+++ /dev/null
-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);
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