Bug 1754466

Flag VIR_MIGRATE_PARAM_BANDWIDTH_POSTCOPY accidentally works but is also missing from the list of hints in libvirt-python implementation.

Upstream commits:

commit ebd352515d75036bc1dd2018669c3a5efb5bcf3d
Author: Pavel Hrdina <phrdina>
Date:   Mon Sep 23 12:59:18 2019 +0200

    virDomainMigrate3Params: add missing parallel connections param

commit 1c206858313619672d6eebd3989be13cc8281d26
Author: Pavel Hrdina <phrdina>
Date:   Mon Sep 23 12:53:01 2019 +0200

    virDomainMigrate3Params: add missing bandwidth postcopy param

Verify with python3-libvirt-5.6.0-2.module+el8.1.0+4286+bc7b622c.x86_64.  

1. Set parallel connections number and using 'netstat -tunapc | grep 4915 | grep ESTABLISHED' command to check. 
# python
Python 3.6.8 (default, Aug 29 2019, 22:00:26) 
[GCC 8.3.1 20190507 (Red Hat 8.3.1-4)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import libvirt
>>> conn = libvirt.open()
>>> dom = conn.lookupByName('test')
>>> dom.migrateSetMaxSpeed(100, 0)
0
>>> dconn = libvirt.open("qemu+ssh://10.16.216.141/system")
>>> dom.migrate3(dconn, {'parallel.connections': 5}, flags)    <== Migration succeeds and using 'netstat' to get connections number is 6
<libvirt.virDomain object at 0x7efd23fd74a8>

>>> dom.migrate3(dconn, {}, flags)    <== Migration succeeds and using 'netstat' to get connections number is 3
<libvirt.virDomain object at 0x7efd2413e0b8>

>>> dom.migrate3(dconn, {'parallel.connections': -1}, flags)    <== Migration succeeds and using 'netstat' to get connections number is 256
<libvirt.virDomain object at 0x7efd2413e0b8>

>>> dom.migrate3(dconn, {'parallel.connections': 255}, flags)    <== Migration succeeds and using 'netstat' to get connections number is 256
<libvirt.virDomain object at 0x7efd24802828>


2. Some negative tests.
>>> dom.migrate3(dconn, {'parallel.connections': 256}, flags)
libvirt: QEMU Driver error : internal error: unable to execute QEMU command 'migrate-set-parameters': Parameter 'multifd_channels' expects is invalid, it should be in the range of 1 to 255
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib64/python3.6/site-packages/libvirt.py", line 1670, in migrate3
    if ret is None:raise libvirtError('virDomainMigrate3() failed', dom=self)
libvirt.libvirtError: internal error: unable to execute QEMU command 'migrate-set-parameters': Parameter 'multifd_channels' expects is invalid, it should be in the range of 1 to 255

>>> dom.migrate3(dconn, {'parallel.connections': 0}, flags)
libvirt: QEMU Driver error : internal error: unable to execute QEMU command 'migrate-set-parameters': Parameter 'multifd_channels' expects is invalid, it should be in the range of 1 to 255
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib64/python3.6/site-packages/libvirt.py", line 1670, in migrate3
    if ret is None:raise libvirtError('virDomainMigrate3() failed', dom=self)
libvirt.libvirtError: internal error: unable to execute QEMU command 'migrate-set-parameters': Parameter 'multifd_channels' expects is invalid, it should be in the range of 1 to 255

>>> dom.migrate3(dconn, "{'parallel.connections': 5}", flags)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib64/python3.6/site-packages/libvirt.py", line 1669, in migrate3
    ret = libvirtmod.virDomainMigrate3(self._o, dconn__o, params, flags)
TypeError: migration params must be a dictionary

>>> dom.migrate3(dconn, None, flags)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib64/python3.6/site-packages/libvirt.py", line 1669, in migrate3
    ret = libvirtmod.virDomainMigrate3(self._o, dconn__o, params, flags)
TypeError: migration params must be a dictionary

Add a missing parameter for test steps.

>>> flags = libvirt.VIR_MIGRATE_LIVE | libvirt.VIR_MIGRATE_PARALLEL

Add test steps for 'bandwidth.postcopy' with python3-libvirt-5.6.0-2.module+el8.1.0+4286+bc7b622c.x86_64.

1. Start migration with 'bandwidth.postcopy' parameter. 
# python
Python 3.6.8 (default, Aug 29 2019, 22:00:26) 
[GCC 8.3.1 20190507 (Red Hat 8.3.1-4)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import libvirt
>>> conn = libvirt.open()
>>> dom = conn.lookupByName('test')
>>> dconn = libvirt.open("qemu+ssh://10.16.216.141/system")
>>> flags = libvirt.VIR_MIGRATE_LIVE | libvirt.VIR_MIGRATE_POSTCOPY
>>> dom.migrate3(dconn, {"bandwidth.postcopy": 4}, flags)    <== Migration succeeds.
<libvirt.virDomain object at 0x7efd24802828>

2. On other terminal, switch to postcopy mode and check migration maximum speed.
# python
Python 3.6.8 (default, Aug 29 2019, 22:00:26) 
[GCC 8.3.1 20190507 (Red Hat 8.3.1-4)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import libvirt
>>> conn = libvirt.open()
>>> dom = conn.lookupByName('test')
>>> dom.migrateStartPostCopy(0)
0
>>> dom.migrateGetMaxSpeed(libvirt.VIR_DOMAIN_MIGRATE_MAX_SPEED_POSTCOPY) 
4

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2019:3723