My xml is as follows
<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
<name>OSX-Yosemite-10.10</name>
<uuid>0ba39646-7ba1-4d41-9602-e2969a3fc26d</uuid>
<metadata>
<type>None</type>
</metadata>
<memory unit='KiB'>4194304</memory>
<currentMemory unit='KiB'>4194304</currentMemory>
<vcpu placement='static'>2</vcpu>
<resource>
<partition>/machine</partition>
</resource>
<os>
<type arch='x86_64' machine='pc-q35-2.1'>hvm</type>
<kernel>/mnt/disk1/vm_images/extra/chameleon_svn2549_boot</kernel>
<boot dev='cdrom'/>
<bootmenu enable='yes'/>
</os>
<features>
<acpi/>
</features>
<cpu mode='custom' match='exact'>
<model fallback='allow'>core2duo</model>
</cpu>
<clock offset='utc'/>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>destroy</on_crash>
<devices>
<emulator>/usr/bin/qemu-system-x86_64</emulator>
<disk type='file' device='disk'>
<driver name='qemu' type='qcow2'/>
<source file='/mnt/disk1/vm_images/Yosemite.qcow2'/>
<target dev='hda' bus='ide'/>
<address type='drive' controller='0' bus='0' target='0' unit='0'/>
</disk>
<controller type='usb' index='0'>
<address type='pci' domain='0x0000' bus='0x02' slot='0x01' function='0x0'/>
</controller>
<controller type='ide' index='0'/>
<controller type='sata' index='0'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
</controller>
<controller type='pci' index='0' model='pcie-root'/>
<controller type='pci' index='1' model='dmi-to-pci-bridge'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1e' function='0x0'/>
</controller>
<controller type='pci' index='2' model='pci-bridge'>
<address type='pci' domain='0x0000' bus='0x01' slot='0x01' function='0x0'/>
</controller>
<interface type='bridge'>
<mac address='52:54:00:00:20:20'/>
<source bridge='br0'/>
<model type='e1000-82545em'/>
<address type='pci' domain='0x0000' bus='0x02' slot='0x03' function='0x0'/>
</interface>
<input type='mouse' bus='ps2'/>
<input type='keyboard' bus='ps2'/>
<graphics type='vnc' port='-1' autoport='yes' websocket='-1' listen='0.0.0.0'>
<listen type='address' address='0.0.0.0'/>
</graphics>
<video>
<model type='vga' vram='9216' heads='1'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
</video>
<memballoon model='virtio'>
<address type='pci' domain='0x0000' bus='0x02' slot='0x02' function='0x0'/>
</memballoon>
</devices>
<seclabel type='none' model='none'/>
<qemu:commandline>
<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=pcie.0'/>
<qemu:arg value='-device'/>
<qemu:arg value='usb-kbd'/>
<qemu:arg value='-device'/>
<qemu:arg value='usb-mouse'/>
<qemu:arg value='-device'/>
<qemu:arg value='isa-applesmc,osk=64_Character_OSK_Key'/>
<qemu:arg value='-smbios'/>
<qemu:arg value='type=2'/>
<qemu:arg value='-device'/>
<qemu:arg value='ide-drive,bus=ide.1,drive=MacDVD'/>
<qemu:arg value='-drive'/>
<qemu:arg value='id=MacDVD,if=none,snapshot=on,file=/mnt/disk1/vm_images/installer/Yosemite.iso'/>
</qemu:commandline>
</domain>