Activate IOMMU and iGPU to Passthrough PCI into VM/CT

1. Enable VT-d in the BIOS

• Reboot the server and access the BIOS by pressing the DEL key.
• Enable VT-d in the Chipset tab.
• Save and reboot.

2. Edit the GRUB configuration file

• SSH to the Promox Server by using MobaXterm.
• Edit the grub configuration file by using nano function or using SFTP.

1nano /etc/default/grub

• Now you need to find the line GRUB_CMDLINE_LINUX_DEFAULT in the configuration file and edit it. The default config looks like this:

1GRUB_CMDLINE_LINUX_DEFAULT="quiet"

• Active IOMMU and iGPU

1GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on i915.enable_gvt=1 iommu=pt pcie_acs_override=downstream,multifunction video=efifb:off video=vesa:off vfio_iommu_type1.allow_unsafe_interrupts=1 kvm.ignore_msrs=1 modprobe.blacklist=radeon,nouveau,nvidia,nvidiafb,nvidia-gpu"

• Active IOMMU and split iGPU into 2 parts

1GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on iommu=pt pcie_acs_override=downstream,multifunction initcall_blacklist=sysfb_init video=simplefb:off video=vesafb:off video=efifb:off video=vesa:off disable_vga=1 vfio_iommu_type1.allow_unsafe_interrupts=1 kvm.ignore_msrs=1 modprobe.blacklist=radeon,nouveau,nvidia,nvidiafb,nvidia-gpu,snd_hda_intel,snd_hda_codec_hdmi,i915"

• Save the grub configuration file and update the grub file

1update-grub

3. Config Promox modules to allow PCI Passthrough

• Edit modules file

1nano /etc/modules

• Adding the following line at the bottom of the file

1# Modules required for PCI passthrough
2vfio
3vfio_iommu_type1
4vfio_pci
5vfio_virqfd
6
7# Modules required for Intel GVT-g Split. Do not add if you do not split iGPU
8kvmgt

• Now, your modules file will look like this

• Update the configuration changes

1update-initramfs -u -k all

• Reboot the Promox server to apply the changes

4. Verify IOMMU is enabled

• Run the script below to verify if IOMMU is enabled.

1dmesg | grep -e DMAR -e IOMMU

• You will see the line: DMAR: IOMMU enabled look like this.

• And now, When you add a new PCI device, the notification `No IOMMU detected" has been dissapear.

With only 4 steps you have successfully activated IOMMU and can passthrough PCI to VM.

In my case, Which PCI do I passthrough in each VM/CT ? I will show you in the next article.

The image below is one of my practice.