target/linux/ipq40xx/patches-5.4/0015-v5.7-crypto-qce-use-AES-fallback-for-small-requests.patch

   1 From ce163ba0bf298f1707321ac025ef639f88e62801 Mon Sep 17 00:00:00 2001
   2 From: Eneas U de Queiroz <cotequeiroz@gmail.com>
   3 Date: Fri, 7 Feb 2020 12:02:26 -0300
   4 Subject: [PATCH 10/11] crypto: qce - use AES fallback for small requests
   5
   6 Process small blocks using the fallback cipher, as a workaround for an
   7 observed failure (DMA-related, apparently) when computing the GCM ghash
   8 key.  This brings a speed gain as well, since it avoids the latency of
   9 using the hardware engine to process small blocks.
  10
  11 Using software for all 16-byte requests would be enough to make GCM
  12 work, but to increase performance, a larger threshold would be better.
  13 Measuring the performance of supported ciphers with openssl speed,
  14 software matches hardware at around 768-1024 bytes.
  15
  16 Considering the 256-bit ciphers, software is 2-3 times faster than qce
  17 at 256-bytes, 30% faster at 512, and about even at 768-bytes.  With
  18 128-bit keys, the break-even point would be around 1024-bytes.
  19
  20 This adds the 'aes_sw_max_len' parameter, to set the largest request
  21 length processed by the software fallback.  Its default is being set to
  22 512 bytes, a little lower than the break-even point, to balance the cost
  23 in CPU usage.
  24
  25 Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>
  26 Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
  27 ---
  28
  29 --- a/drivers/crypto/Kconfig
  30 +++ b/drivers/crypto/Kconfig
  31 @@ -683,6 +683,29 @@ choice
  32
  33  endchoice
  34
  35 +config CRYPTO_DEV_QCE_SW_MAX_LEN
  36 +       int "Default maximum request size to use software for AES"
  37 +       depends on CRYPTO_DEV_QCE && CRYPTO_DEV_QCE_SKCIPHER
  38 +       default 512
  39 +       help
  40 +         This sets the default maximum request size to perform AES requests
  41 +         using software instead of the crypto engine.  It can be changed by
  42 +         setting the aes_sw_max_len parameter.
  43 +
  44 +         Small blocks are processed faster in software than hardware.
  45 +         Considering the 256-bit ciphers, software is 2-3 times faster than
  46 +         qce at 256-bytes, 30% faster at 512, and about even at 768-bytes.
  47 +         With 128-bit keys, the break-even point would be around 1024-bytes.
  48 +
  49 +         The default is set a little lower, to 512 bytes, to balance the
  50 +         cost in CPU usage.  The minimum recommended setting is 16-bytes
  51 +         (1 AES block), since AES-GCM will fail if you set it lower.
  52 +         Setting this to zero will send all requests to the hardware.
  53 +
  54 +         Note that 192-bit keys are not supported by the hardware and are
  55 +         always processed by the software fallback, and all DES requests
  56 +         are done by the hardware.
  57 +
  58  config CRYPTO_DEV_QCOM_RNG
  59         tristate "Qualcomm Random Number Generator Driver"
  60         depends on ARCH_QCOM || COMPILE_TEST
  61 --- a/drivers/crypto/qce/skcipher.c
  62 +++ b/drivers/crypto/qce/skcipher.c
  63 @@ -5,6 +5,7 @@
  64
  65  #include <linux/device.h>
  66  #include <linux/interrupt.h>
  67 +#include <linux/moduleparam.h>
  68  #include <linux/types.h>
  69  #include <crypto/aes.h>
  70  #include <crypto/internal/des.h>
  71 @@ -12,6 +13,13 @@
  72
  73  #include "cipher.h"
  74
  75 +static unsigned int aes_sw_max_len = CONFIG_CRYPTO_DEV_QCE_SW_MAX_LEN;
  76 +module_param(aes_sw_max_len, uint, 0644);
  77 +MODULE_PARM_DESC(aes_sw_max_len,
  78 +                "Only use hardware for AES requests larger than this "
  79 +                "[0=always use hardware; anything <16 breaks AES-GCM; default="
  80 +                __stringify(CONFIG_CRYPTO_DEV_QCE_SOFT_THRESHOLD)"]");
  81 +
  82  static LIST_HEAD(skcipher_algs);
  83
  84  static void qce_skcipher_done(void *data)
  85 @@ -166,15 +174,10 @@ static int qce_skcipher_setkey(struct cr
  86         switch (IS_XTS(flags) ? keylen >> 1 : keylen) {
  87         case AES_KEYSIZE_128:
  88         case AES_KEYSIZE_256:
  89 +               memcpy(ctx->enc_key, key, keylen);
  90                 break;
  91 -       default:
  92 -               goto fallback;
  93         }
  94
  95 -       ctx->enc_keylen = keylen;
  96 -       memcpy(ctx->enc_key, key, keylen);
  97 -       return 0;
  98 -fallback:
  99         ret = crypto_sync_skcipher_setkey(ctx->fallback, key, keylen);
 100         if (!ret)
 101                 ctx->enc_keylen = keylen;
 102 @@ -224,8 +227,9 @@ static int qce_skcipher_crypt(struct skc
 103         rctx->flags |= encrypt ? QCE_ENCRYPT : QCE_DECRYPT;
 104         keylen = IS_XTS(rctx->flags) ? ctx->enc_keylen >> 1 : ctx->enc_keylen;
 105
 106 -       if (IS_AES(rctx->flags) && keylen != AES_KEYSIZE_128 &&
 107 -           keylen != AES_KEYSIZE_256) {
 108 +       if (IS_AES(rctx->flags) &&
 109 +           ((keylen != AES_KEYSIZE_128 && keylen != AES_KEYSIZE_256) ||
 110 +            req->cryptlen <= aes_sw_max_len)) {
 111                 SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback);
 112
 113                 skcipher_request_set_sync_tfm(subreq, ctx->fallback);