NVIDIA GPU Passthrough on an Optimus MUXed Laptop (Updated 2023-05)

A year ago, to simultaneously browse webpages and write codes on my Arch Linux installation and use Windows to run tasks infeasible on Linux (such as gaming), I tried GPU passthrough on my Lenovo R720 gaming laptop. But since that laptop has an Optimus MUXless architecture (as mentioned in that post), its dedicated GPU doesn't have output ports, and the integrated GPU is in charge of all the displays. Therefore, severe limitations exist for that setup, and I eventually gave up on it.

But now, I've purchased a new laptop. The HDMI output port on this laptop is directly connected to its NVIDIA dedicated graphics card, or in other words, it has an Optimus MUXed architecture. Since there is a way to make the virtual machine aware of a "monitor on the dedicated GPU", most functionalities work normally. I am finally able to create a GPU passthrough setup that works long-term.


  • 2023-05-08: Update some contents for new version of Looking Glass B6.
  • 2022-01-26: The PCIe power-saving patch isn't effective.


Before following steps in this post, you need to prepare:

  1. A laptop with the Optimus MUXed architecture. My laptop is a HP OMEN 17t-ck000 (i7-11800H, RTX 3070).

    • (2022-01) My operating system is Arch Linux, with the latest updates.
    • (2023-05) My operating system is now NixOS while writing this update. Most of the steps, however, should still apply to other Linux distros.
    • It's recommended to turn off Secure Boot, but you likely did it anyway since you installed Linux. Theoretically, Secure Boot may cause limitations on the PCIe passthrough functionality.
  2. Set up a virtual machine of Windows 10 or Windows 11 with Libvirt (Virt-Manager). I'm using Windows 11.

    • My VM boots in UEFI (OVMF) mode, but theoretically, this guide will also work with BIOS (SeaBIOS) mode. There are no steps that specifically require UEFI boot mode.
    • You MUST turn off Secure Boot in the VM! Or some drivers won't work!
    • Set up the emulated QXL graphics card first, so you get video output from the VM.
  3. (Optional) Depending on the video output ports on your computer, purchase an HDMI, DP, or USB Type-C dummy plug. You can get one for a few bucks on Amazon.

    • (2023-05) Or you can choose to install a virtual monitor driver.
    • HDMI Dummy Plug
  4. (Optional) A USB keyboard and mouse combo.

A reminder before we begin:

  • Multiple reboots of the host OS is required, and your host OS may crash! Back up your data.
  • You don't need to download any NVIDIA driver manually. Windows will do it for you automatically.
    • If it doesn't, don't go any further than downloading the driver EXE and double-clicking.
    • Never specify the exact driver to be used in Device Manager.
    • Debugging will be harder if you do this.

Purchasing A New Optimus MUXed Laptop

If you are interested in GPU passthrough and are looking for a new laptop, you can refer to my guidelines.

The prerequisites for laptop GPU passthrough is:

  1. The NVIDIA GPU itself must be capable of video output
  2. There is at least one video output directly connected to that GPU

However, it's extremely rare for a laptop manufacturer to mention the port connection schemes on their product pages, so we have to infer from more common specifications:

  1. Prefer a laptop with a MUX switch, aka ones that can switch their internal screen onto the dedicated GPU. In this case, the dedicated GPU must be capable of video output, and there's a high chance that the manufacturer connected the chassis video outputs to the dedicated GPU:

    • Common examples are: 2020 and 2021 Lenovo Legion series, HP OMEN series, and Dell G15.
    • I do not guarantee that this list is accurate! Do your own research or ask a sales agent to make sure.
  2. Or choose a laptop with a mid-range to high-end graphics card. For NVIDIA GPUs the model number needs to end with 60 or larger.

    • It's common for mid to top-tier NVIDIA GPUs to have video output functionality, and the manufacturer is likely to connect chassis video ports to them.
    • Do not purchase a laptop with a GPU that ends in 50 or lower, like an RTX 3050 or GTX 1650 Ti. They very likely don't support video output.
  3. Take advantage of unconditional return policies.

    • Since manufacturers won't advertise or won't even care much about their video output connections, we have to guess from the specifications and advertising pages. Therefore, it's possible that you followed every rule above yet got a laptop that doesn't support GPU passthrough. In this case, you may consider returning or reselling it.
    • In some countries, laptop manufacturers will only accept an unconditional return if the preinstalled Windows and Office are never activated online. However, the latest Windows 11 requires you to activate online in its first-boot setup wizard. You may consider trying GPU passthrough with a Linux installation on your USB drive before activating Windows.

About Intel GVT-g Virtual GPUs

5th to 9th-Gen Intel integrated graphics support virtualizing the GPU itself, or in other words, splitting it into several virtual GPUs. The virtual GPUs can be passed through into VMs so they get GPU acceleration, while the host can still display stuff on the very same GPU.

However, the GVT-g driver in Linux doesn't support 10th-Gen or newer Intel CPUs, and Intel has no plan to support them. In addition, the GVT-g virtual GPU cannot form an Optimus configuration with an NVIDIA GPU, so it isn't useful anyway.

That's why we're ignoring GVT-g and focusing on the NVIDIA GPU in this guide.

(2023-05) About Intel SR-IOV Virtual GPUs

11th-Gen and later Intel integrated graphics support another form of virtualization: SR-IOV. Intel has officially released the source code to the kernel module with SR-IOV, but it isn't merged into Linux mainline as of now. There's a third party project that ports the code into a DKMS module, but success rate is not high according to reports in Issues section. I tried it with my i7-11800H and didn't succeed. Therefore, this time we will not try SR-IOV on Intel GPUs.


Stop Host OS from Tampering with NVIDIA GPU

Most of the content is the same as my post in 2021.

The NVIDIA driver on the Host OS will hold control of the dGPU, and stop VM from using it. Therefore you need to replace the driver with vfio-pci, built solely for PCIe passthrough.

Here are the steps for disabling the NVIDIA driver and passing control to the PCIe passthrough module:

  1. Run lspci -nn | grep NVIDIA and obtain an output similar to:

    0000:01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GA104M [GeForce RTX 3070 Mobile / Max-Q] [10de:249d] (rev a1)
    0000:01:00.1 Audio device [0403]: NVIDIA Corporation GA104 High Definition Audio Controller [10de:228b] (rev a1)

    Here [10de:249d] is the vendor ID and device ID of the dGPU, where 10de means this device is manufactured by NVIDIA, and 249d means this is a RTX 3070. 228b is the audio output on the HDMI port, which should also be taken over by vfio-pci.

  2. Create /etc/modprobe.d/lantian.conf with the following content:

    options vfio-pci ids=10de:249d,10de:228b

    This configures vfio-pci, the kernel module responsible for PCIe passthrough, to manage the dGPU. ids is the vendor ID and device ID of the device to be passed through.

  3. Modify /etc/mkinitcpio.conf, add the following contents to MODULES:

    MODULES=(vfio_pci vfio vfio_iommu_type1 vfio_virqfd)

    And remove anything related to NVIDIA drivers (such as nvidia), or make sure they're listed after VFIO drivers. Now PCIe passthrough module will take control of the dGPU in the early booting process, preventing NVIDIA drivers from taking control.

  4. Run mkinitcpio -P to update the initramfs.

  5. Reboot.

(2023-05) If you're using NixOS, you can use the following config:

  boot.kernelModules = ["vfio-pci"];
  boot.extraModprobeConfig = ''
    # Change to your GPU's vendor ID and device ID
    options vfio-pci ids=10de:249d

  boot.blacklistedKernelModules = ["nouveau" "nvidiafb" "nvidia" "nvidia-uvm" "nvidia-drm" "nvidia-modeset"];

Setting up NVIDIA dGPU Passthrough

In my post in 2021, I mentioned a lot of configurations to circumvent restrictions of the NVIDIA driver. But since version 465, NVIDIA lifted most of the restrictions, so theoretically, you pass a GPU into the VM, and everything should just work.

But that's just the theory.

I still recommend everyone to follow all the steps and hide the VM characteristics, because:

  1. (2022-01) Not all restructions are lifted for laptops.

    • At least in my tests, an incorrect PCIe bus address for the GPU and the absence of a battery still causes passthrough to fail, and the driver will error out with the infamous code 43.
    • (2023-05) In the attempt today, the PCIe bus address and absence of battery no longer affects outcome of GPU passthrough.
  2. Even if NVIDIA driver isn't detecting VMs, the programs you run might. Hiding VM characteristics increases the chance to run them successfully.

    • Examples include online games with anti-cheat systems, or commercial software that require online activation.

And here we start:

  1. Unlike the Optimus MUXless architecture, I didn't manually extract the graphic card's BIOS nor modify the UEFI firmware, and everything just works.

    • If you cannot install the GPU driver after passing it into the VM, including the cases that Windows won't automatically install them, or NVIDIA's official installer errors out saying lack of compatible devices, you likely will still need to extract your GPU's video BIOS.
    • To double-check, open Device Manager in the VM, and look at the Hardware ID, which looks like PCI\VEN_10DE&DEV_1C8D&SUBSYS_39D117AA&REV_A1. If SUBSYS is followed by a sequence of zeros, then the GPU video BIOS is missing, and you need the manual steps.
    • Refer to my post last year, specifically the NVIDIA GPU passthrough section, for detailed steps.
  2. Modify your VM configuration, virsh edit Windows, and make the following changes:

    <!-- Modify the features section, so QEMU will hide the fact that this is a VM -->
      <hyperv mode="custom">
        <relaxed state="on"/>
        <vapic state="on"/>
        <spinlocks state="on" retries="8191"/>
        <vpindex state="on"/>
        <runtime state="on"/>
        <synic state="on"/>
        <stimer state="on"/>
        <reset state="on"/>
        <vendor_id state="on" value="GenuineIntel"/>
        <frequencies state="on"/>
        <tlbflush state="on"/>
        <hidden state="on"/>
      <vmport state="off"/>
    <!-- Add the PCIe passthrough device, must be below the hostdev for iGPU -->
    <hostdev mode='subsystem' type='pci' managed='yes'>
        <address domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
      <rom bar='off'/>
      <!-- The PCIe bus address here MUST BE EXACTLY 01:00.0 -->
      <!-- If there is a PCIe bus address conflict when saving config changes, -->
      <!-- Remove <address> of all other devices -->
      <!-- And Libvirt will reallocate PCIe bus addresses -->
      <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0' multifunction='on'/>
    <!-- Add a shared memory between VM and host -->
    <!-- So VM can transfer its display content to host -->
    <shmem name='looking-glass'>
      <model type='ivshmem-plain'/>
      <!-- Size is calculated as: display resolution width x height / 131072 -->
      <!--                        then round up to power of 2 -->
      <!-- Most HDMI dummy plugs have a resolution of 3840 x 2160 -->
      <!-- The result is 63.28MB which rounds up to 64MB -->
      <size unit='M'>64</size>
    <!-- Disable memory ballooning, this hurts performance significantly -->
    <memballoon model="none"/>
    <!-- Add these parameters before </qemu:commandline> -->
    <qemu:arg value='-acpitable'/>
    <qemu:arg value='file=/ssdt1.dat'/>

    The ssdt1.dat is an ACPI table, and it emulates a fully-charged battery. It corresponds to the Base64 below. It can be converted to a binary file with Base64 decoding website or downloaded from this site. Place it in the root folder.

  3. Modify permissions for the shared memory.

    1. Modify /etc/apparmor.d/local/abstractions/libvirt-qemu and add this line:

      /dev/shm/looking-glass rw,

      Then execute sudo systemctl restart apparmor to restart AppArmor.

    2. Create /etc/tmpfiles.d/looking-glass.conf with the following contents, replacing lantian to your username:

      f /dev/shm/looking-glass 0660 lantian kvm -

      Then execute sudo systemd-tmpfiles /etc/tmpfiles.d/looking-glass.conf --create to make it effective.

  4. Start the VM and wait a while. Windows will automatically install NVIDIA drivers.

    • If Device Manager shows the GPU with an exclamation sign and error code 43, you need to check if you've missed any steps and if you've configured everything correctly.
      • (2022-01) Switch Device Manager to Device by Connection and verify that the NVIDIA GPU is at Bus 1, Slot 0, Function 0. The parent PCIe port to the dGPU should be at Bus 0, Slot 1, Function 0.
      • If they don't match, you need to reallocate PCIe addresses with the method above.
      • (2023-05) This step is no longer needed in my attempt today.
    • If the OS didn't automatically install the NVIDIA driver, and your manually downloaded driver installer also shows that the system is incompatible, you need to check the properties of the GPU device. Check if there is a sequence of zeros after SUBSYS in its Hardware ID.
      • If there is, refer to step 1.
  5. Turn off the virtual machine and restart it. This is not just a reboot. Confirm in the device manager that the GPU is working.

    • If you get code 43 this time, check if you have the emulated battery in step 2.
    • I tried first on Windows 10 LTSC 2019 and got this error. Since I didn't have the emulated battery set up, I cannot confirm if it's an incompatibility between the NVIDIA driver and the OS or the lack of battery. I recommend using the latest versions of Windows 10 or Windows 11.
  6. Do either one of the following steps:

    1. (2022-01) Plug your HDMI dummy plug into your laptop, and the VM should detect a new monitor.
    2. (2023-05) Install a virtual monitor driver:
      1. Download the virtual monitor driver from ge9/IddSampleDriver, and decompress it to C:\IddSampleDriver. Note that you must not move the folder anywhere else!
      2. Open C:\IddSampleDriver\option.txt. You'll see the number 1 on the first line (don't change it), followed by a list of resolutions and refresh rates. Only keep the one resolution and refresh rate entry you want, and remove all other items.
      3. Open Device Manager, select "Action - Add Legacy Hardware", click "Let me pick from a list... - All Devices - Have disk", choose the file C:\IddSampleDriver\IddSampleDriver.inf, and complete the installation.
      4. Windows should now detect a new monitor.
      5. In my testing, while using the virtual monitor driver, I saw some corrupted pixels on the Looking Glass display. As long as you can obtain an HDMI dummy plug, I would recommend it over the virtual monitor driver.
  7. (2023-05) Now the newer version of Looking Glass will install IVSHMEM driver automatically (the driver for shared memory between VM and host). You no longer need to install it manually. These manual installation steps are kept for reference only:

    1. (2022-01) Download this Virtio driver, copy it into the VM, and extract it. You MUST use this copy, as no other copies have the IVSHMEM driver!


    2. Open Device Manager in the VM, and find System devices - PCI standard RAM controller:

      1. Right-click and select "Update driver"
      2. Click "Browse my computer for drivers"
      3. Click "Let me pick from a list of device drivers on my computer"
      4. Click "Have disk" button
      5. Navigate to Virtio Drivers/Win10/amd64/ivshmem.inf file
      6. Click next to install the driver. The device's name should change to IVSHMEM
  8. Install Looking Glass, a tool to transfer the display output from the VM to the host.

    • Our dummy plug is going to be the only monitor the VM can see. If we don't install looking glass, we won't be able to see the VM desktop.
    • Click "Windows Host Binary" on the link above, double click in the VM to install it.
  9. (2023-05) If you followed the steps from 2022-01, you won't be able to see the startup screen while the VM is booting, and before Looking Glass starts. Therefore, I recommend disabling the QXL virtual adapter in Device Manager. The following older steps are kept for reference purpose only.

    • (2022-01) Turn off the VM and run virsh edit Windows to edit the VM config.

      Find <video><model type="qxl" ...></video>, change type to none to disable the QXL emulated GPU:

        <model type="none"/>
  10. Install Looking Glass client on the host. Arch Linux users can simply install looking-glass from AUR. Run looking-glass-client to start the client.

  11. Back to Virt-Manager, close the window of the VM (the window that shows the VM desktop and changes VM configurations), right-click on the VM on Virt-Manager's main window, and select Run.

  12. In a moment, you should see the VM's display on Looking Glass client. Now the GPU passthrough setup is complete.

Performance and Experience Optimizations

Although GPU passthrough is done, there is still room for user experience optimization. Particularly:

  1. (2022-01) Looking Glass can relay keyboard and mouse events, but not audio, so we can't hear the VM;
    • (2023-05) The latest Looking Glass can relay audio now.
  2. (2022-01) Looking Glass may miss a few keystrokes from time to time;
    • (2023-05) The latest Looking Glass can relay keyboard and mouse events reliably now.
  3. There is a host kernel module for IVSHMEM, which improves Looking Glass performance with its DMA mode;
  4. After VM shutdown, the GPU is set to PCIe D3hot mode. It still consumes around 10 watts of power, which is undesirable for battery life.

We will fix the problems one by one.

Get Audio Output from VM

(2023-05) The latest Looking Glass can relay audio now. These steps are kept for reference only.

While Virt-Manager can connect to the VM with SPICE protocol to get the VM's sound output, Looking Glass also relays keyboard and mouse events through SPICE. Since the VM only accepts one simultaneous SPICE connection, we cannot get the audio output with Virt-Manager.

We can install Scream, a virtual sound card software in Windows, to transfer audio output over the network. A Scream client can be run on the host to receive the audio signal.

Download the Scream installer from its download page on the VM, extract it, run Install-x64.bat as administrator to install the driver, and reboot.

Install the Scream client on the host. Arch Linux users can install the scream package from AUR.

Open a terminal on the host and run scream -v. Test by playing some sound in the VM. If you can't hear anything, try specifying the network interface to the VM, like scream -i virbr0 -v, where virbr0 is the default NAT network for Virt-Manager, and the network interface between the VM and the host.

Finally, you can create a SystemD service to run the Scream client conveniently later. Create ~/.config/systemd/user/scream.service with the following content:


ExecStart=/usr/bin/scream -i virbr0 -v


You will only need to run systemctl --user start scream in the future.

Passthrough Keyboard & Mouse Operations

The latest Looking Glass can relay keyboard and mouse events reliably now. These steps are kept for reference only.

The relay of the keyboard and mouse in Looking Glass isn't very stable, as misses of operation can happen from time to time. Therefore, if you want to play some games in the VM, you need a more reliable way to pass your keyboard and mouse into the VM.

We have two options: letting Libvirt capture the keyboard and mouse events or simply pass your keyboard and mouse into the VM.

  1. Capturing Keyboard and Mouse Events.

    On Linux, all keyboard and mouse operations are passed to the desktop environment via the evdev (or Event Device) framework. Libvirt can capture your operations and pass them to the VM. In addition, Libvirt can switch the control between the host and the VM whenever you press Left Ctrl and the Right Ctrl, so you can operate on both the host and the VM with one keyboard-mouse combo.

    First run ls -l /dev/input/by-path on the host to see your present evdev devices. I have these ones for example:

    pci-0000:00:14.0-usb-0:1:1.1-event-mouse               # USB mouse
    pci-0000:00:15.0-platform-i2c_designware.0-event-mouse # Builtin Touchpad
    platform-i8042-serio-0-event-kbd                       # Builtin Keyboard

    Those with event-mouse are mouses, and the event-kbd ones are keyboards.

    Then, run virsh edit Windows to edit the VM config. Add these into the <devices> section:

    <input type="evdev">
      <!-- Change the mouse or keyboard path based on your ls result -->
      <source dev="/dev/input/by-path/platform-i8042-serio-0-event-kbd" grab="all" repeat="on"/>
    <!-- Repeat if you have many mouses or keyboards -->
    <input type="evdev">
      <source dev="/dev/input/by-path/pci-0000:00:15.0-platform-i2c_designware.0-event-mouse" grab="all" repeat="on"/>

    Start the VM, and you should notice that your keyboard and mouse aren't working on the host. They're captured by the VM. Press Left Ctrl + Right Ctrl to return control to the host. Press again to control the VM.

    Now we can disable the keyboard and mouse relay of Looking Glass. Create /etc/looking-glass-client.ini with the following content:

  2. USB Keyboard and Mouse Passthrough

    Capturing keyboard and mouse operations doesn't always work. For example, my touchpad cannot be captured properly, as I can't move the cursor in the VM.

    If you also encountered the issue and you have a USB keyboard and mouse combo, you can pass them into the VM and use them specifically for it. USB passthrough to VM is a mature technology, so the chance of running into problems is very low.

    Simply click Add Hardware - USB Host Device in Virt-Manager and select your keyboard and mouse.

Accelerating Looking Glass with Kernel Modules

Most of the content in this section is from https://looking-glass.io/docs/B6/module/

Looking Glass provides a kernel module for the IVSHMEM shared memory device. It allows Looking Glass to read the display output efficiently with DMA to improve the framerate.

  1. Install Linux kernel header files and DKMS, or the packages of linux-headers and dkms on Arch Linux.

  2. Install looking-glass-module-dkms from AUR.

  3. Set up an Udev rule: create /etc/udev/rules.d/99-kvmfr.rules with the following content:

    SUBSYSTEM=="kvmfr", OWNER="lantian", GROUP="kvm", MODE="0660"

    Replace lantian with your own username.

  4. Configure the memory size: create /etc/modprobe.d/looking-glass.conf with the following content:

    # The memory size is calculates in the same way as VM's shmem.
    options kvmfr static_size_mb=64
  5. Load the module automatically on boot: create /etc/modules-load.d/looking-glass.conf with a single line of kvmfr.

  6. Run sudo modprobe kvmfr to load the module. Now a kvmfr0 device should appear under /dev, and this is the memory device for Looking Glass.

  7. Edit /etc/apparmor.d/local/abstractions/libvirt-qemu and add this line:

    /dev/kvmfr0 rw,

    It allows the VM to access the device. Run sudo systemctl restart apparmor to restart AppArmor.

  8. Run virsh edit Windows to change the VM's configuration:

    1. Delete <shmem> section from <devices>:

      <shmem name='looking-glass'>
        <model type='ivshmem-plain'/>
        <size unit='M'>64</size>
    2. Add these lines under <qemu:commandline>:

      <qemu:arg value="-device"/>
      <qemu:arg value="{&quot;driver&quot;:&quot;ivshmem-plain&quot;,&quot;id&quot;:&quot;shmem-looking-glass&quot;,&quot;memdev&quot;:&quot;looking-glass&quot;}"/>
      <qemu:arg value="-object"/>
      <!-- There is a number 67108864 in the next line, which is 64MB * 1048576 -->
      <!-- Change accordingly if you've set a different memory size -->
      <qemu:arg value="{&quot;qom-type&quot;:&quot;memory-backend-file&quot;,&quot;id&quot;:&quot;looking-glass&quot;,&quot;mem-path&quot;:&quot;/dev/kvmfr0&quot;,&quot;size&quot;:67108864,&quot;share&quot;:true}"/>
    3. Start the VM.

  9. Change /etc/looking-glass-client.ini and add the following content:

  10. Start Looking Glass. You should see the VM display now.

  11. (2023-05) If you use NixOS, you can directly use the config below:

  boot.extraModulePackages = with config.boot.kernelPackages; [
  boot.extraModprobeConfig = ''
    # The memory size is calculates in the same way as VM's shmem.
    options kvmfr static_size_mb=64
  boot.kernelModules = ["kvmfr"];
  services.udev.extraRules = ''
    SUBSYSTEM=="kvmfr", OWNER="root", GROUP="libvirtd", MODE="0660"

  environment.etc."looking-glass-client.ini".text = ''

Cutting Power to GPU When Unused

2022-01-26 Update: testing shows that the NVIDIA GPU still isn't completely shut down after applying the patch. The power draw is the same as before. This section is now invalid.

This section only applies to 20-series of NVIDIA GPUs or newer. They can shut themselves down with the NVIDIA official drivers. The 10-series or older GPUs don't support this feature.

This section involves compiling a kernel yourself, and using an patch without extensive inspection or testing. Not intended for novice users. Evaluate the risks yourself.

When you aren't using the VM, the vfio-pci driver in charge of PCIe passthrough sets the device to the D3 mode, aka the power saving mode of PCIe devices. But there are two types of D3 modes: D3hot, where the device is still powered, and D3cold, where the device is shut off completely. Currently, the vfio-pci driver in the kernel only supports D3hot, and the NVIDIA GPU will still consume around 10 watts of power since its chip power isn't cut. This impacts the battery life of laptops.

An NVIDIA engineer posted a patchset for vfio-pci's D3cold support on the Linux kernel mailing list. With this patchset, the NVIDIA GPU will be shut down completely when the VM is off. It saves power for your battery.

The patchset can be found at https://lore.kernel.org/lkml/20211115133640.2231-1-abhsahu@nvidia.com/T/, which consists of three patches. I combined the three patches and uploaded the result to https://github.com/xddxdd/pkgbuild/blob/master/linux-xanmod-lantian/0007-vfio-pci-d3cold.patch.

Patching kernel is relatively simple for Arch Linux. Most kernel PKGBUILDs in AUR can apply patches automatically. All you have to do is to download the PKGBUILD for a kernel and add the patch to its source section. See my commit for an example: https://github.com/xddxdd/pkgbuild/commit/406adb7bf5657cfe07bb17ff561d11ed97ebab39.

DO NOTE that this patch doesn't guarantee stability.

Based on mailing list discussions:

  1. It's an RFC patch, aka a testing patch. There is a big [RFC] on the title of the e-mails.
  2. If the GPU driver in the VM ever attempts to switch the GPU to D3cold mode, with this patch, there are risks of resetting the GPU, losing all states, and crashing the VM. Although I have never encountered such problems in my experience, you should be aware of the possible outcomes.
  3. The developer only tested some GPUs from NVIDIA. It does not guarantee support for other PCIe devices.

Use this at your own risk.


Huge thanks to previous explorers on the topic of GPU passthrough. Without their efforts, this post won't have existed in the first place.

Here are the sources I referenced when I did my configuration:

Appendix: Final Libvirt XML File

<domain xmlns:qemu="http://libvirt.org/schemas/domain/qemu/1.0" type="kvm">
    <libosinfo:libosinfo xmlns:libosinfo="http://libosinfo.org/xmlns/libvirt/domain/1.0">
      <libosinfo:os id="http://microsoft.com/win/11"/>
  <memory unit="KiB">16777216</memory>
  <currentMemory unit="KiB">16777216</currentMemory>
  <vcpu placement="static">16</vcpu>
    <type arch="x86_64" machine="pc-q35-8.0">hvm</type>
    <loader readonly="yes" type="pflash">/run/libvirt/nix-ovmf/OVMF_CODE.fd</loader>
    <nvram template="/run/libvirt/nix-ovmf/OVMF_VARS.fd">/var/lib/libvirt/qemu/nvram/Windows11_VARS.fd</nvram>
    <hyperv mode="custom">
      <relaxed state="on"/>
      <vapic state="on"/>
      <spinlocks state="on" retries="8191"/>
      <vpindex state="on"/>
      <runtime state="on"/>
      <synic state="on"/>
      <stimer state="on"/>
      <reset state="on"/>
      <vendor_id state="on" value="GenuineIntel"/>
      <frequencies state="on"/>
      <tlbflush state="on"/>
      <hidden state="on"/>
    <vmport state="off"/>
  <cpu mode="host-passthrough" check="none" migratable="on">
    <topology sockets="1" dies="1" cores="8" threads="2"/>
  <clock offset="localtime">
    <timer name="rtc" tickpolicy="catchup"/>
    <timer name="pit" tickpolicy="delay"/>
    <timer name="hpet" present="no"/>
    <timer name="hypervclock" present="yes"/>
    <suspend-to-mem enabled="no"/>
    <suspend-to-disk enabled="no"/>
    <disk type="file" device="disk">
      <driver name="qemu" type="qcow2" discard="unmap"/>
      <source file="/var/lib/libvirt/images/Windows11.qcow2"/>
      <target dev="vda" bus="virtio"/>
      <boot order="1"/>
      <address type="pci" domain="0x0000" bus="0x04" slot="0x00" function="0x0"/>
    <disk type="file" device="cdrom">
      <driver name="qemu" type="raw"/>
      <source file="/mnt/root/persistent/media/LegacyOS/Common/virtio-win-0.1.215.iso"/>
      <target dev="sdb" bus="sata"/>
      <address type="drive" controller="0" bus="0" target="0" unit="1"/>
    <controller type="usb" index="0" model="qemu-xhci" ports="15">
      <address type="pci" domain="0x0000" bus="0x02" slot="0x00" function="0x0"/>
    <controller type="pci" index="0" model="pcie-root"/>
    <controller type="pci" index="1" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="1" port="0x10"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x0" multifunction="on"/>
    <controller type="pci" index="2" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="2" port="0x11"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x1"/>
    <controller type="pci" index="3" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="3" port="0x12"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x2"/>
    <controller type="pci" index="4" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="4" port="0x13"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x3"/>
    <controller type="pci" index="5" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="5" port="0x14"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x4"/>
    <controller type="pci" index="6" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="6" port="0x15"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x5"/>
    <controller type="pci" index="7" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="7" port="0x16"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x6"/>
    <controller type="pci" index="8" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="8" port="0x17"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x7"/>
    <controller type="pci" index="9" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="9" port="0x18"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x0" multifunction="on"/>
    <controller type="pci" index="10" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="10" port="0x19"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x1"/>
    <controller type="pci" index="11" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="11" port="0x1a"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x2"/>
    <controller type="pci" index="12" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="12" port="0x1b"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x3"/>
    <controller type="pci" index="13" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="13" port="0x1c"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x4"/>
    <controller type="pci" index="14" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="14" port="0x1d"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x5"/>
    <controller type="sata" index="0">
      <address type="pci" domain="0x0000" bus="0x00" slot="0x1f" function="0x2"/>
    <controller type="virtio-serial" index="0">
      <address type="pci" domain="0x0000" bus="0x03" slot="0x00" function="0x0"/>
    <interface type="network">
      <mac address="52:54:00:f4:bf:15"/>
      <source network="default"/>
      <model type="virtio"/>
      <address type="pci" domain="0x0000" bus="0x01" slot="0x00" function="0x0"/>
    <serial type="pty">
      <target type="isa-serial" port="0">
        <model name="isa-serial"/>
    <console type="pty">
      <target type="serial" port="0"/>
    <channel type="spicevmc">
      <target type="virtio" name="com.redhat.spice.0"/>
      <address type="virtio-serial" controller="0" bus="0" port="1"/>
    <input type="mouse" bus="ps2"/>
    <input type="mouse" bus="virtio">
      <address type="pci" domain="0x0000" bus="0x06" slot="0x00" function="0x0"/>
    <input type="keyboard" bus="ps2"/>
    <input type="keyboard" bus="virtio">
      <address type="pci" domain="0x0000" bus="0x07" slot="0x00" function="0x0"/>
    <tpm model="tpm-crb">
      <backend type="passthrough">
        <device path="/dev/tpm0"/>
    <graphics type="spice" autoport="yes">
      <listen type="address"/>
      <image compression="off"/>
    <sound model="ich9">
      <audio id="1"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x1b" function="0x0"/>
    <audio id="1" type="spice"/>
      <model type="qxl" ram="65536" vram="65536" vgamem="16384" heads="1" primary="yes"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x01" function="0x0"/>
    <hostdev mode="subsystem" type="pci" managed="yes">
        <address domain="0x0000" bus="0x01" slot="0x00" function="0x0"/>
      <address type="pci" domain="0x0000" bus="0x05" slot="0x00" function="0x0"/>
    <redirdev bus="usb" type="spicevmc">
      <address type="usb" bus="0" port="2"/>
    <redirdev bus="usb" type="spicevmc">
      <address type="usb" bus="0" port="3"/>
    <watchdog model="itco" action="reset"/>
    <memballoon model="none"/>
    <qemu:arg value="-device"/>
    <qemu:arg value="{&quot;driver&quot;:&quot;ivshmem-plain&quot;,&quot;id&quot;:&quot;shmem0&quot;,&quot;memdev&quot;:&quot;looking-glass&quot;}"/>
    <qemu:arg value="-object"/>
    <qemu:arg value="{&quot;qom-type&quot;:&quot;memory-backend-file&quot;,&quot;id&quot;:&quot;looking-glass&quot;,&quot;mem-path&quot;:&quot;/dev/kvmfr0&quot;,&quot;size&quot;:67108864,&quot;share&quot;:true}"/>
    <qemu:arg value="-acpitable"/>
    <qemu:arg value="file=/etc/ssdt1.dat"/>