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Bug 1327499

Summary: guest have broken settings after use setvcpus --maximum to make vcpu number < vcpu number in numa
Product: Red Hat Enterprise Linux 7 Reporter: Luyao Huang <lhuang>
Component: libvirtAssignee: Peter Krempa <pkrempa>
Status: CLOSED ERRATA QA Contact: Virtualization Bugs <virt-bugs>
Severity: medium Docs Contact:
Priority: medium    
Version: 7.3CC: dyuan, rbalakri
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: libvirt-1.3.4-1.el7 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2016-11-03 18:42:15 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description Luyao Huang 2016-04-15 09:08:29 UTC
Description of problem:
guest have broken settings after use setvcpus --maximum to make vcpu number < vcpu number in numa

Version-Release number of selected component (if applicable):
libvirt-1.3.3-2.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1.prepare a guest which have numa element in xml

# virsh dumpxml rhel7.0-rhel --inactive
  <vcpu placement='static'>20</vcpu>
...
  <cpu>
    <numa>
      <cell id='0' cpus='0,2' memory='512000' unit='KiB'/>
      <cell id='1' cpus='1,3' memory='512000' unit='KiB'/>
      <cell id='2' cpus='4-19' memory='512000' unit='KiB'/>
    </numa>
  </cpu>
...

2. use setvcpus --maximum to change max vcpu:

# virsh setvcpus rhel7.0-rhel 10 --maximum --config

3. recheck xml:
  <vcpu placement='static'>10</vcpu>
...
  <cpu>
    <numa>
      <cell id='0' cpus='0,2' memory='512000' unit='KiB'/>
      <cell id='1' cpus='1,3' memory='512000' unit='KiB'/>
      <cell id='2' cpus='4-19' memory='512000' unit='KiB'/>
    </numa>
  </cpu>
...

4. restart libvirtd

# service libvirtd restart
Redirecting to /bin/systemctl restart  libvirtd.service

# virsh list --all
 Id    Name                           State
----------------------------------------------------

5. check libvirtd log

internal error: Number of CPUs in <numa> exceeds the <vcpu> count


Actual results:
guest have broken settings after use setvcpus --maximum to make vcpu number < vcpu number in numa, and guest will disappear after restart libvirtd

Expected results:

report error when use setvcpus --maximum or guest won't have broken settings

Additional info:

Comment 1 Peter Krempa 2016-04-28 07:35:02 UTC
commit b527e7c8e2e13c194cf32fee76d3be3d89365524
Author: Peter Krempa <pkrempa>
Date:   Wed Apr 27 16:39:41 2016 +0200

    qemu: Error out if setting vcpu count would lead to invalid config
    
    When the domain definition describes a machine with NUMA, setting the
    maximum vCPU count via the API might lead to an invalid config.
    
    Add a check that will forbid this until we add more advanced cpu config
    capabilities.

Comment 3 Luyao Huang 2016-08-09 06:06:41 UTC
Verify this bug with libvirt-2.0.0-4.el7.x86_64:

1. prepare a guest have numa settings:

  <vcpu placement='static' current='6'>9</vcpu>
...
  <cpu>
    <numa>
      <cell id='0' cpus='0-4' memory='524288' unit='KiB'/>
      <cell id='1' cpus='5-8' memory='524288' unit='KiB'/>
    </numa>
  </cpu>

2. change max vcpu number:

# virsh setvcpus r7 1 --config --maximum
error: invalid argument: Number of CPUs in <numa> exceeds the desired maximum vcpu count

3. recheck xml:

  <vcpu placement='static' current='6'>9</vcpu>
...
  <cpu>
    <numa>
      <cell id='0' cpus='0-4' memory='524288' unit='KiB'/>
      <cell id='1' cpus='5-8' memory='524288' unit='KiB'/>
    </numa>
  </cpu>
...

Comment 5 errata-xmlrpc 2016-11-03 18:42:15 UTC
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://rhn.redhat.com/errata/RHSA-2016-2577.html