crypto: ccp - Rework the unit-size check for XTS-AES

The CCP supports a limited set of unit-size values. Change the check
for this parameter such that acceptable values match the enumeration.
Then clarify the conditions under which we must use the fallback
implementation.

Signed-off-by: Gary R Hook <gary.hook@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 20 insertions, 37 deletions

diff --git a/drivers/crypto/ccp/ccp-crypto-aes-xts.c b/drivers/crypto/ccp/ccp-crypto-aes-xts.c
index 2b5d3a62fad9..5c2df880ab48 100644
--- a/drivers/crypto/ccp/ccp-crypto-aes-xts.c
+++ b/drivers/crypto/ccp/ccp-crypto-aes-xts.c
@@ -39,46 +39,26 @@ struct ccp_unit_size_map {
         u32 value;
 };
 
-static struct ccp_unit_size_map unit_size_map[] = {
+static struct ccp_unit_size_map xts_unit_sizes[] = {
         {
-                .size   = 4096,
-                .value  = CCP_XTS_AES_UNIT_SIZE_4096,
-        },
-        {
-                .size   = 2048,
-                .value  = CCP_XTS_AES_UNIT_SIZE_2048,
-        },
-        {
-                .size   = 1024,
-                .value  = CCP_XTS_AES_UNIT_SIZE_1024,
+                .size   = 16,
+                .value  = CCP_XTS_AES_UNIT_SIZE_16,
         },
         {
-                .size   = 512,
+                .size   = 512,
                 .value  = CCP_XTS_AES_UNIT_SIZE_512,
         },
         {
-                .size   = 256,
-                .value  = CCP_XTS_AES_UNIT_SIZE__LAST,
-        },
-        {
-                .size   = 128,
-                .value  = CCP_XTS_AES_UNIT_SIZE__LAST,
-        },
-        {
-                .size   = 64,
-                .value  = CCP_XTS_AES_UNIT_SIZE__LAST,
-        },
-        {
-                .size   = 32,
-                .value  = CCP_XTS_AES_UNIT_SIZE__LAST,
+                .size   = 1024,
+                .value  = CCP_XTS_AES_UNIT_SIZE_1024,
         },
         {
-                .size   = 16,
-                .value  = CCP_XTS_AES_UNIT_SIZE_16,
+                .size   = 2048,
+                .value  = CCP_XTS_AES_UNIT_SIZE_2048,
         },
         {
-                .size   = 1,
-                .value  = CCP_XTS_AES_UNIT_SIZE__LAST,
+                .size   = 4096,
+                .value  = CCP_XTS_AES_UNIT_SIZE_4096,
         },
 };
 
@@ -138,16 +118,19 @@ static int ccp_aes_xts_crypt(struct ablkcipher_request *req,
         if (!req->info)
                 return -EINVAL;
 
+        /* Check conditions under which the CCP can fulfill a request. The
+         * device can handle input plaintext of a length that is a multiple
+         * of the unit_size, bug the crypto implementation only supports
+         * the unit_size being equal to the input length. This limits the
+         * number of scenarios we can handle.
+         */
         unit_size = CCP_XTS_AES_UNIT_SIZE__LAST;
-        if (req->nbytes <= unit_size_map[0].size) {
-                for (unit = 0; unit < ARRAY_SIZE(unit_size_map); unit++) {
-                        if (!(req->nbytes & (unit_size_map[unit].size - 1))) {
-                                unit_size = unit_size_map[unit].value;
-                                break;
-                        }
+        for (unit = 0; unit < ARRAY_SIZE(xts_unit_sizes); unit++) {
+                if (req->nbytes == xts_unit_sizes[unit].size) {
+                        unit_size = unit;
+                        break;
                 }
         }
-
         if ((unit_size == CCP_XTS_AES_UNIT_SIZE__LAST) ||
             (ctx->u.aes.key_len != AES_KEYSIZE_128)) {
                 SKCIPHER_REQUEST_ON_STACK(subreq, ctx->u.aes.tfm_skcipher);