Inter-Bus Bridge Circuit for Secure Protocol Translation

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Solution Overview

Problem

Compatibility issues arise when connecting buses that implement different protocols, such as the Advanced eXtensible Interface (AXI) and Peripheral Component Interconnect express (PCIe), due to differences in security mechanisms and address spaces, leading to challenges in managing secure and non-secure resource access.

Innovation Solution

A bridge circuit that stores address translation information and security indicators, rejecting non-secure access requests to secure address ranges and translating requests between buses while enforcing security mechanisms by using address range maps to ensure secure access.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If buses with different protocols (AXI and PCIe) are connected directly, then communication between diverse devices is enabled, but security compatibility issues arise due to different security mechanisms

Engineering Contradiction:
Improveprotocol compatibilityVSAvoidsecurity consistency
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces a bridge device as an intermediary between AXI and PCIe buses. This bridge includes an AXI interface coupled to an AXI bus and a PCIe interface coupled to a PCIe bus, with translation logic that mediates security requirements between the two protocols. The bridge translates AXI security attributes (SECURE/NON-SECURE) into PCIe security handling, preventing direct connection security conflicts while enabling protocol compatibility.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes security parameter representation between protocols. The AXI protocol uses explicit SECURE/NON-SECURE attributes in its address and control signals, while PCIe uses different security mechanisms. The bridge translates these security parameters by examining AXI security attributes and generating corresponding PCIe transactions with appropriate security handling, effectively changing the security parameter format to match the target protocol's requirements.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If address translation is implemented to map between different address spaces, then device accessibility is improved, but security enforcement complexity increases

Engineering Contradiction:
Improvedevice accessibilityVSAvoidsecurity enforcement mechanism
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent segments the address space into secure and non-secure regions using address translation tables. The translation logic divides the combined address space into distinct segments, each with specific security attributes. This segmentation allows simple access control decisions (secure vs. non-secure) while maintaining complex address mapping capabilities, reducing the overall enforcement complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary security classification during address translation setup. Security attributes are predetermined and stored in translation tables before actual access occurs. When a translation request is made, the security status is already known from the pre-configured table entries, eliminating the need for complex real-time security analysis and simplifying enforcement to a simple table lookup and attribute propagation.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3167374B1Bridging inter-bus communications
Publication Date: 2018.09.12 XILINX INC
  • EP3167374B1 patent drawingFigure 1
  • EP3167374B1 patent drawingFigure 2
  • EP3167374B1 patent drawingFigure 3

AI summary

Approaches for bridging communication between first and second buses are disclosed. Address translation information and associated security indicators are stored (202) in a memory. Each access request from the first bus includes a first requester security indicator and a requested address. Each access request from the first bus and directed to the second bus is either rejected (214), or translated (210) and communicated (212) to the second bus, based on the requester security indicator and the security indicator associated with the address translation information for the requested address. Each access request from the second bus to the first bus includes the requested address, and the access request is translated (226) and communicated (228) to the first bus along with the security indicator that is associated with the address translation information for the requested address.