Re: [PATCH v6 2/2] xen/domain: adjust domain ID allocation for Arm

[dmkhn@xxxxxxxxx]

On Sun, May 18, 2025 at 10:57:44AM +0200, Jan Beulich wrote:
> On 16.05.2025 04:04, dmkhn@xxxxxxxxx wrote:
> > --- a/xen/common/domain.c
> > +++ b/xen/common/domain.c
> > @@ -85,7 +85,7 @@ void __init domid_init(void)
> >   *
> >   * If hint is outside of valid [0..DOMID_FIRST_RESERVED - 1] range of IDs,
> >   * perform an exhaustive search starting from the end of the used domain ID
> > - * range.
> > + * range, excluding get_initial_domain_id() ID.
> >   */
> >  domid_t domid_alloc(domid_t domid)
> >  {
> > @@ -103,6 +103,9 @@ domid_t domid_alloc(domid_t domid)
> >              if ( domid == DOMID_FIRST_RESERVED )
> >                  domid = 0;
> >
> > +            if ( domid == get_initial_domain_id() )
> > +                continue;
> > +
> >              if ( !rangeset_contains_singleton(domid_rangeset, domid) )
> >                  break;
> >          }
> 
> Isn't there a (perhaps even pre-existing) issue here with a DomU potentially
> getting ID 0 assigned when get_initial_domain_id() returns non-zero?

Yes, thanks.

I have updated commit message in v7 to mention that:

  https://lore.kernel.org/xen-devel/20250519192306.1364471-3-dmukhin@xxxxxxxx/

> 
> Jan