Public bug reported:
== Comment: #0 - Balamuruhan S <[email protected]> - 2017-02-28 03:21:57
==
---Problem Description---
CPU hot unplug fails after migrating a CPU hotplugged guest from source
Perform CPU hotplug before migration,
# virsh setvcpus avocado-vt-vm1-migration 64 --live
Hotplugged CPUs in source are available from guest XML and reflected
from inside guest.
# virsh -c 'qemu:///system' migrate --live --domain avocado-vt-vm1-migration
--desturi qemu+ssh://9.40.192.188/system --timeout 60
Migration is success without any issue
# virsh -c 'qemu+ssh://9.40.192.188/system' setvcpus avocado-vt-vm1-migration 8
--live
error: operation failed: vcpu unplug request timed out
---uname output---
# uname -a Linux c158f2u09os 4.10.0-9-generic #11-Ubuntu SMP Mon Feb 20
13:45:11 UTC 2017 ppc64le ppc64le ppc64le GNU/Linux
# qemu-img --version
qemu-img version 2.8.0(Debian 1:2.8+dfsg-2ubuntu1)
Copyright (c) 2003-2016 Fabrice Bellard and the QEMU Project developers
# dpkg -l | grep libvirt
ii libvirt-bin 2.5.0-3ubuntu2
ppc64el programs for the libvirt library
ii libvirt-clients 2.5.0-3ubuntu2
ppc64el Programs for the libvirt library
ii libvirt-daemon 2.5.0-3ubuntu2
ppc64el Virtualization daemon
ii libvirt-daemon-system 2.5.0-3ubuntu2
ppc64el Libvirt daemon configuration files
ii libvirt-dev:ppc64el 2.5.0-3ubuntu2
ppc64el development files for the libvirt library
ii libvirt-glib-1.0-0:ppc64el 1.0.0-1
ppc64el libvirt GLib and GObject mapping library
ii libvirt0:ppc64el 2.5.0-3ubuntu2
ppc64el library for interfacing with different
virtualization systems
ii python-libvirt 3.0.0-2
ppc64el libvirt Python bindings
Machine Type = Tuleta
---Steps to Reproduce---
1. Created guest with shared storage in NFS
2. Enabled ports 49152:49216 in iptables, virt_use_nfs -> on
3. Mounted the image location in destination and started migration.
4. Perform CPU hotplug to guest in source before migration
5. Perform live migration to other host.
6. CPU Hot unplug fails with "error: operation failed: vcpu unplug request
timed out"
Contact Information = Balamuruhan S / [email protected]
Userspace tool common name: virsh (libvirt)
The userspace tool has the following bit modes: ppc64le
Userspace rpm: libvirt-bin, libvirt-daemon
Userspace tool obtained from project website: na
*Additional Instructions for Balamuruhan S / [email protected]:
-Post a private note with access information to the machine that the bug is
occuring on.
-Attach ltrace and strace of userspace application.
== Comment: #4 - Balamuruhan S <[email protected]> - 2017-03-01
03:17:07 ==
== Comment: #5 - Balamuruhan S <[email protected]> - 2017-03-01 03:17:38
==
== Comment: #9 - Shivaprasad G. Bhat <[email protected]> - 2017-03-24
05:26:57 ==
On new ubuntu kernel 4.10.0.13, with in-kernel hotplug/unplug code, the newly
hotplugged core post migration can be unplugged. The cores hotplugged before
the migration cannot be unplugged post migration.
Discussed with Bharata and he believes the issue belongs to qemu.
== Comment: #11 - BHARATA BHASKER RAO <[email protected]> - 2017-03-27
01:49:59 ==
Usually when a device hotplug is done at the source and the guest is migrated,
the QEMU cmdline at the target is appended with the hot added device at the
source. For example,
At the source:
qemu ... -smp 4,maxcpus=8
(qemu) device_add host-spapr-cpu-core,core-id=4,id=core4
At the target, QEMU is started like this before starting the migration:
qemu ... -smp 4,maxcpus=8 -device host-spapr-cpu-core,core-id=4,id=core4
Thus the hot added CPU at the source became a cold-plugged CPU at the
target. This works.
What is done differently here is that libvirt is in fact doing a hotplug
at the target via QEMU monitor before the migration. In this situation
when the guest is migrated from source to target, the DRC state
information for the added CPU at the target will be wrong. The hot added
CPU at the target will never undergo the DRC state transitions via RTAS
set allocation calls. Hence subsequent hot unplug fails at the target.
This situation can be fixed by migrating the DRC state information and
updating the same for the hot added CPU at the target. This is what
Jianjun Duan's DRC state migration patchset achieves. I have verified
(using his old patchset, v5) that this problem disappears when DRC state
migration is done.
So the fix for this is to get Jianjun's DRC migration patchset upstream
and then to 1704.
** Affects: qemu (Ubuntu)
Importance: Undecided
Assignee: Taco Screen team (taco-screen-team)
Status: New
** Tags: architecture-ppc64le bugnameltc-152065 severity-critical
targetmilestone-inin1704
** Tags added: architecture-ppc64le bugnameltc-152065 severity-critical
targetmilestone-inin1704
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https://bugs.launchpad.net/bugs/1677552
Title:
CPU hot unplug fails after migrating a CPU hotplugged guest from
source
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