Efficient Security Support for CXL Memory through Adaptive Incremental Offloaded (Re-)Encryption

Current DRAM technologies face critical scaling limitations, significantly impacting the expansion of memory bandwidth and capacity required by modern data-intensive applications. Compute eXpress Link (CXL) emerges as a promising technology to address these limitations, enabling efficient cache-coherent memory expansion through direct connections between processors and CXL memory devices. Despite its potential, broad adoption of CXL memory in public cloud computing introduces substantial security challenges. Trusted Execution Environments (TEEs), such as Intel SGX/TDX and AMD SEV, provide robust protection for data integrity and confidentiality in cloud environments, complemented by CXL Integrity and Data Encryption (CXL IDE), which employs XTS encryption and Galois/Counter Mode (GCM) for secure message transmission.However, this approach incurs significant performance overhead due to the latency of XTS encryption on memory-intensive workloads. To mitigate this, we propose Adaptive Incremental Offloaded (Re-)Encryption (AIORE), an adaptive security framework combining Counter (CTR) and XTS encryption. AIORE dynamically selects encryption schemes based on page access frequency, implements incremental and offloaded re-encryption strategies, and leverages memory node computation to reduce overheads. Evaluation with Gem5 across diverse benchmarks reveals that AIORE significantly reduces security overhead by 62.8% on average and maintains overhead within 3.7% relative to an insecure baseline.