diff options
Diffstat (limited to 'target/linux/ipq40xx/patches-4.19/048-crypto-qce-use-AES-fallback-for-small-requests.patch')
| -rw-r--r-- | target/linux/ipq40xx/patches-4.19/048-crypto-qce-use-AES-fallback-for-small-requests.patch | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/target/linux/ipq40xx/patches-4.19/048-crypto-qce-use-AES-fallback-for-small-requests.patch b/target/linux/ipq40xx/patches-4.19/048-crypto-qce-use-AES-fallback-for-small-requests.patch new file mode 100644 index 0000000000..514fde7b63 --- /dev/null +++ b/target/linux/ipq40xx/patches-4.19/048-crypto-qce-use-AES-fallback-for-small-requests.patch @@ -0,0 +1,122 @@ +From 2d3b6fae7d1a2ad821769440daa91d7eec5c8250 Mon Sep 17 00:00:00 2001 +From: Eneas U de Queiroz <cotequeiroz@gmail.com> +Date: Fri, 20 Dec 2019 09:41:44 -0300 +Subject: [PATCH] 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> + +--- a/drivers/crypto/Kconfig ++++ b/drivers/crypto/Kconfig +@@ -585,6 +585,29 @@ config CRYPTO_DEV_QCE + hardware. To compile this driver as a module, choose M here. The + module will be called qcrypto. + ++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 +--- a/drivers/crypto/qce/skcipher.c ++++ b/drivers/crypto/qce/skcipher.c +@@ -13,6 +13,7 @@ + + #include <linux/device.h> + #include <linux/interrupt.h> ++#include <linux/moduleparam.h> + #include <linux/types.h> + #include <crypto/aes.h> + #include <crypto/des.h> +@@ -20,6 +21,13 @@ + + #include "cipher.h" + ++static unsigned int aes_sw_max_len = CONFIG_CRYPTO_DEV_QCE_SW_MAX_LEN; ++module_param(aes_sw_max_len, uint, 0644); ++MODULE_PARM_DESC(aes_sw_max_len, ++ "Only use hardware for AES requests larger than this " ++ "[0=always use hardware; anything <16 breaks AES-GCM; default=" ++ __stringify(CONFIG_CRYPTO_DEV_QCE_SOFT_THRESHOLD)"]"); ++ + static LIST_HEAD(skcipher_algs); + + static void qce_skcipher_done(void *data) +@@ -170,15 +178,7 @@ static int qce_skcipher_setkey(struct cr + if (!key || !keylen) + return -EINVAL; + +- if (IS_AES(flags)) { +- switch (IS_XTS(flags) ? keylen >> 1 : keylen) { +- case AES_KEYSIZE_128: +- case AES_KEYSIZE_256: +- break; +- default: +- goto fallback; +- } +- } else if (IS_DES(flags)) { ++ if (IS_DES(flags)) { + u32 tmp[DES_EXPKEY_WORDS]; + + ret = des_ekey(tmp, key); +@@ -189,8 +189,8 @@ static int qce_skcipher_setkey(struct cr + + ctx->enc_keylen = keylen; + memcpy(ctx->enc_key, key, keylen); +- return 0; +-fallback: ++ if (!IS_AES(flags)) ++ return 0; + ret = crypto_skcipher_setkey(ctx->fallback, key, keylen); + if (!ret) + ctx->enc_keylen = keylen; +@@ -213,8 +213,9 @@ static int qce_skcipher_crypt(struct skc + rctx->flags |= encrypt ? QCE_ENCRYPT : QCE_DECRYPT; + keylen = IS_XTS(rctx->flags) ? ctx->enc_keylen >> 1 : ctx->enc_keylen; + +- if (IS_AES(rctx->flags) && keylen != AES_KEYSIZE_128 && +- keylen != AES_KEYSIZE_256) { ++ if (IS_AES(rctx->flags) && ++ ((keylen != AES_KEYSIZE_128 && keylen != AES_KEYSIZE_256) || ++ req->cryptlen <= aes_sw_max_len)) { + SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback); + + skcipher_request_set_tfm(subreq, ctx->fallback); |