VFIO mediated device framework is the cornerstone of enabling shared GPU virtualization usages. While the framework provides a general mechanism to implement mediated device, there are still device specific usage problems which requires new extension. A key usage requirement in GPU virtualization is to render guest framebuffer in the host side. Remote display protocol (e.g. SPICE) needs to access and stream guest framebuffer to remote clients. Local display may copy or map guest framebuffer to surface which is then composited or directly shown by host window system.

In this talk we will introduce our extension to VFIO mediated device framework to support efficient buffer sharing for GPU virtualization usages, which is general enough for other I/O mediators too. In addition, we will talk about how this mechanism is used by various Qemu graphics user interface (e.g. SPICE).