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.
The threshold is being set a little lower, to 512 bytes, to balance the
cost in CPU usage.
Signed-off-by: Eneas U de Queiroz <cotequeiroz@xxxxxxxxx>
diff --git a/drivers/crypto/qce/skcipher.c b/drivers/crypto/qce/skcipher.c
index 63ae75809cb7..b1b090349a80 100644
--- a/drivers/crypto/qce/skcipher.c
+++ b/drivers/crypto/qce/skcipher.c
@@ -166,15 +166,10 @@ 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 +219,9 @@ 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 <= 512)) {
SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback);
skcipher_request_set_sync_tfm(subreq, ctx->fallback);
