xenstored: rebind event channels after live update in stubdom

After performing a live update in stubdom environment some information
about inter-domain event channels is lost. In order to set this
information again, call xenevtchn_bind() from new_domain() in the
restore case.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>

tools/xenstored/core.c

@@ -49,7 +49,6 @@
 #include "control.h"
 #include "lu.h"
 
-extern xenevtchn_handle *xce_handle; /* in domain.c */
 static int xce_pollfd_idx = -1;
 struct pollfd *poll_fds;
 static unsigned int current_array_size;

tools/xenstored/core.h

@@ -394,6 +394,8 @@ static inline bool domain_is_unprivileged(const struct connection *conn)
 	return conn && domid_is_unprivileged(conn->id);
 }
 
+extern xenevtchn_handle *xce_handle; /* in domain.c */
+
 /* Return the event channel used by xenbus. */
 evtchn_port_t get_xenbus_evtchn(void);
 void early_init(bool live_update, bool dofork, const char *pidfile);
@@ -407,6 +409,7 @@ int get_socket_fd(void);
 void set_socket_fd(int fd);
 
 xenevtchn_handle *evtchn_fdopen(int fd);
+int evtchn_rebind(int port);
 
 #ifdef __MINIOS__
 void mount_9pfs(void);

tools/xenstored/domain.c

@@ -862,9 +862,13 @@ static int new_domain(struct domain *domain, int port, bool restore)
 
 	wrl_domain_new(domain);
 
-	if (restore)
+	if (restore) {
+		if (evtchn_rebind(port)) {
+			errno = ENOMEM;
+			return errno;
+		}
 		domain->port = port;
-	else {
+	} else {
 		/* Tell kernel we're interested in this event. */
 		rc = xenevtchn_bind_interdomain(xce_handle, domain->domid,
 						port);

tools/xenstored/minios.c

@@ -90,6 +90,11 @@ xenevtchn_handle *evtchn_fdopen(int fd)
 	return xenevtchn_open(NULL, XENEVTCHN_NO_CLOEXEC);
 }
 
+int evtchn_rebind(int port)
+{
+	return xenevtchn_bind(xce_handle, port);
+}
+
 static void mount_thread(void *p)
 {
 	xenbus_event_queue events = NULL;

tools/xenstored/posix.c

@@ -413,6 +413,11 @@ xenevtchn_handle *evtchn_fdopen(int fd)
 	return xenevtchn_fdopen(NULL, fd, 0);
 }
 
+int evtchn_rebind(int port)
+{
+	return 0;
+}
+
 const char *xenstore_rundir(void)
 {
 	return xenstore_daemon_rundir();