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[2804:688:21:4::2]) by smtp.gmail.com with ESMTPSA id o12sm252869qke.79.2020.02.06.13.02.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Feb 2020 13:02:44 -0800 (PST) From: Eneas U de Queiroz To: linux-crypto@vger.kernel.org, Herbert Xu , "David S. Miller" Cc: Ard Biesheuvel , Eneas U de Queiroz Subject: [PATCH v4 2/3] crypto: qce - use AES fallback for small requests Date: Thu, 6 Feb 2020 18:02:06 -0300 Message-Id: <20200206210207.21849-2-cotequeiroz@gmail.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20200206210207.21849-1-cotequeiroz@gmail.com> References: <20200206210207.21849-1-cotequeiroz@gmail.com> MIME-Version: 1.0 Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org 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 --- v3 -> v4: Corrected a missing 'static' declaration of aes_sw_max_len v2 -> v3: Corrected style issues pointed out by checkpatch.pl v1 -> v2: Changed the threshold from a fixed number to a module parameter diff --git a/drivers/crypto/Kconfig b/drivers/crypto/Kconfig index c2767ed54dfe..052d3ff7fb20 100644 --- a/drivers/crypto/Kconfig +++ b/drivers/crypto/Kconfig @@ -685,6 +685,29 @@ 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 diff --git a/drivers/crypto/qce/skcipher.c b/drivers/crypto/qce/skcipher.c index 63ae75809cb7..e55348bba36f 100644 --- a/drivers/crypto/qce/skcipher.c +++ b/drivers/crypto/qce/skcipher.c @@ -5,6 +5,7 @@ #include #include +#include #include #include #include @@ -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);