diff --git a/nova/compute/api.py b/nova/compute/api.py
index d5d66fa571a4..d2c08678b8e8 100644
--- a/nova/compute/api.py
+++ b/nova/compute/api.py
@@ -997,12 +997,12 @@ class API(base.Base):
     def set_host_enabled(self, context, host, enabled):
         """Sets the specified host's ability to accept new instances."""
         return self._call_compute_message("set_host_enabled", context,
-                instance_id=None, host=host, params={"enabled": enabled})
+                host=host, params={"enabled": enabled})
 
     def host_power_action(self, context, host, action):
         """Reboots, shuts down or powers up the host."""
         return self._call_compute_message("host_power_action", context,
-                instance_id=None, host=host, params={"action": action})
+                host=host, params={"action": action})
 
     @scheduler_api.reroute_compute("diagnostics")
     def get_diagnostics(self, context, instance_id):
diff --git a/nova/compute/manager.py b/nova/compute/manager.py
index ecfbd3908d44..cb6617c331b1 100644
--- a/nova/compute/manager.py
+++ b/nova/compute/manager.py
@@ -958,14 +958,12 @@ class ComputeManager(manager.SchedulerDependentManager):
                                                        result))
 
     @exception.wrap_exception(notifier=notifier, publisher_id=publisher_id())
-    def host_power_action(self, context, instance_id=None, host=None,
-            action=None):
+    def host_power_action(self, context, host=None, action=None):
         """Reboots, shuts down or powers up the host."""
         return self.driver.host_power_action(host, action)
 
     @exception.wrap_exception(notifier=notifier, publisher_id=publisher_id())
-    def set_host_enabled(self, context, instance_id=None, host=None,
-            enabled=None):
+    def set_host_enabled(self, context, host=None, enabled=None):
         """Sets the specified host's ability to accept new instances."""
         return self.driver.set_host_enabled(host, enabled)
 
diff --git a/nova/virt/xenapi/vmops.py b/nova/virt/xenapi/vmops.py
index b549b33d1d1f..b913e764e3fb 100644
--- a/nova/virt/xenapi/vmops.py
+++ b/nova/virt/xenapi/vmops.py
@@ -1045,7 +1045,7 @@ class VMOps(object):
         xenapi_resp = self._call_xenhost("set_host_enabled", args)
         try:
             resp = json.loads(xenapi_resp)
-        except TypeError  as e:
+        except TypeError as e:
             # Already logged; return the message
             return xenapi_resp.details[-1]
         return resp["status"]
diff --git a/plugins/xenserver/xenapi/etc/xapi.d/plugins/xenhost b/plugins/xenserver/xenapi/etc/xapi.d/plugins/xenhost
index f6a9ac8d8db5..7bf507d0ff24 100755
--- a/plugins/xenserver/xenapi/etc/xapi.d/plugins/xenhost
+++ b/plugins/xenserver/xenapi/etc/xapi.d/plugins/xenhost
@@ -136,7 +136,7 @@ def host_shutdown(self, arg_dict):
 
 @jsonify
 def host_start(self, arg_dict):
-    """Starts the host. NOTE: Currently not feasible, since the host
+    """Starts the host. Currently not feasible, since the host
     runs on the same machine as Xen.
     """
     return _power_action("startup")