecture requires a private page to be accepted before 
using. If guest accesses a not-accepted (pending) page it will get #VE.

For some OS, e.g., Linux TD guest, it doesn't want the #VE on pending 
page so it will set this bit.

> > --- a/qapi/qom.json
> > +++ b/qapi/qom.json
> > @@ -792,10 +792,13 @@
> >   #
> >   # @attributes: TDX guest's attributes (default: 0)
> >   #
> > +# @sept-ve-disable: attributes.sept-ve-disable[bit 28] (default: 0)
>
> I'd suggest to document this here.
>
> thanks,
>    Gerd