Add pcie extender bridge on KVM for ubuntu 20.04.3

Operating Systems & Open Source Virtualization
1

Hi Guys,

I am trying to configure the pci-e extender bus of Mellanox 100 GbE interface cards.

The host is running KVM on Ubuntu 20.04.3
The machine type is
hvm

My server has two NUMA nodes so I need to add the following pci-e extender into the virtual definition:

The below example is from a definition with a server with 4 NUMA nodes.

 </controller>
    <controller type='pci' index='4' model='pcie-expander-bus'>
      <model name='pxb-pcie'/>
      <target busNr='20'>
        <node>0</node>
      </target>
      <alias name='pci.4'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </controller>
    <controller type='pci' index='5' model='pcie-expander-bus'>
      <model name='pxb-pcie'/>
      <target busNr='30'>
        <node>1</node>
      </target>
      <alias name='pci.5'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </controller>
    <controller type='pci' index='6' model='pcie-expander-bus'>
      <model name='pxb-pcie'/>
      <target busNr='40'>
        <node>2</node>
      </target>
      <alias name='pci.6'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </controller>
    <controller type='pci' index='7' model='pcie-expander-bus'>
      <model name='pxb-pcie'/>
      <target busNr='50'>
        <node>3</node>
      </target>
      <alias name='pci.7'/>
     <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
    </controller>

My question is where should I add the pci-e extender bus on the virsh definition? And also do I need to make changes to the bus ,slot and functions?

Thanks.