crypto: caam: add backlogging support

Message ID	1462540733-2170-1-git-send-email-cata.vasile@nxp.com (mailing list archive)
State	Changes Requested
Delegated to:	Herbert Xu
Headers	show Return-Path: <linux-crypto-owner@kernel.org> Received-SPF: Fail (protection.outlook.com: domain of nxp.com does not designate 192.88.158.2 as permitted sender) receiver=protection.outlook.com; client-ip=192.88.158.2; helo=az84smr01.freescale.net; From: Catalin Vasile <cata.vasile@nxp.com> To: <linux-crypto@vger.kernel.org> CC: <linux-crypto-owner@vger.kernel.org>, <horia.geanta@nxp.com>, <alexandru.porosanu@nxp.com>, <scott.wood@nxp.com>, Catalin Vasile <cata.vasile@nxp.com> Subject: [PATCH] crypto: caam: add backlogging support Date: Fri, 6 May 2016 16:18:52 +0300 Message-ID: <1462540733-2170-1-git-send-email-cata.vasile@nxp.com> MIME-Version: 1.0 Content-Type: text/plain X-MS-Office365-Filtering-Correlation-Id: f9930d43-bace-4d92-82d5-08d375b0fc34 X-Microsoft-Exchange-Diagnostics: 1; CY1PR0301MB1228; 2:kh6jiCleBkAPIS3dkisAXgOey4iQxXEnpmmAwqzi8VpJPX9aCXYtrvJ5zfMXYnaz6+VbQsOSPVSzEeidCTTpEfwIrVXD3vD1erKvBvpsk8l7BIfoinwrr7cOZaj8d5UxuyrG+AsJlq2Nwcg9+Lh52svp/7IkxdaP4j9d02pwHsCDxAD0reBFJgwyc8nSco4m; 3:aqzKiXnksPCefT8H31fUplJx0piQb5X27hHf/mporG/NMGOmx/jZHhNHK2tU+L09d6vr5B8QG6BYPJ9rRlMBgnInPBs8uL2mq7Xxfon3x/bhwoDrQrbVkCNRrjmvmedMcixh2gLNnF6CBE8ypMdtdDutEh4pOFU1MImB+vnbCeG+g7DsUvKzrxBEmLCzPBv1Qmt5OfYD5PhZTO6oNWsorBaThogf2dSD6zQekW3WJLM= SpamDiagnosticOutput: 1:23 SpamDiagnosticMetadata: NSPM X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 May 2016 13:18:59.3181 (UTC) Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk

Catalin Vasile May 6, 2016, 1:18 p.m. UTC

caam_jr_enqueue() function returns -EBUSY once there are no more slots
available in the JR, but it doesn't actually save the current request.
This breaks the functionality of users that expect that even if there is
no more space for the request, it is at least queued for later
execution. In other words, all crypto transformations that request
backlogging (i.e. have CRYPTO_TFM_REQ_MAY_BACKLOG set), will hang. Such
an example is dm-crypt. The current patch solves this issue by setting a
threshold after which caam_jr_enqueue() returns -EBUSY, but since the HW
job ring isn't actually full, the job is enqueued.

Signed-off-by: Alexandru Porosanu <alexandru.porosanu@nxp.com>
Tested-by: Catalin Vasile <cata.vasile@nxp.com>
---
 drivers/crypto/caam/caamalg.c  |  88 ++++++++++++++++--
 drivers/crypto/caam/caamhash.c | 101 +++++++++++++++++++--
 drivers/crypto/caam/intern.h   |   7 ++
 drivers/crypto/caam/jr.c       | 196 +++++++++++++++++++++++++++++++++--------
 drivers/crypto/caam/jr.h       |   5 ++
 5 files changed, 343 insertions(+), 54 deletions(-)

Horia Geanta May 9, 2016, 2:50 p.m. UTC | #1

On 5/6/2016 4:19 PM, Catalin Vasile wrote:
> caam_jr_enqueue() function returns -EBUSY once there are no more slots
> available in the JR, but it doesn't actually save the current request.
> This breaks the functionality of users that expect that even if there is
> no more space for the request, it is at least queued for later
> execution. In other words, all crypto transformations that request
> backlogging (i.e. have CRYPTO_TFM_REQ_MAY_BACKLOG set), will hang. Such
> an example is dm-crypt. The current patch solves this issue by setting a
> threshold after which caam_jr_enqueue() returns -EBUSY, but since the HW
> job ring isn't actually full, the job is enqueued.
> 
The commit message should mention that *both* number of tfms / Job Ring
*and* the number of available Job Ring slots (configured by
CRYPTO_DEV_FSL_CAAM_RINGSIZE) is being limited by JOBR_THRESH:
tfms / Job Ring < JOBR_THRESH
available (free) Job Ring slots >= JOBR_THRESH

Shouldn't caam_jr_enqueue() from key_gen.c be changed too?
Generating a split key is supposed to be done on behalf of the
underlying tfm, thus the MAY_BACKLOG flag should be checked here too.

> Signed-off-by: Alexandru Porosanu <alexandru.porosanu@nxp.com>
> Tested-by: Catalin Vasile <cata.vasile@nxp.com>
> ---
>  drivers/crypto/caam/caamalg.c  |  88 ++++++++++++++++--
>  drivers/crypto/caam/caamhash.c | 101 +++++++++++++++++++--
>  drivers/crypto/caam/intern.h   |   7 ++
>  drivers/crypto/caam/jr.c       | 196 +++++++++++++++++++++++++++++++++--------
>  drivers/crypto/caam/jr.h       |   5 ++
>  5 files changed, 343 insertions(+), 54 deletions(-)
> 
> diff --git a/drivers/crypto/caam/caamalg.c b/drivers/crypto/caam/caamalg.c
> index ea8189f..62bce17 100644
> --- a/drivers/crypto/caam/caamalg.c
> +++ b/drivers/crypto/caam/caamalg.c
> @@ -1921,6 +1921,9 @@ static void aead_encrypt_done(struct device *jrdev, u32 *desc, u32 err,
>  
>  	edesc = container_of(desc, struct aead_edesc, hw_desc[0]);
>  
> +	if (err == -EINPROGRESS)
> +		goto out_bklogged;

Checking that err is -EINPROGRESS should be the first thing to do in
*_done callbacks.

> +
>  	if (err)
>  		caam_jr_strstatus(jrdev, err);
>  
> @@ -1928,6 +1931,7 @@ static void aead_encrypt_done(struct device *jrdev, u32 *desc, u32 err,
>  
>  	kfree(edesc);
>  
> +out_bklogged:
>  	aead_request_complete(req, err);
>  }
>  
> @@ -1943,6 +1947,9 @@ static void aead_decrypt_done(struct device *jrdev, u32 *desc, u32 err,
>  
>  	edesc = container_of(desc, struct aead_edesc, hw_desc[0]);
>  
> +	if (err == -EINPROGRESS)
> +		goto out_bklogged;
> +
>  	if (err)
>  		caam_jr_strstatus(jrdev, err);
>  
> @@ -1956,6 +1963,7 @@ static void aead_decrypt_done(struct device *jrdev, u32 *desc, u32 err,
>  
>  	kfree(edesc);
>  
> +out_bklogged:
>  	aead_request_complete(req, err);
>  }
>  
> @@ -1974,6 +1982,9 @@ static void ablkcipher_encrypt_done(struct device *jrdev, u32 *desc, u32 err,
>  	edesc = (struct ablkcipher_edesc *)((char *)desc -
>  		 offsetof(struct ablkcipher_edesc, hw_desc));
>  
> +	if (err == -EINPROGRESS)
> +		goto out_bklogged;
> +
>  	if (err)
>  		caam_jr_strstatus(jrdev, err);
>  
> @@ -1989,6 +2000,7 @@ static void ablkcipher_encrypt_done(struct device *jrdev, u32 *desc, u32 err,
>  	ablkcipher_unmap(jrdev, edesc, req);
>  	kfree(edesc);
>  
> +out_bklogged:
>  	ablkcipher_request_complete(req, err);
>  }
>  
> @@ -2006,6 +2018,10 @@ static void ablkcipher_decrypt_done(struct device *jrdev, u32 *desc, u32 err,
>  
>  	edesc = (struct ablkcipher_edesc *)((char *)desc -
>  		 offsetof(struct ablkcipher_edesc, hw_desc));
> +
> +	if (err == -EINPROGRESS)
> +		goto out_bklogged;
> +
>  	if (err)
>  		caam_jr_strstatus(jrdev, err);
>  
> @@ -2021,6 +2037,7 @@ static void ablkcipher_decrypt_done(struct device *jrdev, u32 *desc, u32 err,
>  	ablkcipher_unmap(jrdev, edesc, req);
>  	kfree(edesc);
>  
> +out_bklogged:
>  	ablkcipher_request_complete(req, err);
>  }
>  
> @@ -2394,7 +2411,15 @@ static int gcm_encrypt(struct aead_request *req)
>  #endif
>  
>  	desc = edesc->hw_desc;
> -	ret = caam_jr_enqueue(jrdev, desc, aead_encrypt_done, req);
> +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> +		ret = caam_jr_enqueue_bklog(jrdev, desc, aead_encrypt_done,
> +					    req);
> +		if (ret == -EBUSY)
> +			return ret;
> +	} else {
> +		ret = caam_jr_enqueue(jrdev, desc, aead_encrypt_done, req);
> +	}
> +
>  	if (!ret) {
>  		ret = -EINPROGRESS;
>  	} else {
> @@ -2438,7 +2463,15 @@ static int aead_encrypt(struct aead_request *req)
>  #endif
>  
>  	desc = edesc->hw_desc;
> -	ret = caam_jr_enqueue(jrdev, desc, aead_encrypt_done, req);
> +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> +		ret = caam_jr_enqueue_bklog(jrdev, desc, aead_encrypt_done,
> +					    req);
> +		if (ret == -EBUSY)
> +			return ret;
> +	} else {
> +		ret = caam_jr_enqueue(jrdev, desc, aead_encrypt_done, req);
> +	}
> +
>  	if (!ret) {
>  		ret = -EINPROGRESS;
>  	} else {
> @@ -2473,7 +2506,15 @@ static int gcm_decrypt(struct aead_request *req)
>  #endif
>  
>  	desc = edesc->hw_desc;
> -	ret = caam_jr_enqueue(jrdev, desc, aead_decrypt_done, req);
> +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> +		ret = caam_jr_enqueue_bklog(jrdev, desc, aead_decrypt_done,
> +					    req);
> +		if (ret == -EBUSY)
> +			return ret;
> +	} else {
> +		ret = caam_jr_enqueue(jrdev, desc, aead_decrypt_done, req);
> +	}
> +
>  	if (!ret) {
>  		ret = -EINPROGRESS;
>  	} else {
> @@ -2523,7 +2564,15 @@ static int aead_decrypt(struct aead_request *req)
>  #endif
>  
>  	desc = edesc->hw_desc;
> -	ret = caam_jr_enqueue(jrdev, desc, aead_decrypt_done, req);
> +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> +		ret = caam_jr_enqueue_bklog(jrdev, desc, aead_decrypt_done,
> +					    req);
> +		if (ret == -EBUSY)
> +			return ret;
> +	} else {
> +		ret = caam_jr_enqueue(jrdev, desc, aead_decrypt_done, req);
> +	}
> +
>  	if (!ret) {
>  		ret = -EINPROGRESS;
>  	} else {
> @@ -2672,7 +2721,15 @@ static int ablkcipher_encrypt(struct ablkcipher_request *req)
>  		       desc_bytes(edesc->hw_desc), 1);
>  #endif
>  	desc = edesc->hw_desc;
> -	ret = caam_jr_enqueue(jrdev, desc, ablkcipher_encrypt_done, req);
> +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> +		ret = caam_jr_enqueue_bklog(jrdev, desc,
> +					    ablkcipher_encrypt_done, req);
> +		if (ret == -EBUSY)
> +			return ret;
> +	} else {
> +		ret = caam_jr_enqueue(jrdev, desc, ablkcipher_encrypt_done,
> +				      req);
> +	}
>  
>  	if (!ret) {
>  		ret = -EINPROGRESS;
> @@ -2710,7 +2767,16 @@ static int ablkcipher_decrypt(struct ablkcipher_request *req)
>  		       desc_bytes(edesc->hw_desc), 1);
>  #endif
>  
> -	ret = caam_jr_enqueue(jrdev, desc, ablkcipher_decrypt_done, req);
> +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> +		ret = caam_jr_enqueue_bklog(jrdev, desc,
> +					    ablkcipher_decrypt_done, req);
> +		if (ret == -EBUSY)
> +			return ret;
> +	} else {
> +		ret = caam_jr_enqueue(jrdev, desc, ablkcipher_decrypt_done,
> +				      req);
> +	}
> +
>  	if (!ret) {
>  		ret = -EINPROGRESS;
>  	} else {
> @@ -2851,7 +2917,15 @@ static int ablkcipher_givencrypt(struct skcipher_givcrypt_request *creq)
>  		       desc_bytes(edesc->hw_desc), 1);
>  #endif
>  	desc = edesc->hw_desc;
> -	ret = caam_jr_enqueue(jrdev, desc, ablkcipher_encrypt_done, req);
> +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> +		ret = caam_jr_enqueue_bklog(jrdev, desc,
> +					    ablkcipher_encrypt_done, req);
> +		if (ret == -EBUSY)
> +			return ret;
> +	} else {
> +		ret = caam_jr_enqueue(jrdev, desc, ablkcipher_encrypt_done,
> +				      req);
> +	}
>  
>  	if (!ret) {
>  		ret = -EINPROGRESS;
> diff --git a/drivers/crypto/caam/caamhash.c b/drivers/crypto/caam/caamhash.c
> index 5845d4a..910a350 100644
> --- a/drivers/crypto/caam/caamhash.c
> +++ b/drivers/crypto/caam/caamhash.c
> @@ -650,6 +650,10 @@ static void ahash_done(struct device *jrdev, u32 *desc, u32 err,
>  
>  	edesc = (struct ahash_edesc *)((char *)desc -
>  		 offsetof(struct ahash_edesc, hw_desc));
> +
> +	if (err == -EINPROGRESS)
> +		goto out_bklogged;
> +
>  	if (err)
>  		caam_jr_strstatus(jrdev, err);
>  
> @@ -666,6 +670,7 @@ static void ahash_done(struct device *jrdev, u32 *desc, u32 err,
>  			       digestsize, 1);
>  #endif
>  
> +out_bklogged:
>  	req->base.complete(&req->base, err);
>  }
>  
> @@ -685,6 +690,10 @@ static void ahash_done_bi(struct device *jrdev, u32 *desc, u32 err,
>  
>  	edesc = (struct ahash_edesc *)((char *)desc -
>  		 offsetof(struct ahash_edesc, hw_desc));
> +
> +	if (err == -EINPROGRESS)
> +		goto out_bklogged;
> +
>  	if (err)
>  		caam_jr_strstatus(jrdev, err);
>  
> @@ -701,6 +710,7 @@ static void ahash_done_bi(struct device *jrdev, u32 *desc, u32 err,
>  			       digestsize, 1);
>  #endif
>  
> +out_bklogged:
>  	req->base.complete(&req->base, err);
>  }
>  
> @@ -720,6 +730,10 @@ static void ahash_done_ctx_src(struct device *jrdev, u32 *desc, u32 err,
>  
>  	edesc = (struct ahash_edesc *)((char *)desc -
>  		 offsetof(struct ahash_edesc, hw_desc));
> +
> +	if (err == -EINPROGRESS)
> +		goto out_bklogged;
> +
>  	if (err)
>  		caam_jr_strstatus(jrdev, err);
>  
> @@ -736,6 +750,7 @@ static void ahash_done_ctx_src(struct device *jrdev, u32 *desc, u32 err,
>  			       digestsize, 1);
>  #endif
>  
> +out_bklogged:
>  	req->base.complete(&req->base, err);
>  }
>  
> @@ -755,6 +770,10 @@ static void ahash_done_ctx_dst(struct device *jrdev, u32 *desc, u32 err,
>  
>  	edesc = (struct ahash_edesc *)((char *)desc -
>  		 offsetof(struct ahash_edesc, hw_desc));
> +
> +	if (err == -EINPROGRESS)
> +		goto out_bklogged;
> +
>  	if (err)
>  		caam_jr_strstatus(jrdev, err);
>  
> @@ -771,6 +790,7 @@ static void ahash_done_ctx_dst(struct device *jrdev, u32 *desc, u32 err,
>  			       digestsize, 1);
>  #endif
>  
> +out_bklogged:
>  	req->base.complete(&req->base, err);
>  }
>  
> @@ -876,7 +896,15 @@ static int ahash_update_ctx(struct ahash_request *req)
>  			       desc_bytes(desc), 1);
>  #endif
>  
> -		ret = caam_jr_enqueue(jrdev, desc, ahash_done_bi, req);
> +		if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> +			ret = caam_jr_enqueue_bklog(jrdev, desc, ahash_done_bi,
> +						    req);
> +			if (ret == -EBUSY)
> +				return ret;
> +		} else {
> +			ret = caam_jr_enqueue(jrdev, desc, ahash_done_bi, req);
> +		}
> +
>  		if (!ret) {
>  			ret = -EINPROGRESS;
>  		} else {
> @@ -973,7 +1001,15 @@ static int ahash_final_ctx(struct ahash_request *req)
>  		       DUMP_PREFIX_ADDRESS, 16, 4, desc, desc_bytes(desc), 1);
>  #endif
>  
> -	ret = caam_jr_enqueue(jrdev, desc, ahash_done_ctx_src, req);
> +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> +		ret = caam_jr_enqueue_bklog(jrdev, desc, ahash_done_ctx_src,
> +					    req);
> +		if (ret == -EBUSY)
> +			return ret;
> +	} else {
> +		ret = caam_jr_enqueue(jrdev, desc, ahash_done_ctx_src, req);
> +	}
> +
>  	if (!ret) {
>  		ret = -EINPROGRESS;
>  	} else {
> @@ -1065,7 +1101,15 @@ static int ahash_finup_ctx(struct ahash_request *req)
>  		       DUMP_PREFIX_ADDRESS, 16, 4, desc, desc_bytes(desc), 1);
>  #endif
>  
> -	ret = caam_jr_enqueue(jrdev, desc, ahash_done_ctx_src, req);
> +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> +		ret = caam_jr_enqueue_bklog(jrdev, desc, ahash_done_ctx_src,
> +					    req);
> +		if (ret == -EBUSY)
> +			return ret;
> +	} else {
> +		ret = caam_jr_enqueue(jrdev, desc, ahash_done_ctx_src, req);
> +	}
> +
>  	if (!ret) {
>  		ret = -EINPROGRESS;
>  	} else {
> @@ -1145,7 +1189,14 @@ static int ahash_digest(struct ahash_request *req)
>  		       DUMP_PREFIX_ADDRESS, 16, 4, desc, desc_bytes(desc), 1);
>  #endif
>  
> -	ret = caam_jr_enqueue(jrdev, desc, ahash_done, req);
> +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> +		ret = caam_jr_enqueue_bklog(jrdev, desc, ahash_done, req);
> +		if (ret == -EBUSY)
> +			return ret;
> +	} else {
> +		ret = caam_jr_enqueue(jrdev, desc, ahash_done, req);
> +	}
> +
>  	if (!ret) {
>  		ret = -EINPROGRESS;
>  	} else {
> @@ -1207,7 +1258,14 @@ static int ahash_final_no_ctx(struct ahash_request *req)
>  		       DUMP_PREFIX_ADDRESS, 16, 4, desc, desc_bytes(desc), 1);
>  #endif
>  
> -	ret = caam_jr_enqueue(jrdev, desc, ahash_done, req);
> +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> +		ret = caam_jr_enqueue_bklog(jrdev, desc, ahash_done, req);
> +		if (ret == -EBUSY)
> +			return ret;
> +	} else {
> +		ret = caam_jr_enqueue(jrdev, desc, ahash_done, req);
> +	}
> +
>  	if (!ret) {
>  		ret = -EINPROGRESS;
>  	} else {
> @@ -1308,7 +1366,16 @@ static int ahash_update_no_ctx(struct ahash_request *req)
>  			       desc_bytes(desc), 1);
>  #endif
>  
> -		ret = caam_jr_enqueue(jrdev, desc, ahash_done_ctx_dst, req);
> +		if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> +			ret = caam_jr_enqueue_bklog(jrdev, desc,
> +						    ahash_done_ctx_dst, req);
> +			if (ret == -EBUSY)
> +				return ret;
> +		} else {
> +			ret = caam_jr_enqueue(jrdev, desc, ahash_done_ctx_dst,
> +					      req);
> +		}
> +
>  		if (!ret) {
>  			ret = -EINPROGRESS;
>  			state->update = ahash_update_ctx;
> @@ -1411,7 +1478,15 @@ static int ahash_finup_no_ctx(struct ahash_request *req)
>  		       DUMP_PREFIX_ADDRESS, 16, 4, desc, desc_bytes(desc), 1);
>  #endif
>  
> -	ret = caam_jr_enqueue(jrdev, desc, ahash_done, req);
> +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> +		ret = caam_jr_enqueue_bklog(jrdev, desc, ahash_done,
> +					    req);
> +		if (ret == -EBUSY)
> +			return ret;
> +	} else {
> +		ret = caam_jr_enqueue(jrdev, desc, ahash_done, req);
> +	}
> +
>  	if (!ret) {
>  		ret = -EINPROGRESS;
>  	} else {
> @@ -1514,8 +1589,16 @@ static int ahash_update_first(struct ahash_request *req)
>  			       desc_bytes(desc), 1);
>  #endif
>  
> -		ret = caam_jr_enqueue(jrdev, desc, ahash_done_ctx_dst,
> -				      req);
> +		if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> +			ret = caam_jr_enqueue_bklog(jrdev, desc,
> +						    ahash_done_ctx_dst, req);
> +			if (ret == -EBUSY)
> +				return ret;
> +		} else {
> +			ret = caam_jr_enqueue(jrdev, desc, ahash_done_ctx_dst,
> +					      req);
> +		}
> +
>  		if (!ret) {
>  			ret = -EINPROGRESS;
>  			state->update = ahash_update_ctx;
> diff --git a/drivers/crypto/caam/intern.h b/drivers/crypto/caam/intern.h
> index e2bcacc..aa4e257 100644
> --- a/drivers/crypto/caam/intern.h
> +++ b/drivers/crypto/caam/intern.h
> @@ -11,6 +11,12 @@
>  
>  /* Currently comes from Kconfig param as a ^2 (driver-required) */
>  #define JOBR_DEPTH (1 << CONFIG_CRYPTO_DEV_FSL_CAAM_RINGSIZE)
> +/*
> + * If the user tries to enqueue a job and the number of slots available
> + * is less than this value, then the job will be backlogged (if the user
> + * allows for it) or it will be dropped.
> + */
> +#define JOBR_THRESH (JOBR_DEPTH / 2 - 1)
>  
>  /* Kconfig params for interrupt coalescing if selected (else zero) */
>  #ifdef CONFIG_CRYPTO_DEV_FSL_CAAM_INTC
> @@ -33,6 +39,7 @@ struct caam_jrentry_info {
>  	u32 *desc_addr_virt;	/* Stored virt addr for postprocessing */
>  	dma_addr_t desc_addr_dma;	/* Stored bus addr for done matching */
>  	u32 desc_size;	/* Stored size for postprocessing, header derived */
> +	bool is_backlogged; /* True if the request has been backlogged */
>  };
>  
>  /* Private sub-storage for a single JobR */
> diff --git a/drivers/crypto/caam/jr.c b/drivers/crypto/caam/jr.c
> index 5ef4be2..49790e1 100644
> --- a/drivers/crypto/caam/jr.c
> +++ b/drivers/crypto/caam/jr.c
> @@ -168,6 +168,7 @@ static void caam_jr_dequeue(unsigned long devarg)
>  	void (*usercall)(struct device *dev, u32 *desc, u32 status, void *arg);
>  	u32 *userdesc, userstatus;
>  	void *userarg;
> +	bool is_backlogged;
>  
>  	while (rd_reg32(&jrp->rregs->outring_used)) {
>  
> @@ -201,6 +202,9 @@ static void caam_jr_dequeue(unsigned long devarg)
>  		userarg = jrp->entinfo[sw_idx].cbkarg;
>  		userdesc = jrp->entinfo[sw_idx].desc_addr_virt;
>  		userstatus = jrp->outring[hw_idx].jrstatus;
> +		is_backlogged = jrp->entinfo[sw_idx].is_backlogged;
> +		/* Reset backlogging status here */
> +		jrp->entinfo[sw_idx].is_backlogged = false;
>  
>  		/*
>  		 * Make sure all information from the job has been obtained
> @@ -231,6 +235,20 @@ static void caam_jr_dequeue(unsigned long devarg)
>  
>  		spin_unlock(&jrp->outlock);
>  
> +		if (is_backlogged)
> +			/*
> +			 * For backlogged requests, the user callback needs to
> +			 * be called twice: once when starting to process it
> +			 * (with a status of -EINPROGRESS and once when it's
			   ^ paranthesis not closed

> +			 * done. Since SEC cheats by enqueuing the request in
> +			 * its HW ring but returning -EBUSY, the time when the
> +			 * request's processing has started is not known.
> +			 * Thus notify here the user. The second call is on the
> +			 * normal path (i.e. the one that is called even for
> +			 * non-backlogged requests).
> +			 */
> +			usercall(dev, userdesc, -EINPROGRESS, userarg);
> +
>  		/* Finally, execute user's callback */
>  		usercall(dev, userdesc, userstatus, userarg);
>  	}
> @@ -261,6 +279,15 @@ struct device *caam_jr_alloc(void)
>  
>  	list_for_each_entry(jrpriv, &driver_data.jr_list, list_node) {
>  		tfm_cnt = atomic_read(&jrpriv->tfm_count);
> +
> +		/*
> +		 * Don't allow more than JOBR_THRES jobs on this JR. If more

What's being limited here is not the number of jobs, but the number of tfms.

> +		 * are allowed, then backlogging API contract won't work (each
> +		 * "backloggable" tfm must allow for at least 1 enqueue.
> +		 */
> +		if (tfm_cnt == JOBR_THRESH)
> +			continue;
> +
>  		if (tfm_cnt < min_tfm_cnt) {
>  			min_tfm_cnt = tfm_cnt;
>  			min_jrpriv = jrpriv;
> @@ -292,6 +319,80 @@ void caam_jr_free(struct device *rdev)
>  }
>  EXPORT_SYMBOL(caam_jr_free);
>  
> +static inline int __caam_jr_enqueue(struct caam_drv_private_jr *jrp, u32 *desc,
> +				    int desc_size, dma_addr_t desc_dma,
> +				    void (*cbk)(struct device *dev, u32 *desc,
> +						u32 status, void *areq),
> +				    void *areq,
> +				    bool can_be_backlogged)
> +{
> +	int head, tail;
> +	struct caam_jrentry_info *head_entry;
> +	int ret = 0, hw_slots, sw_slots;
> +
> +	spin_lock_bh(&jrp->inplock);
> +
> +	head = jrp->head;
> +	tail = ACCESS_ONCE(jrp->tail);
> +
> +	head_entry = &jrp->entinfo[head];
> +
> +	hw_slots = rd_reg32(&jrp->rregs->inpring_avail);
> +	sw_slots = CIRC_SPACE(head, tail, JOBR_DEPTH);
> +
> +	if (hw_slots <= JOBR_THRESH || sw_slots <= JOBR_THRESH) {
> +		/*
> +		 * The state below can be reached in three cases:
> +		 * 1) A badly behaved backlogging user doesn't back off when
> +		 *    told so by the -EBUSY return code
> +		 * 2) More than JOBR_THRESH backlogging users requests

AFAICS, this case is no longer possible, since the number of "users"
(tfms) is being limited to JOBR_THRESH in caam_jr_alloc().

> +		 * 3) Due to the high system load, the entries reserved for the
> +		 *    backlogging users are being filled (slowly) in between
> +		 *    the successive calls to the user callback (the first one
> +		 *    with -EINPROGRESS and the 2nd one with the real result.
> +		 * The code below is a last-resort measure which will DROP
> +		 * any request if there is physically no more space. This will
> +		 * lead to data-loss for disk-related users.
		   ^^^^^^^^^^^^^^^^^^^^^^^^^^
This should be enough to reject the solution.
It's way too easy / probable to start losing data, when compared with a
SW-only queue that is bounded only by system memory.

> +		 */
> +		if (!hw_slots || !sw_slots) {
> +			ret = -EIO;
> +			goto out_unlock;
> +		}
> +
> +		ret = -EBUSY;
> +		if (!can_be_backlogged)
> +			goto out_unlock;
> +
> +		head_entry->is_backlogged = true;
> +	}
> +
> +	head_entry->desc_addr_virt = desc;
> +	head_entry->desc_size = desc_size;
> +	head_entry->callbk = (void *)cbk;
> +	head_entry->cbkarg = areq;
> +	head_entry->desc_addr_dma = desc_dma;
> +
> +	jrp->inpring[jrp->inp_ring_write_index] = desc_dma;
> +
> +	/*
> +	 * Guarantee that the descriptor's DMA address has been written to
> +	 * the next slot in the ring before the write index is updated, since
> +	 * other cores may update this index independently.
> +	 */
> +	smp_wmb();
> +
> +	jrp->inp_ring_write_index = (jrp->inp_ring_write_index + 1) &
> +				    (JOBR_DEPTH - 1);
> +	jrp->head = (head + 1) & (JOBR_DEPTH - 1);
> +
> +	wr_reg32(&jrp->rregs->inpring_jobadd, 1);
> +
> +out_unlock:
> +	spin_unlock_bh(&jrp->inplock);
> +
> +	return ret;
> +}
> +
>  /**
>   * caam_jr_enqueue() - Enqueue a job descriptor head. Returns 0 if OK,
>   * -EBUSY if the queue is full, -EIO if it cannot map the caller's
> @@ -326,8 +427,7 @@ int caam_jr_enqueue(struct device *dev, u32 *desc,
>  		    void *areq)
>  {
>  	struct caam_drv_private_jr *jrp = dev_get_drvdata(dev);
> -	struct caam_jrentry_info *head_entry;
> -	int head, tail, desc_size;
> +	int desc_size, ret;
>  	dma_addr_t desc_dma;
>  
>  	desc_size = (*desc & HDR_JD_LENGTH_MASK) * sizeof(u32);
> @@ -337,51 +437,71 @@ int caam_jr_enqueue(struct device *dev, u32 *desc,
>  		return -EIO;
>  	}
>  
> -	spin_lock_bh(&jrp->inplock);
> -
> -	head = jrp->head;
> -	tail = ACCESS_ONCE(jrp->tail);
> -
> -	if (!rd_reg32(&jrp->rregs->inpring_avail) ||
> -	    CIRC_SPACE(head, tail, JOBR_DEPTH) <= 0) {
> -		spin_unlock_bh(&jrp->inplock);
> +	ret = __caam_jr_enqueue(jrp, desc, desc_size, desc_dma, cbk, areq,
> +				false);
> +	if (unlikely(ret))
>  		dma_unmap_single(dev, desc_dma, desc_size, DMA_TO_DEVICE);
> -		return -EBUSY;
> -	}
>  
> -	head_entry = &jrp->entinfo[head];
> -	head_entry->desc_addr_virt = desc;
> -	head_entry->desc_size = desc_size;
> -	head_entry->callbk = (void *)cbk;
> -	head_entry->cbkarg = areq;
> -	head_entry->desc_addr_dma = desc_dma;
> -
> -	jrp->inpring[jrp->inp_ring_write_index] = desc_dma;
> +	return 0;
> +}
> +EXPORT_SYMBOL(caam_jr_enqueue);
>  
> -	/*
> -	 * Guarantee that the descriptor's DMA address has been written to
> -	 * the next slot in the ring before the write index is updated, since
> -	 * other cores may update this index independently.
> -	 */
> -	smp_wmb();
> +/**
> + * caam_jr_enqueue_bklog() - Enqueue a job descriptor head, returns 0 if OK, or
> + * -EBUSY if the number of available entries in the Job Ring is less
> + * than the threshold configured through JOBR_THRESH, and -EIO if it cannot map
> + * the caller's descriptor or if there is really no more space in the hardware
> + * job ring.
> + * @dev:  device of the job ring to be used. This device should have
> + *        been assigned prior by caam_jr_register().
> + * @desc: points to a job descriptor that execute our request. All
> + *        descriptors (and all referenced data) must be in a DMAable
> + *        region, and all data references must be physical addresses
> + *        accessible to CAAM (i.e. within a PAMU window granted
> + *        to it).
> + * @cbk:  pointer to a callback function to be invoked upon completion
> + *        of this request. This has the form:
> + *        callback(struct device *dev, u32 *desc, u32 stat, void *arg)
> + *        where:
> + *        @dev:    contains the job ring device that processed this
> + *                 response.
> + *        @desc:   descriptor that initiated the request, same as
> + *                 "desc" being argued to caam_jr_enqueue().
> + *        @status: untranslated status received from CAAM. See the
> + *                 reference manual for a detailed description of
> + *                 error meaning, or see the JRSTA definitions in the
> + *                 register header file
> + *        @areq:   optional pointer to an argument passed with the
> + *                 original request
> + * @areq: optional pointer to a user argument for use at callback
> + *        time.
> + **/
> +int caam_jr_enqueue_bklog(struct device *dev, u32 *desc,
> +			  void (*cbk)(struct device *dev, u32 *desc,
> +				      u32 status, void *areq),
> +			  void *areq)
> +{
> +	struct caam_drv_private_jr *jrp = dev_get_drvdata(dev);
> +	int desc_size, ret;
> +	dma_addr_t desc_dma;
>  
> -	jrp->inp_ring_write_index = (jrp->inp_ring_write_index + 1) &
> -				    (JOBR_DEPTH - 1);
> -	jrp->head = (head + 1) & (JOBR_DEPTH - 1);
>  
> -	/*
> -	 * Ensure that all job information has been written before
> -	 * notifying CAAM that a new job was added to the input ring.
> -	 */
> -	wmb();
> +	desc_size = (*desc & HDR_JD_LENGTH_MASK) * sizeof(u32);
> +	desc_dma = dma_map_single(dev, desc, desc_size, DMA_TO_DEVICE);
> +	if (dma_mapping_error(dev, desc_dma)) {
> +		dev_err(dev, "caam_jr_enqueue(): can't map jobdesc\n");
> +		return -EIO;
> +	}
>  
> -	wr_reg32(&jrp->rregs->inpring_jobadd, 1);
> +	ret = __caam_jr_enqueue(jrp, desc, desc_size, desc_dma, cbk, areq,
> +				true);
> +	if (unlikely(ret && (ret != -EBUSY)))
> +		dma_unmap_single(dev, desc_dma, desc_size, DMA_TO_DEVICE);
>  
> -	spin_unlock_bh(&jrp->inplock);
> +	return ret;
>  
> -	return 0;
>  }
> -EXPORT_SYMBOL(caam_jr_enqueue);
> +EXPORT_SYMBOL(caam_jr_enqueue_bklog);
>  
>  /*
>   * Init JobR independent of platform property detection
> diff --git a/drivers/crypto/caam/jr.h b/drivers/crypto/caam/jr.h
> index 97113a6..21558df 100644
> --- a/drivers/crypto/caam/jr.h
> +++ b/drivers/crypto/caam/jr.h
> @@ -15,4 +15,9 @@ int caam_jr_enqueue(struct device *dev, u32 *desc,
>  				void *areq),
>  		    void *areq);
>  
> +int caam_jr_enqueue_bklog(struct device *dev, u32 *desc,
> +			  void (*cbk)(struct device *dev, u32 *desc, u32 status,
> +				      void *areq),
> +			  void *areq);
> +
>  #endif /* JR_H */
> 

Regards,
Horia
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Herbert Xu May 10, 2016, 9:46 a.m. UTC | #2

Catalin Vasile <cata.vasile@nxp.com> wrote:
> caam_jr_enqueue() function returns -EBUSY once there are no more slots
> available in the JR, but it doesn't actually save the current request.
> This breaks the functionality of users that expect that even if there is
> no more space for the request, it is at least queued for later
> execution. In other words, all crypto transformations that request
> backlogging (i.e. have CRYPTO_TFM_REQ_MAY_BACKLOG set), will hang. Such
> an example is dm-crypt. The current patch solves this issue by setting a
> threshold after which caam_jr_enqueue() returns -EBUSY, but since the HW
> job ring isn't actually full, the job is enqueued.
> 
> Signed-off-by: Alexandru Porosanu <alexandru.porosanu@nxp.com>
> Tested-by: Catalin Vasile <cata.vasile@nxp.com>

This is not acceptable.  The request that triggers EBUSY must
be allowed to queue.  As the number of tfms is unlimited you
can't just put them onto the hardware queue and hope that it
works out.

You should use a software queue instead.

Cheers,

Alexandru Porosanu May 10, 2016, 2:59 p.m. UTC | #3

Hi,

> -----Original Message-----
> From: Horia Ioan Geanta Neag
> Sent: Monday, May 09, 2016 5:51 PM
> To: Catalin Vasile <cata.vasile@nxp.com>; linux-crypto@vger.kernel.org
> Cc: linux-crypto-owner@vger.kernel.org; Alexandru Porosanu
> <alexandru.porosanu@nxp.com>; Scott Wood <scott.wood@nxp.com>
> Subject: Re: [PATCH] crypto: caam: add backlogging support
> 
> On 5/6/2016 4:19 PM, Catalin Vasile wrote:
> > caam_jr_enqueue() function returns -EBUSY once there are no more slots
> > available in the JR, but it doesn't actually save the current request.
> > This breaks the functionality of users that expect that even if there
> > is no more space for the request, it is at least queued for later
> > execution. In other words, all crypto transformations that request
> > backlogging (i.e. have CRYPTO_TFM_REQ_MAY_BACKLOG set), will hang.
> > Such an example is dm-crypt. The current patch solves this issue by
> > setting a threshold after which caam_jr_enqueue() returns -EBUSY, but
> > since the HW job ring isn't actually full, the job is enqueued.
> >
> The commit message should mention that *both* number of tfms / Job Ring
> *and* the number of available Job Ring slots (configured by
> CRYPTO_DEV_FSL_CAAM_RINGSIZE) is being limited by JOBR_THRESH:
> tfms / Job Ring < JOBR_THRESH
> available (free) Job Ring slots >= JOBR_THRESH
[AP] I'm not sure that we need to confuse the user even more; setting the # of slots is anyhow not so obvious. On the other hand, we have a self-imposed limitation for the # of slots (power of two). I'd like to run some benchmarks and see if the cpu load is affected that much when giving up this constraint. If so, then we can go up to 1023 slots per JR.

> 
> Shouldn't caam_jr_enqueue() from key_gen.c be changed too?
> Generating a split key is supposed to be done on behalf of the underlying
> tfm, thus the MAY_BACKLOG flag should be checked here too.
[AP] I'd actually like to fail the tunnel creation in case split key fails. Either way, the code needs to be adjusted.

> 
> > Signed-off-by: Alexandru Porosanu <alexandru.porosanu@nxp.com>
> > Tested-by: Catalin Vasile <cata.vasile@nxp.com>
> > ---
> >  drivers/crypto/caam/caamalg.c  |  88 ++++++++++++++++--
> > drivers/crypto/caam/caamhash.c | 101 +++++++++++++++++++--
> >  drivers/crypto/caam/intern.h   |   7 ++
> >  drivers/crypto/caam/jr.c       | 196
> +++++++++++++++++++++++++++++++++--------
> >  drivers/crypto/caam/jr.h       |   5 ++
> >  5 files changed, 343 insertions(+), 54 deletions(-)
> >
> > diff --git a/drivers/crypto/caam/caamalg.c
> > b/drivers/crypto/caam/caamalg.c index ea8189f..62bce17 100644
> > --- a/drivers/crypto/caam/caamalg.c
> > +++ b/drivers/crypto/caam/caamalg.c
> > @@ -1921,6 +1921,9 @@ static void aead_encrypt_done(struct device
> > *jrdev, u32 *desc, u32 err,
> >
> >  	edesc = container_of(desc, struct aead_edesc, hw_desc[0]);
> >
> > +	if (err == -EINPROGRESS)
> > +		goto out_bklogged;
> 
> Checking that err is -EINPROGRESS should be the first thing to do in *_done
> callbacks.
> 
> > +
> >  	if (err)
> >  		caam_jr_strstatus(jrdev, err);
> >
> > @@ -1928,6 +1931,7 @@ static void aead_encrypt_done(struct device
> > *jrdev, u32 *desc, u32 err,
> >
> >  	kfree(edesc);
> >
> > +out_bklogged:
> >  	aead_request_complete(req, err);
> >  }
> >
> > @@ -1943,6 +1947,9 @@ static void aead_decrypt_done(struct device
> > *jrdev, u32 *desc, u32 err,
> >
> >  	edesc = container_of(desc, struct aead_edesc, hw_desc[0]);
> >
> > +	if (err == -EINPROGRESS)
> > +		goto out_bklogged;
> > +
> >  	if (err)
> >  		caam_jr_strstatus(jrdev, err);
> >
> > @@ -1956,6 +1963,7 @@ static void aead_decrypt_done(struct device
> > *jrdev, u32 *desc, u32 err,
> >
> >  	kfree(edesc);
> >
> > +out_bklogged:
> >  	aead_request_complete(req, err);
> >  }
> >
> > @@ -1974,6 +1982,9 @@ static void ablkcipher_encrypt_done(struct
> device *jrdev, u32 *desc, u32 err,
> >  	edesc = (struct ablkcipher_edesc *)((char *)desc -
> >  		 offsetof(struct ablkcipher_edesc, hw_desc));
> >
> > +	if (err == -EINPROGRESS)
> > +		goto out_bklogged;
> > +
> >  	if (err)
> >  		caam_jr_strstatus(jrdev, err);
> >
> > @@ -1989,6 +2000,7 @@ static void ablkcipher_encrypt_done(struct
> device *jrdev, u32 *desc, u32 err,
> >  	ablkcipher_unmap(jrdev, edesc, req);
> >  	kfree(edesc);
> >
> > +out_bklogged:
> >  	ablkcipher_request_complete(req, err);  }
> >
> > @@ -2006,6 +2018,10 @@ static void ablkcipher_decrypt_done(struct
> > device *jrdev, u32 *desc, u32 err,
> >
> >  	edesc = (struct ablkcipher_edesc *)((char *)desc -
> >  		 offsetof(struct ablkcipher_edesc, hw_desc));
> > +
> > +	if (err == -EINPROGRESS)
> > +		goto out_bklogged;
> > +
> >  	if (err)
> >  		caam_jr_strstatus(jrdev, err);
> >
> > @@ -2021,6 +2037,7 @@ static void ablkcipher_decrypt_done(struct
> device *jrdev, u32 *desc, u32 err,
> >  	ablkcipher_unmap(jrdev, edesc, req);
> >  	kfree(edesc);
> >
> > +out_bklogged:
> >  	ablkcipher_request_complete(req, err);  }
> >
> > @@ -2394,7 +2411,15 @@ static int gcm_encrypt(struct aead_request
> > *req)  #endif
> >
> >  	desc = edesc->hw_desc;
> > -	ret = caam_jr_enqueue(jrdev, desc, aead_encrypt_done, req);
> > +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> > +		ret = caam_jr_enqueue_bklog(jrdev, desc,
> aead_encrypt_done,
> > +					    req);
> > +		if (ret == -EBUSY)
> > +			return ret;
> > +	} else {
> > +		ret = caam_jr_enqueue(jrdev, desc, aead_encrypt_done,
> req);
> > +	}
> > +
> >  	if (!ret) {
> >  		ret = -EINPROGRESS;
> >  	} else {
> > @@ -2438,7 +2463,15 @@ static int aead_encrypt(struct aead_request
> > *req)  #endif
> >
> >  	desc = edesc->hw_desc;
> > -	ret = caam_jr_enqueue(jrdev, desc, aead_encrypt_done, req);
> > +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> > +		ret = caam_jr_enqueue_bklog(jrdev, desc,
> aead_encrypt_done,
> > +					    req);
> > +		if (ret == -EBUSY)
> > +			return ret;
> > +	} else {
> > +		ret = caam_jr_enqueue(jrdev, desc, aead_encrypt_done,
> req);
> > +	}
> > +
> >  	if (!ret) {
> >  		ret = -EINPROGRESS;
> >  	} else {
> > @@ -2473,7 +2506,15 @@ static int gcm_decrypt(struct aead_request
> > *req)  #endif
> >
> >  	desc = edesc->hw_desc;
> > -	ret = caam_jr_enqueue(jrdev, desc, aead_decrypt_done, req);
> > +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> > +		ret = caam_jr_enqueue_bklog(jrdev, desc,
> aead_decrypt_done,
> > +					    req);
> > +		if (ret == -EBUSY)
> > +			return ret;
> > +	} else {
> > +		ret = caam_jr_enqueue(jrdev, desc, aead_decrypt_done,
> req);
> > +	}
> > +
> >  	if (!ret) {
> >  		ret = -EINPROGRESS;
> >  	} else {
> > @@ -2523,7 +2564,15 @@ static int aead_decrypt(struct aead_request
> > *req)  #endif
> >
> >  	desc = edesc->hw_desc;
> > -	ret = caam_jr_enqueue(jrdev, desc, aead_decrypt_done, req);
> > +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> > +		ret = caam_jr_enqueue_bklog(jrdev, desc,
> aead_decrypt_done,
> > +					    req);
> > +		if (ret == -EBUSY)
> > +			return ret;
> > +	} else {
> > +		ret = caam_jr_enqueue(jrdev, desc, aead_decrypt_done,
> req);
> > +	}
> > +
> >  	if (!ret) {
> >  		ret = -EINPROGRESS;
> >  	} else {
> > @@ -2672,7 +2721,15 @@ static int ablkcipher_encrypt(struct
> ablkcipher_request *req)
> >  		       desc_bytes(edesc->hw_desc), 1);  #endif
> >  	desc = edesc->hw_desc;
> > -	ret = caam_jr_enqueue(jrdev, desc, ablkcipher_encrypt_done, req);
> > +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> > +		ret = caam_jr_enqueue_bklog(jrdev, desc,
> > +					    ablkcipher_encrypt_done, req);
> > +		if (ret == -EBUSY)
> > +			return ret;
> > +	} else {
> > +		ret = caam_jr_enqueue(jrdev, desc,
> ablkcipher_encrypt_done,
> > +				      req);
> > +	}
> >
> >  	if (!ret) {
> >  		ret = -EINPROGRESS;
> > @@ -2710,7 +2767,16 @@ static int ablkcipher_decrypt(struct
> ablkcipher_request *req)
> >  		       desc_bytes(edesc->hw_desc), 1);  #endif
> >
> > -	ret = caam_jr_enqueue(jrdev, desc, ablkcipher_decrypt_done, req);
> > +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> > +		ret = caam_jr_enqueue_bklog(jrdev, desc,
> > +					    ablkcipher_decrypt_done, req);
> > +		if (ret == -EBUSY)
> > +			return ret;
> > +	} else {
> > +		ret = caam_jr_enqueue(jrdev, desc,
> ablkcipher_decrypt_done,
> > +				      req);
> > +	}
> > +
> >  	if (!ret) {
> >  		ret = -EINPROGRESS;
> >  	} else {
> > @@ -2851,7 +2917,15 @@ static int ablkcipher_givencrypt(struct
> skcipher_givcrypt_request *creq)
> >  		       desc_bytes(edesc->hw_desc), 1);  #endif
> >  	desc = edesc->hw_desc;
> > -	ret = caam_jr_enqueue(jrdev, desc, ablkcipher_encrypt_done, req);
> > +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> > +		ret = caam_jr_enqueue_bklog(jrdev, desc,
> > +					    ablkcipher_encrypt_done, req);
> > +		if (ret == -EBUSY)
> > +			return ret;
> > +	} else {
> > +		ret = caam_jr_enqueue(jrdev, desc,
> ablkcipher_encrypt_done,
> > +				      req);
> > +	}
> >
> >  	if (!ret) {
> >  		ret = -EINPROGRESS;
> > diff --git a/drivers/crypto/caam/caamhash.c
> > b/drivers/crypto/caam/caamhash.c index 5845d4a..910a350 100644
> > --- a/drivers/crypto/caam/caamhash.c
> > +++ b/drivers/crypto/caam/caamhash.c
> > @@ -650,6 +650,10 @@ static void ahash_done(struct device *jrdev, u32
> > *desc, u32 err,
> >
> >  	edesc = (struct ahash_edesc *)((char *)desc -
> >  		 offsetof(struct ahash_edesc, hw_desc));
> > +
> > +	if (err == -EINPROGRESS)
> > +		goto out_bklogged;
> > +
> >  	if (err)
> >  		caam_jr_strstatus(jrdev, err);
> >
> > @@ -666,6 +670,7 @@ static void ahash_done(struct device *jrdev, u32
> *desc, u32 err,
> >  			       digestsize, 1);
> >  #endif
> >
> > +out_bklogged:
> >  	req->base.complete(&req->base, err);  }
> >
> > @@ -685,6 +690,10 @@ static void ahash_done_bi(struct device *jrdev,
> > u32 *desc, u32 err,
> >
> >  	edesc = (struct ahash_edesc *)((char *)desc -
> >  		 offsetof(struct ahash_edesc, hw_desc));
> > +
> > +	if (err == -EINPROGRESS)
> > +		goto out_bklogged;
> > +
> >  	if (err)
> >  		caam_jr_strstatus(jrdev, err);
> >
> > @@ -701,6 +710,7 @@ static void ahash_done_bi(struct device *jrdev, u32
> *desc, u32 err,
> >  			       digestsize, 1);
> >  #endif
> >
> > +out_bklogged:
> >  	req->base.complete(&req->base, err);  }
> >
> > @@ -720,6 +730,10 @@ static void ahash_done_ctx_src(struct device
> > *jrdev, u32 *desc, u32 err,
> >
> >  	edesc = (struct ahash_edesc *)((char *)desc -
> >  		 offsetof(struct ahash_edesc, hw_desc));
> > +
> > +	if (err == -EINPROGRESS)
> > +		goto out_bklogged;
> > +
> >  	if (err)
> >  		caam_jr_strstatus(jrdev, err);
> >
> > @@ -736,6 +750,7 @@ static void ahash_done_ctx_src(struct device
> *jrdev, u32 *desc, u32 err,
> >  			       digestsize, 1);
> >  #endif
> >
> > +out_bklogged:
> >  	req->base.complete(&req->base, err);  }
> >
> > @@ -755,6 +770,10 @@ static void ahash_done_ctx_dst(struct device
> > *jrdev, u32 *desc, u32 err,
> >
> >  	edesc = (struct ahash_edesc *)((char *)desc -
> >  		 offsetof(struct ahash_edesc, hw_desc));
> > +
> > +	if (err == -EINPROGRESS)
> > +		goto out_bklogged;
> > +
> >  	if (err)
> >  		caam_jr_strstatus(jrdev, err);
> >
> > @@ -771,6 +790,7 @@ static void ahash_done_ctx_dst(struct device
> *jrdev, u32 *desc, u32 err,
> >  			       digestsize, 1);
> >  #endif
> >
> > +out_bklogged:
> >  	req->base.complete(&req->base, err);  }
> >
> > @@ -876,7 +896,15 @@ static int ahash_update_ctx(struct ahash_request
> *req)
> >  			       desc_bytes(desc), 1);
> >  #endif
> >
> > -		ret = caam_jr_enqueue(jrdev, desc, ahash_done_bi, req);
> > +		if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> > +			ret = caam_jr_enqueue_bklog(jrdev, desc,
> ahash_done_bi,
> > +						    req);
> > +			if (ret == -EBUSY)
> > +				return ret;
> > +		} else {
> > +			ret = caam_jr_enqueue(jrdev, desc, ahash_done_bi,
> req);
> > +		}
> > +
> >  		if (!ret) {
> >  			ret = -EINPROGRESS;
> >  		} else {
> > @@ -973,7 +1001,15 @@ static int ahash_final_ctx(struct ahash_request
> *req)
> >  		       DUMP_PREFIX_ADDRESS, 16, 4, desc, desc_bytes(desc),
> 1);
> > #endif
> >
> > -	ret = caam_jr_enqueue(jrdev, desc, ahash_done_ctx_src, req);
> > +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> > +		ret = caam_jr_enqueue_bklog(jrdev, desc,
> ahash_done_ctx_src,
> > +					    req);
> > +		if (ret == -EBUSY)
> > +			return ret;
> > +	} else {
> > +		ret = caam_jr_enqueue(jrdev, desc, ahash_done_ctx_src,
> req);
> > +	}
> > +
> >  	if (!ret) {
> >  		ret = -EINPROGRESS;
> >  	} else {
> > @@ -1065,7 +1101,15 @@ static int ahash_finup_ctx(struct ahash_request
> *req)
> >  		       DUMP_PREFIX_ADDRESS, 16, 4, desc, desc_bytes(desc),
> 1);
> > #endif
> >
> > -	ret = caam_jr_enqueue(jrdev, desc, ahash_done_ctx_src, req);
> > +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> > +		ret = caam_jr_enqueue_bklog(jrdev, desc,
> ahash_done_ctx_src,
> > +					    req);
> > +		if (ret == -EBUSY)
> > +			return ret;
> > +	} else {
> > +		ret = caam_jr_enqueue(jrdev, desc, ahash_done_ctx_src,
> req);
> > +	}
> > +
> >  	if (!ret) {
> >  		ret = -EINPROGRESS;
> >  	} else {
> > @@ -1145,7 +1189,14 @@ static int ahash_digest(struct ahash_request
> *req)
> >  		       DUMP_PREFIX_ADDRESS, 16, 4, desc, desc_bytes(desc),
> 1);
> > #endif
> >
> > -	ret = caam_jr_enqueue(jrdev, desc, ahash_done, req);
> > +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> > +		ret = caam_jr_enqueue_bklog(jrdev, desc, ahash_done,
> req);
> > +		if (ret == -EBUSY)
> > +			return ret;
> > +	} else {
> > +		ret = caam_jr_enqueue(jrdev, desc, ahash_done, req);
> > +	}
> > +
> >  	if (!ret) {
> >  		ret = -EINPROGRESS;
> >  	} else {
> > @@ -1207,7 +1258,14 @@ static int ahash_final_no_ctx(struct
> ahash_request *req)
> >  		       DUMP_PREFIX_ADDRESS, 16, 4, desc, desc_bytes(desc),
> 1);
> > #endif
> >
> > -	ret = caam_jr_enqueue(jrdev, desc, ahash_done, req);
> > +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> > +		ret = caam_jr_enqueue_bklog(jrdev, desc, ahash_done,
> req);
> > +		if (ret == -EBUSY)
> > +			return ret;
> > +	} else {
> > +		ret = caam_jr_enqueue(jrdev, desc, ahash_done, req);
> > +	}
> > +
> >  	if (!ret) {
> >  		ret = -EINPROGRESS;
> >  	} else {
> > @@ -1308,7 +1366,16 @@ static int ahash_update_no_ctx(struct
> ahash_request *req)
> >  			       desc_bytes(desc), 1);
> >  #endif
> >
> > -		ret = caam_jr_enqueue(jrdev, desc, ahash_done_ctx_dst,
> req);
> > +		if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> > +			ret = caam_jr_enqueue_bklog(jrdev, desc,
> > +						    ahash_done_ctx_dst, req);
> > +			if (ret == -EBUSY)
> > +				return ret;
> > +		} else {
> > +			ret = caam_jr_enqueue(jrdev, desc,
> ahash_done_ctx_dst,
> > +					      req);
> > +		}
> > +
> >  		if (!ret) {
> >  			ret = -EINPROGRESS;
> >  			state->update = ahash_update_ctx;
> > @@ -1411,7 +1478,15 @@ static int ahash_finup_no_ctx(struct
> ahash_request *req)
> >  		       DUMP_PREFIX_ADDRESS, 16, 4, desc, desc_bytes(desc),
> 1);
> > #endif
> >
> > -	ret = caam_jr_enqueue(jrdev, desc, ahash_done, req);
> > +	if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> > +		ret = caam_jr_enqueue_bklog(jrdev, desc, ahash_done,
> > +					    req);
> > +		if (ret == -EBUSY)
> > +			return ret;
> > +	} else {
> > +		ret = caam_jr_enqueue(jrdev, desc, ahash_done, req);
> > +	}
> > +
> >  	if (!ret) {
> >  		ret = -EINPROGRESS;
> >  	} else {
> > @@ -1514,8 +1589,16 @@ static int ahash_update_first(struct
> ahash_request *req)
> >  			       desc_bytes(desc), 1);
> >  #endif
> >
> > -		ret = caam_jr_enqueue(jrdev, desc, ahash_done_ctx_dst,
> > -				      req);
> > +		if (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
> > +			ret = caam_jr_enqueue_bklog(jrdev, desc,
> > +						    ahash_done_ctx_dst, req);
> > +			if (ret == -EBUSY)
> > +				return ret;
> > +		} else {
> > +			ret = caam_jr_enqueue(jrdev, desc,
> ahash_done_ctx_dst,
> > +					      req);
> > +		}
> > +
> >  		if (!ret) {
> >  			ret = -EINPROGRESS;
> >  			state->update = ahash_update_ctx;
> > diff --git a/drivers/crypto/caam/intern.h
> > b/drivers/crypto/caam/intern.h index e2bcacc..aa4e257 100644
> > --- a/drivers/crypto/caam/intern.h
> > +++ b/drivers/crypto/caam/intern.h
> > @@ -11,6 +11,12 @@
> >
> >  /* Currently comes from Kconfig param as a ^2 (driver-required) */
> > #define JOBR_DEPTH (1 << CONFIG_CRYPTO_DEV_FSL_CAAM_RINGSIZE)
> > +/*
> > + * If the user tries to enqueue a job and the number of slots
> > +available
> > + * is less than this value, then the job will be backlogged (if the
> > +user
> > + * allows for it) or it will be dropped.
> > + */
> > +#define JOBR_THRESH (JOBR_DEPTH / 2 - 1)
> >
> >  /* Kconfig params for interrupt coalescing if selected (else zero) */
> > #ifdef CONFIG_CRYPTO_DEV_FSL_CAAM_INTC @@ -33,6 +39,7 @@ struct
> > caam_jrentry_info {
> >  	u32 *desc_addr_virt;	/* Stored virt addr for postprocessing */
> >  	dma_addr_t desc_addr_dma;	/* Stored bus addr for done matching
> */
> >  	u32 desc_size;	/* Stored size for postprocessing, header derived */
> > +	bool is_backlogged; /* True if the request has been backlogged */
> >  };
> >
> >  /* Private sub-storage for a single JobR */ diff --git
> > a/drivers/crypto/caam/jr.c b/drivers/crypto/caam/jr.c index
> > 5ef4be2..49790e1 100644
> > --- a/drivers/crypto/caam/jr.c
> > +++ b/drivers/crypto/caam/jr.c
> > @@ -168,6 +168,7 @@ static void caam_jr_dequeue(unsigned long devarg)
> >  	void (*usercall)(struct device *dev, u32 *desc, u32 status, void *arg);
> >  	u32 *userdesc, userstatus;
> >  	void *userarg;
> > +	bool is_backlogged;
> >
> >  	while (rd_reg32(&jrp->rregs->outring_used)) {
> >
> > @@ -201,6 +202,9 @@ static void caam_jr_dequeue(unsigned long devarg)
> >  		userarg = jrp->entinfo[sw_idx].cbkarg;
> >  		userdesc = jrp->entinfo[sw_idx].desc_addr_virt;
> >  		userstatus = jrp->outring[hw_idx].jrstatus;
> > +		is_backlogged = jrp->entinfo[sw_idx].is_backlogged;
> > +		/* Reset backlogging status here */
> > +		jrp->entinfo[sw_idx].is_backlogged = false;
> >
> >  		/*
> >  		 * Make sure all information from the job has been obtained
> @@
> > -231,6 +235,20 @@ static void caam_jr_dequeue(unsigned long devarg)
> >
> >  		spin_unlock(&jrp->outlock);
> >
> > +		if (is_backlogged)
> > +			/*
> > +			 * For backlogged requests, the user callback needs
> to
> > +			 * be called twice: once when starting to process it
> > +			 * (with a status of -EINPROGRESS and once when it's
> 			   ^ paranthesis not closed
> 
> > +			 * done. Since SEC cheats by enqueuing the request
> in
> > +			 * its HW ring but returning -EBUSY, the time when
> the
> > +			 * request's processing has started is not known.
> > +			 * Thus notify here the user. The second call is on the
> > +			 * normal path (i.e. the one that is called even for
> > +			 * non-backlogged requests).
> > +			 */
> > +			usercall(dev, userdesc, -EINPROGRESS, userarg);
> > +
> >  		/* Finally, execute user's callback */
> >  		usercall(dev, userdesc, userstatus, userarg);
> >  	}
> > @@ -261,6 +279,15 @@ struct device *caam_jr_alloc(void)
> >
> >  	list_for_each_entry(jrpriv, &driver_data.jr_list, list_node) {
> >  		tfm_cnt = atomic_read(&jrpriv->tfm_count);
> > +
> > +		/*
> > +		 * Don't allow more than JOBR_THRES jobs on this JR. If more
> 
> What's being limited here is not the number of jobs, but the number of tfms.
> 
> > +		 * are allowed, then backlogging API contract won't work
> (each
> > +		 * "backloggable" tfm must allow for at least 1 enqueue.
> > +		 */
> > +		if (tfm_cnt == JOBR_THRESH)
> > +			continue;
> > +
> >  		if (tfm_cnt < min_tfm_cnt) {
> >  			min_tfm_cnt = tfm_cnt;
> >  			min_jrpriv = jrpriv;
> > @@ -292,6 +319,80 @@ void caam_jr_free(struct device *rdev)  }
> > EXPORT_SYMBOL(caam_jr_free);
> >
> > +static inline int __caam_jr_enqueue(struct caam_drv_private_jr *jrp, u32
> *desc,
> > +				    int desc_size, dma_addr_t desc_dma,
> > +				    void (*cbk)(struct device *dev, u32 *desc,
> > +						u32 status, void *areq),
> > +				    void *areq,
> > +				    bool can_be_backlogged)
> > +{
> > +	int head, tail;
> > +	struct caam_jrentry_info *head_entry;
> > +	int ret = 0, hw_slots, sw_slots;
> > +
> > +	spin_lock_bh(&jrp->inplock);
> > +
> > +	head = jrp->head;
> > +	tail = ACCESS_ONCE(jrp->tail);
> > +
> > +	head_entry = &jrp->entinfo[head];
> > +
> > +	hw_slots = rd_reg32(&jrp->rregs->inpring_avail);
> > +	sw_slots = CIRC_SPACE(head, tail, JOBR_DEPTH);
> > +
> > +	if (hw_slots <= JOBR_THRESH || sw_slots <= JOBR_THRESH) {
> > +		/*
> > +		 * The state below can be reached in three cases:
> > +		 * 1) A badly behaved backlogging user doesn't back off when
> > +		 *    told so by the -EBUSY return code
> > +		 * 2) More than JOBR_THRESH backlogging users requests
> 
> AFAICS, this case is no longer possible, since the number of "users"
> (tfms) is being limited to JOBR_THRESH in caam_jr_alloc().
> 
> > +		 * 3) Due to the high system load, the entries reserved for
> the
> > +		 *    backlogging users are being filled (slowly) in between
> > +		 *    the successive calls to the user callback (the first one
> > +		 *    with -EINPROGRESS and the 2nd one with the real result.
> > +		 * The code below is a last-resort measure which will DROP
> > +		 * any request if there is physically no more space. This will
> > +		 * lead to data-loss for disk-related users.
> 		   ^^^^^^^^^^^^^^^^^^^^^^^^^^
> This should be enough to reject the solution.
> It's way too easy / probable to start losing data, when compared with a SW-
> only queue that is bounded only by system memory.
> 
> > +		 */
> > +		if (!hw_slots || !sw_slots) {
> > +			ret = -EIO;
> > +			goto out_unlock;
> > +		}
> > +
> > +		ret = -EBUSY;
> > +		if (!can_be_backlogged)
> > +			goto out_unlock;
> > +
> > +		head_entry->is_backlogged = true;
> > +	}
> > +
> > +	head_entry->desc_addr_virt = desc;
> > +	head_entry->desc_size = desc_size;
> > +	head_entry->callbk = (void *)cbk;
> > +	head_entry->cbkarg = areq;
> > +	head_entry->desc_addr_dma = desc_dma;
> > +
> > +	jrp->inpring[jrp->inp_ring_write_index] = desc_dma;
> > +
> > +	/*
> > +	 * Guarantee that the descriptor's DMA address has been written to
> > +	 * the next slot in the ring before the write index is updated, since
> > +	 * other cores may update this index independently.
> > +	 */
> > +	smp_wmb();
> > +
> > +	jrp->inp_ring_write_index = (jrp->inp_ring_write_index + 1) &
> > +				    (JOBR_DEPTH - 1);
> > +	jrp->head = (head + 1) & (JOBR_DEPTH - 1);
> > +
> > +	wr_reg32(&jrp->rregs->inpring_jobadd, 1);
> > +
> > +out_unlock:
> > +	spin_unlock_bh(&jrp->inplock);
> > +
> > +	return ret;
> > +}
> > +
> >  /**
> >   * caam_jr_enqueue() - Enqueue a job descriptor head. Returns 0 if OK,
> >   * -EBUSY if the queue is full, -EIO if it cannot map the caller's @@
> > -326,8 +427,7 @@ int caam_jr_enqueue(struct device *dev, u32 *desc,
> >  		    void *areq)
> >  {
> >  	struct caam_drv_private_jr *jrp = dev_get_drvdata(dev);
> > -	struct caam_jrentry_info *head_entry;
> > -	int head, tail, desc_size;
> > +	int desc_size, ret;
> >  	dma_addr_t desc_dma;
> >
> >  	desc_size = (*desc & HDR_JD_LENGTH_MASK) * sizeof(u32); @@ -
> 337,51
> > +437,71 @@ int caam_jr_enqueue(struct device *dev, u32 *desc,
> >  		return -EIO;
> >  	}
> >
> > -	spin_lock_bh(&jrp->inplock);
> > -
> > -	head = jrp->head;
> > -	tail = ACCESS_ONCE(jrp->tail);
> > -
> > -	if (!rd_reg32(&jrp->rregs->inpring_avail) ||
> > -	    CIRC_SPACE(head, tail, JOBR_DEPTH) <= 0) {
> > -		spin_unlock_bh(&jrp->inplock);
> > +	ret = __caam_jr_enqueue(jrp, desc, desc_size, desc_dma, cbk, areq,
> > +				false);
> > +	if (unlikely(ret))
> >  		dma_unmap_single(dev, desc_dma, desc_size,
> DMA_TO_DEVICE);
> > -		return -EBUSY;
> > -	}
> >
> > -	head_entry = &jrp->entinfo[head];
> > -	head_entry->desc_addr_virt = desc;
> > -	head_entry->desc_size = desc_size;
> > -	head_entry->callbk = (void *)cbk;
> > -	head_entry->cbkarg = areq;
> > -	head_entry->desc_addr_dma = desc_dma;
> > -
> > -	jrp->inpring[jrp->inp_ring_write_index] = desc_dma;
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL(caam_jr_enqueue);
> >
> > -	/*
> > -	 * Guarantee that the descriptor's DMA address has been written to
> > -	 * the next slot in the ring before the write index is updated, since
> > -	 * other cores may update this index independently.
> > -	 */
> > -	smp_wmb();
> > +/**
> > + * caam_jr_enqueue_bklog() - Enqueue a job descriptor head, returns 0
> > +if OK, or
> > + * -EBUSY if the number of available entries in the Job Ring is less
> > + * than the threshold configured through JOBR_THRESH, and -EIO if it
> > +cannot map
> > + * the caller's descriptor or if there is really no more space in the
> > +hardware
> > + * job ring.
> > + * @dev:  device of the job ring to be used. This device should have
> > + *        been assigned prior by caam_jr_register().
> > + * @desc: points to a job descriptor that execute our request. All
> > + *        descriptors (and all referenced data) must be in a DMAable
> > + *        region, and all data references must be physical addresses
> > + *        accessible to CAAM (i.e. within a PAMU window granted
> > + *        to it).
> > + * @cbk:  pointer to a callback function to be invoked upon completion
> > + *        of this request. This has the form:
> > + *        callback(struct device *dev, u32 *desc, u32 stat, void *arg)
> > + *        where:
> > + *        @dev:    contains the job ring device that processed this
> > + *                 response.
> > + *        @desc:   descriptor that initiated the request, same as
> > + *                 "desc" being argued to caam_jr_enqueue().
> > + *        @status: untranslated status received from CAAM. See the
> > + *                 reference manual for a detailed description of
> > + *                 error meaning, or see the JRSTA definitions in the
> > + *                 register header file
> > + *        @areq:   optional pointer to an argument passed with the
> > + *                 original request
> > + * @areq: optional pointer to a user argument for use at callback
> > + *        time.
> > + **/
> > +int caam_jr_enqueue_bklog(struct device *dev, u32 *desc,
> > +			  void (*cbk)(struct device *dev, u32 *desc,
> > +				      u32 status, void *areq),
> > +			  void *areq)
> > +{
> > +	struct caam_drv_private_jr *jrp = dev_get_drvdata(dev);
> > +	int desc_size, ret;
> > +	dma_addr_t desc_dma;
> >
> > -	jrp->inp_ring_write_index = (jrp->inp_ring_write_index + 1) &
> > -				    (JOBR_DEPTH - 1);
> > -	jrp->head = (head + 1) & (JOBR_DEPTH - 1);
> >
> > -	/*
> > -	 * Ensure that all job information has been written before
> > -	 * notifying CAAM that a new job was added to the input ring.
> > -	 */
> > -	wmb();
> > +	desc_size = (*desc & HDR_JD_LENGTH_MASK) * sizeof(u32);
> > +	desc_dma = dma_map_single(dev, desc, desc_size,
> DMA_TO_DEVICE);
> > +	if (dma_mapping_error(dev, desc_dma)) {
> > +		dev_err(dev, "caam_jr_enqueue(): can't map jobdesc\n");
> > +		return -EIO;
> > +	}
> >
> > -	wr_reg32(&jrp->rregs->inpring_jobadd, 1);
> > +	ret = __caam_jr_enqueue(jrp, desc, desc_size, desc_dma, cbk, areq,
> > +				true);
> > +	if (unlikely(ret && (ret != -EBUSY)))
> > +		dma_unmap_single(dev, desc_dma, desc_size,
> DMA_TO_DEVICE);
> >
> > -	spin_unlock_bh(&jrp->inplock);
> > +	return ret;
> >
> > -	return 0;
> >  }
> > -EXPORT_SYMBOL(caam_jr_enqueue);
> > +EXPORT_SYMBOL(caam_jr_enqueue_bklog);
> >
> >  /*
> >   * Init JobR independent of platform property detection diff --git
> > a/drivers/crypto/caam/jr.h b/drivers/crypto/caam/jr.h index
> > 97113a6..21558df 100644
> > --- a/drivers/crypto/caam/jr.h
> > +++ b/drivers/crypto/caam/jr.h
> > @@ -15,4 +15,9 @@ int caam_jr_enqueue(struct device *dev, u32 *desc,
> >  				void *areq),
> >  		    void *areq);
> >
> > +int caam_jr_enqueue_bklog(struct device *dev, u32 *desc,
> > +			  void (*cbk)(struct device *dev, u32 *desc, u32
> status,
> > +				      void *areq),
> > +			  void *areq);
> > +
> >  #endif /* JR_H */
> >
> 
> Regards,
> Horia

BR,

Alex P.
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Catalin Vasile May 11, 2016, 7:53 a.m. UTC | #4

> 

> ________________________________________
> From: Herbert Xu <herbert@gondor.apana.org.au>
> Sent: Tuesday, May 10, 2016 12:46 PM
> To: Catalin Vasile
> Cc: linux-crypto@vger.kernel.org; linux-crypto-owner@vger.kernel.org; Horia Ioan Geanta Neag; Alexandru Porosanu; Scott Wood; Catalin Vasile
> Subject: Re: [PATCH] crypto: caam: add backlogging support> 

> Catalin Vasile <cata.vasile@nxp.com> wrote:
> > caam_jr_enqueue() function returns -EBUSY once there are no more slots
> > available in the JR, but it doesn't actually save the current request.
> > This breaks the functionality of users that expect that even if there is
> > no more space for the request, it is at least queued for later
> > execution. In other words, all crypto transformations that request
> > backlogging (i.e. have CRYPTO_TFM_REQ_MAY_BACKLOG set), will hang. Such
> > an example is dm-crypt. The current patch solves this issue by setting a
> > threshold after which caam_jr_enqueue() returns -EBUSY, but since the HW
> > job ring isn't actually full, the job is enqueued.
> >
> > Signed-off-by: Alexandru Porosanu <alexandru.porosanu@nxp.com>
> > Tested-by: Catalin Vasile <cata.vasile@nxp.com>> 

> This is not acceptable.  The request that triggers EBUSY must
> be allowed to queue.  As the number of tfms is unlimited you
> can't just put them onto the hardware queue and hope that it
> works out.>
Every request will be queued and eventually done.
The hardware equipment has a constraint on the number of tfms it can have.
Is there a requirement to support an infinite number of tfms on a device?

> You should use a software queue instead.> 

> 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
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Herbert Xu May 11, 2016, 10:54 a.m. UTC | #5

On Wed, May 11, 2016 at 07:53:19AM +0000, Catalin Vasile wrote:
>
> Every request will be queued and eventually done.
> The hardware equipment has a constraint on the number of tfms it can have.
> Is there a requirement to support an infinite number of tfms on a device?
> 
> > You should use a software queue instead.> 

As I said you drivers are always supposed to have a software queue
in addition to any hardware queues.  There is no reason why your
driver should be special in this regard.

Cheers,

Catalin Vasile May 13, 2016, 12:55 p.m. UTC | #6

> ________________________________________
> From: Herbert Xu <herbert@gondor.apana.org.au>
> Sent: Wednesday, May 11, 2016 1:54 PM
> To: Catalin Vasile
> Cc: linux-crypto@vger.kernel.org; linux-crypto-owner@vger.kernel.org; Horia Ioan Geanta Neag; Alexandru Porosanu; Scott Wood
> Subject: Re: [PATCH] crypto: caam: add backlogging support> 

> On Wed, May 11, 2016 at 07:53:19AM +0000, Catalin Vasile wrote:
> >
> > Every request will be queued and eventually done.
> > The hardware equipment has a constraint on the number of tfms it can have.
> > Is there a requirement to support an infinite number of tfms on a device?
> >
> > > You should use a software queue instead.>> 

> As I said you drivers are always supposed to have a software queue
> in addition to any hardware queues.  There is no reason why your
> driver should be special in this regard.>

Hi Herbert,

We are inclining towards a hardware backlogging solution because on
low end devices the software queue does not scale very well.
Regarding your concerns, we are now evaluating adding a software queue based
fallback solution: if the hardware backlogging fails because no hardware slots
are available, backlog the job inside a crypto software queue.
Is this hybrid configurable solution acceptable? Namely, if the hardware queue
is full, to fallback to the crypto software queue.

> 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
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Herbert Xu May 13, 2016, 1:50 p.m. UTC | #7

On Fri, May 13, 2016 at 12:55:09PM +0000, Catalin Vasile wrote:
> 
> We are inclining towards a hardware backlogging solution because on
> low end devices the software queue does not scale very well.
> Regarding your concerns, we are now evaluating adding a software queue based
> fallback solution: if the hardware backlogging fails because no hardware slots
> are available, backlog the job inside a crypto software queue.
> Is this hybrid configurable solution acceptable? Namely, if the hardware queue
> is full, to fallback to the crypto software queue.

It is but you need to be very careful so as to not introduce
reordering.

Essentially if you go to the fallback then you have to wait for
all the outstanding requests to complete before you complete the
fallback request.

A number of existing drivers that make use of fallbacks get this
wrong and we need to fix them.

Cheers,

crypto: caam: add backlogging support

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