PARA-VIRTUALIZATION IN A NESTED VIRTUALIZATION ENVIROMENT

• US 20110047544A1
• Filed: 08/23/2009
• Published: 02/24/2011
• Est. Priority Date: 08/23/2009
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Yassour, Ben-Ami, Wasserman, Orit, Yehuda, Shmuel Ben
• Granted Patent: US 8,495,628 B2
• Time in Patent Office: Days
• US Class Current: 718/1
• CPC Class Codes: G06F 2009/45566 Nested virtual machines
• CPC Class Codes: G06F 9/4555 Para-virtualisation, i.e. guest operating system has to be modified
• CPC Class Codes: G06F 9/45558 Hypervisor-specific management and integration aspects

Abstract

A para-virtualization method is provided. The method comprises implementing a virtual machine (VM) for guest software running on first host software. In response to a privileged instruction, the guest software causes a first VM exit. If the first host software is not running directly on hardware, the privileged instruction is managed without causing a second VM exit. Otherwise, the privileged instruction is managed normally.

Claims

1. A para-virtualization method comprising:

implementing a virtual machine (VM) for guest software running on first host software, wherein the guest software causes a first VM exit in response to a privileged instruction;

determining whether the first host software is running directly on hardware; and

managing the privileged instruction without causing a second VM exit, in response to determining that the first host software is not running directly on the hardware.

2. The method of claim 1, wherein the determining comprises performing a hypercall.

3. The method of claim 2, wherein the first host software is determined to be running directly on the hardware, in response to failure of the hypercall.

4. The method of claim 3, wherein the first host software is determined to be running on a second host software, in response to success of the hypercall.

5. The method of claim 4, wherein the first host software is marked as a para-virtualized nested host software.

6. The method of claim 1, wherein the determining comprises requesting an identification of underlying hardware.

7. The method of claim 6, wherein the first host software is determined to be running on a second host software, in response to the identification being a value associated with a VM.

8. The method of claim 7, wherein the first host software is determined to be running directly on the hardware, in response to the identification not being a value associated with a VM.

9. A system comprising:

a logic unit for implementing a virtual machine (VM) for guest software running on first host software, wherein the guest software causes a first VM exit in response to a privileged instruction;

a logic unit for determining whether the first host software is running directly on hardware; and

a logic unit for managing the privileged instruction without causing a second VM exit, in response to determining that the first host software is not running directly on the hardware.

10. The method of claim 9, wherein the determining comprises performing a hypercall.

11. The method of claim 10, wherein the first host software is determined to be running directly on the hardware, in response to failure of the hypercall.

12. The method of claim 11, wherein the first host software is determined to be running on a second host software, in response to success of the hypercall.

13. The method of claim 12, wherein the first host software is marked as a para-virtualized nested host software.

14. The method of claim 9, wherein the determining comprises requesting an identification of underlying hardware.

15. The method of claim 14, wherein the first host software is determined to be running on a second host software, in response to the identification being a value associated with a VM.

16. The method of claim 15, wherein the first host software is determined to be running directly on the hardware, in response to the identification not being a value associated with a VM.

17. A computer program product comprising a computer readable medium having logic code stored thereon, wherein the logic code when executed on a computer causes the computer to:

implement a virtual machine (VM) for guest software running on first host software, wherein the guest software causes a first VM exit in response to a privileged instruction;

determine whether the first host software is running directly on hardware; and

manage the privileged instruction without causing a second VM exit, in response to determining that the first host software is not running directly on the hardware.

18. The method of claim 17, wherein the determining comprises performing a hypercall.

19. The method of claim 18, wherein the first host software is determined to be running directly on the hardware, in response to failure of the hypercall.

20. The method of claim 19, wherein the first host software is determined to be running on a second host software, in response to success of the hypercall.

21. The method of claim 20, wherein the first host software is marked as a para-virtualized nested host software.

22. The method of claim 17, wherein the determining comprises requesting an identification of underlying hardware.

23. The method of claim 22, wherein the first host software is determined to be running on a second host software, in response to the identification being a value associated with a VM.

24. The method of claim 23, wherein the first host software is determined to be running directly on the hardware, in response to the identification not being a value associated with a VM.