VFIO In Linux 4.10 Adds Mediated Device Interface: Used For Intel KVM-GT, NVIDIA vGPU

VFIO, the Virtual Function I/O framework for exposing direct device access to user-space in a secure manner with IOMMU protection, has an important new interface with Linux 4.10.

VFIO in Linux 4.10 adds a Mediated Device Interface. This Mediated Device Interface is used for allowing software-defined devices to be exposed through VFIO while the host driver manages access to the interface.

The initial use-case for the VFIO Mediated Device interface is for exposing virtual GPUs that map to a portion of a physical GPU. Intel's KVM-GT code paired with QEMU is using this mediated VFIO support for allowing guest operating systems to access the native HD/Iris Graphics hardware from the VM. The Intel DRM updates for Linux 4.10 have added their side of the GVT support code for supporting Xen/KVM graphics.

NVIDIA is also working on vGPU support for Linux making use of this mediated support in VFIO. Back in August was this presentation by NVIDIA on the mediated VFIO support. Will be interesting to see if NVIDIA rolls out their vGPU support soon now that this code is mainline.

More details via the pull request.