HyperTransport I/O Adapter LPAR Isolation via Unit ID Validation
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Solution Overview
Problem
In logically partitioned data processing systems using HyperTransport technology, there is a lack of mechanism to isolate I/O adapter DMA and interrupt requests, leading to potential interference between partitions, as the operating system does not guarantee successful communications and lacks address verification for I/O adapters.
Innovation Solution
Assigning HyperTransport-defined Unit IDs to individual I/O adapters and using these IDs to isolate them to their owning logical partition, with processors validating the Unit IDs instead of PCI-defined requester IDs to verify DMA and interrupt requests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If I/O adapters are allocated to different logical partitions in an LPAR system, then resource isolation and security are improved, but the ability of I/O adapters to access physical memory is restricted
Solution Approach 1:
The patent segments the I/O adapter functionality into two distinct components: a HyperTransport interface unit with a Unit ID for identification and isolation, and a functional I/O adapter unit for actual operations. This segmentation allows the system to maintain both isolation security and memory access capability by routing requests through the identified Unit ID while performing actual I/O operations through the functional adapter.
Solution Approach 2:
The patent introduces an intermediary mechanism in the form of Unit ID validation logic that sits between the I/O adapter and the memory access pathway. This intermediary validates whether an I/O adapter is authorized to access specific physical memory regions, thereby enabling both isolation and access control without compromising either security or functionality.
2Speed
If HyperTransport technology is used to link devices, then communication speed and efficiency are improved, but the lack of address verification mechanism causes interference between partitions
Solution Approach 1:
The patent applies preliminary action by validating the Unit ID of the I/O adapter before allowing any HyperTransport communication or memory access to occur. This pre-validation ensures that only authorized adapters can initiate communication, preventing partition interference while maintaining the high-speed communication capabilities of HyperTransport technology.
Solution Approach 2:
The patent implements a feedback mechanism where the system continuously monitors and validates Unit IDs during HyperTransport operations. This feedback loop ensures that even during high-speed communication, the system can detect and prevent unauthorized access attempts, thereby maintaining both speed and reliability.
3Ease of operation
If the operating system provides commands to I/O adapters without address verification, then ease of operation is improved, but harmful factors increase due to potential unauthorized access
Solution Approach 1:
The patent introduces the Unit ID validation mechanism as an intermediary between the operating system and the I/O adapter. This intermediary automatically verifies the authorization of each I/O adapter before allowing it to execute commands or access memory, thereby maintaining ease of operation for the OS while preventing harmful unauthorized access through automated security checks.
Data Source
AI summary
Disclosed are a data processing system and a method of isolating a plurality of input/output adapter units of that system. The data processing system comprises, in addition to the input/output adapter units, a set of processors, a host bridge, and a system bus connecting the set of processors and the host bridge. Each of the input/output adapter units has a respective identifier; and the set of processors send commands to the host bridge, said commands including one or more of the identifiers of the input/output adapter units. In the preferred embodiment, these identifiers are HyperTransport defined Unit IDs, and the commands issued by the set of processors include a Unit ID field including one or more of the Unit IDs of input/output adapters.