Intel Makes XenGT For Mediated GPU Passthrough

Intel has announced an interesting project in the space of GPU virtualization and being able to share a graphics processor with a virtualization hypervisor while still achieving a level of shareability.

Xen has long supported VGA/GPU pass-through support for passing a graphics processor to the virtualized OS so that it may load the GPU driver for the guest platform and use it exclusively to obtain 2D/3D/video acceleration. Xen VGA pass-through is even good enough for some interesting game demos by Ubisoft. QEMU has also been working on VGA pass-through as another means of 3D hardware support in guest VMs without having to have an emulated GPU where the guest drivers end up passing the 3D commands onto the host system and its drivers for processing.

Intel has now announced XenGT as another way for improving Xen's GPU tech. The announcement by Intel's Dexuan Cui reads:

We're pleased to announce an update to XenGT since its first disclosure in last Sep. XenGT is a full GPU virtualization solution with mediated pass-through, on Intel Processor Graphics. A virtual GPU instance is maintained for each VM, with part of performance critical resources directly assigned. The capability of running native graphics driver inside a VM, without hypervisor intervention in performance critical paths, achieves a good balance among performance, feature, and sharing capability. Though we only support Xen on Intel Processor Graphics so far, the core logic can be easily ported to other hypervisors.

XenGT now supports multiple monitors, supports VMs with different resolutions, improves monitor hot-plug handling, has preliminary support for GPU recovery, and has improved sharing quality of the render engine and display engine. The new release is re-based to the Linux 3.11.6 kernel and Xen 4.3.1. There's also a qemu-vgt fork and that now includes working GRUB2 graphics mode. It's through modified versions of Xen, QEMU, and the Linux kernel that XenGT works. This 3D feature also appears limited to supporting Intel "Haswell" HD Graphics.

More details on Intel's XenGT graphics project can be found from this week's mailing list announcement.