MMU Crossbar Mapping for Secure Multi-Tenant Memory Protection
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Solution Overview
Problem
High-assurance systems with multiple tenants face challenges in managing memory protection due to the exponential growth of MMU mappings, exceeding static MMU-table capacities and necessitating runtime reconfigurations, which introduces security vulnerabilities.
Innovation Solution
Implement a configuration of a crossbar in the memory management unit with a N plus D mapping of workers to partitions, utilizing a hardware interposer to remap fictive addresses to physical ones, allowing static MMU configuration and eliminating the need for runtime reconfiguration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dedicated MMU mappings are created for each worker-partition pair, then memory access control security is improved, but the number of MMU mappings exceeds static table capacities
Solution Approach 1:
The patent segments the MMU mapping problem by separating worker address spaces from partition address spaces. Instead of creating N×D combined mappings, it creates N worker mappings and D partition mappings independently, reducing the total number of mappings while maintaining security through the crossbar switch architecture.
Solution Approach 2:
The patent introduces a new dimensional approach by using a crossbar switch matrix that provides N+D mapping dimensions instead of the traditional N×D product mapping. This allows workers and partitions to be mapped independently through the crossbar structure, reducing mapping complexity from exponential to linear scaling.
2Reliability
If runtime MMU reconfiguration is performed to manage excessive mappings, then memory protection is maintained, but security vulnerabilities are introduced
Solution Approach 1:
The patent applies preliminary action by establishing static MMU mappings during system initialization rather than performing runtime reconfiguration. The crossbar switch is pre-configured with the N+D mapping structure, allowing memory protection to be maintained without introducing security vulnerabilities associated with dynamic reconfiguration.
Solution Approach 2:
The patent resolves the contradiction by making the MMU mapping structure static rather than dynamic. The crossbar switch provides a fixed N+D mapping configuration that eliminates the need for runtime changes, thereby preventing security vulnerabilities while maintaining memory protection through the inherent structure of the crossbar architecture.
3Adaptability or versatility
If N×D worker-partition mappings are implemented, then fine-grained access control is achieved, but device complexity increases beyond manageable levels
Solution Approach 1:
The patent segments the complex N×D mapping problem into simpler N worker mappings and D partition mappings. The crossbar switch architecture enables this segmentation by providing independent mapping paths for workers and partitions, reducing device complexity while preserving fine-grained access control capabilities.
Solution Approach 2:
The patent transitions from the traditional N×D product mapping dimension to an N+D linear mapping dimension using the crossbar switch. This dimensional change simplifies the mapping structure from exponential complexity to linear complexity, making the system manageable while maintaining fine-grained access control through the crossbar's inherent routing capabilities.
Data Source
AI summary
An embodiment includes configuring a configuration of a crossbar of a memory management unit comprising a set of regions of N workers and D partitions. The embodiment includes writing by a worker, to D partitions in the set of regions of the crossbar. The embodiment also includes reading by a partition, N regions in the set of regions of the crossbar where each of the N regions is assigned an address that is mapped to a physical memory address and where an access control is achieved by the configuration of a N plus D mapping of workers to partitions of the crossbar of the memory management unit.