On 10.11.2023 18:38, Julien Grall wrote: > Hi Jan, > > On 10/11/2023 12:44, 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? > > This would only work for x86. I think we want to have a generic > hypercalls so it can be used by all arch.
Hmm, yes, perhaps. Otoh it would seem desirable to me if arch-es also provided some extension to an arch-natural way of feature detection (which CPUID is on x86), without the need to invoke any hypercalls. Jan
