Re: [PATCH v2 11/17] xen: Add capabilities to get_domain_state

[Jürgen Groß <jgross@xxxxxxxx>]

On 17.07.25 22:16, Jason Andryuk wrote:
> On 2025-07-17 02:24, Juergen Gross wrote:
> > On 16.07.25 23:14, Jason Andryuk wrote:
> > > Expose a domain's capabilities - control, hardware or xenstore - through
> > > stable get domain state hypercall.
> > >
> > > The xenstore domain can use this information to assign appropriate
> > > permissions on connections.
> > >
> > > Repurpose the 16bit pad field for this purpose.
> > >
> > > Signed-off-by: Jason Andryuk <jason.andryuk@xxxxxxx>
> > > ---
> > >   xen/common/domain.c         | 8 +++++++-
> > >   xen/include/public/domctl.h | 7 +++++--
> > >   2 files changed, 12 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/xen/common/domain.c b/xen/common/domain.c
> > > index c347de4335..8b0151a8f7 100644
> > > --- a/xen/common/domain.c
> > > +++ b/xen/common/domain.c
> > > @@ -195,6 +195,12 @@ static void set_domain_state_info(struct 
> > > xen_domctl_get_domain_state *info,
> > >           info->state |= XEN_DOMCTL_GETDOMSTATE_STATE_DYING;
> > >       if ( d->is_dying == DOMDYING_dead )
> > >           info->state |= XEN_DOMCTL_GETDOMSTATE_STATE_DEAD;
> I'll add:
>
> +
> +    info->caps = 0
>
> here, to ensure all the caps bits start off cleared.
>
> > > +    if ( is_control_domain(d) )
> > > +        info->caps |= XEN_DOMCTL_GETDOMSTATE_CAP_CONTROL;
> > > +    if ( is_hardware_domain(d) )
> > > +        info->caps |= XEN_DOMCTL_GETDOMSTATE_CAP_HARDWARE;
> > > +    if ( is_xenstore_domain(d) )
> > > +        info->caps |= XEN_DOMCTL_GETDOMSTATE_CAP_XENSTORE;
> > >       info->unique_id = d->unique_id;
> > >   }
> > > diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
> > > index f1f6f96bc2..879343b21d 100644
> > > --- a/xen/include/public/domctl.h
> > > +++ b/xen/include/public/domctl.h
> > > @@ -1269,8 +1269,11 @@ struct xen_domctl_get_domain_state {
> > >   #define XEN_DOMCTL_GETDOMSTATE_STATE_SHUTDOWN  0x0002  /* Shutdown 
> > > finished. */
> > >   #define XEN_DOMCTL_GETDOMSTATE_STATE_DYING     0x0004  /* Domain dying. */
> > >   #define XEN_DOMCTL_GETDOMSTATE_STATE_DEAD      0x0008  /* Domain dead. */
> > > -    uint16_t pad0;           /* Must be 0 on input, returned as 0. */
> > > -    uint32_t pad1;           /* Must be 0 on input, returned as 0. */
> > > +    uint16_t caps;           /* Must be 0 on input, returned as 0. */
> > I'd drop the "returned as 0" in the comment. :-)
> :)
>
> I'll drop the whole comment since the input value is not checked.
>
> > With that fixed:
> >
> > Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
> Does this stand with the above changes?
Yes, it does.


Juergen

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