Avatar缓存：通过可变形缓存架构实现按需安全
The Avatar Cache: Enabling On-Demand Security with Morphable Cache Architecture
AI总结：
Avatar通过可变形缓存架构在传统LLC基础上实现按需安全，兼顾性能、功率和面积开销。
摘要：
将最后一级缓存（LLC）在多个核心之间共享使其容易受到跨核心冲突和占用攻击的威胁。尽管有大量先前的工作，现代处理器仍然使用不安全的集合关联LLC。现有的安全LLC设计大致分为两类：（i）随机化和（ii）分区。最先进的随机化设计Mirage减轻了冲突攻击，但带来了显著的面积开销（额外20%的存储）和设计复杂性。分区LLC减轻了冲突和占用攻击，但通常会遭受较大的性能开销（平均超过5%且最高达49%），需要操作系统支持在集合方案中，或在方式方案中面临可扩展性问题。这些因素对安全LLC的工业采用构成了重大障碍。本文询问是否可以通过对传统集合关联LLC进行最小的修改来实现强大的LLC安全，从而在需要时启用安全，同时保持低性能、功率和面积开销。我们提出了Avatar，一种安全且可变形的LLC，支持三种模式：不安全（Avatar-N）、随机化安全（Avatar-R）和分区安全（Avatar-P），并且可以在它们之间动态切换。Avatar与传统集合关联LLC非常相似，有助于工业采用。Avatar-R引入额外的无效条目，并利用高关联性，通过几乎不损失容量提供强安全保证，实现每$10^{30}$年仅有一个集合关联驱逐，同时带来1.5%的存储开销，静态功率增加2.7%，以及比16MB基准线慢0.2%。Avatar-P仅以3%的性能开销减轻了冲突和占用攻击，大大优于先前的方式基于分区LLC。当不需要安全时，Avatar切换到Avatar-N以最大化性能和能源效率。
英文摘要：
The sharing of the last-level cache (LLC) among multiple cores makes it vulnerable to cross-core conflict- and occupancy-based attacks. Despite extensive prior work, modern processors still employ non-secure set-associative LLCs. Existing secure LLC designs broadly fall into two categories: (i) randomized and (ii) partitioned. The state-of-the-art randomized design, Mirage, mitigates conflict-based attacks but incurs significant area overhead (20% additional storage) and design complexity. Partitioned LLCs mitigate both conflict- and occupancy-based attacks, but often suffer from large performance overheads (on average over 5% and up to 49%), require OS support in set-based schemes, or face scalability issues in way-based schemes. These factors pose major obstacles to the industrial adoption of secure LLCs. This paper asks whether strong LLC security can be achieved with minimal changes to a conventional set-associative LLC, enabling security only when needed while preserving low performance, power, and area overheads. We propose Avatar, a secure and morphable LLC that supports three modes: non-secure (Avatar-N), randomized secure (Avatar-R), and partitioned secure (Avatar-P), and can switch dynamically between them. Avatar closely resembles a conventional set-associative LLC, facilitating industrial adoption. Avatar-R introduces extra invalid entries and leverages high associativity to provide a strong security guarantee with little capacity loss, achieving only one set-associative eviction per $10^{30}$ years, while incurring 1.5% storage overhead, a 2.7% increase in static power, and a 0.2% slowdown over a 16~MB baseline. Avatar-P mitigates both conflict- and occupancy-based attacks with only a 3% performance overhead, substantially outperforming prior way-based partitioned LLCs. When security is unnecessary, Avatar switches to Avatar-N to maximize performance and energy efficiency.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
