1. In a computing device executing a hypervisor hosting a trusted virtual machine and a non-trusted virtual machine, a method for preventing the non-trusted virtual machine from reading the graphical output of the trusted virtual machine, comprising: receiving, by a graphics manager executed by a processor of the computing device, a first request from the trusted virtual machine executed by the computing device to render graphical data using a graphics processing unit of the computing device; assigning, by the graphics manager to the trusted virtual machine, a secure section of a memory of the graphics processing unit; rendering, by the graphics manager, graphics from the trusted virtual machine graphical data to the secure section of the graphics processing unit memory; receiving, by the graphics manager, a second request from the non-trusted virtual machine executed by the computing device to read graphics rendered from the trusted virtual machine graphical data and stored in the secure section of the graphics processing unit memory; preventing, by the graphics manager responsive to receiving the second request, the non- trusted virtual machine from reading the trusted virtual machine rendered graphics stored in the secure section of the graphics processing unit memory; receiving, by the graphics manager, a third request from an application executing on the non-trusted virtual machine to render a second set of graphical data using the graphics processing unit, the application generating the second set of graphical data; and rendering, by the graphics manager, graphics from the second set of graphical data to a section of the graphics processing unit memory not comprising the secure section of the graphics processing unit memory.