Using capability indicators to indicate support for guest driven surprise removal of virtual PCI devices

• US 10,394,586 B2
• Filed: 08/13/2015
• Issued: 08/27/2019
• Est. Priority Date: 08/13/2015
• Status: Active Grant

• Current Assignee: Red Hat Israel Ltd. (International Business Machines Corporation)
• Original Assignee: Red Hat Israel Ltd. (International Business Machines Corporation)
• Inventors: Tsirkin, Michael
• Primary Examiner(s): An, Meng Ai T
• Assistant Examiner(s): Ayers, Michael W
• Application Number:
  US14/826,037
• Publication Number:
  US 20170046187A1
• Time in Patent Office: 1,475 Days
• CPC Class Codes: G06F 2009/45562 Creating, deleting, cloning virtual machine instances
• CPC Class Codes: G06F 2009/45579 I/O management, e.g. providing access to device drivers or storage
• CPC Class Codes: G06F 9/45554 Instruction set architectures of guest OS and hypervisor or native processor differ, e.g. Bochs or VirtualPC on PowerPC MacOS
• CPC Class Codes: G06F 9/45558 Hypervisor-specific management and integration aspects

Abstract

A hypervisor receives a notification from a guest operating system of a virtual machine that includes a capability indicator of support provided by a virtual device driver for recovering from a surprise removal of a corresponding virtual device from the virtual machine. The hypervisor, upon receiving a request to remove the virtual device from the virtual machine, uses the capability indicator received from the guest operating system to identify one or more actions to be performed to remove the virtual device from the virtual machine. The hypervisor then removes the virtual device from the virtual machine using the identified actions.

Claims

1. A method for removing a virtual device from a virtual machine having a guest operating system (OS), the virtual machine managed by a hypervisor executing on a processing device, comprising:

receiving, by the hypervisor, a notification from the guest OS, the notification comprising a capability indicator value indicating a support level for surprise removal of a virtual device of the guest OS, the surprise removal of the virtual device comprising removal of the virtual device from the virtual machine without first providing a warning to the guest OS;

storing, by the hypervisor, the capability indicator value corresponding to the virtual device in a mapping table;

subsequently receiving, by the processing device executing the hypervisor, a request to remove the virtual device from the virtual machine;

responsive to receiving the request to remove the virtual device, accessing, by the hypervisor, the mapping table to obtain the capability indicator value corresponding to the virtual device;

identifying, by the processing device executing the hypervisor, in view of the obtained capability indicator value, a particular set of actions associated with the obtained capability indicator value, the particular set of actions to be performed to remove the virtual device from the virtual machine, the particular set of actions including at least removing the virtual device from the virtual machine without first providing the warning to the guest OS when the capability indicator indicates a safe support level, or at least first providing the warning to the guest OS before removing the virtual device from the virtual machine when the capability indicator indicates an unsafe support level; and

removing the virtual device from the virtual machine using the particular set of actions.

2. The method of claim 1, wherein the capability indicator value is one of a plurality of capability indicator values that are each associated with a plurality of support levels, wherein each of the plurality of support levels corresponds to a set of one or more actions to be performed for virtual device removal in the mapping table.

3. The method of claim 1, wherein the obtained capability indicator value corresponds to the safe support level and wherein removing the virtual device comprises:

unmapping the virtual device from the guest operating system of the virtual machine;

sending a removal notification to the guest operating system that the virtual device has been removed from the virtual machine by the hypervisor; and

responsive to receiving an acknowledgment from the guest operating system of the removal notification, freeing hypervisor resources associated with the virtual device.

4. The method of claim 1, wherein the obtained capability indicator value corresponds to a supported support level and wherein removing the virtual device comprises:

sending a removal notification to the guest operating system that the virtual device is to be removed;

starting a timer upon sending the removal notification;

detecting an expiration of the timer prior to receiving a first acknowledgment of the removal notification;

unmapping the virtual device from the guest operating system;

sending a removal acknowledgement notification to the guest operating system that the virtual device has been removed from the virtual machine by the hypervisor; and

responsive to receiving a second acknowledgment from the guest operating system of the removal acknowledgement notification, freeing hypervisor resources associated with the virtual device.

5. The method of claim 4, further comprising:

sending an alert to an administrator to request confirmation to unmap the virtual device from the guest operating system.

6. The method of claim 1, wherein the obtained capability indicator value corresponds to the unsafe support level and wherein removing the virtual device comprises:

sending a removal notification to the guest operating system of the virtual machine that the virtual device is to be removed; and

responsive to receiving an acknowledgment from the guest operating system of the removal notification, unmapping the virtual device from the guest operating system of the virtual machine and freeing hypervisor resources associated with the virtual device.

7. The method of claim 1, wherein a guest operating system of the virtual machine is to:

detect an assignment of the virtual device to the virtual machine;

load a virtual device driver for the virtual device into memory accessible to the guest operating system;

determine the capability indicator value that identifies the support provided by the virtual device driver for recovering from the surprise removal of the virtual device from the virtual machine; and

send the notification to the hypervisor, the notification comprising the capability indicator value.

8. A computing apparatus for removing a virtual device from a virtual machine having a guest operating system (OS), the virtual machine managed by a hypervisor executing on a processing device, the computing apparatus comprising:

a memory; and

a processing device, operatively coupled to the memory, to execute the hypervisor to;

receive a notification from the guest OS, the notification comprising a capability indicator value indicating a support level for surprise removal of a virtual device of the guest OS, the surprise removal of the virtual device from the virtual machine without first providing a warning to the guest OS;

store the capability indicator value corresponding to the virtual device in a mapping table;

subsequently receive a request to remove the virtual device from the virtual machine;

responsive to receiving the request to remove the virtual device, access the mapping table to obtain the capability indicator value corresponding to the virtual device;

identify, in view of the obtained capability indicator value, a particular set of actions associated with the obtained capability indicator value, the particular set of actions to be performed to remove the virtual device from the virtual machine, the particular set of actions including at least removing the virtual device from the virtual machine without first providing the warning to the guest OS when the capability indicator indicates a safe support level, or at least first providing the warning to the guest OS before removing the virtual device from the virtual machine when the capability indicator indicates an unsafe support level; and

remove the virtual device from the virtual machine using the particular set of actions.

9. The computing apparatus of claim 8, wherein the capability indicator value is one of a plurality of capability indicator values that are each associated with a plurality of support levels, wherein each of the plurality of support levels corresponds to a set of one or more actions to be performed for virtual device removal in the mapping table.

10. The computing apparatus of claim 8, wherein the obtained capability indicator value corresponds to the safe support level and wherein to remove the virtual device, the processing device is to:

unmap the virtual device from the guest operating system of the virtual machine;

send a removal notification to the guest operating system that the virtual device has been removed from the virtual machine by the hypervisor; and

responsive to receiving an acknowledgment from the guest operating system of the removal notification, free hypervisor resources associated with the virtual device.

11. The computing apparatus of claim 8, wherein the obtained capability indicator value corresponds to a supported support level and wherein to remove the virtual device, the processing device is to:

send a removal notification to the guest operating system that the virtual device is to be removed;

start a timer upon sending the removal notification;

detect an expiration of the timer prior to receiving a first acknowledgment of the removal notification;

unmap the virtual device from the guest operating system;

send a removal acknowledgement notification to the guest operating system that the virtual device has been removed from the virtual machine by the hypervisor; and

responsive to receiving a second acknowledgment from the guest operating system of the removal acknowledgement notification, free hypervisor resources associated with the virtual device.

12. The computing apparatus of claim 8, wherein the obtained capability indicator value corresponds to the unsafe support level and wherein to remove the virtual device, the processing device is to:

send a removal notification to the guest operating system of the virtual machine that the virtual device is to be removed; and

responsive to receiving an acknowledgment from the guest operating system of the removal notification, unmap the virtual device from the guest operating system of the virtual machine and freeing hypervisor resources associated with the virtual device.

13. The computing apparatus of claim 8, wherein the virtual machine is to:

detect an assignment of the virtual device to the virtual machine;

load the virtual device driver for the virtual device into memory accessible to the guest operating system of the virtual machine;

determine the capability indicator value that identifies the support provided by the virtual device driver for recovering from the surprise removal of the virtual device from the virtual machine; and

send the notification to the hypervisor, the notification comprising the capability indicator value.

15. The computing apparatus of claim 11, wherein the processing device is further to send an alert to an administrator to request confirmation to unmap the virtual device from the guest operating system.

14. A non-transitory computer readable storage medium for removing a virtual device from a virtual machine having a guest operating system (OS), the virtual machine managed by a hypervisor, the non-transitory computer-readable storage medium having instructions stored therein, which when executed by a processing device of a computer system, cause the processing device to:

receive, by the hypervisor, a notification from the guest OS, the notification comprising a capability indicator value indicating a support level for surprise removal of a virtual device of the guest OS, the surprise removal of the virtual device comprising removal of the virtual device from the virtual machine without first providing a warning to the guest OS;

store, by the hypervisor, the capability indicator value corresponding to the virtual device in a mapping table;

subsequently receive, by the hypervisor, a request to remove the virtual device from the virtual machine;

responsive to receiving the request to remove the virtual device, access, by the hypervisor, the mapping table to obtain the capability indicator value corresponding to the virtual device;

identify, by the hypervisor, in view of the obtained capability indicator value, a particular set of actions associated with the obtained capability indicator value, the particular set of actions to be performed to remove the virtual device from the virtual machine, the particular set of actions including at least removing the virtual device from the virtual machine without first providing the warning to the guest OS when the capability indicator indicates a safe support level, or at least first providing the warning to the guest OS before removing the virtual device from the virtual machine when the capability indicator indicates an unsafe support level; and

remove the virtual device from the virtual machine using the particular set of actions.

16. The non-transitory computer readable storage medium of claim 14, wherein the obtained capability indicator value corresponds to the safe support level and wherein to remove the virtual device, the processing device is to:

unmap the virtual device from the guest operating system of the virtual machine;

send a removal notification to the guest operating system that the virtual device has been removed from the virtual machine by the hypervisor; and

responsive to receiving an acknowledgment from the guest operating system of the removal notification, free hypervisor resources associated with the virtual device.

17. The non-transitory computer readable storage medium of claim 14, wherein the obtained capability indicator value corresponds to a supported support level and wherein to remove the virtual device, the processing device is to:

send a removal notification to the guest operating system that the virtual device is to be removed;

start a timer upon sending the removal notification;

detect an expiration of the timer prior to receiving a first acknowledgment of the removal notification;

unmap the virtual device from the guest operating system;

send a removal acknowledgement notification to the guest operating system that the virtual device has been removed from the virtual machine by the hypervisor; and

responsive to receiving a second acknowledgment from the guest operating system of the removal acknowledgement notification, free hypervisor resources associated with the virtual device.

18. The non-transitory computer readable storage medium of claim 14, wherein the obtained capability indicator value corresponds to the unsafe support level and wherein to remove the virtual device, the processing device is to:

send a removal notification to the guest operating system of the virtual machine that the virtual device is to be removed; and

responsive to receiving an acknowledgment from the guest operating system of the removal notification, unmap the virtual device from the guest operating system of the virtual machine and freeing hypervisor resources associated with the virtual device.

19. The non-transitory computer readable storage medium of claim 14 wherein the guest operating system of the virtual machine is to:

detect an assignment of the virtual device to the virtual machine;

load the virtual device driver for the virtual device into memory accessible to the guest operating system;

determine the capability indicator value that identifies the support provided by the virtual device driver for recovering from the surprise removal of the virtual device from the virtual machine; and

send the notification to the hypervisor, the notification comprising the capability indicator value.

20. The non-transitory computer readable storage medium of claim 14, wherein the capability indicator value is one of a plurality of capability indicator values that are each associated with a plurality of support levels, wherein each of the plurality of support levels corresponds to a set of one or more actions to be performed for virtual device removal in the mapping table.