| Message ID | 47e9ddd8c9ea9ad9e29c8cb027d19d8459ea1479.1464346333.git.baolin.wang@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
Hi Herbet, On 2 June 2016 at 16:26, Herbert Xu <herbert@gondor.apana.org.au> wrote: > On Fri, May 27, 2016 at 07:11:23PM +0800, Baolin Wang wrote: >> Now some cipher hardware engines prefer to handle bulk block rather than one >> sector (512 bytes) created by dm-crypt, cause these cipher engines can handle >> the intermediate values (IV) by themselves in one bulk block. This means we >> can increase the size of the request by merging request rather than always 512 >> bytes and thus increase the hardware engine processing speed. >> >> So introduce 'CRYPTO_ALG_BULK' flag to indicate this cipher can support bulk >> mode. >> >> Signed-off-by: Baolin Wang <baolin.wang@linaro.org> > > I think a better aproach would be to explicitly move the IV generation > into the crypto API, similar to how we handle IPsec. Once you do > that then every algorithm can be handled through the bulk interface. > Sorry for late reply. If we move the IV generation into the crypto API, we also can not handle every algorithm with the bulk interface. Cause we also need to use different methods to map one whole bio or map one sector according to the algorithm whether can support bulk mode or not. Please correct me if I misunderstand your points. Thanks. > Cheers, > -- > Email: Herbert Xu <herbert@gondor.apana.org.au> > Home Page: http://gondor.apana.org.au/~herbert/ > PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- Baolin.wang Best Regards
On 3 June 2016 at 14:51, Herbert Xu <herbert@gondor.apana.org.au> wrote: > On Fri, Jun 03, 2016 at 02:48:34PM +0800, Baolin Wang wrote: >> >> If we move the IV generation into the crypto API, we also can not >> handle every algorithm with the bulk interface. Cause we also need to >> use different methods to map one whole bio or map one sector according >> to the algorithm whether can support bulk mode or not. Please correct >> me if I misunderstand your points. Thanks. > > Which ones can't be handled this way? What I mean is bulk mode and sector mode's difference is not only the IV handling method, but also the method to map the data with scatterlists. Then we have two processes in dm-crypt ( crypt_convert_block() and crypt_convert_bulk_block() ) to handle the data, so we can not handle every algorithm with the bulk interface. > > Cheers, > -- > Email: Herbert Xu <herbert@gondor.apana.org.au> > Home Page: http://gondor.apana.org.au/~herbert/ > PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- Baolin.wang Best Regards
On 3 June 2016 at 16:21, Herbert Xu <herbert@gondor.apana.org.au> wrote: > On Fri, Jun 03, 2016 at 04:15:28PM +0800, Baolin Wang wrote: >> >> Suppose the cbc(aes) algorithm, which can not be handled through bulk >> interface, it need to map the data sector by sector. >> If we also handle the cbc(aes) algorithm with bulk interface, we need >> to divide the sg table into sectors and need to allocate request >> memory for each divided sectors (As Mike pointed out this is in the >> IO mapping >> path and we try to avoid memory allocations at all costs -- due to the >> risk of deadlock when issuing IO to stacked block devices (dm-crypt >> could be part of a much more elaborate IO stack). ), that will >> introduce more messy things I think. > > Perhaps I'm not making myself very clear. If you move the IV > generation into the crypto API, those crypto API algorithms will > be operating at the sector level. Yeah, IV generation is OK. But it is not only related to IV thing. For example: (1) For ecb(aes) algorithm which don't need to handle IV generation, so it can support bulk mode: Assuming one 64K size bio coming , we can map the whole bio with one sg table in dm-crypt (assume it used 16 scatterlists from sg table), then issue the 'skcipher_request_set_crypt()' function to set one request with the mapped sg table, which will be sent to crypto driver to be handled. (2) For cbc(aes) algorithm which need to handle IV generation sector by sector, so it can not support bulk mode and can not use bulk interface: Assuming one 64K size bio coming , we should map the bio sector by sector with one scatterlist at one time. Each time we will issue the 'skcipher_request_set_crypt()' function to set one request with only one mapped scatterlist, until it handled done the whole bio. (3) As your suggestion, if we also use bulk interface for cbc(aes) algorithm assuming it did all the requisite magic to generate the correct IV: Assuming one 64K size bio coming, we can map the whole bio with one sg table in crypt_convert_bulk_block() function. But if we send this bulk request to crypto layer, we should divide the bulk request into small requests, and each small request should be one sector size (512 bytes) with assuming the correct IV, but we need to allocate small requests memory for the division, which will not good for IO mapping, and how each small request connect to dm-crypt (how to notify the request is done?)? Thus we should not handle every algorithm with bulk interface. > > For example, assuming you're doing lmk, then the algorithm would > be called lmk(cbc(aes)) and it will take as its input one or more > sectors and for each sector it should generate an IV and operate > on it. > > Cheers, > -- > Email: Herbert Xu <herbert@gondor.apana.org.au> > Home Page: http://gondor.apana.org.au/~herbert/ > PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- Baolin.wang Best Regards
On 3 June 2016 at 18:09, Herbert Xu <herbert@gondor.apana.org.au> wrote: > On Fri, Jun 03, 2016 at 05:23:59PM +0800, Baolin Wang wrote: >> >> Assuming one 64K size bio coming, we can map the whole bio with one sg >> table in crypt_convert_bulk_block() function. But if we send this bulk >> request to crypto layer, we should divide the bulk request into small >> requests, and each small request should be one sector size (512 bytes) >> with assuming the correct IV, but we need to allocate small requests >> memory for the division, which will not good for IO mapping, and how >> each small request connect to dm-crypt (how to notify the request is >> done?)? > > Why won't it be good? The actual AES block size is 16 and yet we Like I said, we should avoid memory allocation to improve efficiency in the IO path. Another hand is how the divided small requests (allocate request memory at crypt layer) connect with dm-crypt? Since dm-crypt just send one bulk request to crypt layer, but it will be divided into small requests at crypt layer. > have no trouble when you feed it a block of 512 bytes. That's right. -- Baolin.wang Best Regards
diff --git a/include/crypto/skcipher.h b/include/crypto/skcipher.h index 0f987f5..d89d29a 100644 --- a/include/crypto/skcipher.h +++ b/include/crypto/skcipher.h @@ -519,5 +519,12 @@ static inline void skcipher_request_set_crypt( req->iv = iv; } +static inline unsigned int skcipher_is_bulk_mode(struct crypto_skcipher *sk_tfm) +{ + struct crypto_tfm *tfm = crypto_skcipher_tfm(sk_tfm); + + return crypto_tfm_alg_bulk(tfm); +} + #endif /* _CRYPTO_SKCIPHER_H */ diff --git a/include/linux/crypto.h b/include/linux/crypto.h index 6e28c89..a315487 100644 --- a/include/linux/crypto.h +++ b/include/linux/crypto.h @@ -63,6 +63,7 @@ #define CRYPTO_ALG_DEAD 0x00000020 #define CRYPTO_ALG_DYING 0x00000040 #define CRYPTO_ALG_ASYNC 0x00000080 +#define CRYPTO_ALG_BULK 0x00000100 /* * Set this bit if and only if the algorithm requires another algorithm of @@ -623,6 +624,11 @@ static inline u32 crypto_tfm_alg_type(struct crypto_tfm *tfm) return tfm->__crt_alg->cra_flags & CRYPTO_ALG_TYPE_MASK; } +static inline unsigned int crypto_tfm_alg_bulk(struct crypto_tfm *tfm) +{ + return tfm->__crt_alg->cra_flags & CRYPTO_ALG_BULK; +} + static inline unsigned int crypto_tfm_alg_blocksize(struct crypto_tfm *tfm) { return tfm->__crt_alg->cra_blocksize;
Now some cipher hardware engines prefer to handle bulk block rather than one sector (512 bytes) created by dm-crypt, cause these cipher engines can handle the intermediate values (IV) by themselves in one bulk block. This means we can increase the size of the request by merging request rather than always 512 bytes and thus increase the hardware engine processing speed. So introduce 'CRYPTO_ALG_BULK' flag to indicate this cipher can support bulk mode. Signed-off-by: Baolin Wang <baolin.wang@linaro.org> --- include/crypto/skcipher.h | 7 +++++++ include/linux/crypto.h | 6 ++++++ 2 files changed, 13 insertions(+) -- 1.7.9.5