i just use to the unarid device passthrough for mouse/keyboard, and a 6950hd for gpu passthrough, thing is its all working fine, boot is super fast until i hit the high memory numbers, ill do some more testing with vnc, and different core numbers to see what makes a difference
eidt: so i did abunch of test with different vcpu/memory numbers, and it seems both raising vcpus and memory triggers the slower boots, but memory more so than cores, gpu/usb didnt seem to effect it at all, neither did machine, and ive tried it with OMVF aswell earlier and i think i had similar boot times(will have to restest this).
All in all its very usable just slightly annoying, performance seems really good after the boot hiccup
xml of what i was planning to use
<domain type='kvm' id='9'>
<name>Client Windows 8.1</name>
<uuid>1cb15b09-ccfb-7688-da03-f2a6271e853f</uuid>
<metadata>
<vmtemplate xmlns="unraid" name="Windows 8.x" icon="windows.png" os="windows"/>
</metadata>
<memory unit='KiB'>33554432</memory>
<currentMemory unit='KiB'>33554432</currentMemory>
<memoryBacking>
<nosharepages/>
<locked/>
</memoryBacking>
<vcpu placement='static'>20</vcpu>
<cputune>
<vcpupin vcpu='0' cpuset='2'/>
<vcpupin vcpu='1' cpuset='3'/>
<vcpupin vcpu='2' cpuset='4'/>
<vcpupin vcpu='3' cpuset='5'/>
<vcpupin vcpu='4' cpuset='6'/>
<vcpupin vcpu='5' cpuset='7'/>
<vcpupin vcpu='6' cpuset='8'/>
<vcpupin vcpu='7' cpuset='9'/>
<vcpupin vcpu='8' cpuset='10'/>
<vcpupin vcpu='9' cpuset='11'/>
<vcpupin vcpu='10' cpuset='14'/>
<vcpupin vcpu='11' cpuset='15'/>
<vcpupin vcpu='12' cpuset='16'/>
<vcpupin vcpu='13' cpuset='17'/>
<vcpupin vcpu='14' cpuset='18'/>
<vcpupin vcpu='15' cpuset='19'/>
<vcpupin vcpu='16' cpuset='20'/>
<vcpupin vcpu='17' cpuset='21'/>
<vcpupin vcpu='18' cpuset='22'/>
<vcpupin vcpu='19' cpuset='23'/>
</cputune>
<resource>
<partition>/machine</partition>
</resource>
<os>
<type arch='x86_64' machine='pc-q35-2.5'>hvm</type>
</os>
<features>
<acpi/>
<apic/>
<hyperv>
<relaxed state='on'/>
<vapic state='on'/>
<spinlocks state='on' retries='8191'/>
<vendor id='none'/>
</hyperv>
</features>
<cpu mode='host-passthrough'>
<topology sockets='1' cores='10' threads='2'/>
</cpu>
<clock offset='localtime'>
<timer name='hypervclock' present='yes'/>
<timer name='hpet' present='no'/>
</clock>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>restart</on_crash>
<devices>
<emulator>/usr/local/sbin/qemu</emulator>
<disk type='file' device='disk'>
<driver name='qemu' type='raw' cache='unsafe'/>
<source file='/mnt/user/Vidisks/Client Windows 8.1/vdisk1.img'/>
<backingStore/>
<target dev='hdc' bus='virtio'/>
<boot order='1'/>
<alias name='virtio-disk2'/>
<address type='pci' domain='0x0000' bus='0x02' slot='0x03' function='0x0'/>
</disk>
<controller type='usb' index='0' model='nec-xhci'>
<alias name='usb'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
</controller>
<controller type='sata' index='0'>
<alias name='ide'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
</controller>
<controller type='pci' index='0' model='pcie-root'>
<alias name='pcie.0'/>
</controller>
<controller type='pci' index='1' model='dmi-to-pci-bridge'>
<model name='i82801b11-bridge'/>
<alias name='pci.1'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1e' function='0x0'/>
</controller>
<controller type='pci' index='2' model='pci-bridge'>
<model name='pci-bridge'/>
<target chassisNr='2'/>
<alias name='pci.2'/>
<address type='pci' domain='0x0000' bus='0x01' slot='0x01' function='0x0'/>
</controller>
<controller type='virtio-serial' index='0'>
<alias name='virtio-serial0'/>
<address type='pci' domain='0x0000' bus='0x02' slot='0x02' function='0x0'/>
</controller>
<interface type='bridge'>
<mac address='52:54:00:c4:d3:81'/>
<source bridge='br0'/>
<target dev='vnet0'/>
<model type='virtio'/>
<alias name='net0'/>
<address type='pci' domain='0x0000' bus='0x02' slot='0x01' function='0x0'/>
</interface>
<serial type='pty'>
<source path='/dev/pts/0'/>
<target port='0'/>
<alias name='serial0'/>
</serial>
<console type='pty' tty='/dev/pts/0'>
<source path='/dev/pts/0'/>
<target type='serial' port='0'/>
<alias name='serial0'/>
</console>
<channel type='unix'>
<source mode='bind' path='/var/lib/libvirt/qemu/channel/target/domain-Client Windows 8.1/org.qemu.guest_agent.0'/>
<target type='virtio' name='org.qemu.guest_agent.0' state='disconnected'/>
<alias name='channel0'/>
<address type='virtio-serial' controller='0' bus='0' port='1'/>
</channel>
<hostdev mode='subsystem' type='pci' managed='yes' xvga='yes'>
<driver name='vfio'/>
<source>
<address domain='0x0000' bus='0x03' slot='0x00' function='0x0'/>
</source>
<alias name='hostdev0'/>
<rom bar='on' file='/mnt/user/ISOs/asus6950.rom'/>
<address type='pci' domain='0x0000' bus='0x02' slot='0x04' function='0x0'/>
</hostdev>
<hostdev mode='subsystem' type='pci' managed='yes'>
<driver name='vfio'/>
<source>
<address domain='0x0000' bus='0x00' slot='0x1b' function='0x0'/>
</source>
<alias name='hostdev1'/>
<address type='pci' domain='0x0000' bus='0x02' slot='0x05' function='0x0'/>
</hostdev>
<hostdev mode='subsystem' type='usb' managed='no'>
<source>
<vendor id='0x046d'/>
<product id='0xc051'/>
<address bus='3' device='2'/>
</source>
<alias name='hostdev2'/>
</hostdev>
<hostdev mode='subsystem' type='usb' managed='no'>
<source>
<vendor id='0x04b4'/>
<product id='0x0101'/>
<address bus='3' device='3'/>
</source>
<alias name='hostdev3'/>
</hostdev>
<memballoon model='virtio'>
<alias name='balloon0'/>
<address type='pci' domain='0x0000' bus='0x02' slot='0x06' function='0x0'/>
</memballoon>
</devices>
</domain>