[pve-devel] [PATCH docs v5 4/5] added vIOMMU documentation

[Markus Frank <m.frank@proxmox.com>]

Signed-off-by: Markus Frank <m.frank@proxmox.com>
---
 qm-pci-passthrough.adoc | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/qm-pci-passthrough.adoc b/qm-pci-passthrough.adoc
index df6cf21..0db9b06 100644
--- a/qm-pci-passthrough.adoc
+++ b/qm-pci-passthrough.adoc
@@ -400,6 +400,31 @@ Example configuration with an `Intel GVT-g vGPU` (`Intel Skylake 6700k`):
 With this set, {pve} automatically creates such a device on VM start, and
 cleans it up again when the VM stops.
 
+[[qm_pci_viommu]]
+vIOMMU
+~~~~~~
+
+vIOMMU enables the option to passthrough pci devices to Level-2 VMs
+in Level-1 VMs via Nested Virtualisation.
+
+Host Requirement: Add `intel_iommu=on` or `amd_iommu=on`
+depending on your CPU to your kernel command line.
+
+VM Requirement: For both Intel and AMD CPUs, set `intel_iommu=on`
+as the kernel parameter in the vIOMMU enabled VM, since qemu-server currently
+uses the Intel variant. The guest vIOMMU only works with the *q35* machine
+type and with *kvm* enabled.
+
+To enable vIOMMU, add `viommu=1` to the machine-parameter in the
+configuration of the VM that should be able to passthrough pci devices.
+
+----
+# qm set VMID -machine q35,viommu=1
+----
+
+
+https://wiki.qemu.org/Features/VT-d
+
 ifdef::wiki[]
 
 See Also
-- 
2.30.2