PCI-Express Function Proxy

• US 20090248947A1
• Filed: 11/05/2008
• Published: 10/01/2009
• Est. Priority Date: 03/25/2008
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Aprius Incorporated
• Inventors: Malwankar, Kiron, Talayco, Daniel, Ekici, Ali
• Granted Patent: US 7,934,033 B2
• Time in Patent Office: Days
• US Class Current: 710/316
• CPC Class Codes: G06F 13/4022 using switching circuits, e.g. switching matrix, connection or expansion network G06F13/4009 takes precedence
• CPC Class Codes: G06F 13/404 with address mapping
• CPC Class Codes: G06F 2213/0026 PCI express

Abstract

Embodiments are described for executing embedded functions in endpoint devices by proxy in a shared PCI Express subsystem. The shared subsystem comprises a plurality of proxy devices coupled to a PCIe fabric, wherein each one of the proxy devices is associated with an endpoint device and coupled to a controlling server through a PCIe link. An associated proxy device comprises a copy of the configuration space of the target endpoint device. Embedded functions of an endpoint device can be accessed by controlling servers through the associated proxy devices. Devices in the shared subsystem use PCI protocol to communicate. The duplication of the endpoint configuration space in the proxy device is administrated by a proxy configuration manager. The proxy device translates destination addresses in upstream and downstream transactions. A proxy interrupt conveyance mechanism relays interrupt messages from an endpoint device to the controlling server via the associated proxy device.

Claims

1. A PCI-Express (PCIe) function proxy subsystem for enabling a plurality of servers to access a plurality of functions residing in a plurality of endpoint devices comprising:

a PCIe fabric comprising at least one PCIe switch operable to couple the plurality of endpoint devices with a plurality of proxy devices; and

a proxy configuration manager for configuring each one of the plurality of proxy devices;

wherein each one of the plurality of proxy devices includes a memory configuration space,

wherein the proxy configuration manager copies a configuration space of a target endpoint device to the memory configuration space of an associated proxy device,

wherein the associated proxy device is coupled to a controlling server for executing by proxy a specific function of the target endpoint device.

2. The PCI-Express function proxy subsystem of claim 1, wherein each one of the plurality of proxy devices is coupled with one of the plurality of servers through a PCI-Express high speed serial link comprising at least one lane.

3. The PCI-Express function proxy subsystem of claim 1, wherein the associated proxy device is viewed as the target endpoint device from the perspective of the controlling server.

4. The PCI-Express function proxy subsystem of claim 1, wherein the associated proxy device further performs address translation for upstream and downstream transactions between the target endpoint device and the controlling server.

5. The PCI-Express function proxy subsystem of claim 1, wherein at least one of the proxy devices further comprises a flow control buffering for congestion management.

6. The PCI-Express function proxy subsystem of claim 1, wherein at least one of the proxy devices further comprises a mechanism for receiving at least one of message signaled interrupt (MSI) and MSI-X transactions, and for directing them to the controlling server.

7. The PCI-Express function proxy subsystem of claim 1, wherein each proxy device of the proxy devices further comprises extended flow control buffering for congestion management.

8. The PCI-Express function proxy subsystem of claim 1, wherein the configuration space of the target endpoint device is in accordance with the PCI Specification.

9. The PCI-Express function proxy subsystem of claim 1, wherein the proxy configuration manager further comprises a proxy interrupt conveyance mechanism.

10. The PCI-Express function proxy subsystem of claim 9, wherein the proxy interrupt conveyance mechanism communicates interrupt transactions from the target endpoint device to the associated proxy device.

11. The PCI-Express function proxy subsystem of claim 9, wherein the proxy interrupt conveyance mechanism verifies the validity of interrupt transactions prior to directing them to the associated proxy device.

12. The PCI-Express function proxy subsystem of claim 9, wherein the proxy interrupt conveyance mechanism determines priority of interrupt transactions and handles them correspondingly.

13. A method for distributing functions embedded in endpoint devices to a plurality of servers in a PCI-Express subsystem, the method comprising:

providing a plurality of proxy devices, each one of the plurality of proxy devices coupled to one of a plurality of servers;

copying a PCI configuration space of a target endpoint device to a memory configuration space of an associated proxy device, the associated proxy device coupled to a controlling server via a PCIe link; and

executing a specific function of the target endpoint device through the associated proxy device.

14. The method of claim 13, wherein the controlling server communicates with the associated proxy device using transaction packets in accordance with a PCI Express protocol.

15. The method of claim 13, wherein the associated proxy device further comprises a checking mechanism for detecting transaction errors.

16. The method of claim 13, wherein the associated proxy device further comprises an address translation mechanism for translating destination addresses embedded in upstream and downstream transaction packets.

17. The method of claim 16, wherein the address translation mechanism is one of the direct offset translation mechanism and a lookup table-based translation mechanism.

18. The method of claim 13, wherein the copying the configuration space is performed by a proxy configuration manager.

19. The method of claim 18, wherein the proxy configuration manager further comprises a proxy interrupt conveyance mechanism.

20. The method of claim 19, wherein the proxy interrupt conveyance mechanism further comprises:

receiving at least one of MSI and MSI-X interrupt transactions from endpoint devices;

verifying the validity of the interrupt transactions; and

directing them to the associate proxy device if interrupt transactions are valid.

21. A method for conveying interrupts from a plurality of endpoint devices to respective controlling servers in a shared PCI Express system including a PCIe fabric coupled to the plurality of endpoint devices and associated proxy devices, the method comprising:

connecting a first controlling server to a first proxy device, the first proxy device is associated with a target endpoint device;

generating an interrupt transaction at the target endpoint device;

receiving the interrupt transaction by a proxy interrupt conveyance mechanism; and

relaying the interrupt transaction to the first controlling server by way of the first proxy device.

22. The method of claim 21, wherein connecting the first controlling server to the first proxy device comprises connecting via a serial PCIe link comprising at least one lane.

23. The method of claim 21, wherein the generated interrupt transaction comprises at least one of a message signaled interrupt (MSI) and an MSI extended (MSI-X).

24. The method of claim 21, wherein the proxy interrupt conveyance mechanism is co-located with a proxy configuration manager which configures the first proxy device.

25. The method of claim 21, wherein the relaying the interrupt transaction comprises:

directing the interrupt transaction to the associated first proxy device; and

sending the interrupt transaction from the first proxy device to the first controlling server.

26. The method of claim 21, wherein the relaying the interrupt transaction further comprises:

verifying the interrupt transaction validity by the proxy interrupt conveyance mechanism; and

determining the interrupt transaction priority.