Note: I'm currently not using this, so my ability to provide support is limited. If you encounter issues or have questions about the setup, I recommend asking at r/VFIO.

Table Of Contents

• IOMMU Setup
• Installing Packages
• Enabling Services
• Guest Setup
• Attching PCI Devices
• Libvirt Hooks
• Keyboard/Mouse Passthrough
• Video Card Virtualisation Detection
• Audio Passthrough
• GPU vBIOS Patching

Enable & Verify IOMMU

BIOS Settings \ Enable Intel VT-d or AMD-Vi in BIOS settings. If these options are not present, it is likely that your hardware does not support IOMMU.

Disable Resizable BAR Support in BIOS settings. Cards that support Resizable BAR can cause problems with black screens following driver load if Resizable BAR is enabled in UEFI/BIOS. There doesn't seem to be a large performance penalty for disabling it, so turn it off for now until ReBAR support is available for KVM.

Set the kernel paramater depending on your CPU.

Reboot your system for the changes to take effect.

To verify IOMMU, run the following command.

dmesg | grep IOMMU

The output should include the message Intel-IOMMU: enabled for Intel CPUs or AMD-Vi: AMD IOMMUv2 loaded and initialized for AMD CPUs.

To view the IOMMU groups and attached devices, run the following script:

#!/bin/bash
shopt -s nullglob
for g in `find /sys/kernel/iommu_groups/* -maxdepth 0 -type d | sort -V`; do
    echo "IOMMU Group ${g##*/}:"
    for d in $g/devices/*; do
        echo -e "\t$(lspci -nns ${d##*/})"
    done;
done;

When using passthrough, it is necessary to pass every device in the group that includes your GPU. \ You can avoid having to pass everything by using ACS override patch.

Install required tools

Enable required services

Sometimes, you might need to start default network manually.

virsh net-start default
virsh net-autostart default

Setup Guest OS

NOTE: You should replace win10 with your VM's name where applicable \ You should add your user to libvirt group to be able to run VM without root. And, input and kvm group for passing input devices.

usermod -aG kvm,input,libvirt username

Download virtio driver. \ Launch virt-manager and create a new virtual machine. Select Customize before install on Final Step. \ In Overview section, set Chipset to Q35, and Firmware to UEFI \ In CPUs section, set CPU model to host-passthrough, and CPU Topology to whatever fits your system. \ For SATA disk of VM, set Disk Bus to virtio. \ In NIC section, set Device Model to virtio \ Add Hardware > CDROM: virtio-win.iso \ Now, Begin Installation. Windows can't detect the virtio disk, so you need to Load Driver and select virtio-iso/amd64/win10 when prompted. \ After successful installation of Windows, install virtio drivers from virtio CDROM. You can then remove virtio iso.

Attaching PCI devices

Remove Channel Spice, Display Spice, Video QXL, Sound ich* and other unnecessary devices. \ Now, click on Add Hardware, select PCI Devices and add the PCI Host devices for your GPU's VGA and HDMI Audio.

Libvirt Hooks

Libvirt hooks automate the process of running specific tasks during VM state change. \ More info at: PassthroughPost

Note: Comment Unbind/rebind EFI framebuffer line from start and stop script if you're using AMD 6000 series cards (https://github.com/QaidVoid/Complete-Single-GPU-Passthrough/issues/9). Also, move the line to unload AMD kernal module below detaching devices from host. These might also apply to older AMD cards.

Keyboard/Mouse Passthrough

In order to be able to use keyboard/mouse in the VM, you can either passthrough the USB Host device or use Evdev passthrough.

Using USB Host Device is simple, \ Add Hardware > USB Host Device, add your keyboard and mouse device.

For Evdev passthrough, follow these steps: \ Modify libvirt configuration of your VM. \ Note: Save only after adding keyboard and mouse devices or the changes gets lost. \ Change first line to:

Find your keyboard and mouse devices in /dev/input/by-id. You'd generally use the devices ending with event-kbd and event-mouse. And the devices in your configuration right before closing </domain> tag. \ Replace MOUSE_NAME and KEYBOARD_NAME with your device id.

You need to include these devices in your qemu config.

Also, switch from PS/2 devices to virtio devices. Add the devices inside <devices> block

Audio Passthrough

VM's audio can be routed to the host using Pipewire or Pulseaudio. \ You can also use Scream instead.

Video card driver virtualisation detection

Video Card drivers refuse to run in Virtual Machine, so you need to spoof Hyper-V Vendor ID.

NVIDIA guest drivers also require hiding the KVM CPU leaf:

vBIOS Patching

NOTE: You are only making changes on dumped ROM file. Your hardware is safe. \ While most of the GPU can be passed with stock vBIOS, some GPU requires vBIOS patching to passthrough. \ In order to patch vBIOS, you need to first dump the GPU vBIOS from your system. \ If you have Windows installed, you can use GPU-Z to dump vBIOS. \ To dump vBIOS on Linux, you can use following command (replace PCI id with yours):

echo 1 > /sys/bus/pci/devices/0000:01:00.0/rom
cat /sys/bus/pci/devices/0000:01:00.0/rom > path/to/dump/vbios.rom
echo 0 > /sys/bus/pci/devices/0000:01:00.0/rom

If you're not in root shell, you should use the above commands with sudo as:

echo 1 | sudo tee /sys/bus/pci/devices/0000:01:00.0/rom
sudo cat /sys/bus/pci/devices/0000:01:00.0/rom > path/to/dump/vbios.rom
echo 0 | sudo tee /sys/bus/pci/devices/0000:01:00.0/rom

To patch vBIOS, you need to use Hex Editor (eg., Okteta) and trim unnecessary header. \ For NVIDIA GPU, using hex editor, search string “VIDEO”, and remove everything before HEX value 55. \ I'm not sure about AMD, but the process should be similar.

To use patched vBIOS, edit VM's configuration to include patched vBIOS inside hostdev block of VGA

See Also

Single GPU Passthrough Troubleshooting
Single GPU Passthrough by joeknock90
Single GPU Passthrough by YuriAlek
Single GPU Passthrough by wabulu
ArchLinux PCI Passthrough
Gentoo GPU Passthrough