1 Enter BIOS/UEFI menu

2. Enable the VT-d/AMD-d CPU flags

Because some menus are different look for something like Enable Virtualization Technology



3. Set boot priority for your UEFI-based Proxmox drive

You may see Proxmox and (UEFI) Proxmox boot options or something similar

You may need to disable CSM to ensure the system boots using UEFI



Proxmox SSH/Shell

4. SSH or Shell into Proxmox then:

GRUB

Edit /etc/default/grub and modify the appropriate line:

Intel: GRUB_CMDLINE_LINUX_DEFAULT=quiet intel_iommu=on iommu=pt vga=off

AMD: GRUB_CMDLINE_LINUX_DEFAULT=quiet amd_iommu=on iommu=pt vga=off

Save and close file then run update-grub2 to apply the changes

ZFS

Edit /etc/kernel/cmdline and modify the appropriate line:

Intel: root=ZFS=rpool/ROOT/pve-1 boot=zfs quiet intel_iommu=on iommu=pt

AMD: root=ZFS=rpool/ROOT/pve-1 boot=zfs quiet amd_iommu=on iommu=pt

Save and close file then run pve-efiboot-tool refresh to apply the changes

You may need to put quiet ... iommu=pt on its own line

Thanks to u/edfreitag for supplying the sourcing!



5. Still in Proxmox SSH/Shell, edit Kernel Modules /etc/modules and add the following lines:

vfio
vfio_iommu_type1
vfio_pci
vfio_virqfd
6. Save and close modules file then run update-initramfs to add the kernel modules

7. Reboot host machine



Proxmox WebUI

8. Create a new VM with OVMF BIOS and as a q35 machine. DO NOT SKIP setting processor type!

# Use whatever other settings you want, but the following are required

SYSTEM
  BIOS: OVMF(UEFI)
  Machine: q35

PROCESSOR
  TYPE: IvyBridge        # Your CPU may not be an IvyBridge
https://preview.redd.it/w9ir4kyafif61.png?width=722&format=png&auto=webp&s=202019ae95d2ad10fb081d2a0dc099f69b32dc9a

9. Add your graphics card as a new PCI device

10. Set device to use All functions and PCI Express. DO NOT set as primary GPU!

11. Start VM and install OS



Virtual Machine

12. Boot OS and install graphics card driver

13. Open Device Manager and confirm you see both the GPU name and an error 43 on your display driver

14. Enable RDP (optional as this guide allows you to use both Console and RDP)

15. Safely reboot then power down VM



Proxmox VM Settings

16. In Proxmox VM settings:

Set Display to VirtIO-GPU (virtio)

Set PCI Device as Primary GPU



Endgame

17. Start VM and confirm error 43 is gone

18. Start gaming!



Cheers!