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authorEneas U de Queiroz <cotequeiroz@gmail.com>2020-02-07 12:02:26 -0300
committerHerbert Xu <herbert@gondor.apana.org.au>2020-02-13 17:05:27 +0800
commitce163ba0bf298f1707321ac025ef639f88e62801 (patch)
tree0d5548b88ef4c1cecf98435d66893d6770e17836 /drivers/crypto/qce
parentd6364b8128439a8c0e381f80c38667de9f15eef8 (diff)
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/qce')
-rw-r--r--drivers/crypto/qce/skcipher.c20
1 files changed, 12 insertions, 8 deletions
diff --git a/drivers/crypto/qce/skcipher.c b/drivers/crypto/qce/skcipher.c
index 63ae75809cb7..fc7c940b5a43 100644
--- 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 crypto_skcipher *ablk, const u8 *key,
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 skcipher_request *req, int encrypt)
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);