Host Devices Assignment
Last updated
Last updated
KubeVirt provides a mechanism for assigning host devices to a virtual machine. This mechanism is generic and allows various types of PCI devices, such as accelerators (including GPUs) or any other devices attached to a PCI bus, to be assigned. It also allows , such as pre-configured virtual GPUs to be assigned using the same mechanism.
Host Devices passthrough requires the virtualization extension and the IOMMU extension (Intel VT-d or AMD IOMMU) to be enabled in the BIOS.
To enable IOMMU, depending on the CPU type, a host should be booted with an additional kernel parameter, intel_iommu=on for Intel and amd_iommu=on for AMD.
Append these parameters to the end of the GRUB_CMDLINE_LINUX line in the grub configuration file.
The vfio-pci kernel module should be enabled on the host.
At this time, KubeVirt is only able to assign PCI devices that are using the vfio-pci driver. To prepare a specific device for device assignment, it should first be unbound from its original driver and bound to the vfio-pci driver.
Find the PCI address of the desired device:
Bind that device to the vfio-pci driver:
At this time, configuration of a Mediated device (mdev) should be done according to the vendor directions. Once the mdev is configured, KubeVirt will be able to discover and use it for device assignment.
Administrators can control which host devices are exposed and permitted to be used in the cluster. Permitted host devices in the cluster will need to be allowlisted in KubeVirt CR by its vendor:product selector for PCI devices or mediated device names.
pciVendorSelector is a PCI vendor ID and product ID tuple in the form vendor_id:product_id. This tuple can identify specific types of devices on a host. For example, the identifier 10de:1eb8, shown above, can be found using lspci.
mdevNameSelector is a name of a Mediated device type that can identify specific types of Mediated devices on a host.
You can see what mediated types a given PCI device supports by examining the contents of /sys/bus/pci/devices/SLOT:BUS:DOMAIN.FUNCTION/mdev_supported_types/TYPE/name. For example, if you have an NVIDIA T4 GPU on your system, and you substitute in the SLOT, BUS, DOMAIN, and FUNCTION values that are correct for your system into the above path name, you will see that a TYPE of nvidia-226 contains the selector string GRID T4-2A in its name file.
Taking GRID T4-2A and specifying it as the mdevNameSelector allows KubeVirt to find a corresponding mediated device by matching it against /sys/class/mdev_bus/SLOT:BUS:DOMAIN.FUNCTION/$mdevUUID/mdev_type/name for some values of SLOT:BUS:DOMAIN.FUNCTION and $mdevUUID.
External providers: externalResourceProvider field indicates that this resource is being provided by an external device plugin. In this case, KubeVirt will only permit the usage of this device in the cluster but will leave the allocation and monitoring to an external device plugin.
Host devices can be assigned to virtual machines via the gpus and hostDevices fields. The deviceNames can reference both PCI and Mediated device resource names.