NAME¶

lsiommu - Enumerate IOMMU groups, and list the PCIe devices and USB controllers associated with each group

DESCRIPTION¶

lsiommu is a hardware inspection utility that shows the relationships between IOMMU groups, physical PCIe hardware, and nested USB buses.

It is commonly used when setting up Kernel-based Virtual Machines (KVM) with VFIO hardware passthrough (i.e., PCIe passthrough of a host device, such as a graphics card or a network interface, to a guest VM).

The utility performs four core actions:

Group Mapping

Iterates sequentially through the system kernel directory /sys/kernel/iommu_groups/ to discover physical hardware isolation clusters.

Hardware Details

Executes lspci(8) queries to extract and cleanly format vendor names, hardware descriptions, and precise hardware IDs for graphics cards, network interfaces, and storage drives.

Reset Support Flag

Checks the system tree for device reset capabilities. It appends an [R] flag if a hardware device natively supports a function-level reset, which is required for reliable virtual machine attach/detach cycles.

USB Mapping

Correlates nested USB controllers via lsusb(8) with their parent PCIe buses. This exposes exactly which physical USB ports belong to which isolated IOMMU group.

NOTES¶

IOMMU groups are a part of the kernel's VFIO (Virtual Function IO) driver framework:

https://docs.kernel.org/driver-api/vfio.html

SEE ALSO¶

lspci(8), lsusb(8),