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[Matt Riedemann <mriedem.os@xxxxxxxxx>]

** Changed in: nova
   Importance: Undecided => Medium

** Also affects: nova/rocky
   Importance: Undecided
       Status: New

** Changed in: nova/rocky
       Status: New => Triaged

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https://bugs.launchpad.net/bugs/1788014

Title:
  when live migration fails due to a internal error rollback is not
  handeled correctly.

Status in OpenStack Compute (nova):
  In Progress
Status in OpenStack Compute (nova) rocky series:
  Triaged

Bug description:
  Description
  ===========
  While testing livemigration between ovs and ovs-dpdk on centos 7.5 i encountered
  a qemu internal error the resulted in the qemu monitor closeing.
  when the migration failed during the virDomainMigrateToURI3 it 
  rolled back the migration leaving the vm running on the souce node
  the vm however no longer had network connectivity because the vm port
  on the source node had no vif type as the host-id in the port was no long set.
  this is likely due to not reactivating the souce node binding when the migration fails.

  if the vm is hard-rebooted in this state it enters teh error state as
  the vif bingins are broken.

  note the qemu error is out of scope of this bug. this bug just focuses on the fact
  that nova does not correctly roll back the migration and result in the vm still running
  correctly with networking on the source node when a qemu error is thrown.

  
  Steps to reproduce
  ==================
  A chronological list of steps which will bring off the
  issue you noticed:
  deploy a two node devstack with ovs on the controler and ovs-dpdk on the second node.
  configure nova compute with libvirt/kvm virt type on both nodes.
  alloate hugepages on both nodes and boot a vm on either node.
  attempt to live migrate the vm to the other node.

  Expected result
  ===============
  if qemu has a bug that results in migration failure
  the vif bindings should be resotred to there premigration
  state and if networkig cannot be resore the vm should go directly
  to error state.

  Actual result
  =============
  the vm remained running on the source node with state active.
  the vm interface no longer had a host_id set in the neutron vif:binding-details
  and the vif type was none.

  on hard reboot the vm entered error state with the following message
  Error: Failed to perform requested operation on instance "dpdk", the instance has an error status: Please try again later [Error: vif_type parameter must be present for this vif_driver implementation].

  Environment
  ===========
  1. openstack rocky RC1 
     nova sha: afe4512bf66c89a061b1a7ccd3e7ac8e3b1b284d
     neutron sha: 1dda2bca862b1268c0f5ae39b7508f1b1cab6f15

  2. Which hypervisor did you use?
     libvirt + kvm
     libvirtd (libvirt) 3.9.0
     QEMU emulator version 2.10.0(qemu-kvm-ev-2.10.0-21.el7_5.4.1)
     centos 7.5
      
  2. Which storage type did you use?
    boot from volume using default lvm backed deploy by devstack.

  3. Which networking type did you use?
    neutron ml2/ovs with ovs and ovs-dpdk
    this is not really relevent to the bug.

  Logs & Configs
  ==============

  n-cpu log

  Aug 16 12:19:00 devstack5 nova-compute[14766]: 2018-08-16T11:19:00.057596Z qemu-kvm: load of migration failed: Invalid argument: libvirtError: internal error: qemu unexpectedly closed the monitor: 2018-08-16T11:19:00.055479Z qemu-kvm: get_pci_config_device: Bad config data: i=0x10 read: 61 device: 1 cmask: ff wmask: c0 w1cmask:0
  Aug 16 12:19:00 devstack5 nova-compute[14766]: DEBUG nova.virt.libvirt.driver [-] [instance: 05a564c2-2e25-4b07-911f-2ded60fb6756] Migration operation thread notification {{(pid=14766) thread_finished /opt/stack/nova/nova/virt/libvirt/driver.py:7478}}
  Aug 16 12:19:00 devstack5 nova-compute[14766]: Traceback (most recent call last):
  Aug 16 12:19:00 devstack5 nova-compute[14766]: File "/usr/lib/python2.7/site-packages/eventlet/hubs/hub.py", line 457, in fire_timers
  Aug 16 12:19:00 devstack5 nova-compute[14766]: timer()
  Aug 16 12:19:00 devstack5 nova-compute[14766]: File "/usr/lib/python2.7/site-packages/eventlet/hubs/timer.py", line 58, in __call__
  Aug 16 12:19:00 devstack5 nova-compute[14766]: cb(*args, **kw)
  Aug 16 12:19:00 devstack5 nova-compute[14766]: File "/usr/lib/python2.7/site-packages/eventlet/event.py", line 168, in _do_send
  Aug 16 12:19:00 devstack5 nova-compute[14766]: waiter.switch(result)
  Aug 16 12:19:00 devstack5 nova-compute[14766]: File "/usr/lib/python2.7/site-packages/eventlet/greenthread.py", line 214, in main
  Aug 16 12:19:00 devstack5 nova-compute[14766]: result = function(*args, **kwargs)
  Aug 16 12:19:00 devstack5 nova-compute[14766]: File "/opt/stack/nova/nova/utils.py", line 810, in context_wrapper
  Aug 16 12:19:00 devstack5 nova-compute[14766]: return func(*args, **kwargs)
  Aug 16 12:19:00 devstack5 nova-compute[14766]: File "/opt/stack/nova/nova/virt/libvirt/driver.py", line 7134, in _live_migration_operation
  Aug 16 12:19:00 devstack5 nova-compute[14766]: LOG.error("Live Migration failure: %s", e, instance=instance)
  Aug 16 12:19:00 devstack5 nova-compute[14766]: File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 220, in __exit__
  Aug 16 12:19:00 devstack5 nova-compute[14766]: self.force_reraise()
  Aug 16 12:19:00 devstack5 nova-compute[14766]: File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 196, in force_reraise
  Aug 16 12:19:00 devstack5 nova-compute[14766]: six.reraise(self.type_, self.value, self.tb)
  Aug 16 12:19:00 devstack5 nova-compute[14766]: File "/opt/stack/nova/nova/virt/libvirt/driver.py", line 7127, in _live_migration_operation
  Aug 16 12:19:00 devstack5 nova-compute[14766]: bandwidth=CONF.libvirt.live_migration_bandwidth)
  Aug 16 12:19:00 devstack5 nova-compute[14766]: File "/opt/stack/nova/nova/virt/libvirt/guest.py", line 673, in migrate
  Aug 16 12:19:00 devstack5 nova-compute[14766]: destination, params=params, flags=flags)
  Aug 16 12:19:00 devstack5 nova-compute[14766]: File "/usr/lib/python2.7/site-packages/eventlet/tpool.py", line 186, in doit
  Aug 16 12:19:00 devstack5 nova-compute[14766]: result = proxy_call(self._autowrap, f, *args, **kwargs)
  Aug 16 12:19:00 devstack5 nova-compute[14766]: File "/usr/lib/python2.7/site-packages/eventlet/tpool.py", line 144, in proxy_call
  Aug 16 12:19:00 devstack5 nova-compute[14766]: rv = execute(f, *args, **kwargs)
  Aug 16 12:19:00 devstack5 nova-compute[14766]: File "/usr/lib/python2.7/site-packages/eventlet/tpool.py", line 125, in execute
  Aug 16 12:19:00 devstack5 nova-compute[14766]: six.reraise(c, e, tb)
  Aug 16 12:19:00 devstack5 nova-compute[14766]: File "/usr/lib/python2.7/site-packages/eventlet/tpool.py", line 83, in tworker
  Aug 16 12:19:00 devstack5 nova-compute[14766]: rv = meth(*args, **kwargs)
  Aug 16 12:19:00 devstack5 nova-compute[14766]: File "/usr/lib64/python2.7/site-packages/libvirt.py", line 1745, in migrateToURI3
  Aug 16 12:19:00 devstack5 nova-compute[14766]: if ret == -1: raise libvirtError ('virDomainMigrateToURI3() failed', dom=self)
  Aug 16 12:19:00 devstack5 nova-compute[14766]: libvirtError: internal error: qemu unexpectedly closed the monitor: 2018-08-16T11:19:00.055479Z qemu-kvm: get_pci_config_device: Bad config data: i=0x10 read: 61 device: 1 cmask: ff wmask: c0 w1cmask:0
  Aug 16 12:19:00 devstack5 nova-compute[14766]: 2018-08-16T11:19:00.055541Z qemu-kvm: Failed to load PCIDevice:config
  Aug 16 12:19:00 devstack5 nova-compute[14766]: 2018-08-16T11:19:00.055555Z qemu-kvm: Failed to load virtio-net:virtio
  Aug 16 12:19:00 devstack5 nova-compute[14766]: 2018-08-16T11:19:00.055568Z qemu-kvm: error while loading state for instance 0x0 of device '0000:00:03.0/virtio-net'
  Aug 16 12:19:00 devstack5 nova-compute[14766]: 2018-08-16T11:19:00.055761Z qemu-kvm: warning: TSC frequency mismatch between VM (2712005 kHz) and host (2712000 kHz), and TSC scaling unavailable
  Aug 16 12:19:00 devstack5 nova-compute[14766]: 2018-08-16T11:19:00.057082Z qemu-kvm: warning: TSC frequency mismatch between VM (2712005 kHz) and host (2712000 kHz), and TSC scaling unavailable

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