lib: utils/mpxy: bind channel access to owning domain

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@oss.qualcomm.com>
Reviewed-by: Rahul Pathak <rahul.pathak@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20260721215758.695736-1-pawandeep.oza@oss.qualcomm.com
Signed-off-by: Anup Patel <anup@brainfault.org>

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)
 
@@ -97,6 +98,8 @@ 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 +184,4 @@ 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