Bug 1611061

Summary:	The cpu number in error info is wrong when enable/disable a vcpu which is followed by non-hotpluggable online vcpus
Product:	Red Hat Enterprise Linux Advanced Virtualization	Reporter:	Fangge Jin <fjin>
Component:	libvirt	Assignee:	Peter Krempa <pkrempa>
Status:	CLOSED ERRATA	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	low	Docs Contact:
Priority:	low
Version:	8.0	CC:	dyuan, jdenemar, jsuchane, lhuang, lmen, pkrempa, rbalakri, xuzhang, yalzhang
Target Milestone:	rc	Keywords:	Triaged
Target Release:	8.0
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:	libvirt-6.2.0-1.el8	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-11-17 17:44:45 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 Fangge Jin 2018-08-02 03:13:29 UTC

Description of problem:
The cpu number in error info is wrong when enable/disable a vcpu which is followed by non-hotpluggable online vcpus

Version-Release number of selected component:
libvirt-4.5.0-6.virtcov.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Prepare a guest with more than two vcpus:
# virsh vcpucount rhel7.5
maximum      config       240
current      config         8

Don't set the hotpluggable attribute for each vcpu. By default,t the first 8 vcpus are enabled and not hotpluggable.
# virsh dumpxml rhel7.5 |grep hotpluggable

2.Try to disable or enable one vcpu (select one among vcpu 1-6):
# virsh setvcpu rhel7.5 4 --disable --config
error: invalid argument: vcpu '-1' can't be modified as it is followed by non-hotpluggable online vcpus

# virsh setvcpu rhel7.5 4 --enable --config
error: invalid argument: vcpu '-1' can't be modified as it is followed by non-hotpluggable online vcpus

Actual results:
As step2 , the vcpu number in error message is not correct

Expected results:
It should be:
error: invalid argument: vcpu '4' can't be modified as it is followed by non-hotpluggable online vcpus

Comment 3 Peter Krempa 2020-03-19 09:19:20 UTC

Fixed upstream:

commit 5ed97c22865c86ccca3802d24c9893dd1109ab34
Author: Peter Krempa <pkrempa>
Date:   Tue Mar 17 18:33:31 2020 +0100

    qemuDomainVcpuValidateConfig: Properly initialize 'firstcpu' variable
    
    The loop which checks whether the vcpus are in proper configuration for
    the requested hot(un)plug skips the first modified vcpu. This means
    that 'firstvcpu' which is used to print the error message in case the
    configuration is not suitable would never point to the first modified
    vcpu.
    
    In cases such as:
    
      <vcpu placement='auto' current='5'>8</vcpu>
      <vcpus>
        <vcpu id='0' enabled='yes' hotpluggable='no'/>
        <vcpu id='1' enabled='yes' hotpluggable='no'/>
        <vcpu id='2' enabled='yes' hotpluggable='no'/>
        <vcpu id='3' enabled='yes' hotpluggable='no'/>
        <vcpu id='4' enabled='yes' hotpluggable='no'/>
        <vcpu id='5' enabled='no' hotpluggable='yes'/>
        <vcpu id='6' enabled='no' hotpluggable='yes'/>
        <vcpu id='7' enabled='no' hotpluggable='yes'/>
      </vcpus>
    
     # virsh setvcpu --config --disable  upstream 1
     error: invalid argument: vcpu '-1' can't be modified as it is followed by non-hotpluggable online vcpus
    
    After this fix the proper vcpu is reported in the error message:
    
     # virsh setvcpu --config --disable  upstream 1
     error: invalid argument: vcpu '1' can't be modified as it is followed by non-hotpluggable online vcpu

Comment 6 jiyan 2020-05-13 04:15:13 UTC

Reproduced this bug libvirt-6.0.0-14.module+el8.3.0+6124+819ee737.x86_64 with and verified this bug with libvirt-6.3.0-1.module+el8.3.0+6478+69f490bb.x86_64.

Version:
libvirt-6.0.0-14.module+el8.3.0+6124+819ee737.x86_64
qemu-kvm-4.2.0-19.module+el8.3.0+6478+69f490bb.x86_64
kernel-4.18.0-196.el8.x86_64

Steps:
1. Prepare a shutdown VM with the following XML
# virsh domstate test83
shut off

# virsh dumpxml test83 --inactive | grep "<vcpu"
  <vcpu placement='static' current='7'>10</vcpu>

2. Start the VM and check vcpucount info
# virsh start test83
Domain test83 started

# virsh console test83
Connected to domain test83
Escape character is ^]

Red Hat Enterprise Linux 8.2 Beta (Ootpa)
Kernel 4.18.0-187.el8.x86_64 on an x86_64

localhost login: 

# virsh vcpucount test83 
maximum      config        10
maximum      live          10
current      config         7
current      live           7

3. Disable/Enable vCPU 1 by "virsh setvcpu" cmd with --config parameter
# virsh setvcpu test83 1 --enable --config 
error: invalid argument: vcpu '-1' can't be modified as it is followed by non-hotpluggable online vcpus

# virsh setvcpu test83 1 --disable --config 
error: invalid argument: vcpu '-1' can't be modified as it is followed by non-hotpluggable online vcpus

4. Upgrade libvirt
# yum upgrade libvirt* -y

# rpm -qa libvirt
libvirt-6.3.0-1.module+el8.3.0+6478+69f490bb.x86_64

# systemctl restart libvirtd

5. Repeat step-3
# virsh setvcpu test83 1 --enable --config 
error: invalid argument: vcpu '1' can't be modified as it is followed by non-hotpluggable online vcpus

# virsh setvcpu test83 1 --disable --config 
error: invalid argument: vcpu '1' can't be modified as it is followed by non-hotpluggable online vcpus

# virsh setvcpu test83 4 --disable --config 
error: invalid argument: vcpu '4' can't be modified as it is followed by non-hotpluggable online vcpus

All the test results are as expected, move this bug to e verified.

Comment 10 errata-xmlrpc 2020-11-17 17:44:45 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 (virt:8.3 bug fix and enhancement update), 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-2020:5137