Re: [PATCH v2 2/5] Mini-OS: get own domid

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Fri, Nov 10, 2023 at 01:44:50PM +0100, Jan Beulich wrote:
> On 10.11.2023 13:23, Roger Pau Monné wrote:
> > On Fri, Nov 10, 2023 at 12:34:32PM +0100, Juergen Gross wrote:
> >> Get the own domid via creation of a temporary event channel. There is
> >> no "official" way to read the own domid in PV guests, so use the event
> >> channel interface to get it:
> >>
> >> - allocate an unbound event channel specifying DOMID_SELF for the
> >>   other end
> >>
> >> - read the event channel status which will contain the own domid in
> >>   unbound.dom
> >>
> >> - close the event channel
> > 
> > Should we look into introducing a way to expose the domid, so that in
> > the future we might not need to resort to this workarounds to get the
> > domid?
> > 
> > Maybe in the PV-specific cpuid leaf?  It's a shame we didn't put it in
> > a non-HVM specific leaf when it was made available to HVM for pvshim
> > reasons.
> 
> Couldn't we retroactively generalize the type-agnostic parts of that
> leaf?

Hm, maybe.  In retrospective heaving leafs with PV or HVM only fields
was not the best decision.  It would have been better to have a generic
leaf and then fields/flags that only apply to HVM or PV as necessary.

Thanks, Roger.