Managing loading and unloading of shared kernel extensions in isolated virtual space

• US 8,397,245 B2
• Filed: 07/12/2010
• Issued: 03/12/2013
• Est. Priority Date: 07/12/2010
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Filali-Adib, Khalid, Fought, Kevin L., Sheffield, David W., Tomsic, Nathaniel S., Yook, Sungjin
• Primary Examiner(s): Anya, Charles E
• Application Number:
  US12/834,492
• Publication Number:
  US 20120011503A1
• Time in Patent Office: 974 Days
• Field of Search: 713/2, 713/164, 718/1, 719/319
• US Class Current: 719/319
• CPC Class Codes: G06F 9/45533 Hypervisors; Virtual machine monitors
• CPC Class Codes: G06F 9/45545 Guest-host, i.e. hypervisor is an application program itself, e.g. VirtualBox

Abstract

Some embodiments of the inventive subject matter are directed to receiving a request from a first instance of an operating system (e.g., a virtual operating system) to load a kernel extension that extends functionality of a kernel, where the kernel and the first instance of the operating system are managed by a second instance of the operating system (e.g., a global operating system), and where the first and second instances of the operating system share the kernel. Some embodiments are further directed to loading the kernel extension as a shared kernel extension. Some embodiments are further directed to receiving a request by the first instances of the operating system to unload the kernel extension and determining that a third instance of the operating system (e.g., another virtual operating system also managed by the global operating system) requires the kernel extension to remain loaded. Some embodiments are further directed to notifying the first instance of the operating system that the kernel extension was unloaded while leaving the kernel extension loaded in the kernel.

Claims

1. A method comprising:

receiving a request from a first of a plurality of instances of an operating system to load a kernel extension that extends functionality of a kernel, wherein the kernel and the plurality of instances of the operating system are managed by a second of the plurality of the instances of the operating system, and wherein the plurality of the instances of the operating system share the kernel;

after receiving the request from the first of the plurality of instances of the operating system to load the kernel extension, writing a first instance of an identifier for the kernel extension in a list;

determining that the kernel extension can be shared globally by the plurality of the instances of the operating system;

loading the kernel extension to be shared by the plurality of the instances of the operating system;

receiving a request by a third of the plurality of the instances of the operating system to load the kernel extension;

writing a second instance of the identifier for the kernel extension in the list;

receiving a request by the first of the plurality of the instances of the operating system to unload the kernel extension;

after receiving the request by the first of the plurality of the instances of the operating system to unload the kernel extension, removing the first instance of the identifier from the list;

determining that the third of the plurality of the instances of the operating system requires the kernel extension to remain loaded, the determining including determining that the second instance of the identifier remains in the list, wherein said determining that the second instance of the identifier remains in the list indicates that the third of the plurality of the instances of the operating system requires the kernel extension to remain loaded; and

notifying the first of the plurality of the instances of the operating system that the kernel extension was unloaded while leaving the kernel extension loaded in the kernel.

2. The method of claim 1, wherein determining that the third of the plurality of the instances of the operating system requires the kernel extension to remain loaded comprises:

tracking a count of the plurality of instances of the operating system that require the kernel extension; and

determining, from the count, that the third of the plurality of instances of the operating system requires the kernel extension to remain loaded.

3. The method of claim 1, further comprising

incrementing a count from a first value to a second value when the first of the plurality of the instances of the operating system requests to load the kernel extension;

detecting a request from the third of the plurality of the instances of the operating system to load the kernel extension;

incrementing the count from the second value to a third value when the third of the plurality of the instances of the operating system requests to load the kernel extension;

decrementing the count from the third value to the second value when the first of the plurality of the instances of the operating system requests to unload the kernel extension; and

determining that the count is not equal to the first value.

4. The method of claim 1, wherein notifying the first of the plurality of the instances of the operating system that the kernel extension was unloaded while leaving the kernel extension loaded in the kernel comprises:

providing a message to the first of the plurality of the instances of the operating system that indicates that the kernel extension is unloaded, wherein the first of the plurality of the instances of the operating system is configured to use the message to terminate a process associated with the kernel extension.

5. The method of claim 1, further comprising:

before receiving the request from the first of the plurality of instances of the operating system to load the kernel extension;

providing the first of the plurality of instances of the operating system with administrative rights to load the kernel extension; and

performing one or more security checking procedures to verify that the kernel extension is safe to load into the kernel.

6. The method of claim 1, wherein said first of the plurality of the instances of the operating system is installed on a software partition and the second of the plurality of the instances of the operating system is installed on one or more of a logical partition and a server.

7. A computer program product for managing kernel extensions for one or more virtual operating systems, the computer program product comprising:

a computer readable storage medium having computer readable program code embodied therewith, the computer readable program code comprising;

computer readable program code configured to,

receive a request from a first of a plurality of instances of an operating system to load a kernel extension that extends functionality of a kernel, wherein the kernel and the plurality of instances of the operating system are managed by a second of the plurality of the instances of the operating system, and wherein the plurality of the instances of the operating system share the kernel,

write a first instance of an identifier for the kernel extension in a list,

determine that the kernel extension can be shared globally by the plurality of the instances of the operating system,

load the kernel extension to be shared by the plurality of the instances of the operating system,

receive a request by a third of the plurality of the instances of the operating system to load the kernel extension,

write a second instance of the identifier for the kernel extension in the list,

receive a request by the first of the plurality of the instances of the operating system to unload the kernel extension,

after receiving the request by the first of the plurality of the instances of the operating system to unload the kernel extension, remove the first instance of the identifier from the list,

determine that the second instance of the identifier remains in the list, wherein the second instance of the identifier indicates that the third of the plurality of the instances of the operating system requires the kernel extension to remain loaded, and

notify the first of the plurality of the instances of the operating system that the kernel extension was unloaded while leaving the kernel extension loaded in the kernel.

8. The computer program product of claim 7, said computer readable program code configured to determine that the third of the plurality of the instances of the operating system requires the kernel extension to remain loaded being configured to

track a count of the plurality of instances of the operating system that require the kernel extension, and

determine, from the count, that the third of the plurality of instances of the operating system requires the kernel extension to remain loaded.

9. The computer program product of claim 7, said computer readable program code configured to determine that the third of the plurality of the instances of the operating system requires the kernel extension to remain loaded being configured to

increment a count from a first value to a second value when the first of the plurality of the instances of the operating system requests to load the kernel extension,

increment the count from the second value to a third value when the third of the plurality of the instances of the operating system requests to load the kernel extension,

decrement the count from the third value to the second value when the first of the plurality of the instances of the operating system requests to unload the kernel extension, and

determine that the count is not equal to the first value.

10. The computer program product of claim 9, wherein the first value is zero, and said computer readable program code being configured to determine that the count is not equal to zero.

11. The computer program product of claim 7, wherein the first of the plurality of instances of the operating system is installed on a first software partition, wherein the third of the plurality of instances of the operating system is installed on a second software partition, and wherein the second of the plurality of instances of the operating system is installed on one or more of a logical partition and a computer.

12. The computer program product of claim 7, said computer readable program code being configured to notify the first of the plurality of the instances of the operating system that the kernel extension was unloaded while leaving the kernel extension loaded in the kernel being further configured to,

provide a message to the first of the plurality of the instances of the operating system that indicates that the kernel extension is unloaded, wherein the first of the plurality of the instances of the operating system is configured to use the message to terminate a process associated with the kernel extension.

13. The computer program product of claim 7, said computer readable program code being further configured to,

before receiving the request from the first of the plurality of instances of the operating system to load the kernel extension,

provide the first of the plurality of instances of the operating system with administrative rights to load the kernel extension, and

perform one or more security checking procedures to verify that the kernel extension is safe to load into the kernel.

14. An apparatus comprising:

a processing unit;

a network interface; and

a virtual operating system manager operable to, via the processing unit,

receive a request from a first of a plurality of instances of an operating system to load a kernel extension that extends functionality of a kernel, wherein the kernel and the plurality of instances of the operating system are managed by a second of the plurality of the instances of the operating system, and wherein the plurality of the instances of the operating system share the kernel,

after receiving the request from the first of the plurality of instances of the operating system to load the kernel extension, write a first instance of an identifier for the kernel extension in a list,

load the kernel extension to be shared by the plurality of the instances of the operating system,

receive a request by a third of the plurality of the instances of the operating system to load the kernel extension,

after receiving the request by the third of the plurality of the instances of the operating system to load the kernel extension, write a second instance of the identifier for the kernel extension in the list,

receive a request by the third of the plurality of the instances of the operating system to unload the kernel extension,

remove the second instance of the identifier for the kernel extension from the list,

receive a request by the first of the plurality of the instances of the operating system to unload the kernel extension,

after receiving the request by the first of the plurality of the instances of the operating system to unload the kernel extension, remove the first instance of the identifier from the list,

determine that the plurality of the instances of the operating system does not require the kernel extension to remain loaded, including determining that no other instances of the identifier are in the list before unloading the kernel extension, and

unload the kernel extension.

15. The apparatus of claim 14, said virtual operating system manager operable to

track a count of the plurality of instances of the operating system that require the kernel extension, and

determine, from the count, that the plurality of instances of the operating system requires the kernel extension to remain loaded.

16. The apparatus of claim 14, said virtual operating system manager operable to

receive a request from a third of the plurality of the instances of the operating system to load the kernel extension,

increment the count from the a first value to a second value when the third of the plurality of the instances of the operating system requests to load the kernel extension,

increment the count from the second value to a third value when the first of the plurality of the instances of the operating system requests to load the kernel extension,

receive a request by the third of the plurality of the instances of the operating system to unload the kernel extension,

decrement the count from the third value to the second value when the third of the plurality of the instances of the operating system requests to unload the kernel extension,

decrement the count from the second value to the first value when the first of the plurality of the instances of the operating system requests to unload the kernel extension, and

determine that the count is equal to the first value.

17. The apparatus of claim 14, wherein the first of the plurality of instances of the operating system is installed on a software partition, and wherein the second of the plurality of instances of the operating system is installed on one or more of a logical partition and a computer.

18. The apparatus of claim 14, wherein the virtual operating system manager is configured to:

provide the first of the plurality of instances of the operating system with administrative rights to load the kernel extension; and

perform one or more security checking procedures to verify that the kernel extension is safe to load into the kernel.

19. The apparatus of claim 14, wherein said first of the plurality of the instances of the operating system is installed on a software partition and the second of the plurality of the instances of the operating system is installed on one or more of a logical partition and a server.