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: assigning, by a graphics manager to the trusted virtual machine, a secure section of the memory of the graphics processing unit when a first request is received from the trusted virtual machine; receiving, by a graphics manager executed by a processor of the computing device, a second request from the non-trusted virtual machine executed by the computing device to read a first set of graphical data rendered from the trusted virtual machine 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 first set of graphical data 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 a graphics processing unit of the computing device, 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.