一句话：提出 Toleo，用 CXL 连接的可信智能内存替代 Merkle 树，实现 TB 级内存的新鲜性保护。
可信硬件的新鲜性保证可防止敌手重放旧值，但现有方案需为每个缓存块维护版本号并用 Merkle 树保证完整性，其额外访存随保护内存增大而不可扩展，通常只能保护数 MB 内存。Toleo 通过安全 CXL IDE 网络连接可信智能内存来存储版本号，以智能内存作为信任根，从而消除 Merkle 树；同时保证版本机密性，用隐蔽版本将版本存储开销减半，并利用页粒度版本局部性将版本号压缩 240 倍。由此，单个 168 GB Toleo 智能内存设备可为机架服务器中 28 TB 的 CXL 扩展内存池提供低开销新鲜性保护，并在基因组、图、生成式 AI 和数据库等隐私敏感负载上分析收益。
Trusted hardware's freshness guarantee ensures that an adversary cannot replay an old value in response to a memory read request. They rely on maintaining a version number for each cache block and ensuring their integrity using a Merkle tree. However, these existing solutions protect only a small amount of main memory (few MBs), as the extraneous memory accesses to the Merkle tree increase prohibitively with the protected memory size. We present Toleo, which uses trusted smart memory connected through a secure CXL IDE network to safely store version numbers. Toleo eliminates the need for an unscalable Merkle tree to protect the integrity of version numbers by instead using smart memory as the root of trust. Additionally, Toleo ensures version confidentiality which enables stealth versions that reduce the version storage overhead in half. Furthermore, in the absence of Merkle tree imposed constraints, we effectively exploit version locality at page granularity to compress version number by a factor of 240. These space optimizations make it feasible for one 168 GB Toleo smart memory device to provide freshness to a 28 TB CXL-expanded main memory pool in a rack server for a negligible performance overhead. We analyze the benefits of Toleo using several privacy-sensitive genomics, graph, generative AI, and database workloads.