Mechanism for Memory Change Tracking During Migration of Virtual Machine (VM) with VM-Controlled Assigned Peripherals

• US 20120179855A1
• Filed: 01/07/2011
• Published: 07/12/2012
• Est. Priority Date: 01/07/2011
• Status: Active Grant

• Current Assignee: Red Hat Israel Ltd. (International Business Machines Corporation)
• Original Assignee: Red Hat Israel Ltd. (International Business Machines Corporation)
• Inventors: Laor, Dor, Kivity, Avi, Tsirkin, Michael S.
• Granted Patent: US 9,104,459 B2
• Time in Patent Office: Days
• US Class Current: 711/6
• CPC Class Codes: G06F 2009/4557 Distribution of virtual machine instances; Migration and load balancing
• CPC Class Codes: G06F 9/45558 Hypervisor-specific management and integration aspects

Abstract

A mechanism for memory change tracking during migration of a virtual machine (VM) with VM-controlled assigned peripherals is disclosed. A method of the invention includes informing a write tracking module of an interest by a hypervisor of a host machine in a specific memory location associated with a peripheral device that is controlled by a VM managed by the hypervisor, receiving notification from the write tracking module that the identified specific memory location has been modified by the peripheral device, and marking a memory page of the specific identified memory location as dirty in order for the migration of the memory page to be repeated as part of a migration process of the VM to a destination host machine.

Claims

1. A computer-implemented method, comprising:

informing, by a hypervisor of a host machine, a write tracking module of an interest by the hypervisor in a specific memory location associated with a peripheral device that is controlled by a virtual machine (VM) managed by the hypervisor;

receiving, by the hypervisor, notification from the write tracking module that the identified specific memory location has been modified by the peripheral device; and

marking, by the hypervisor, a memory page of the specific identified memory location as dirty in order for the migration of the memory page to be repeated as part of a migration process of the VM to a destination host machine.

2. The method of claim 1, wherein the write tracking module is located on the host machine.

3. The method of claim 2, wherein receiving notification that the identified specific memory location has been modified further comprises the write tracking module providing the notification to the hypervisor each time a direct memory access (DMA) write that targets the memory location has been completed.

4. The method of claim 1, wherein the write tracking module resides in the peripheral device and wherein the hypervisor utilizes a special peripheral communication channel established directly from the hypervisor to the peripheral device to inform the write tracking module of the interest in the memory location without interfering with the VM.

5. The method of claim 4, wherein receiving notification that the identified specific memory location has been modified further comprises the write tracking providing the notification to the hypervisor each time a direct memory access (DMA) write that targets the memory location has been completed.

6. The method of claim 5, wherein the hypervisor retrieves information regarding the DMA write to the memory location from one or more registers of the peripheral device in response to receiving the notification from the write tracking module.

7. The method of claim 5, wherein the hypervisor receives information regarding the DMA write to the memory location from the write tracking module directly via the special peripheral communication channel between the hypervisor and the peripheral device.

8. The method of claim 1, further comprising receiving notification of initialization of the migration process from a migration agent of at least one of a host controller of the hypervisor or the host machine, wherein the migration agent is responsible for performing the migration of the VM to the destination host machine.

9. A system, comprising:

a processing device;

a memory communicably coupled to the processing device; and

a hypervisor to execute one or more virtual machines (VMs) from the memory that share use of the processing device, the hypervisor configured to;

inform a write tracking module of an interest by the hypervisor in a specific memory location associated with a peripheral device that is controlled by a VM of the one or more VMs;

receive notification from the write tracking module that the identified specific memory location has been modified by the peripheral device; and

mark a memory page of the specific identified memory location as dirty in order for the migration of the memory page to be repeated as part of a migration process of the VM to a destination host machine.

10. The system of claim 9, wherein the write tracking module is located on the system and wherein receiving notification that the identified specific memory location has been modified further comprises the write tracking module providing the notification to the hypervisor each time a direct memory access (DMA) write that targets the memory location has been completed.

11. The system of claim 9, wherein the write tracking module resides in the peripheral device and wherein the hypervisor utilizes a special peripheral communication channel established directly from the hypervisor to the peripheral device to inform the write tracking module of the interest in the memory location without interfering with the VM.

12. The system of claim 11, wherein receiving notification that the identified specific memory location has been modified further comprises the write tracking providing the notification to the hypervisor each time a direct memory access (DMA) write that targets the memory location has been completed.

13. The system of claim 12, wherein the hypervisor retrieves information regarding the DMA write to the memory location from one or more registers of the peripheral device in response to receiving the notification from the write tracking module.

14. The system of claim 12, wherein the hypervisor receives information regarding the DMA write to the memory location from the write tracking module directly via the special peripheral communication channel between the hypervisor and the peripheral device.

15. An article of manufacture comprising a machine-readable storage medium including data that, when accessed by a machine, cause the machine to perform operations comprising:

informing a write tracking module of an interest by a hypervisor of a host machine in a specific memory location associated with a peripheral device that is controlled by a virtual machine (VM) managed by the hypervisor;

receiving notification from the write tracking module that the identified specific memory location has been modified by the peripheral device; and

marking a memory page of the specific identified memory location as dirty in order for the migration of the memory page to be repeated as part of a migration process of the VM to a destination host machine.

16. The article of manufacture of claim 15, wherein the write tracking module is located on the host machine and wherein receiving notification that the identified specific memory location has been modified further comprises the write tracking module providing the notification to the hypervisor each time a direct memory access (DMA) write that targets the memory location has been completed.

17. The article of manufacture of claim 15, wherein the write tracking module resides in the peripheral device and wherein the hypervisor utilizes a special peripheral communication channel established directly from the hypervisor to the peripheral device to inform the write tracking module of the interest in the memory location without interfering with the VM.

18. The article of manufacture of claim 17, wherein receiving notification that the identified specific memory location has been modified further comprises the write tracking providing the notification to the hypervisor each time a direct memory access (DMA) write that targets the memory location has been completed.

19. The article of manufacture of claim 18, wherein the hypervisor retrieves information regarding the DMA write to the memory location from one or more registers of the peripheral device in response to receiving the notification from the write tracking module.

20. The article of manufacture of claim 18, wherein the hypervisor receives information regarding the DMA write to the memory location from the write tracking module directly via the special peripheral communication channel between the hypervisor and the peripheral device.