Comment 1 for bug 1848497

With a migration Bionic to Eoan with a balloon device I can confirm this.

Guestconfig:
    <memballoon model='virtio'>
      <alias name='balloon0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </memballoon>

root@testkvm-bionic-from:~# virsh migrate --unsafe --live testguest qemu+ssh://10.192.69.27/system
error: internal error: qemu unexpectedly closed the monitor: 2019-10-21T13:44:16.155100Z qemu-system-x86_64: warning: host doesn't support requested feature: CPUID.80000001H:ECX.svm [bit 2]
2019-10-21T13:44:18.530641Z qemu-system-x86_64: get_pci_config_device: Bad config data: i=0x10 read: e1 device: 1 cmask: ff wmask: c0 w1cmask:0
2019-10-21T13:44:18.530657Z qemu-system-x86_64: Failed to load PCIDevice:config
2019-10-21T13:44:18.530660Z qemu-system-x86_64: Failed to load virtio-balloon:virtio
2019-10-21T13:44:18.530663Z qemu-system-x86_64: error while loading state for instance 0x0 of device '0000:00:06.0/virtio-balloon'
2019-10-21T13:44:18.530839Z qemu-system-x86_64: load of migration failed: Invalid argument