Secure hardware desktop buffer composition

• US 20070018992A1
• Filed: 07/22/2005
• Published: 01/25/2007
• Est. Priority Date: 07/22/2005
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Wong, Dan
• Granted Patent: US 7,681,200 B2
• Time in Patent Office: Days
• US Class Current: 345/545
• CPC Class Codes: G06F 21/84 output devices, e.g. displays or monitors
• CPC Class Codes: G06F 3/1431 using a single graphics controller
• CPC Class Codes: G06F 3/1438 using more than one graphics controller
• CPC Class Codes: G09G 2340/12 Overlay of images, i.e. displayed pixel being the result of switching between the corresponding input pixels
• CPC Class Codes: G09G 2352/00 Parallel handling of streams of display data
• CPC Class Codes: G09G 2360/18 Use of a frame buffer in a display terminal, inclusive of the display panel
• CPC Class Codes: G09G 5/363 Graphics controllers

Abstract

A plurality of virtual machines are executed on a host computer, the host computer including graphics hardware, and a display. The virtual machines write display data to their respective virtual desktop buffers. A virtual machine is selected to output to the display of the host computer. A composition buffer on the graphics hardware is enabled with respect to the selected virtual machine. The contents of the virtual desktop buffer associated with the selected virtual machine are copied to the composition buffer by the graphics hardware. The contents of the composition buffer are rendered and displayed by the graphics hardware. In addition, read access to the compositing buffer is restricted to the graphics hardware, thus preventing malicious software applications from capturing the display data across partitions.

Claims

1. A method for desktop composition, the method comprising:

executing at least one virtual machines at a host computer, each virtual machine comprising a virtual desktop buffer;

generating display data by the virtual machines to their corresponding virtual desktop buffer;

enabling at least one of the virtual desktop buffers; and

copying the contents of the enabled virtual desktop buffers to a composition buffer.

2. The method of claim 1, further comprising rendering the contents of the composition buffer to a display.

3. The method of claim 1, further comprising executing a secure process at the host computer to determine which virtual desktop buffer should be enabled.

4. The method of claim 3, wherein the secure process comprises a hypervisor.

5. The method of claim 3, wherein the composition buffer is implemented in a hardware device, and copying the contents of the enabled virtual desktop buffers to the composition buffer comprises the hardware device reading the contents of the enabled virtual desktop buffers and writing the contents of the enabled virtual desktop buffers to the composition buffer.

6. The method of claim 5, wherein read access to the virtual desktop buffers is denied to software processes.

7. The method of claim 5, wherein read access to the virtual desktop buffers is denied to non-secure software processes.

8. The method of claim 1, wherein the composition buffer is a double buffer.

9. A computer, the computer comprising:

a processor adapted to execute at least one virtual machine, each virtual machine generating display data into an associated virtual machine buffer;

memory adapted to store the virtual machine buffers;

memory adapted to store the virtual machine buffers; and

a graphics processor, the graphics processor comprising a composition buffer, and the graphics processor adapted to copy the contents of the virtual machine buffers from the memory to the composition buffer.

10. The computer of claim 9, wherein the graphics processor is further adapted to render the contents of the composition buffer.

11. The computer of claim 9, wherein the processor is further adapted to execute a secure process, wherein the secure process enables at least one virtual machine.

12. The computer of claim 11, wherein the secure process comprises a hypervisor.

13. The computer of claim 11, wherein the graphics processor is further adapted to determine which virtual machine is enabled, and copy the contents of the virtual machine buffer corresponding to the enabled virtual machine from the memory to the composition buffer.

14. The computer of claim 9, wherein the memory is further adapted to deny read access to software processes.

15. The computer of claim 9, wherein the memory is further adapted to only provide read access to secure software processes.

16. The computer of claim 9, wherein the memory is further adapted to only provide read access to the graphics processor.

17. The computer of claim 9, wherein the composition buffer is a double buffer.

18. A system for desktop composition, the system comprising:

an enabling component for enabling at least one virtual machine, the virtual machine executing on a host computer;

a retrieval component for retrieving display data from the enabled virtual machine;

a composition buffer for storing the retrieved display data; and

a translation component for transforming the stored display data into a format suitable for display on the host computer.

19. The system of claim 18, wherein the retrieval component is part of a graphics hardware device, and the display data is retrieved from memory on the host computer by the graphics hardware.

20. The system of claim 18, wherein the enabling component comprises a secure process executing on the host computer.