crypto: ahash - Add virtual address support

This patch adds virtual address support to ahash.  Virtual addresses
were previously only supported through shash.  The user may choose
to use virtual addresses with ahash by calling ahash_request_set_virt
instead of ahash_request_set_crypt.

The API will take care of translating this to an SG list if necessary,
unless the algorithm declares that it supports chaining.  Therefore
in order for an ahash algorithm to support chaining, it must also
support virtual addresses directly.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

include/crypto/internal/hash.h

@@ -252,6 +252,11 @@ static inline bool ahash_request_chained(struct ahash_request *req)
 	return crypto_request_chained(&req->base);
 }
 
+static inline bool ahash_request_isvirt(struct ahash_request *req)
+{
+	return req->base.flags & CRYPTO_AHASH_REQ_VIRT;
+}
+
 static inline bool crypto_ahash_req_chain(struct crypto_ahash *tfm)
 {
 	return crypto_tfm_req_chain(&tfm->base);