# Copyright (c) 2016 Red Hat, Inc # # Licensed under the Apache License, Version 2.0 (the "License"); you may # not use this file except in compliance with the License. You may obtain # a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the # License for the specific language governing permissions and limitations # under the License. """Utility methods to manage guests migration """ from collections import deque from lxml import etree from oslo_log import log as logging from nova.compute import power_state import nova.conf from nova import exception from nova import objects from nova.virt import hardware from nova.virt.libvirt import config as vconfig LOG = logging.getLogger(__name__) CONF = nova.conf.CONF # TODO(berrange): hack to avoid a "import libvirt" in this file. # Remove this and similar hacks in guest.py, driver.py, host.py # etc in Ocata. libvirt = None def graphics_listen_addrs(migrate_data): """Returns listen addresses of vnc/spice from a LibvirtLiveMigrateData""" listen_addrs = None if (migrate_data.obj_attr_is_set('graphics_listen_addr_vnc') or migrate_data.obj_attr_is_set('graphics_listen_addr_spice')): listen_addrs = {'vnc': None, 'spice': None} if migrate_data.obj_attr_is_set('graphics_listen_addr_vnc'): listen_addrs['vnc'] = str(migrate_data.graphics_listen_addr_vnc) if migrate_data.obj_attr_is_set('graphics_listen_addr_spice'): listen_addrs['spice'] = str( migrate_data.graphics_listen_addr_spice) return listen_addrs def get_updated_guest_xml(instance, guest, migrate_data, get_volume_config, get_vif_config=None, new_resources=None): xml_doc = etree.fromstring(guest.get_xml_desc(dump_migratable=True)) xml_doc = _update_graphics_xml(xml_doc, migrate_data) xml_doc = _update_serial_xml(xml_doc, migrate_data) xml_doc = _update_volume_xml( xml_doc, migrate_data, instance, get_volume_config) xml_doc = _update_perf_events_xml(xml_doc, migrate_data) xml_doc = _update_memory_backing_xml(xml_doc, migrate_data) if get_vif_config is not None: xml_doc = _update_vif_xml(xml_doc, migrate_data, get_vif_config) if 'dst_numa_info' in migrate_data: xml_doc = _update_numa_xml(xml_doc, migrate_data) if new_resources: xml_doc = _update_device_resources_xml(xml_doc, new_resources) return etree.tostring(xml_doc, encoding='unicode') def _update_device_resources_xml(xml_doc, new_resources): vpmems = [] for resource in new_resources: if 'metadata' in resource: res_meta = resource.metadata if isinstance(res_meta, objects.LibvirtVPMEMDevice): vpmems.append(res_meta) # If there are other resources in the future, the xml should # be updated here like vpmems xml_doc = _update_vpmems_xml(xml_doc, vpmems) return xml_doc def _update_vpmems_xml(xml_doc, vpmems): memory_devices = xml_doc.findall("./devices/memory") for pos, memory_dev in enumerate(memory_devices): if memory_dev.get('model') == 'nvdimm': devpath = memory_dev.find('./source/path') devpath.text = vpmems[pos].devpath return xml_doc def _update_numa_xml(xml_doc, migrate_data): LOG.debug('_update_numa_xml input xml=%s', etree.tostring(xml_doc, encoding='unicode', pretty_print=True)) info = migrate_data.dst_numa_info # NOTE(artom) cpu_pins, cell_pins and emulator_pins should always come # together, or not at all. if ('cpu_pins' in info and 'cell_pins' in info and 'emulator_pins' in info): for guest_id, host_ids in info.cpu_pins.items(): vcpupin = xml_doc.find( './cputune/vcpupin[@vcpu="%d"]' % int(guest_id)) vcpupin.set('cpuset', hardware.format_cpu_spec(host_ids)) emulatorpin = xml_doc.find('./cputune/emulatorpin') emulatorpin.set('cpuset', hardware.format_cpu_spec(info.emulator_pins)) all_cells = [] for guest_id, host_ids in info.cell_pins.items(): all_cells.extend(host_ids) memnode = xml_doc.find( './numatune/memnode[@cellid="%d"]' % int(guest_id)) memnode.set('nodeset', hardware.format_cpu_spec(host_ids)) memory = xml_doc.find('./numatune/memory') memory.set('nodeset', hardware.format_cpu_spec(set(all_cells))) if 'sched_vcpus' and 'sched_priority' in info: cputune = xml_doc.find('./cputune') # delete the old variant(s) for elem in cputune.findall('./vcpusched'): elem.getparent().remove(elem) # ...and create a new, shiny one vcpusched = vconfig.LibvirtConfigGuestCPUTuneVCPUSched() vcpusched.vcpus = info.sched_vcpus vcpusched.priority = info.sched_priority # TODO(stephenfin): Stop assuming scheduler type. We currently only # create these elements for real-time instances and 'fifo' is the only # scheduler policy we currently support so this is reasonably safe to # assume, but it's still unnecessary vcpusched.scheduler = 'fifo' cputune.append(vcpusched.format_dom()) LOG.debug('_update_numa_xml output xml=%s', etree.tostring(xml_doc, encoding='unicode', pretty_print=True)) return xml_doc def _update_graphics_xml(xml_doc, migrate_data): listen_addrs = graphics_listen_addrs(migrate_data) # change over listen addresses for dev in xml_doc.findall('./devices/graphics'): gr_type = dev.get('type') listen_tag = dev.find('listen') if gr_type in ('vnc', 'spice'): if listen_tag is not None: listen_tag.set('address', listen_addrs[gr_type]) if dev.get('listen') is not None: dev.set('listen', listen_addrs[gr_type]) return xml_doc def _update_serial_xml(xml_doc, migrate_data): listen_addr = migrate_data.serial_listen_addr listen_ports = migrate_data.serial_listen_ports def set_listen_addr_and_port(source, listen_addr, serial_listen_ports): # The XML nodes can be empty, which would make checks like # "if source.get('host'):" different to an explicit check for # None. That's why we have to check for None in this method. if source.get('host') is not None: source.set('host', listen_addr) device = source.getparent() target = device.find("target") if target is not None and source.get('service') is not None: port_index = int(target.get('port')) # NOTE (markus_z): Previous releases might not give us the # ports yet, that's why we have this check here. if len(serial_listen_ports) > port_index: source.set('service', str(serial_listen_ports[port_index])) # This updates all "LibvirtConfigGuestSerial" devices for source in xml_doc.findall("./devices/serial[@type='tcp']/source"): set_listen_addr_and_port(source, listen_addr, listen_ports) # This updates all "LibvirtConfigGuestConsole" devices for source in xml_doc.findall("./devices/console[@type='tcp']/source"): set_listen_addr_and_port(source, listen_addr, listen_ports) return xml_doc def _update_volume_xml(xml_doc, migrate_data, instance, get_volume_config): """Update XML using device information of destination host.""" migrate_bdm_info = migrate_data.bdms # Update volume xml parser = etree.XMLParser(remove_blank_text=True) disk_nodes = xml_doc.findall('./devices/disk') bdm_info_by_serial = {x.serial: x for x in migrate_bdm_info} for pos, disk_dev in enumerate(disk_nodes): serial_source = disk_dev.findtext('serial') bdm_info = bdm_info_by_serial.get(serial_source) if (serial_source is None or not bdm_info or not bdm_info.connection_info or serial_source not in bdm_info_by_serial): continue conf = get_volume_config( instance, bdm_info.connection_info, bdm_info.as_disk_info()) if bdm_info.obj_attr_is_set('encryption_secret_uuid'): conf.encryption = vconfig.LibvirtConfigGuestDiskEncryption() conf.encryption.format = 'luks' secret = vconfig.LibvirtConfigGuestDiskEncryptionSecret() secret.type = 'passphrase' secret.uuid = bdm_info.encryption_secret_uuid conf.encryption.secret = secret xml_doc2 = etree.XML(conf.to_xml(), parser) serial_dest = xml_doc2.findtext('serial') # Compare source serial and destination serial number. # If these serial numbers match, continue the process. if (serial_dest and (serial_source == serial_dest)): LOG.debug("Find same serial number: pos=%(pos)s, " "serial=%(num)s", {'pos': pos, 'num': serial_source}) for cnt, item_src in enumerate(disk_dev): # If source and destination have same item, update # the item using destination value. for item_dst in xml_doc2.findall(item_src.tag): if item_dst.tag != 'address': # hw address presented to guest must never change, # especially during live migration as it can be fatal disk_dev.remove(item_src) item_dst.tail = None disk_dev.insert(cnt, item_dst) # If destination has additional items, thses items should be # added here. for item_dst in list(xml_doc2): if item_dst.tag != 'address': # again, hw address presented to guest must never change item_dst.tail = None disk_dev.insert(cnt, item_dst) return xml_doc def _update_perf_events_xml(xml_doc, migrate_data): """Update XML by the supported events of destination host.""" supported_perf_events = [] old_xml_has_perf = True if 'supported_perf_events' in migrate_data: supported_perf_events = migrate_data.supported_perf_events perf_events = xml_doc.findall('./perf') # remove perf events from xml if not perf_events: perf_events = etree.Element("perf") old_xml_has_perf = False else: perf_events = perf_events[0] for _, event in enumerate(perf_events): perf_events.remove(event) if not supported_perf_events: return xml_doc # add supported perf events for e in supported_perf_events: new_event = etree.Element("event", enabled="yes", name=e) perf_events.append(new_event) if not old_xml_has_perf: xml_doc.append(perf_events) return xml_doc def _update_memory_backing_xml(xml_doc, migrate_data): """Update libvirt domain XML for file-backed memory If incoming XML has a memoryBacking element, remove access, source, and allocation children elements to get it to a known consistent state. If no incoming memoryBacking element, create one. If destination wants file-backed memory, add source, access, and allocation children. """ old_xml_has_memory_backing = True file_backed = False memory_backing = xml_doc.findall('./memoryBacking') if 'dst_wants_file_backed_memory' in migrate_data: file_backed = migrate_data.dst_wants_file_backed_memory if not memory_backing: # Create memoryBacking element memory_backing = etree.Element("memoryBacking") old_xml_has_memory_backing = False else: memory_backing = memory_backing[0] # Remove existing file-backed memory tags, if they exist. for name in ("access", "source", "allocation", "discard"): tag = memory_backing.findall(name) if tag: memory_backing.remove(tag[0]) # Leave empty memoryBacking element if not file_backed: return xml_doc # Add file_backed memoryBacking children memory_backing.append(etree.Element("source", type="file")) memory_backing.append(etree.Element("access", mode="shared")) memory_backing.append(etree.Element("allocation", mode="immediate")) memory_backing.append(etree.Element("discard")) if not old_xml_has_memory_backing: xml_doc.append(memory_backing) return xml_doc def _update_vif_xml(xml_doc, migrate_data, get_vif_config): # Loop over each interface element in the original xml and find the # corresponding vif based on mac and then overwrite the xml with the new # attributes but maintain the order of the interfaces and maintain the # guest pci address. instance_uuid = xml_doc.findtext('uuid') parser = etree.XMLParser(remove_blank_text=True) interface_nodes = xml_doc.findall('./devices/interface') # MAC address stored for port in neutron DB and in domain XML # might be in different cases, so to harmonize that # we convert MAC to lower case for dict key. migrate_vif_by_mac = {vif.source_vif['address'].lower(): vif for vif in migrate_data.vifs} for interface_dev in interface_nodes: mac = interface_dev.find('mac') mac = mac if mac is not None else {} mac_addr = mac.get('address') if mac_addr: # MAC address stored in libvirt should always be normalized # and stored in lower case. But just to be extra safe here # we still normalize MAC retrieved from XML to be absolutely # sure it will be the same with the Neutron provided one. migrate_vif = migrate_vif_by_mac[mac_addr.lower()] vif = migrate_vif.get_dest_vif() # get_vif_config is a partial function of # nova.virt.libvirt.vif.LibvirtGenericVIFDriver.get_config # with all but the 'vif' kwarg set already and returns a # LibvirtConfigGuestInterface object. vif_config = get_vif_config(vif=vif) else: # This shouldn't happen but if it does, we need to abort the # migration. raise exception.NovaException( 'Unable to find MAC address in interface XML for ' 'instance %s: %s' % ( instance_uuid, etree.tostring(interface_dev, encoding='unicode'))) # At this point we want to replace the interface elements with the # destination vif config xml *except* for the guest PCI address. conf_xml = vif_config.to_xml() LOG.debug('Updating guest XML with vif config: %s', conf_xml, instance_uuid=instance_uuid) dest_interface_elem = etree.XML(conf_xml, parser) # Save off the hw address and MTU presented to the guest since that # can't change during live migration. address = interface_dev.find('address') mtu = interface_dev.find('mtu') # Now clear the interface's current elements and insert everything # from the destination vif config xml. interface_dev.clear() # Insert attributes. for attr_name, attr_value in dest_interface_elem.items(): interface_dev.set(attr_name, attr_value) # Insert sub-elements. for index, dest_interface_subelem in enumerate(dest_interface_elem): # NOTE(mnaser): If we don't have an MTU, don't define one, else # the live migration will crash. if dest_interface_subelem.tag == 'mtu' and mtu is None: continue interface_dev.insert(index, dest_interface_subelem) # And finally re-insert the hw address. interface_dev.insert(index + 1, address) return xml_doc def find_job_type(guest, instance, logging_ok=True): """Determine the (likely) current migration job type :param guest: a nova.virt.libvirt.guest.Guest :param instance: a nova.objects.Instance :param logging_ok: If logging in this method is OK. If called from a native thread then logging is generally prohibited. Annoyingly when job type == NONE and migration is no longer running, we don't know whether we stopped because of failure or completion. We can distinguish these cases by seeing if the VM still exists & is running on the current host :returns: a libvirt job type constant """ def _log(func, msg, *args, **kwargs): if logging_ok: func(msg, *args, **kwargs) try: if guest.is_active(): _log(LOG.debug, "VM running on src, migration failed", instance=instance) return libvirt.VIR_DOMAIN_JOB_FAILED else: _log(LOG.debug, "VM is shutoff, migration finished", instance=instance) return libvirt.VIR_DOMAIN_JOB_COMPLETED except libvirt.libvirtError as ex: _log(LOG.debug, "Error checking domain status %(ex)s", {"ex": ex}, instance=instance) if ex.get_error_code() == libvirt.VIR_ERR_NO_DOMAIN: _log(LOG.debug, "VM is missing, migration finished", instance=instance) return libvirt.VIR_DOMAIN_JOB_COMPLETED else: _log(LOG.info, "Error %(ex)s, migration failed", {"ex": ex}, instance=instance) return libvirt.VIR_DOMAIN_JOB_FAILED def should_trigger_timeout_action(instance, elapsed, completion_timeout, migration_status): """Determine if the migration timeout action should be triggered :param instance: a nova.objects.Instance :param elapsed: total elapsed time of migration in secs :param completion_timeout: time in secs to allow for completion :param migration_status: current status of the migration Check the completion timeout to determine if it has been hit, and should thus cause migration timeout action to be triggered. Avoid migration to be aborted or triggered post-copy again if it is running in post-copy mode :returns: True if the migration completion timeout action should be performed, False otherwise """ if not completion_timeout: return False if migration_status == 'running (post-copy)': return False if elapsed > completion_timeout: LOG.warning("Live migration not completed after %d sec", completion_timeout, instance=instance) return True return False def update_downtime(guest, instance, olddowntime, downtime_steps, elapsed): """Update max downtime if needed :param guest: a nova.virt.libvirt.guest.Guest to set downtime for :param instance: a nova.objects.Instance :param olddowntime: current set downtime, or None :param downtime_steps: list of downtime steps :param elapsed: total time of migration in secs Determine if the maximum downtime needs to be increased based on the downtime steps. Each element in the downtime steps list should be a 2 element tuple. The first element contains a time marker and the second element contains the downtime value to set when the marker is hit. The guest object will be used to change the current downtime value on the instance. Any errors hit when updating downtime will be ignored :returns: the new downtime value """ LOG.debug("Current %(dt)s elapsed %(elapsed)d steps %(steps)s", {"dt": olddowntime, "elapsed": elapsed, "steps": downtime_steps}, instance=instance) thisstep = None for step in downtime_steps: if elapsed > step[0]: thisstep = step if thisstep is None: LOG.debug("No current step", instance=instance) return olddowntime if thisstep[1] == olddowntime: LOG.debug("Downtime does not need to change", instance=instance) return olddowntime LOG.info("Increasing downtime to %(downtime)d ms " "after %(waittime)d sec elapsed time", {"downtime": thisstep[1], "waittime": thisstep[0]}, instance=instance) try: guest.migrate_configure_max_downtime(thisstep[1]) except libvirt.libvirtError as e: LOG.warning("Unable to increase max downtime to %(time)d ms: %(e)s", {"time": thisstep[1], "e": e}, instance=instance) return thisstep[1] def save_stats(instance, migration, info, remaining): """Save migration stats to the database :param instance: a nova.objects.Instance :param migration: a nova.objects.Migration :param info: a nova.virt.libvirt.guest.JobInfo :param remaining: percentage data remaining to transfer Update the migration and instance objects with the latest available migration stats """ # The fully detailed stats migration.memory_total = info.memory_total migration.memory_processed = info.memory_processed migration.memory_remaining = info.memory_remaining migration.disk_total = info.disk_total migration.disk_processed = info.disk_processed migration.disk_remaining = info.disk_remaining migration.save() # The coarse % completion stats instance.progress = 100 - remaining instance.save() def trigger_postcopy_switch(guest, instance, migration): try: guest.migrate_start_postcopy() except libvirt.libvirtError as e: LOG.warning("Failed to switch to post-copy live migration: %s", e, instance=instance) else: # NOTE(ltomas): Change the migration status to indicate that # it is in post-copy active mode, i.e., the VM at # destination is the active one LOG.info("Switching to post-copy migration mode", instance=instance) migration.status = 'running (post-copy)' migration.save() def run_tasks(guest, instance, active_migrations, on_migration_failure, migration, is_post_copy_enabled): """Run any pending migration tasks :param guest: a nova.virt.libvirt.guest.Guest :param instance: a nova.objects.Instance :param active_migrations: dict of active migrations :param on_migration_failure: queue of recovery tasks :param migration: a nova.objects.Migration :param is_post_copy_enabled: True if post-copy can be used Run any pending migration tasks queued against the provided instance object. The active migrations dict should use instance UUIDs for keys and a queue of tasks as the values. Currently the valid tasks that can be requested are "pause" and "force-complete". Other tasks will be ignored. """ tasks = active_migrations.get(instance.uuid, deque()) while tasks: task = tasks.popleft() if task == 'force-complete': if migration.status == 'running (post-copy)': LOG.warning("Live-migration %s already switched " "to post-copy mode.", instance=instance) elif is_post_copy_enabled: trigger_postcopy_switch(guest, instance, migration) else: try: guest.pause() on_migration_failure.append("unpause") except Exception as e: LOG.warning("Failed to pause instance during " "live-migration %s", e, instance=instance) else: LOG.warning("Unknown migration task '%(task)s'", {"task": task}, instance=instance) def run_recover_tasks(host, guest, instance, on_migration_failure): """Run any pending migration recovery tasks :param host: a nova.virt.libvirt.host.Host :param guest: a nova.virt.libvirt.guest.Guest :param instance: a nova.objects.Instance :param on_migration_failure: queue of recovery tasks Run any recovery tasks provided in the on_migration_failure queue. Currently the only valid task that can be requested is "unpause". Other tasks will be ignored """ while on_migration_failure: task = on_migration_failure.popleft() # NOTE(tdurakov): there is still possibility to leave # instance paused in case of live-migration failure. # This check guarantee that instance will be resumed # in this case if task == 'unpause': try: state = guest.get_power_state(host) if state == power_state.PAUSED: guest.resume() except Exception as e: LOG.warning("Failed to resume paused instance " "before live-migration rollback %s", e, instance=instance) else: LOG.warning("Unknown migration task '%(task)s'", {"task": task}, instance=instance) def downtime_steps(data_gb): '''Calculate downtime value steps and time between increases. :param data_gb: total GB of RAM and disk to transfer This looks at the total downtime steps and upper bound downtime value and uses a linear function. For example, with 10 steps, 30 second step delay, 3 GB of RAM and 400ms target maximum downtime, the downtime will be increased every 90 seconds in the following progression: - 0 seconds -> set downtime to 40ms - 90 seconds -> set downtime to 76ms - 180 seconds -> set downtime to 112ms - 270 seconds -> set downtime to 148ms - 360 seconds -> set downtime to 184ms - 450 seconds -> set downtime to 220ms - 540 seconds -> set downtime to 256ms - 630 seconds -> set downtime to 292ms - 720 seconds -> set downtime to 328ms - 810 seconds -> set downtime to 364ms - 900 seconds -> set downtime to 400ms This allows the guest a good chance to complete migration with a small downtime value. ''' downtime = CONF.libvirt.live_migration_downtime steps = CONF.libvirt.live_migration_downtime_steps delay = CONF.libvirt.live_migration_downtime_delay delay = int(delay * data_gb) base = downtime / steps offset = (downtime - base) / steps for i in range(steps + 1): yield (int(delay * i), int(base + offset * i))