Virgil is the new virtual OpenGL renderer option for KVM/QEMU guests that makes use of DRM+Gallium3D for providing hardware acceleration to open-source guest VMs. The project has been a work-in-progress going back a long time and led by Red Hat's David Airlie. All of the pieces of Virgil 3D have finally come together in the mainline code-bases of all relevant pieces of the stack.
The Phoronix reader who got Virgil up and running on Arch, Niccolò Belli, has shared a video of "having fun with Virgil 3D."
I've been meaning to run some more guest 3D VM benchmarks and will likely do so soon using Fedora 25 packages where all of the support should be in good standing.