crypto: inside-secure - remove request list to improve performance

This patch main goal is to improve driver performance by moving the
crypto request from a list to a RDR ring shadow.

This is possible since there is one producer and one consume for this
RDR request shadow and one ring descriptor is left unused.
Doing this change eliminates the use of spinlock when accessing the
descriptor ring and the need to dynamicaly allocate memory per crypto
request.

The crypto request is placed in the first RDR shadow descriptor only
if there are enough descriptors, when the result handler is invoked,
it fetches the first result descriptor from RDR shadow.

Signed-off-by: Ofer Heifetz <oferh@marvell.com>
Signed-off-by: Antoine Tenart <antoine.tenart@bootlin.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/inside-secure/safexcel.c

@@ -509,7 +509,6 @@ void safexcel_dequeue(struct safexcel_crypto_priv *priv, int ring)
 {
 	struct crypto_async_request *req, *backlog;
 	struct safexcel_context *ctx;
-	struct safexcel_request *request;
 	int ret, nreq = 0, cdesc = 0, rdesc = 0, commands, results;
 
 	/* If a request wasn't properly dequeued because of a lack of resources,
@@ -533,16 +532,10 @@ void safexcel_dequeue(struct safexcel_crypto_priv *priv, int ring)
 		}
 
 handle_req:
-		request = kzalloc(sizeof(*request), EIP197_GFP_FLAGS(*req));
-		if (!request)
-			goto request_failed;
-
 		ctx = crypto_tfm_ctx(req->tfm);
-		ret = ctx->send(req, ring, request, &commands, &results);
-		if (ret) {
-			kfree(request);
+		ret = ctx->send(req, ring, &commands, &results);
+		if (ret)
 			goto request_failed;
-		}
 
 		if (backlog)
 			backlog->complete(backlog, -EINPROGRESS);
@@ -551,14 +544,8 @@ handle_req:
 		 * to the engine because the input data was cached, continue to
 		 * dequeue other requests as this is valid and not an error.
 		 */
-		if (!commands && !results) {
-			kfree(request);
+		if (!commands && !results)
 			continue;
-		}
-
-		spin_lock_bh(&priv->ring[ring].egress_lock);
-		list_add_tail(&request->list, &priv->ring[ring].list);
-		spin_unlock_bh(&priv->ring[ring].egress_lock);
 
 		cdesc += commands;
 		rdesc += results;
@@ -576,7 +563,7 @@ finalize:
 	if (!nreq)
 		return;
 
-	spin_lock_bh(&priv->ring[ring].egress_lock);
+	spin_lock_bh(&priv->ring[ring].lock);
 
 	priv->ring[ring].requests += nreq;
 
@@ -585,7 +572,7 @@ finalize:
 		priv->ring[ring].busy = true;
 	}
 
-	spin_unlock_bh(&priv->ring[ring].egress_lock);
+	spin_unlock_bh(&priv->ring[ring].lock);
 
 	/* let the RDR know we have pending descriptors */
 	writel((rdesc * priv->config.rd_offset) << 2,
@@ -617,6 +604,24 @@ inline int safexcel_rdesc_check_errors(struct safexcel_crypto_priv *priv,
 	return -EINVAL;
 }
 
+inline void safexcel_rdr_req_set(struct safexcel_crypto_priv *priv,
+				 int ring,
+				 struct safexcel_result_desc *rdesc,
+				 struct crypto_async_request *req)
+{
+	int i = safexcel_ring_rdr_rdesc_index(priv, ring, rdesc);
+
+	priv->ring[ring].rdr_req[i] = req;
+}
+
+inline struct crypto_async_request *
+safexcel_rdr_req_get(struct safexcel_crypto_priv *priv, int ring)
+{
+	int i = safexcel_ring_first_rdr_index(priv, ring);
+
+	return priv->ring[ring].rdr_req[i];
+}
+
 void safexcel_complete(struct safexcel_crypto_priv *priv, int ring)
 {
 	struct safexcel_command_desc *cdesc;
@@ -645,21 +650,16 @@ void safexcel_inv_complete(struct crypto_async_request *req, int error)
 
 int safexcel_invalidate_cache(struct crypto_async_request *async,
 			      struct safexcel_crypto_priv *priv,
-			      dma_addr_t ctxr_dma, int ring,
-			      struct safexcel_request *request)
+			      dma_addr_t ctxr_dma, int ring)
 {
 	struct safexcel_command_desc *cdesc;
 	struct safexcel_result_desc *rdesc;
 	int ret = 0;
 
-	spin_lock_bh(&priv->ring[ring].egress_lock);
-
 	/* Prepare command descriptor */
 	cdesc = safexcel_add_cdesc(priv, ring, true, true, 0, 0, 0, ctxr_dma);
-	if (IS_ERR(cdesc)) {
-		ret = PTR_ERR(cdesc);
-		goto unlock;
-	}
+	if (IS_ERR(cdesc))
+		return PTR_ERR(cdesc);
 
 	cdesc->control_data.type = EIP197_TYPE_EXTENDED;
 	cdesc->control_data.options = 0;
@@ -674,21 +674,20 @@ int safexcel_invalidate_cache(struct crypto_async_request *async,
 		goto cdesc_rollback;
 	}
 
-	request->req = async;
-	goto unlock;
+	safexcel_rdr_req_set(priv, ring, rdesc, async);
+
+	return ret;
 
 cdesc_rollback:
 	safexcel_ring_rollback_wptr(priv, &priv->ring[ring].cdr);
 
-unlock:
-	spin_unlock_bh(&priv->ring[ring].egress_lock);
 	return ret;
 }
 
 static inline void safexcel_handle_result_descriptor(struct safexcel_crypto_priv *priv,
 						     int ring)
 {
-	struct safexcel_request *sreq;
+	struct crypto_async_request *req;
 	struct safexcel_context *ctx;
 	int ret, i, nreq, ndesc, tot_descs, handled = 0;
 	bool should_complete;
@@ -703,28 +702,22 @@ handle_results:
 		goto requests_left;
 
 	for (i = 0; i < nreq; i++) {
-		spin_lock_bh(&priv->ring[ring].egress_lock);
-		sreq = list_first_entry(&priv->ring[ring].list,
-					struct safexcel_request, list);
-		list_del(&sreq->list);
-		spin_unlock_bh(&priv->ring[ring].egress_lock);
-
-		ctx = crypto_tfm_ctx(sreq->req->tfm);
-		ndesc = ctx->handle_result(priv, ring, sreq->req,
+		req = safexcel_rdr_req_get(priv, ring);
+
+		ctx = crypto_tfm_ctx(req->tfm);
+		ndesc = ctx->handle_result(priv, ring, req,
 					   &should_complete, &ret);
 		if (ndesc < 0) {
-			kfree(sreq);
 			dev_err(priv->dev, "failed to handle result (%d)", ndesc);
 			goto acknowledge;
 		}
 
 		if (should_complete) {
 			local_bh_disable();
-			sreq->req->complete(sreq->req, ret);
+			req->complete(req, ret);
 			local_bh_enable();
 		}
 
-		kfree(sreq);
 		tot_descs += ndesc;
 		handled++;
 	}
@@ -743,7 +736,7 @@ acknowledge:
 		goto handle_results;
 
 requests_left:
-	spin_lock_bh(&priv->ring[ring].egress_lock);
+	spin_lock_bh(&priv->ring[ring].lock);
 
 	priv->ring[ring].requests -= handled;
 	safexcel_try_push_requests(priv, ring);
@@ -751,7 +744,7 @@ requests_left:
 	if (!priv->ring[ring].requests)
 		priv->ring[ring].busy = false;
 
-	spin_unlock_bh(&priv->ring[ring].egress_lock);
+	spin_unlock_bh(&priv->ring[ring].lock);
 }
 
 static void safexcel_dequeue_work(struct work_struct *work)
@@ -1073,6 +1066,14 @@ static int safexcel_probe(struct platform_device *pdev)
 		if (ret)
 			goto err_reg_clk;
 
+		priv->ring[i].rdr_req = devm_kzalloc(dev,
+			sizeof(priv->ring[i].rdr_req) * EIP197_DEFAULT_RING_SIZE,
+			GFP_KERNEL);
+		if (!priv->ring[i].rdr_req) {
+			ret = -ENOMEM;
+			goto err_reg_clk;
+		}
+
 		ring_irq = devm_kzalloc(dev, sizeof(*ring_irq), GFP_KERNEL);
 		if (!ring_irq) {
 			ret = -ENOMEM;
@@ -1108,9 +1109,7 @@ static int safexcel_probe(struct platform_device *pdev)
 		crypto_init_queue(&priv->ring[i].queue,
 				  EIP197_DEFAULT_RING_SIZE);
 
-		INIT_LIST_HEAD(&priv->ring[i].list);
 		spin_lock_init(&priv->ring[i].lock);
-		spin_lock_init(&priv->ring[i].egress_lock);
 		spin_lock_init(&priv->ring[i].queue_lock);
 	}
 

drivers/crypto/inside-secure/safexcel.h

@@ -512,8 +512,7 @@ struct safexcel_desc_ring {
 	void *write;
 	void *read;
 
-	/* number of elements used in the ring */
-	unsigned nr;
+	/* descriptor element offset */
 	unsigned offset;
 };
 
@@ -523,11 +522,6 @@ enum safexcel_alg_type {
 	SAFEXCEL_ALG_TYPE_AHASH,
 };
 
-struct safexcel_request {
-	struct list_head list;
-	struct crypto_async_request *req;
-};
-
 struct safexcel_config {
 	u32 pes;
 	u32 rings;
@@ -547,9 +541,7 @@ struct safexcel_work_data {
 
 struct safexcel_ring {
 	spinlock_t lock;
-	spinlock_t egress_lock;
 
-	struct list_head list;
 	struct workqueue_struct *workqueue;
 	struct safexcel_work_data work_data;
 
@@ -557,6 +549,9 @@ struct safexcel_ring {
 	struct safexcel_desc_ring cdr;
 	struct safexcel_desc_ring rdr;
 
+	/* result ring crypto API request */
+	struct crypto_async_request **rdr_req;
+
 	/* queue */
 	struct crypto_queue queue;
 	spinlock_t queue_lock;
@@ -618,8 +613,7 @@ struct safexcel_crypto_priv {
 
 struct safexcel_context {
 	int (*send)(struct crypto_async_request *req, int ring,
-		    struct safexcel_request *request, int *commands,
-		    int *results);
+		    int *commands, int *results);
 	int (*handle_result)(struct safexcel_crypto_priv *priv, int ring,
 			     struct crypto_async_request *req, bool *complete,
 			     int *ret);
@@ -668,14 +662,14 @@ int safexcel_rdesc_check_errors(struct safexcel_crypto_priv *priv,
 void safexcel_complete(struct safexcel_crypto_priv *priv, int ring);
 int safexcel_invalidate_cache(struct crypto_async_request *async,
 			      struct safexcel_crypto_priv *priv,
-			      dma_addr_t ctxr_dma, int ring,
-			      struct safexcel_request *request);
+			      dma_addr_t ctxr_dma, int ring);
 int safexcel_init_ring_descriptors(struct safexcel_crypto_priv *priv,
 				   struct safexcel_desc_ring *cdr,
 				   struct safexcel_desc_ring *rdr);
 int safexcel_select_ring(struct safexcel_crypto_priv *priv);
 void *safexcel_ring_next_rptr(struct safexcel_crypto_priv *priv,
 			      struct safexcel_desc_ring *ring);
+void *safexcel_ring_first_rptr(struct safexcel_crypto_priv *priv, int  ring);
 void safexcel_ring_rollback_wptr(struct safexcel_crypto_priv *priv,
 				 struct safexcel_desc_ring *ring);
 struct safexcel_command_desc *safexcel_add_cdesc(struct safexcel_crypto_priv *priv,
@@ -688,6 +682,17 @@ struct safexcel_result_desc *safexcel_add_rdesc(struct safexcel_crypto_priv *pri
 						 int ring_id,
 						bool first, bool last,
 						dma_addr_t data, u32 len);
+int safexcel_ring_first_rdr_index(struct safexcel_crypto_priv *priv,
+				  int ring);
+int safexcel_ring_rdr_rdesc_index(struct safexcel_crypto_priv *priv,
+				  int ring,
+				  struct safexcel_result_desc *rdesc);
+void safexcel_rdr_req_set(struct safexcel_crypto_priv *priv,
+			  int ring,
+			  struct safexcel_result_desc *rdesc,
+			  struct crypto_async_request *req);
+inline struct crypto_async_request *
+safexcel_rdr_req_get(struct safexcel_crypto_priv *priv, int ring);
 void safexcel_inv_complete(struct crypto_async_request *req, int error);
 int safexcel_hmac_setkey(const char *alg, const u8 *key, unsigned int keylen,
 			 void *istate, void *ostate);

drivers/crypto/inside-secure/safexcel_cipher.c

@@ -336,7 +336,6 @@ static int safexcel_handle_req_result(struct safexcel_crypto_priv *priv, int rin
 
 	*ret = 0;
 
-	spin_lock_bh(&priv->ring[ring].egress_lock);
 	do {
 		rdesc = safexcel_ring_next_rptr(priv, &priv->ring[ring].rdr);
 		if (IS_ERR(rdesc)) {
@@ -353,7 +352,6 @@ static int safexcel_handle_req_result(struct safexcel_crypto_priv *priv, int rin
 	} while (!rdesc->last_seg);
 
 	safexcel_complete(priv, ring);
-	spin_unlock_bh(&priv->ring[ring].egress_lock);
 
 	if (src == dst) {
 		dma_unmap_sg(priv->dev, src,
@@ -374,7 +372,6 @@ static int safexcel_handle_req_result(struct safexcel_crypto_priv *priv, int rin
 }
 
 static int safexcel_send_req(struct crypto_async_request *base, int ring,
-			     struct safexcel_request *request,
 			     struct safexcel_cipher_req *sreq,
 			     struct scatterlist *src, struct scatterlist *dst,
 			     unsigned int cryptlen, unsigned int assoclen,
@@ -384,7 +381,7 @@ static int safexcel_send_req(struct crypto_async_request *base, int ring,
 	struct safexcel_cipher_ctx *ctx = crypto_tfm_ctx(base->tfm);
 	struct safexcel_crypto_priv *priv = ctx->priv;
 	struct safexcel_command_desc *cdesc;
-	struct safexcel_result_desc *rdesc;
+	struct safexcel_result_desc *rdesc, *first_rdesc;
 	struct scatterlist *sg;
 	unsigned int totlen = cryptlen + assoclen;
 	int nr_src, nr_dst, n_cdesc = 0, n_rdesc = 0, queued = totlen;
@@ -424,8 +421,6 @@ static int safexcel_send_req(struct crypto_async_request *base, int ring,
 		       ctx->opad, ctx->state_sz);
 	}
 
-	spin_lock_bh(&priv->ring[ring].egress_lock);
-
 	/* command descriptors */
 	for_each_sg(src, sg, nr_src, i) {
 		int len = sg_dma_len(sg);
@@ -472,12 +467,12 @@ static int safexcel_send_req(struct crypto_async_request *base, int ring,
 			ret = PTR_ERR(rdesc);
 			goto rdesc_rollback;
 		}
+		if (first)
+			first_rdesc = rdesc;
 		n_rdesc++;
 	}
 
-	spin_unlock_bh(&priv->ring[ring].egress_lock);
-
-	request->req = base;
+	safexcel_rdr_req_set(priv, ring, first_rdesc, base);
 
 	*commands = n_cdesc;
 	*results = n_rdesc;
@@ -490,8 +485,6 @@ cdesc_rollback:
 	for (i = 0; i < n_cdesc; i++)
 		safexcel_ring_rollback_wptr(priv, &priv->ring[ring].cdr);
 
-	spin_unlock_bh(&priv->ring[ring].egress_lock);
-
 	if (src == dst) {
 		dma_unmap_sg(priv->dev, src,
 			     sg_nents_for_len(src, totlen),
@@ -519,7 +512,6 @@ static int safexcel_handle_inv_result(struct safexcel_crypto_priv *priv,
 
 	*ret = 0;
 
-	spin_lock_bh(&priv->ring[ring].egress_lock);
 	do {
 		rdesc = safexcel_ring_next_rptr(priv, &priv->ring[ring].rdr);
 		if (IS_ERR(rdesc)) {
@@ -536,7 +528,6 @@ static int safexcel_handle_inv_result(struct safexcel_crypto_priv *priv,
 	} while (!rdesc->last_seg);
 
 	safexcel_complete(priv, ring);
-	spin_unlock_bh(&priv->ring[ring].egress_lock);
 
 	if (ctx->base.exit_inv) {
 		dma_pool_free(priv->context_pool, ctx->base.ctxr,
@@ -612,15 +603,13 @@ static int safexcel_aead_handle_result(struct safexcel_crypto_priv *priv,
 }
 
 static int safexcel_cipher_send_inv(struct crypto_async_request *base,
-				    int ring, struct safexcel_request *request,
-				    int *commands, int *results)
+				    int ring, int *commands, int *results)
 {
 	struct safexcel_cipher_ctx *ctx = crypto_tfm_ctx(base->tfm);
 	struct safexcel_crypto_priv *priv = ctx->priv;
 	int ret;
 
-	ret = safexcel_invalidate_cache(base, priv, ctx->base.ctxr_dma, ring,
-					request);
+	ret = safexcel_invalidate_cache(base, priv, ctx->base.ctxr_dma, ring);
 	if (unlikely(ret))
 		return ret;
 
@@ -631,7 +620,6 @@ static int safexcel_cipher_send_inv(struct crypto_async_request *base,
 }
 
 static int safexcel_skcipher_send(struct crypto_async_request *async, int ring,
-				  struct safexcel_request *request,
 				  int *commands, int *results)
 {
 	struct skcipher_request *req = skcipher_request_cast(async);
@@ -643,18 +631,16 @@ static int safexcel_skcipher_send(struct crypto_async_request *async, int ring,
 	BUG_ON(!(priv->flags & EIP197_TRC_CACHE) && sreq->needs_inv);
 
 	if (sreq->needs_inv)
-		ret = safexcel_cipher_send_inv(async, ring, request, commands,
-					       results);
+		ret = safexcel_cipher_send_inv(async, ring, commands, results);
 	else
-		ret = safexcel_send_req(async, ring, request, sreq, req->src,
+		ret = safexcel_send_req(async, ring, sreq, req->src,
 					req->dst, req->cryptlen, 0, 0, req->iv,
 					commands, results);
 	return ret;
 }
 
 static int safexcel_aead_send(struct crypto_async_request *async, int ring,
-			      struct safexcel_request *request, int *commands,
-			      int *results)
+			      int *commands, int *results)
 {
 	struct aead_request *req = aead_request_cast(async);
 	struct crypto_aead *tfm = crypto_aead_reqtfm(req);
@@ -666,11 +652,10 @@ static int safexcel_aead_send(struct crypto_async_request *async, int ring,
 	BUG_ON(!(priv->flags & EIP197_TRC_CACHE) && sreq->needs_inv);
 
 	if (sreq->needs_inv)
-		ret = safexcel_cipher_send_inv(async, ring, request, commands,
-					       results);
+		ret = safexcel_cipher_send_inv(async, ring, commands, results);
 	else
-		ret = safexcel_send_req(async, ring, request, sreq, req->src,
-					req->dst, req->cryptlen, req->assoclen,
+		ret = safexcel_send_req(async, ring, sreq, req->src, req->dst,
+					req->cryptlen, req->assoclen,
 					crypto_aead_authsize(tfm), req->iv,
 					commands, results);
 	return ret;

drivers/crypto/inside-secure/safexcel_hash.c

@@ -160,7 +160,6 @@ static int safexcel_handle_req_result(struct safexcel_crypto_priv *priv, int rin
 
 	*ret = 0;
 
-	spin_lock_bh(&priv->ring[ring].egress_lock);
 	rdesc = safexcel_ring_next_rptr(priv, &priv->ring[ring].rdr);
 	if (IS_ERR(rdesc)) {
 		dev_err(priv->dev,
@@ -171,7 +170,6 @@ static int safexcel_handle_req_result(struct safexcel_crypto_priv *priv, int rin
 	}
 
 	safexcel_complete(priv, ring);
-	spin_unlock_bh(&priv->ring[ring].egress_lock);
 
 	if (sreq->nents) {
 		dma_unmap_sg(priv->dev, areq->src, sreq->nents, DMA_TO_DEVICE);
@@ -204,7 +202,6 @@ static int safexcel_handle_req_result(struct safexcel_crypto_priv *priv, int rin
 }
 
 static int safexcel_ahash_send_req(struct crypto_async_request *async, int ring,
-				   struct safexcel_request *request,
 				   int *commands, int *results)
 {
 	struct ahash_request *areq = ahash_request_cast(async);
@@ -251,16 +248,12 @@ static int safexcel_ahash_send_req(struct crypto_async_request *async, int ring,
 		}
 	}
 
-	spin_lock_bh(&priv->ring[ring].egress_lock);
-
 	/* Add a command descriptor for the cached data, if any */
 	if (cache_len) {
 		req->cache_dma = dma_map_single(priv->dev, req->cache,
 						cache_len, DMA_TO_DEVICE);
-		if (dma_mapping_error(priv->dev, req->cache_dma)) {
-			spin_unlock_bh(&priv->ring[ring].egress_lock);
+		if (dma_mapping_error(priv->dev, req->cache_dma))
 			return -EINVAL;
-		}
 
 		req->cache_sz = cache_len;
 		first_cdesc = safexcel_add_cdesc(priv, ring, 1,
@@ -333,14 +326,12 @@ send_command:
 		goto unmap_result;
 	}
 
-	spin_unlock_bh(&priv->ring[ring].egress_lock);
+	safexcel_rdr_req_set(priv, ring, rdesc, &areq->base);
 
 	req->processed[0] += len;
 	if (req->processed[0] < len)
 		req->processed[1]++;
 
-	request->req = &areq->base;
-
 	*commands = n_cdesc;
 	*results = 1;
 	return 0;
@@ -360,7 +351,6 @@ unmap_cache:
 		req->cache_sz = 0;
 	}
 
-	spin_unlock_bh(&priv->ring[ring].egress_lock);
 	return ret;
 }
 
@@ -398,7 +388,6 @@ static int safexcel_handle_inv_result(struct safexcel_crypto_priv *priv,
 
 	*ret = 0;
 
-	spin_lock_bh(&priv->ring[ring].egress_lock);
 	rdesc = safexcel_ring_next_rptr(priv, &priv->ring[ring].rdr);
 	if (IS_ERR(rdesc)) {
 		dev_err(priv->dev,
@@ -409,7 +398,6 @@ static int safexcel_handle_inv_result(struct safexcel_crypto_priv *priv,
 	}
 
 	safexcel_complete(priv, ring);
-	spin_unlock_bh(&priv->ring[ring].egress_lock);
 
 	if (ctx->base.exit_inv) {
 		dma_pool_free(priv->context_pool, ctx->base.ctxr,
@@ -460,15 +448,14 @@ static int safexcel_handle_result(struct safexcel_crypto_priv *priv, int ring,
 }
 
 static int safexcel_ahash_send_inv(struct crypto_async_request *async,
-				   int ring, struct safexcel_request *request,
-				   int *commands, int *results)
+				   int ring, int *commands, int *results)
 {
 	struct ahash_request *areq = ahash_request_cast(async);
 	struct safexcel_ahash_ctx *ctx = crypto_ahash_ctx(crypto_ahash_reqtfm(areq));
 	int ret;
 
 	ret = safexcel_invalidate_cache(async, ctx->priv,
-					ctx->base.ctxr_dma, ring, request);
+					ctx->base.ctxr_dma, ring);
 	if (unlikely(ret))
 		return ret;
 
@@ -479,19 +466,17 @@ static int safexcel_ahash_send_inv(struct crypto_async_request *async,
 }
 
 static int safexcel_ahash_send(struct crypto_async_request *async,
-			       int ring, struct safexcel_request *request,
-			       int *commands, int *results)
+			       int ring, int *commands, int *results)
 {
 	struct ahash_request *areq = ahash_request_cast(async);
 	struct safexcel_ahash_req *req = ahash_request_ctx(areq);
 	int ret;
 
 	if (req->needs_inv)
-		ret = safexcel_ahash_send_inv(async, ring, request,
-					      commands, results);
+		ret = safexcel_ahash_send_inv(async, ring, commands, results);
 	else
-		ret = safexcel_ahash_send_req(async, ring, request,
-					      commands, results);
+		ret = safexcel_ahash_send_req(async, ring, commands, results);
+
 	return ret;
 }
 

drivers/crypto/inside-secure/safexcel_ring.c

@@ -24,7 +24,7 @@ int safexcel_init_ring_descriptors(struct safexcel_crypto_priv *priv,
 	if (!cdr->base)
 		return -ENOMEM;
 	cdr->write = cdr->base;
-	cdr->base_end = cdr->base + cdr->offset * EIP197_DEFAULT_RING_SIZE;
+	cdr->base_end = cdr->base + cdr->offset * (EIP197_DEFAULT_RING_SIZE - 1);
 	cdr->read = cdr->base;
 
 	rdr->offset = sizeof(u32) * priv->config.rd_offset;
@@ -34,7 +34,7 @@ int safexcel_init_ring_descriptors(struct safexcel_crypto_priv *priv,
 	if (!rdr->base)
 		return -ENOMEM;
 	rdr->write = rdr->base;
-	rdr->base_end = rdr->base + rdr->offset * EIP197_DEFAULT_RING_SIZE;
+	rdr->base_end = rdr->base + rdr->offset  * (EIP197_DEFAULT_RING_SIZE - 1);
 	rdr->read = rdr->base;
 
 	return 0;
@@ -50,14 +50,15 @@ static void *safexcel_ring_next_wptr(struct safexcel_crypto_priv *priv,
 {
 	void *ptr = ring->write;
 
-	if (ring->nr == EIP197_DEFAULT_RING_SIZE - 1)
+	if ((ring->write == ring->read - ring->offset) ||
+	    (ring->read == ring->base && ring->write == ring->base_end))
 		return ERR_PTR(-ENOMEM);
 
-	ring->write += ring->offset;
 	if (ring->write == ring->base_end)
 		ring->write = ring->base;
+	else
+		ring->write += ring->offset;
 
-	ring->nr++;
 	return ptr;
 }
 
@@ -66,29 +67,52 @@ void *safexcel_ring_next_rptr(struct safexcel_crypto_priv *priv,
 {
 	void *ptr = ring->read;
 
-	if (!ring->nr)
+	if (ring->write == ring->read)
 		return ERR_PTR(-ENOENT);
 
-	ring->read += ring->offset;
 	if (ring->read == ring->base_end)
 		ring->read = ring->base;
+	else
+		ring->read += ring->offset;
 
-	ring->nr--;
 	return ptr;
 }
 
+inline void *safexcel_ring_curr_rptr(struct safexcel_crypto_priv *priv,
+				     int ring)
+{
+	struct safexcel_desc_ring *rdr = &priv->ring[ring].rdr;
+
+	return rdr->read;
+}
+
+inline int safexcel_ring_first_rdr_index(struct safexcel_crypto_priv *priv,
+					 int ring)
+{
+	struct safexcel_desc_ring *rdr = &priv->ring[ring].rdr;
+
+	return (rdr->read - rdr->base) / rdr->offset;
+}
+
+inline int safexcel_ring_rdr_rdesc_index(struct safexcel_crypto_priv *priv,
+					 int ring,
+					 struct safexcel_result_desc *rdesc)
+{
+	struct safexcel_desc_ring *rdr = &priv->ring[ring].rdr;
+
+	return ((void *)rdesc - rdr->base) / rdr->offset;
+}
+
 void safexcel_ring_rollback_wptr(struct safexcel_crypto_priv *priv,
 				 struct safexcel_desc_ring *ring)
 {
-	if (!ring->nr)
+	if (ring->write == ring->read)
 		return;
 
 	if (ring->write == ring->base)
-		ring->write = ring->base_end - ring->offset;
+		ring->write = ring->base_end;
 	else
 		ring->write -= ring->offset;
-
-	ring->nr--;
 }
 
 struct safexcel_command_desc *safexcel_add_cdesc(struct safexcel_crypto_priv *priv,