[PATCH] lib: utils/mpxy: bind channel access to owning domain

[Pawandeep Oza]

On Fri, Jul 3, 2026 at 4:19 AM Rahul Pathak
<rahul.pathak at oss.qualcomm.com> wrote:
>
> On Mon, Jun 29, 2026 at 11:47 PM Pawandeep Oza
> <pawandeep.oza at oss.qualcomm.com> wrote:
> >
> > From: Oza Pawandeep <pawandeep.oza at oss.qualcomm.com>
> >
> > The MPXY framework currently stores registered channels in a global
> > list and exposes them to all callers. However, the intended model is
> > that each channel is assigned to a single supervisor domain at boot and
> > remains owned by that domain for its lifetime.
> >
> > Introduce fixed owner-domain tracking in struct sbi_mpxy_channel and
> > make channel lookup and enumeration domain-aware. A channel is now
> > visible only when accessed from its owning domain. Also require the
> > owner to be set before channel registration.
> >
> > This allows MPXY to support systems where the same hart may be reused by
> > multiple domains while keeping channel ownership and visibility fixed to
> > the domain that owns the service.
> >
> > Signed-off-by: Oza Pawandeep <pawandeep.oza at oss.qualcomm.com>
> >
> > diff --git a/include/sbi/sbi_mpxy.h b/include/sbi/sbi_mpxy.h
> > index 9da2791e..e7b28527 100644
> > --- a/include/sbi/sbi_mpxy.h
> > +++ b/include/sbi/sbi_mpxy.h
> > @@ -13,6 +13,7 @@
> >  #include <sbi/sbi_list.h>
> >
> >  struct sbi_scratch;
> > +struct sbi_domain;
> >
> >  #define SBI_MPXY_MSGPROTO_VERSION(Major, Minor) ((Major << 16) | Minor)
> >
> > @@ -91,12 +92,13 @@ struct sbi_mpxy_channel_attrs {
> >         /* Events State Control */
> >         u32 eventsstate_ctrl;
> >  };
> > -
> >  /** A Message proxy channel accessible through SBI interface */
> >  struct sbi_mpxy_channel {
> >         /** List head to a set of channels */
> >         struct sbi_dlist head;
> >         u32 channel_id;
> > +
> > +       struct sbi_domain *owner_domain;
> >         struct sbi_mpxy_channel_attrs attrs;
> >
> >         /**
> > @@ -181,5 +183,4 @@ int sbi_mpxy_send_message(u32 channel_id, u8 msg_id,
> >  /** Get Message proxy notification events */
> >  int sbi_mpxy_get_notification_events(u32 channel_id,
> >                                         unsigned long *events_len);
> > -
> >  #endif
> > diff --git a/lib/sbi/sbi_mpxy.c b/lib/sbi/sbi_mpxy.c
> > index ff5c6ab6..08e10dca 100644
> > --- a/lib/sbi/sbi_mpxy.c
> > +++ b/lib/sbi/sbi_mpxy.c
> > @@ -145,14 +145,23 @@ static inline bool mpxy_is_std_attr(u32 attr_id)
> >         return (attr_id >> 31) ? false : true;
> >  }
> >
> > +static inline bool mpxy_channel_visible(struct sbi_mpxy_channel *channel,
> > +                                       struct sbi_domain *dom)
> > +{
> > +       return channel->owner_domain == dom;
> > +}
> > +
> >  /** Find channel_id in registered channels list */
> > -static struct sbi_mpxy_channel *mpxy_find_channel(u32 channel_id)
> > +static struct sbi_mpxy_channel *mpxy_find_channel(u32 channel_id,
> > +                                       struct sbi_domain *dom)
> >  {
> >         struct sbi_mpxy_channel *channel;
> >
> > -       sbi_list_for_each_entry(channel, &mpxy_channel_list, head)
> > -               if (channel->channel_id == channel_id)
> > +       sbi_list_for_each_entry(channel, &mpxy_channel_list, head) {
> > +               if (channel->channel_id == channel_id &&
> > +                   mpxy_channel_visible(channel, dom))
> >                         return channel;
> > +       }
> >
> >         return NULL;
> >  }
> > @@ -222,9 +231,12 @@ static void mpxy_std_attrs_init(struct sbi_mpxy_channel *channel)
> >  int sbi_mpxy_register_channel(struct sbi_mpxy_channel *channel)
> >  {
> >         if (!channel)
> > +               return SBI_EINVAL;
> > +
> > +       if (!channel->owner_domain)
> >                 return SBI_EINVAL;
> >
> > -       if (mpxy_find_channel(channel->channel_id))
> > +       if (mpxy_find_channel(channel->channel_id, channel->owner_domain))
> >                 return SBI_EALREADY;
> >
> >         /* Initialize channel specific attributes */
> > @@ -397,12 +409,15 @@ int sbi_mpxy_get_channel_ids(u32 start_index)
> >         struct sbi_mpxy_channel *channel;
> >         u32 channels_count = 0;
> >         u32 *shmem_base;
> > +       struct sbi_domain *dom = sbi_domain_thishart_ptr();
> >
> >         if (!mpxy_shmem_enabled(ms))
> >                 return SBI_ERR_NO_SHMEM;
> >
> > -       sbi_list_for_each_entry(channel, &mpxy_channel_list, head)
> > -               channels_count += 1;
> > +       sbi_list_for_each_entry(channel, &mpxy_channel_list, head) {
> > +               if (mpxy_channel_visible(channel, dom))
> > +                       channels_count += 1;
> > +       }
> >
> >         if (start_index > channels_count)
> >                 return SBI_ERR_INVALID_PARAM;
> > @@ -420,6 +435,9 @@ int sbi_mpxy_get_channel_ids(u32 start_index)
> >
> >         // Iterate over the list of channels to get the channel ids.
> >         sbi_list_for_each_entry(channel, &mpxy_channel_list, head) {
> > +               if (!mpxy_channel_visible(channel, sbi_domain_thishart_ptr()))
>
> NIT: You can use dom here also instead of sbi_domain_thishart_ptr()
Oza: will fix this
>
> > +                       continue;
> > +
>
> >
>
> Question: Now a domain may have all the channels owned and another may have
> none, since MPXY extension will be registered anyways,
> sbi_probe_extension(SBI_EXT_MPXY)
> will return a present for the domain which does not own any channels.
> Is this intended?
Oza: yes, I think that is okay not to have channels, since ownership
is tied to the channels only. so once the channel is registered
ownership is established.
comain without channel is fine, but if it decides to send/recive
messages across domains, I will be adding some support fo the same as
well. this patch is just fixing the part where we only had root domain
so far.

>
> Thanks
> Rahul