114 lines
4.2 KiB
Diff
114 lines
4.2 KiB
Diff
From ce163ba0bf298f1707321ac025ef639f88e62801 Mon Sep 17 00:00:00 2001
|
|
From: Eneas U de Queiroz <cotequeiroz@gmail.com>
|
|
Date: Fri, 7 Feb 2020 12:02:26 -0300
|
|
Subject: [PATCH 10/11] 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>
|
|
---
|
|
|
|
--- a/drivers/crypto/Kconfig
|
|
+++ b/drivers/crypto/Kconfig
|
|
@@ -683,6 +683,29 @@ 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
|
|
--- a/drivers/crypto/qce/skcipher.c
|
|
+++ b/drivers/crypto/qce/skcipher.c
|
|
@@ -5,6 +5,7 @@
|
|
|
|
#include <linux/device.h>
|
|
#include <linux/interrupt.h>
|
|
+#include <linux/moduleparam.h>
|
|
#include <linux/types.h>
|
|
#include <crypto/aes.h>
|
|
#include <crypto/internal/des.h>
|
|
@@ -12,6 +13,13 @@
|
|
|
|
#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)
|
|
@@ -166,15 +174,10 @@ static int qce_skcipher_setkey(struct cr
|
|
switch (IS_XTS(flags) ? keylen >> 1 : keylen) {
|
|
case AES_KEYSIZE_128:
|
|
case AES_KEYSIZE_256:
|
|
+ memcpy(ctx->enc_key, key, keylen);
|
|
break;
|
|
- default:
|
|
- goto fallback;
|
|
}
|
|
|
|
- ctx->enc_keylen = keylen;
|
|
- memcpy(ctx->enc_key, key, keylen);
|
|
- return 0;
|
|
-fallback:
|
|
ret = crypto_sync_skcipher_setkey(ctx->fallback, key, keylen);
|
|
if (!ret)
|
|
ctx->enc_keylen = keylen;
|
|
@@ -224,8 +227,9 @@ 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)) {
|
|
SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback);
|
|
|
|
skcipher_request_set_sync_tfm(subreq, ctx->fallback);
|