KVM Forum 2021

GPU passthrough technology guarantees users nearly full GPU performance within a virtual machine(VM), by giving a VM the direct access to GPU hardware. Since a passthrough GPU is fully controlled by guest, usually it’s non-trivial to share a passthrough GPU’s frame buffers with host-controlled devices. In the client virtualization field, there’s a trend to share guest applications’ or compositor’s frame buffers with the host display compositor, so that those guest frame buffers can be composited and posted to the display monitor. With a passthrough GPU, the guest frame buffer sharing could be very challenging, especially considering frame buffers 0-copy and synchronization between the guest applications and host display compositor. In this session, we’re going to present a solution that combines passthrough GPU with a paravirtualization display provided by virtio-gpu to achieve the frame buffers 0-copy goal as well as the synchronization. We will talk about the architecture design, the implementation challenges as well as some use cases based on the solution.