xen: events: add event channel allocation for domain-0

This commit adds interface for evtchn allocation that can be used by
privilaged domain. Domain 0 can specify both dom and remote_dom
parameters for hypercall, where in others domains dom should be always
DOMID_SELF. It is needed for creating pre-defined channels during
domain setup in Zephyr Dom0.

Signed-off-by: Dmytro Firsov <[email protected]>

Author: firscity

drivers/xen/events.c

@@ -47,6 +47,24 @@ int alloc_unbound_event_channel(domid_t remote_dom)
 	return rc;
 }
 
+#ifdef CONFIG_XEN_DOM0
+int alloc_unbound_event_channel_dom0(domid_t dom, domid_t remote_dom)
+{
+	int rc;
+	struct evtchn_alloc_unbound alloc = {
+		.dom = dom,
+		.remote_dom = remote_dom,
+	};
+
+	rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound, &alloc);
+	if (rc == 0) {
+		rc = alloc.port;
+	}
+
+	return rc;
+}
+#endif /* CONFIG_XEN_DOM0 */
+
 int bind_interdomain_event_channel(domid_t remote_dom, evtchn_port_t remote_port,
 		evtchn_cb_t cb, void *data)
 {

include/zephyr/xen/events.h

@@ -36,6 +36,17 @@ void notify_evtchn(evtchn_port_t port);
  */
 int alloc_unbound_event_channel(domid_t remote_dom);
 
+#ifdef CONFIG_XEN_DOM0
+/*
+ * Allocate event-channel between remote domains. Can be used only from Dom0.
+ *
+ * @param dom - first remote domain domid (may be DOMID_SELF)
+ * @param remote_dom - second remote domain domid
+ * @return - local event channel port on success, negative on error
+ */
+int alloc_unbound_event_channel_dom0(domid_t dom, domid_t remote_dom);
+#endif /* CONFIG_XEN_DOM0 */
+
 /*
  * Allocate local event channel, binded to remote port and attach specified callback
  * to it