can hotplug vcpus to running Windows 10 guest, but not unplug

[Peter Krempa]

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?