enable the IOMMU feature on an AMD or Intel

To enable the IOMMU feature on an AMD Ryzen system, modify your grub config. Run sudo nano /etc/default/grub and edit the line which starts with GRUB_CMDLINE_LINUX_DEFAULT, to match:

GRUB_CMDLINE_LINUX_DEFAULT="amd_iommu=on iommu=pt kvm_amd.npt=1 kvm_amd.avic=1"

in case you are using an Intel CPU the line should read:

GRUB_CMDLINE_LINUX_DEFAULT="intel_iommu=on"

Save the changes and update grub.

sudo update-grub

Reboot your system when the command has finished.