What is wrong with my powernv xml ?
===
$virsh define  ~/xml/powernv.xml
error: Failed to define domain from /home/michel/xml/powernv.xml
error: unsupported configuration: Option 'modelName' is not valid for PCI controller with index '0', model 'pci-root' and modelName 'spapr-pci-host-bridge'
===
$cat ~/xml/powernv.xml
<domain type='kvm' id='2'>
  <name>powernv</name>
  <memory unit='KiB'>4194304</memory>
  <currentMemory unit='KiB'>4194304</currentMemory>
  <vcpu placement='static'>4</vcpu>
  <resource>
    <partition>/machine</partition>
  </resource>
  <os>
    <type arch='ppc64' machine='powernv'>hvm</type>
    <boot dev='cdrom'/>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
  </features>
  <cpu>
    <topology sockets='1' cores='2' threads='2'/>
  </cpu>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/bin/qemu-system-ppc64</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2' cache='none'/>
      <source file='/home/michel/images/powernv.disk1.qcow2'/>
      <backingStore/>
      <target dev='sda' bus='scsi'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <disk type='network' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <source protocol='http' name='/pub/linux/fedora/rawhide/ppc64le/iso/latest'>
        <host name='sf1.tlslab.ibm.com' port='80'/>
      </source>
      <target dev='sde' bus='scsi'/>
      <readonly/>
      <address type='drive' controller='0' bus='0' target='0' unit='4'/>
    </disk>
    <controller type='pci' index='0' model='pci-root'>
      <model name='spapr-pci-host-bridge'/>
      <target index='0'/>
    </controller>
    <controller type='usb' index='0' model='qemu-xhci'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
    </controller>
    <controller type='scsi' index='0' model='virtio-scsi'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </controller>
    <interface type='bridge'>
      <source bridge='virbr0'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>
    <serial type='pty'>
      <source path='/dev/pts/2'/>
      <target type='spapr-vio-serial' port='0'>
        <model name='spapr-vty'/>
      </target>
      <address type='spapr-vio' reg='0x30001000'/>
    </serial>
    <console type='pty' tty='/dev/pts/2'>
      <source path='/dev/pts/2'/>
      <target type='serial' port='0'/>
      <address type='spapr-vio' reg='0x30001000'/>
    </console>
    <memballoon model='virtio'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </memballoon>
    <panic model='pseries'/>
  </devices>
  <seclabel type='dynamic' model='selinux' relabel='yes'>
    <label>unconfined_u:unconfined_r:svirt_t:s0:c628,c632</label>
    <imagelabel>unconfined_u:object_r:svirt_image_t:s0:c628,c632</imagelabel>
  </seclabel>
</domain>
===
$hostnamectl
   Static hostname: abanc.tlslab.ibm.com
         Icon name: computer
        Machine ID: 085bb1198e8d4ff996c6a02a1d71366e
           Boot ID: 2dd16214ef824e11b01e93a57a23c22c
  Operating System: Fedora 31 (Server Edition)
       CPE OS Name: cpe:/o:fedoraproject:fedora:31
            Kernel: Linux 5.3.15-300.fc31.ppc64le
      Architecture: ppc64-le
===