Virtualization with Merged Guest Page Table and Shadow Page Directory

• US 20090300263A1
• Filed: 05/14/2009
• Published: 12/03/2009
• Est. Priority Date: 05/30/2008
• Status: Active Grant

• Current Assignee: VMware, Inc. (Broadcom, Inc.)
• Original Assignee: VMware, Inc. (Broadcom, Inc.)
• Inventors: ROGEL, Lawrence S., DEVINE, Scott W., BUNGALE, Prashanth P., FRY, Gerald A.
• Granted Patent: US 8,127,107 B2
• Time in Patent Office: Days
• US Class Current: 711/6
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/06 Addressing a physical block of locations, e.g. base addressing, module addressing, memory dedication G06F12/08 takes precedence
• CPC Class Codes: G06F 12/08 in hierarchically structured memory systems, e.g. virtual memory systems
• CPC Class Codes: G06F 12/10 Address translation
• CPC Class Codes: G06F 12/1009 using page tables, e.g. page table structures
• CPC Class Codes: G06F 12/1036 for multiple virtual address spaces, e.g. segmentation G06F12/1045 takes precedence
• CPC Class Codes: G06F 12/109 for multiple virtual address spaces, e.g. segmentation G06F12/1036 takes precedence
• CPC Class Codes: G06F 2212/151 Emulated environment, e.g. virtual machine
• CPC Class Codes: G06F 2212/152 Virtualized environment, e.g. logically partitioned system
• CPC Class Codes: G06F 8/40 Transformation of program code
• CPC Class Codes: G06F 9/455 Emulation; Interpretation; Software simulation, e.g. virtualisation or emulation of application or operating system execution engines
• CPC Class Codes: G06F 9/54 Interprogram communication

Abstract

In a computing system having virtualization software including a guest operating system (OS), a method for providing page tables that includes: providing a guest page table used by the guest OS and a shadow page table and a shadow page directory used by the virtualization software wherein: at least a portion of the guest page table and the shadow page directory are the same; and the portions that are the same are shared in computer memory by the guest page table and the shadow page directory.

Claims

1. In a computing system comprised of virtualization software including a guest operating system (OS), a method for providing page tables that comprises:

providing a guest page table used by the guest OS and a shadow page table and a shadow page directory used by the virtualization software wherein;

at least a portion of the guest page table and the shadow page directory are the same; and

the portions that are the same are shared in computer memory by the guest page table and the shadow page directory.

2. The method of claim 2 further comprising:

a directory difference structure identifying which portions, if any, of the guest page table and the shadow page directory are different.

3. The method of claim 3 further comprising:

the directory difference structure indicating when an entry in a guest page table identifies a machine address because the entry in guest page table and the entry in the shadow page directory are the same, and when the entry in the guest page table must be converted to the machine address because the entry in the guest page table and the entry in the shadow page directory are not the same.

4. The method of claim 3 further comprising:

the virtualization software merging and separating portions of the guest page table and the shadow page directory as the guest OS operates.

5. The method of claim 4 further comprising:

the virtualization software updating the directory difference structure when either merging or separating portions of the guest page table and the shadow page directory.