Para-virtualization in a nested virtualization environment using reduced number of nested VM exits

• US 8,495,628 B2
• Filed: 08/23/2009
• Issued: 07/23/2013
• Est. Priority Date: 08/23/2009
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ben Yehuda, Shmuel, Wasserman, Orit, Yassour, Ben-Ami
• Primary Examiner(s): To, Jennifer
• Assistant Examiner(s): Zhao, Bing
• Application Number:
  US12/545,834
• Publication Number:
  US 20110047544A1
• Time in Patent Office: 1,430 Days
• Field of Search: None
• 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 to the first host software from the guest software, due to a privileged instruction;

determining whether the first host software is running directly on hardware having a processor and a memory by way of the first host software submitting a request for hardware identity information during a startup process, wherein the identity information indicates if the first host software is running directly on the hardware or on a second host software; and

managing the privileged instruction without causing a second VM exit to the second host software from the first host software, in response to determining that the first host software is executed over the second host software that is running directly on the hardware,

wherein the second host software loads a first control structure into the memory, in response to determining that the first host software is running on the second host software,

wherein the first host software loads a second control structure into the memory, in response to determining that the guest software is running on the first host software, and

wherein the second host software loads a third control structure into the memory and updates value of the second control structure with value stored in the third control structure, in response to the first VM exit caused by the guest software due to the privileged instruction,

wherein the address of the second control structure in the memory is known to the second host software such that control for handling the privileged instruction is transferred to the first host software and so that the first host software directly accesses the second control structure instead of having the second host software access the second control structure, since the value of the second control structure has been previously updated with the value stored in the third control structure.

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 having processors 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 to the first host software from the guest software, due to a privileged instruction;

a logic unit for determining whether the first host software is running directly on hardware having a processor and a memory by way of the first host software submitting

a request for hardware identity information during a startup process, wherein the identity information indicates if the first host software is running directly on the hardware or on a second host software; and

a logic unit for managing the privileged instruction without causing a second VM exit to the second host software from the first host software, in response to determining that the first host software is executed over the second host software that is running directly on the hardware,

wherein the second host software loads a first control structure into the memory, in response to determining that the first host software is running on the second host software,

wherein the first host software loads a second control structure into the memory, in response to determining that the guest software is running on the first host software, and

wherein the second host software loads a third control structure into the memory and updates value of the second control structure with value stored in the third control structure, in response to the first VM exit caused by the guest software due to the privileged instruction,

wherein the address of the second control structure in the memory is known to the second host software such that control for handling the privileged instruction is transferred to the first host software and so that the first host software directly accesses the second control structure instead of having the second host software access the second control structure, since the value of the second control structure has been previously updated with the value stored in the third control structure.

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 non-transitory data storage 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 to the first host software from the guest software, due to a privileged instruction;

determine whether the first host software is running directly on hardware having a processor and a memory by way of the first host software submitting a request for hardware identity information during a startup process, wherein the identity information indicates if the first host software is running directly on the hardware or on a second host software; and

manage the privileged instruction without causing a second VM exit to the second host software from the first host software, in response to determining that the first host software is executed over the second host software that is running directly on the hardware,

wherein the second host software loads a first control structure into the memory, in response to determining that the first host software is running on the second host software,

wherein the first host software loads a second control structure into the memory, in response to determining that the guest software is running on the first host software, and

wherein the second host software loads a third control structure into the memory and updates value of the second control structure with value stored in the third control structure, in response to the first VM exit caused by the guest software due to the privileged instruction,

wherein the address of the second control structure in the memory is known to the second host software such that control for handling the privileged instruction is transferred to the first host software and so that the first host software directly accesses the second control structure instead of having the second host software access the second control structure, since the value of the second control structure has been previously updated with the value stored in the third control structure.

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.