I could be totally wrong because a ton of this is waaaay over my head, so take this with a grain of salt.... but instead of this:
<qemu:arg value='-device'/>
<qemu:arg value='ioh3420,bus=pcie.0,addr=1c.0,multifunction=on,port=1,chassis=1,id=root.1'/>
<qemu:arg value='-device'/>
<qemu:arg value='vfio-pci,host=0000:01:00.0,bus=root.1,addr=00.0,multifunction=on,x-vga=on' />
<qemu:arg value='-device'/>
<qemu:arg value='vfio-pci,host=0000:01:00.1,bus=root.1,addr=00.1'/>
Shouldn't it be this (deleting the '0000')?
<qemu:arg value='-device'/>
<qemu:arg value='ioh3420,bus=pcie.0,addr=1c.0,multifunction=on,port=1,chassis=1,id=root.1'/>
<qemu:arg value='-device'/>
<qemu:arg value='vfio-pci,host=01:00.0,bus=root.1,addr=00.0,multifunction=on,x-vga=on' />
<qemu:arg value='-device'/>
<qemu:arg value='vfio-pci,host=01:00.1,bus=root.1,addr=00.1'/>