IBM POWER7+ processor on-chip accelerators for cryptography and active memory expansion

With the heightened focus on computer security, IBM POWER® server workloads are spending an increasing number of cycles performing cryptographic functions. Active memory expansion (AME), a technology to dynamically increase the effective memory capacity of a system by compressing and decompressing memory pages, is also enjoying increasing deployment in POWER server systems. Together, cryptography and AME consume enough central processing unit (CPU) cycles in a typical installation to warrant adding dedicated hardware accelerators on the processor chip to offload the compute-intensive parts of these functions from the processor cores. IBM POWER7+™ is the first POWER server to include on-chip hardware accelerators for symmetric (shared key) and asymmetric (public key) cryptography and memory compression/decompression for AME. A true random number generator (RNG) is also integrated on-chip. This paper describes the hardware accelerator framework, including location relative to the cores and memory, accelerator invocation, data movement, and error handling. A description of each type of accelerator follows, including details of supported algorithms and the corresponding hardware data flows. Algorithms supported include the Advanced Encryption Standard, Secure Hash Algorithm, and Message Digest 5 algorithm as bulk cryptographic functions; asymmetric cryptographic functions in support of RSA and elliptic curve cryptography; and a novel dictionary-based compression algorithm with high throughput supporting AME. A presentation of accelerator performance is included.