I have a 6800XT, try it this way
<features>
<acpi/>
<apic/>
<hap state='on'/>
<hyperv mode='custom'>
<relaxed state='on'/>
<vapic state='on'/>
<spinlocks state='on' retries='8191'/>
<vpindex state='on'/>
<synic state='on'/>
<stimer state='on'>
<direct state='on'/>
</stimer>
<reset state='on'/>
<vendor_id state='on' value='1234567890ab'/>
<frequencies state='on'/>
<reenlightenment state='off'/>
<tlbflush state='on'/>
<ipi state='on'/>
</hyperv>
<vmport state='off'/>
<ioapic driver='kvm'/>
</features>
<hostdev mode='subsystem' type='pci' managed='yes'>
<source>
<address domain='0x0000' bus='0x0d' slot='0x00' function='0x0'/>
</source>
<address type='pci' domain='0x0000' bus='0x17' slot='0x00' function='0x0' multifunction='on'/>
</hostdev>
<hostdev mode='subsystem' type='pci' managed='yes'>
<source>
<address domain='0x0000' bus='0x0d' slot='0x00' function='0x1'/>
</source>
<address type='pci' domain='0x0000' bus='0x17' slot='0x00' function='0x1'/>
</hostdev>
<hostdev mode='subsystem' type='pci' managed='yes'>
<source>
<address domain='0x0000' bus='0x0d' slot='0x00' function='0x2'/>
</source>
<address type='pci' domain='0x0000' bus='0x17' slot='0x00' function='0x2'/>
</hostdev>
<hostdev mode='subsystem' type='pci' managed='yes'>
<source>
<address domain='0x0000' bus='0x0d' slot='0x00' function='0x3'/>
</source>
<address type='pci' domain='0x0000' bus='0x17' slot='0x00' function='0x3'/>
</hostdev>