libvirt users - Feb 2020 - can hotplug vcpus to running Windows 10 guest, but not unplug

Hi,

i'm playing a bit around with vcpus.
My guest is Windows 10 1903.
This is the excerpt from the config:
 ...
 <vcpu placement='static' current='2'>4</vcpu>
  <vcpus>
    <vcpu id='0' enabled='yes' hotpluggable='no'/>
    <vcpu id='1' enabled='yes'
hotpluggable='yes'/>
    <vcpu id='2' enabled='no' hotpluggable='yes'/>
    <vcpu id='3' enabled='no' hotpluggable='yes'/>
  </vcpus>
 ...

I'm able to hotplug vcpus, but when i want to unplug them i get the
following:

virsh # setvcpus pathway 3 --live
virsh # setvcpus pathway 4 --live
virsh # setvcpus pathway 2 --live
error: internal error: unable to execute QEMU command 'device_del':
acpi: device unplug request for not supported device type: qemu64-x86_64-cpu

Does anyone know why it can't be unplugged ?

Thanks.


Brtnf

-- 

Bernd Lentes 
Systemadministration 
Institute for Metabolism and Cell Death (MCD) 
Building 35.34 - Raum 208 
HelmholtzZentrum münchen 
bernd.lentes@helmholtz-muenchen.de 
phone: +49 89 3187 1241 
phone: +49 89 3187 3827 
fax: +49 89 3187 2294 
http://www.helmholtz-muenchen.de/mcd 

Perfekt ist wer keine Fehler macht 
Also sind Tote perfekt
Helmholtz Zentrum München

Helmholtz Zentrum Muenchen
Deutsches Forschungszentrum fuer Gesundheit und Umwelt (GmbH)
Ingolstaedter Landstr. 1
85764 Neuherberg
www.helmholtz-muenchen.de
Aufsichtsratsvorsitzende: MinDir.in Prof. Dr. Veronika von Messling
Geschaeftsfuehrung: Prof. Dr. med. Dr. h.c. Matthias Tschoep, Kerstin Guenther
Registergericht: Amtsgericht Muenchen HRB 6466
USt-IdNr: DE 129521671

On Fri, Feb 14, 2020 at 16:05:00 +0100, Lentes, Bernd
wrote:
> Hi,
> 
> i'm playing a bit around with vcpus.
> My guest is Windows 10 1903.
> This is the excerpt from the config:
>  ...
>  <vcpu placement='static' current='2'>4</vcpu>
>   <vcpus>
>     <vcpu id='0' enabled='yes'
hotpluggable='no'/>
>     <vcpu id='1' enabled='yes'
hotpluggable='yes'/>
>     <vcpu id='2' enabled='no'
hotpluggable='yes'/>
>     <vcpu id='3' enabled='no'
hotpluggable='yes'/>
>   </vcpus>
>  ...
> 
> I'm able to hotplug vcpus, but when i want to unplug them i get the
following:
> 
> virsh # setvcpus pathway 3 --live
> virsh # setvcpus pathway 4 --live
> virsh # setvcpus pathway 2 --live
> error: internal error: unable to execute QEMU command 'device_del':
acpi: device unplug request for not supported device type: qemu64-x86_64-cpu
> 
> Does anyone know why it can't be unplugged ?
Sounds like qemu doesn't support unplug of vcpus. Which version of qemu
do you use?

----- On Feb 14, 2020, at 4:13 PM, Peter Krempa pkrempa@redhat.com wrote:
> 
> Sounds like qemu doesn't support unplug of vcpus. Which version of qemu
> do you use?
ha-idg-2:~ # rpm -qa|grep qemu
qemu-seabios-1.11.0-5.18.1.noarch
qemu-ovmf-x86_64-2017+git1510945757.b2662641d5-3.16.1.noarch
qemu-block-curl-2.11.2-5.18.1.x86_64
qemu-sgabios-8-5.18.1.noarch
qemu-x86-2.11.2-5.18.1.x86_64
libvirt-daemon-qemu-4.0.0-8.15.2.x86_64
qemu-ipxe-1.0.0+-5.18.1.noarch
qemu-tools-2.11.2-5.18.1.x86_64
qemu-vgabios-1.11.0-5.18.1.noarch
qemu-block-ssh-2.11.2-5.18.1.x86_64
qemu-kvm-2.11.2-5.18.1.x86_64
qemu-2.11.2-5.18.1.x86_64
libvirt-daemon-driver-qemu-4.0.0-8.15.2.x86_64
qemu-block-rbd-2.11.2-5.18.1.x86_64

I found a table on
https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.3/html/virtual_machine_management_guide/cpu_hot_plug
saying that hotplugging is possible but no hotunplugging.
But i don't know how recent this information is and if RedHat uses
libvirt/qemu.

Bernd
Helmholtz Zentrum München

Helmholtz Zentrum Muenchen
Deutsches Forschungszentrum fuer Gesundheit und Umwelt (GmbH)
Ingolstaedter Landstr. 1
85764 Neuherberg
www.helmholtz-muenchen.de
Aufsichtsratsvorsitzende: MinDir.in Prof. Dr. Veronika von Messling
Geschaeftsfuehrung: Prof. Dr. med. Dr. h.c. Matthias Tschoep, Kerstin Guenther
Registergericht: Amtsgericht Muenchen HRB 6466
USt-IdNr: DE 129521671

Would you mind sharing your xml? I have strange high host load on idle 
windows guest/domain

 

-----Original Message-----
Sent: 14 February 2020 16:05
To: libvirt-ML
Subject: can hotplug vcpus to running Windows 10 guest, but not unplug

Hi,

i'm playing a bit around with vcpus.
My guest is Windows 10 1903.
This is the excerpt from the config:
 ...
 <vcpu placement='static' current='2'>4</vcpu>
  <vcpus>
    <vcpu id='0' enabled='yes' hotpluggable='no'/>
    <vcpu id='1' enabled='yes'
hotpluggable='yes'/>
    <vcpu id='2' enabled='no' hotpluggable='yes'/>
    <vcpu id='3' enabled='no' hotpluggable='yes'/>
  </vcpus>
 ...

I'm able to hotplug vcpus, but when i want to unplug them i get the 
following:

virsh # setvcpus pathway 3 --live
virsh # setvcpus pathway 4 --live
virsh # setvcpus pathway 2 --live
error: internal error: unable to execute QEMU command 'device_del': 
acpi: device unplug request for not supported device type: 
qemu64-x86_64-cpu

Does anyone know why it can't be unplugged ?

Thanks.


Brtnf

-- 

Bernd Lentes
Systemadministration
Institute for Metabolism and Cell Death (MCD) Building 35.34 - Raum 208 
HelmholtzZentrum münchen bernd.lentes@helmholtz-muenchen.de
phone: +49 89 3187 1241
phone: +49 89 3187 3827
fax: +49 89 3187 2294
http://www.helmholtz-muenchen.de/mcd 

Perfekt ist wer keine Fehler macht
Also sind Tote perfekt
Helmholtz Zentrum München

Helmholtz Zentrum Muenchen
Deutsches Forschungszentrum fuer Gesundheit und Umwelt (GmbH) 
Ingolstaedter Landstr. 1
85764 Neuherberg
www.helmholtz-muenchen.de
Aufsichtsratsvorsitzende: MinDir.in Prof. Dr. Veronika von Messling
Geschaeftsfuehrung: Prof. Dr. med. Dr. h.c. Matthias Tschoep, Kerstin 
Guenther
Registergericht: Amtsgericht Muenchen HRB 6466
USt-IdNr: DE 129521671