Minerva: Rethinking Secure Architectures for the Era of Fabric-Attached Memory Architectures

Abstract

Fabric-attached memory (FAM) is proposed to enable the seamless integration of directly accessible memory modules attached to the shared system fabric, which will provide future systems with flexible memory integration options, mitigate underutilization, and facilitate data sharing. Recently proposed interconnects, such as Gen-Z and Compute Express Link (CXL), define security, correctness, and performance requirements of fabric-attached devices, including memory. These initiatives are supported by most major system and processor vendors, bringing widespread adoption of FAM-enabled systems one step closer to reality and security concerns to the forefront. This paper discusses the challenges for adapting secure memory implementations to FAM-enabled systems for the first time in literature. Specifically, we observe that handling the security metadata used to protect fabric-attached memories needs to be done deliberately to eliminate unintentional integrity check failures and/or security vulnerabilities, caused by an inconsistent view of the shared security metadata across nodes. Our scheme, Minerva, elegantly adapts secure memory implementations to support FAM-enabled systems with negligible performance over-heads (3.8% of an ideal scheme), compared to the performance overhead (99.5% of an ideal scheme) for a scheme that uses conventional invalidation-based cache coherence to ensure the consistency of security metadata across nodes.