diff options
| author | Eneas U de Queiroz <cotequeiroz@gmail.com> | 2020-02-07 18:02:26 +0300 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2020-02-13 12:05:27 +0300 |
| commit | ce163ba0bf298f1707321ac025ef639f88e62801 (patch) | |
| tree | 0d5548b88ef4c1cecf98435d66893d6770e17836 /drivers/crypto/Kconfig | |
| parent | d6364b8128439a8c0e381f80c38667de9f15eef8 (diff) | |
| download | linux-ce163ba0bf298f1707321ac025ef639f88e62801.tar.xz | |
crypto: qce - use AES fallback for small requests
Process small blocks using the fallback cipher, as a workaround for an
observed failure (DMA-related, apparently) when computing the GCM ghash
key. This brings a speed gain as well, since it avoids the latency of
using the hardware engine to process small blocks.
Using software for all 16-byte requests would be enough to make GCM
work, but to increase performance, a larger threshold would be better.
Measuring the performance of supported ciphers with openssl speed,
software matches hardware at around 768-1024 bytes.
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.
This adds the 'aes_sw_max_len' parameter, to set the largest request
length processed by the software fallback. Its default is being set to
512 bytes, a little lower than the break-even point, to balance the cost
in CPU usage.
Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'drivers/crypto/Kconfig')
| -rw-r--r-- | drivers/crypto/Kconfig | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/drivers/crypto/Kconfig b/drivers/crypto/Kconfig index c2767ed54dfe..052d3ff7fb20 100644 --- a/drivers/crypto/Kconfig +++ b/drivers/crypto/Kconfig @@ -685,6 +685,29 @@ choice endchoice +config CRYPTO_DEV_QCE_SW_MAX_LEN + int "Default maximum request size to use software for AES" + depends on CRYPTO_DEV_QCE && CRYPTO_DEV_QCE_SKCIPHER + default 512 + help + 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. + config CRYPTO_DEV_QCOM_RNG tristate "Qualcomm Random Number Generator Driver" depends on ARCH_QCOM || COMPILE_TEST |