Default maximum request size to use software for AES

configname: CONFIG_CRYPTO_DEV_QCE_SW_MAX_LEN

Linux Kernel Configuration
└─>Cryptographic API
└─>Hardware crypto devices
└─>Default maximum request size to use software for AES
In linux kernel since version 5.1 (release Date: 2019-05-05)  
This sets the default maximum request size to perform AES requests
using software instead of the crypto engine. It can be changed by
setting the aes_sw_max_len parameter.

Small blocks are processed faster in software than hardware.
Considering the 256-bit ciphers, software is 2-3 times faster than
qce at 256-bytes, 30% faster at 512, and about even at 768-bytes.
With 128-bit keys, the break-even point would be around 1024-bytes.

The default is set a little lower, to 512 bytes, to balance the
cost in CPU usage. The minimum recommended setting is 16-bytes
(1 AES block), since AES-GCM will fail if you set it lower.
Setting this to zero will send all requests to the hardware.

Note that 192-bit keys are not supported by the hardware and are
always processed by the software fallback, and all DES requests
are done by the hardware.