Virtualization of graphics resources and thread blocking is disclosed. In one exemplary embodiment, a system and method of a kernel in an operating system including generating a data structure having an identifier of a graphics resource assigned to a physical memory location in video memory, and blocking access to the physical memory location if a data within the physical memory location is in transition between video memory and system memory wherein a client application accesses memory in the system memory directly and accesses memory in the video memory through a virtual memory map.