tools/oxenstored: Bind the DOM_EXC VIRQ in in Event.init()

Xenstored always needs to bind the DOM_EXC VIRQ.

Instead of doing it shortly after the call to Event.init(), do it in the
constructor directly.  This removes the need for the field to be a mutable
option.

It will also simplify a future change to support live update.  Rename the
field from virq_port (which could be any VIRQ) to it's proper name.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Edwin Török <edvin.torok@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
(cherry picked from commit 9804a5db43)

tools/ocaml/xenstored/event.ml

@@ -17,12 +17,15 @@
 (**************** high level binding ****************)
 type t = {
 	handle: Xeneventchn.handle;
-	mutable virq_port: Xeneventchn.t option;
+	domexc: Xeneventchn.t;
 }
 
-let init () = { handle = Xeneventchn.init (); virq_port = None; }
+let init () =
+	let handle = Xeneventchn.init () in
+	let domexc = Xeneventchn.bind_dom_exc_virq handle in
+	{ handle; domexc }
+
 let fd eventchn = Xeneventchn.fd eventchn.handle
-let bind_dom_exc_virq eventchn = eventchn.virq_port <- Some (Xeneventchn.bind_dom_exc_virq eventchn.handle)
 let bind_interdomain eventchn domid port = Xeneventchn.bind_interdomain eventchn.handle domid port
 let unbind eventchn port = Xeneventchn.unbind eventchn.handle port
 let notify eventchn port = Xeneventchn.notify eventchn.handle port

tools/ocaml/xenstored/xenstored.ml

@@ -397,7 +397,6 @@ let _ =
 	if cf.restart && Sys.file_exists Disk.xs_daemon_database then (
 		let rwro = DB.from_file store domains cons Disk.xs_daemon_database in
 		info "Live reload: database loaded";
-		Event.bind_dom_exc_virq eventchn;
 		Process.LiveUpdate.completed ();
 		rwro
 	) else (
@@ -413,7 +412,6 @@ let _ =
 
 		if cf.domain_init then (
 			Connections.add_domain cons (Domains.create0 domains);
-			Event.bind_dom_exc_virq eventchn
 		);
 		rw_sock
 	) in
@@ -451,7 +449,7 @@ let _ =
 			let port = Event.pending eventchn in
 			debug "pending port %d" (Xeneventchn.to_int port);
 			finally (fun () ->
-				if Some port = eventchn.Event.virq_port then (
+				if port = eventchn.Event.domexc then (
 					let (notify, deaddom) = Domains.cleanup domains in
 					List.iter (Store.reset_permissions store) deaddom;
 					List.iter (Connections.del_domain cons) deaddom;