Bug 1035108

Summary:	Implement the error message while plug more CPUs than set in "current" using the guest agent
Product:	Red Hat Enterprise Linux 7	Reporter:	zhenfeng wang <zhwang>
Component:	libvirt	Assignee:	Peter Krempa <pkrempa>
Status:	CLOSED CURRENTRELEASE	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	low	Docs Contact:
Priority:	low
Version:	7.0	CC:	acathrow, ajia, chao.zhou, dyuan, gsun, hliu, mzhan, pkrempa, shyu, yang.z.zhang, ydu
Target Milestone:	rc
Target Release:	---
Hardware:	x86_64
OS:	Unspecified
Whiteboard:
Fixed In Version:	libvirt-1.1.1-14.el7	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:
Clones:	1035109 (view as bug list)		Environment:
Last Closed:	2014-06-13 12:07:50 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:
Bug Depends On:
Bug Blocks:	1035109

Description zhenfeng wang 2013-11-27 05:48:52 UTC

Description of problem:
Implement the error message while plug more CPUs than set in "current" using the guest agent

Version-Release number of selected component (if applicable):
 qemu-kvm-rhev-1.5.3-19.el7.x86_64
 libvirt-1.1.1-13.el7.x86_64
 kernel-3.10.0-47.el7.x86_6
 qemu-guest-agent-1.5.3-19.el7.x86_64.rpm

How reproducible:
100%

Steps
1.Prepare a running guest with qemu-ga service installed
# virsh list
 Id    Name                           State
----------------------------------------------------
 32    rhel7                          running

# virsh dumpxml rhel7 |grep cpu -A 3
  <vcpu placement='static' current='1'>3</vcpu>

2. Start the qemu-guest-agent service in the guest
#systemctl start qemu-guest-agent

3. Do cpu hotpulug and plug more CPUs than set in "current" using the guest agent, it report an unclear error

# virsh setvcpus rhel7 --guest 2
error: internal error: guest agent reports less cpu than requested

# virsh vcpucount rhel7 --guest
1

4.Both rhel6 and rhel7 have the same result with step3   

Actual results:
Didn't report an clear error while plug more CPUs than set in "current" using the guest agent
Expected results:
Should report an clear error message

Comment 2 Peter Krempa 2013-12-06 10:16:07 UTC

Fixed upstream:

commit 34b8449027adc44bd38151f384f5a5cdd64d996f
Author: Peter Krempa <pkrempa>
Date:   Thu Dec 5 17:47:14 2013 +0100

    qemu: Improve error when setting invalid count of vcpus via agent
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1035108
    
    When attempting to enable more vCPUs in the guest than is currently
    enabled in the guest but less than the maximum count for the VM we
    currently reported an unhelpful message:
    
     error: internal error: guest agent reports less cpu than requested
    
    This patch changes it to:
    
     error: invalid argument: requested vcpu count is greater than the count
     of enabled vcpus in the domain: 3 > 2

Comment 5 Hao Liu 2013-12-09 08:23:59 UTC

This bug is VERIFIED.

Verification steps:
Same as https://bugzilla.redhat.com/show_bug.cgi?id=1035108#c0

When calling:
# setvcpus rhel7 --guest 2

Results for libvirt-1.1.1-13.el7:
error: internal error: guest agent reports less cpu than requested

Results for libvirt-1.1.1-14.el7:
error: invalid argument: requested vcpu count is greater than the count of enabled vcpus in the domain: 2 > 1

So this patch is verified to fix the unhelpful message.

Comment 6 chao.zhou 2013-12-27 07:27:09 UTC

Hi, after hotadd the vcpu,
# virsh setvcpus rhel7 --guest 2
error: internal error: guest agent reports less cpu than requested

# virsh vcpucount rhel7 --guest
1

why vcpucount still report guest has 1 vcpu? should it be 3?

Comment 7 dyuan 2013-12-27 07:47:06 UTC

(In reply to chao.zhou from comment #6)
> Hi, after hotadd the vcpu,
> # virsh setvcpus rhel7 --guest 2
> error: internal error: guest agent reports less cpu than requested
> 
> # virsh vcpucount rhel7 --guest
> 1
> 
> why vcpucount still report guest has 1 vcpu? should it be 3?

http://www.libvirt.org/formatdomain.html#elementsCPUAllocation
the optional attribute current can be used to specify whether fewer than the maximum number of virtual CPUs should be enabled.

Comment 8 chao.zhou 2013-12-27 13:09:37 UTC

(In reply to dyuan from comment #7)
> (In reply to chao.zhou from comment #6)
> Hi, after hotadd the vcpu,
> #
> virsh setvcpus rhel7 --guest 2
> error: internal error: guest agent reports
> less cpu than requested
> 
> # virsh vcpucount rhel7 --guest
> 1
> 
> why
> vcpucount still report guest has 1 vcpu? should it be 3?
> http://www.libvirt.org/formatdomain.html#elementsCPUAllocation
the optional
> attribute current can be used to specify whether fewer than the maximum
> number of virtual CPUs should be enabled.

# virsh dumpxml rhel7 |grep cpu -A 3
  <vcpu placement='static' current='1'>3</vcpu>

This means the maximum number of vCPUs is 3, and the guest boots up with 1 online vCPU.

# virsh setvcpus rhel7 --guest 2

This means to set the vCPU number to 2 which is less than the maximum number 3. But why the vcpucount number is still 1? Is hot-add vCPU is not supported? 
Please correct me if I'm thinking the wrong way. 

Thanks.

Comment 9 zhenfeng wang 2013-12-30 02:02:11 UTC

(In reply to chao.zhou from comment #8)
> (In reply to dyuan from comment #7)
> > (In reply to chao.zhou from comment #6)
> > Hi, after hotadd the vcpu,
> > #
> > virsh setvcpus rhel7 --guest 2
> > error: internal error: guest agent reports
> > less cpu than requested
> > 
> > # virsh vcpucount rhel7 --guest
> > 1
> > 
> > why
> > vcpucount still report guest has 1 vcpu? should it be 3?
> > http://www.libvirt.org/formatdomain.html#elementsCPUAllocation
> the optional
> > attribute current can be used to specify whether fewer than the maximum
> > number of virtual CPUs should be enabled.
> 
> # virsh dumpxml rhel7 |grep cpu -A 3
>   <vcpu placement='static' current='1'>3</vcpu>
> 
> This means the maximum number of vCPUs is 3, and the guest boots up with 1
> online vCPU.
> 
> # virsh setvcpus rhel7 --guest 2
> 
> This means to set the vCPU number to 2 which is less than the maximum number
> 3. But why the vcpucount number is still 1? Is hot-add vCPU is not
> supported? 
> Please correct me if I'm thinking the wrong way. 
> 
> Thanks.

The virsh setvcpus --guest command only change the cpu numbers in the guest instead of the the hypervisor, you can find it via in virsh man page, so the cpu numbers in the guest's xml wasn't changed. In fact, you can check it with the following method 
1.login the guest ,check the guest's cpu with
 #cat /proc/cpuinfo command
2.check the cpu numbers with the virsh command in the host
#virsh vcpucount $guest_name --guest

Comment 10 Ludek Smid 2014-06-13 12:07:50 UTC

This request was resolved in Red Hat Enterprise Linux 7.0.

Contact your manager or support representative in case you have further questions about the request.