crypto: qat - add backlog mechanism

The implementations of the crypto algorithms (aead, skcipher, etc) in
the QAT driver do not properly support requests with the
CRYPTO_TFM_REQ_MAY_BACKLOG flag set. If the HW queue is full, the driver
returns -EBUSY but does not enqueue the request. This can result in
applications like dm-crypt waiting indefinitely for the completion of a
request that was never submitted to the hardware.

Fix this by adding a software backlog queue: if the ring buffer is more
than eighty percent full, then the request is enqueued to a backlog
list and the error code -EBUSY is returned back to the caller.
Requests in the backlog queue are resubmitted at a later time, in the
context of the callback of a previously submitted request.
The request for which -EBUSY is returned is then marked as -EINPROGRESS
once submitted to the HW queues.

The submission loop inside the function qat_alg_send_message() has been
modified to decide which submission policy to use based on the request
flags. If the request does not have the CRYPTO_TFM_REQ_MAY_BACKLOG set,
the previous behaviour has been preserved.

Based on a patch by
Vishnu Das Ramachandran <vishnu.dasx.ramachandran@intel.com>

Cc: stable@vger.kernel.org
Fixes: d370cec321 ("crypto: qat - Intel(R) QAT crypto interface")
Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Reported-by: Kyle Sanderson <kyle.leet@gmail.com>
Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Reviewed-by: Marco Chiappero <marco.chiappero@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/qat/qat_common/adf_transport.c

@@ -8,6 +8,9 @@
 #include "adf_cfg.h"
 #include "adf_common_drv.h"
 
+#define ADF_MAX_RING_THRESHOLD		80
+#define ADF_PERCENT(tot, percent)	(((tot) * (percent)) / 100)
+
 static inline u32 adf_modulo(u32 data, u32 shift)
 {
 	u32 div = data >> shift;
@@ -77,6 +80,11 @@ static void adf_disable_ring_irq(struct adf_etr_bank_data *bank, u32 ring)
 				      bank->irq_mask);
 }
 
+bool adf_ring_nearly_full(struct adf_etr_ring_data *ring)
+{
+	return atomic_read(ring->inflights) > ring->threshold;
+}
+
 int adf_send_message(struct adf_etr_ring_data *ring, u32 *msg)
 {
 	struct adf_hw_csr_ops *csr_ops = GET_CSR_OPS(ring->bank->accel_dev);
@@ -217,6 +225,7 @@ int adf_create_ring(struct adf_accel_dev *accel_dev, const char *section,
 	struct adf_etr_bank_data *bank;
 	struct adf_etr_ring_data *ring;
 	char val[ADF_CFG_MAX_VAL_LEN_IN_BYTES];
+	int max_inflights;
 	u32 ring_num;
 	int ret;
 
@@ -263,6 +272,8 @@ int adf_create_ring(struct adf_accel_dev *accel_dev, const char *section,
 	ring->ring_size = adf_verify_ring_size(msg_size, num_msgs);
 	ring->head = 0;
 	ring->tail = 0;
+	max_inflights = ADF_MAX_INFLIGHTS(ring->ring_size, ring->msg_size);
+	ring->threshold = ADF_PERCENT(max_inflights, ADF_MAX_RING_THRESHOLD);
 	atomic_set(ring->inflights, 0);
 	ret = adf_init_ring(ring);
 	if (ret)

drivers/crypto/qat/qat_common/adf_transport.h

@@ -14,6 +14,7 @@ int adf_create_ring(struct adf_accel_dev *accel_dev, const char *section,
 		    const char *ring_name, adf_callback_fn callback,
 		    int poll_mode, struct adf_etr_ring_data **ring_ptr);
 
+bool adf_ring_nearly_full(struct adf_etr_ring_data *ring);
 int adf_send_message(struct adf_etr_ring_data *ring, u32 *msg);
 void adf_remove_ring(struct adf_etr_ring_data *ring);
 #endif

drivers/crypto/qat/qat_common/adf_transport_internal.h

@@ -22,6 +22,7 @@ struct adf_etr_ring_data {
 	spinlock_t lock;	/* protects ring data struct */
 	u16 head;
 	u16 tail;
+	u32 threshold;
 	u8 ring_number;
 	u8 ring_size;
 	u8 msg_size;

drivers/crypto/qat/qat_common/qat_algs.c

@@ -935,19 +935,25 @@ void qat_alg_callback(void *resp)
 	struct icp_qat_fw_la_resp *qat_resp = resp;
 	struct qat_crypto_request *qat_req =
 				(void *)(__force long)qat_resp->opaque_data;
+	struct qat_instance_backlog *backlog = qat_req->alg_req.backlog;
 
 	qat_req->cb(qat_resp, qat_req);
+
+	qat_alg_send_backlog(backlog);
 }
 
 static int qat_alg_send_sym_message(struct qat_crypto_request *qat_req,
-				    struct qat_crypto_instance *inst)
+				    struct qat_crypto_instance *inst,
+				    struct crypto_async_request *base)
 {
-	struct qat_alg_req req;
+	struct qat_alg_req *alg_req = &qat_req->alg_req;
 
-	req.fw_req = (u32 *)&qat_req->req;
-	req.tx_ring = inst->sym_tx;
+	alg_req->fw_req = (u32 *)&qat_req->req;
+	alg_req->tx_ring = inst->sym_tx;
+	alg_req->base = base;
+	alg_req->backlog = &inst->backlog;
 
-	return qat_alg_send_message(&req);
+	return qat_alg_send_message(alg_req);
 }
 
 static int qat_alg_aead_dec(struct aead_request *areq)
@@ -987,7 +993,7 @@ static int qat_alg_aead_dec(struct aead_request *areq)
 	auth_param->auth_off = 0;
 	auth_param->auth_len = areq->assoclen + cipher_param->cipher_length;
 
-	ret = qat_alg_send_sym_message(qat_req, ctx->inst);
+	ret = qat_alg_send_sym_message(qat_req, ctx->inst, &areq->base);
 	if (ret == -ENOSPC)
 		qat_alg_free_bufl(ctx->inst, qat_req);
 
@@ -1031,7 +1037,7 @@ static int qat_alg_aead_enc(struct aead_request *areq)
 	auth_param->auth_off = 0;
 	auth_param->auth_len = areq->assoclen + areq->cryptlen;
 
-	ret = qat_alg_send_sym_message(qat_req, ctx->inst);
+	ret = qat_alg_send_sym_message(qat_req, ctx->inst, &areq->base);
 	if (ret == -ENOSPC)
 		qat_alg_free_bufl(ctx->inst, qat_req);
 
@@ -1212,7 +1218,7 @@ static int qat_alg_skcipher_encrypt(struct skcipher_request *req)
 
 	qat_alg_set_req_iv(qat_req);
 
-	ret = qat_alg_send_sym_message(qat_req, ctx->inst);
+	ret = qat_alg_send_sym_message(qat_req, ctx->inst, &req->base);
 	if (ret == -ENOSPC)
 		qat_alg_free_bufl(ctx->inst, qat_req);
 
@@ -1278,7 +1284,7 @@ static int qat_alg_skcipher_decrypt(struct skcipher_request *req)
 	qat_alg_set_req_iv(qat_req);
 	qat_alg_update_iv(qat_req);
 
-	ret = qat_alg_send_sym_message(qat_req, ctx->inst);
+	ret = qat_alg_send_sym_message(qat_req, ctx->inst, &req->base);
 	if (ret == -ENOSPC)
 		qat_alg_free_bufl(ctx->inst, qat_req);
 

drivers/crypto/qat/qat_common/qat_algs_send.c

@@ -6,7 +6,7 @@
 
 #define ADF_MAX_RETRIES		20
 
-int qat_alg_send_message(struct qat_alg_req *req)
+static int qat_alg_send_message_retry(struct qat_alg_req *req)
 {
 	int ret = 0, ctr = 0;
 
@@ -19,3 +19,68 @@ int qat_alg_send_message(struct qat_alg_req *req)
 
 	return -EINPROGRESS;
 }
+
+void qat_alg_send_backlog(struct qat_instance_backlog *backlog)
+{
+	struct qat_alg_req *req, *tmp;
+
+	spin_lock_bh(&backlog->lock);
+	list_for_each_entry_safe(req, tmp, &backlog->list, list) {
+		if (adf_send_message(req->tx_ring, req->fw_req)) {
+			/* The HW ring is full. Do nothing.
+			 * qat_alg_send_backlog() will be invoked again by
+			 * another callback.
+			 */
+			break;
+		}
+		list_del(&req->list);
+		req->base->complete(req->base, -EINPROGRESS);
+	}
+	spin_unlock_bh(&backlog->lock);
+}
+
+static void qat_alg_backlog_req(struct qat_alg_req *req,
+				struct qat_instance_backlog *backlog)
+{
+	INIT_LIST_HEAD(&req->list);
+
+	spin_lock_bh(&backlog->lock);
+	list_add_tail(&req->list, &backlog->list);
+	spin_unlock_bh(&backlog->lock);
+}
+
+static int qat_alg_send_message_maybacklog(struct qat_alg_req *req)
+{
+	struct qat_instance_backlog *backlog = req->backlog;
+	struct adf_etr_ring_data *tx_ring = req->tx_ring;
+	u32 *fw_req = req->fw_req;
+
+	/* If any request is already backlogged, then add to backlog list */
+	if (!list_empty(&backlog->list))
+		goto enqueue;
+
+	/* If ring is nearly full, then add to backlog list */
+	if (adf_ring_nearly_full(tx_ring))
+		goto enqueue;
+
+	/* If adding request to HW ring fails, then add to backlog list */
+	if (adf_send_message(tx_ring, fw_req))
+		goto enqueue;
+
+	return -EINPROGRESS;
+
+enqueue:
+	qat_alg_backlog_req(req, backlog);
+
+	return -EBUSY;
+}
+
+int qat_alg_send_message(struct qat_alg_req *req)
+{
+	u32 flags = req->base->flags;
+
+	if (flags & CRYPTO_TFM_REQ_MAY_BACKLOG)
+		return qat_alg_send_message_maybacklog(req);
+	else
+		return qat_alg_send_message_retry(req);
+}

drivers/crypto/qat/qat_common/qat_algs_send.h

@@ -6,5 +6,6 @@
 #include "qat_crypto.h"
 
 int qat_alg_send_message(struct qat_alg_req *req);
+void qat_alg_send_backlog(struct qat_instance_backlog *backlog);
 
 #endif

drivers/crypto/qat/qat_common/qat_asym_algs.c

@@ -136,17 +136,21 @@ struct qat_asym_request {
 	} areq;
 	int err;
 	void (*cb)(struct icp_qat_fw_pke_resp *resp);
+	struct qat_alg_req alg_req;
 } __aligned(64);
 
 static int qat_alg_send_asym_message(struct qat_asym_request *qat_req,
-				     struct qat_crypto_instance *inst)
+				     struct qat_crypto_instance *inst,
+				     struct crypto_async_request *base)
 {
-	struct qat_alg_req req;
+	struct qat_alg_req *alg_req = &qat_req->alg_req;
 
-	req.fw_req = (u32 *)&qat_req->req;
-	req.tx_ring = inst->pke_tx;
+	alg_req->fw_req = (u32 *)&qat_req->req;
+	alg_req->tx_ring = inst->pke_tx;
+	alg_req->base = base;
+	alg_req->backlog = &inst->backlog;
 
-	return qat_alg_send_message(&req);
+	return qat_alg_send_message(alg_req);
 }
 
 static void qat_dh_cb(struct icp_qat_fw_pke_resp *resp)
@@ -350,7 +354,7 @@ static int qat_dh_compute_value(struct kpp_request *req)
 	msg->input_param_count = n_input_params;
 	msg->output_param_count = 1;
 
-	ret = qat_alg_send_asym_message(qat_req, ctx->inst);
+	ret = qat_alg_send_asym_message(qat_req, inst, &req->base);
 	if (ret == -ENOSPC)
 		goto unmap_all;
 
@@ -557,8 +561,11 @@ void qat_alg_asym_callback(void *_resp)
 {
 	struct icp_qat_fw_pke_resp *resp = _resp;
 	struct qat_asym_request *areq = (void *)(__force long)resp->opaque;
+	struct qat_instance_backlog *backlog = areq->alg_req.backlog;
 
 	areq->cb(resp);
+
+	qat_alg_send_backlog(backlog);
 }
 
 #define PKE_RSA_EP_512 0x1c161b21
@@ -748,7 +755,7 @@ static int qat_rsa_enc(struct akcipher_request *req)
 	msg->input_param_count = 3;
 	msg->output_param_count = 1;
 
-	ret = qat_alg_send_asym_message(qat_req, ctx->inst);
+	ret = qat_alg_send_asym_message(qat_req, inst, &req->base);
 	if (ret == -ENOSPC)
 		goto unmap_all;
 
@@ -901,7 +908,7 @@ static int qat_rsa_dec(struct akcipher_request *req)
 
 	msg->output_param_count = 1;
 
-	ret = qat_alg_send_asym_message(qat_req, ctx->inst);
+	ret = qat_alg_send_asym_message(qat_req, inst, &req->base);
 	if (ret == -ENOSPC)
 		goto unmap_all;
 

drivers/crypto/qat/qat_common/qat_crypto.c

@@ -353,6 +353,9 @@ static int qat_crypto_create_instances(struct adf_accel_dev *accel_dev)
 				      &inst->pke_rx);
 		if (ret)
 			goto err;
+
+		INIT_LIST_HEAD(&inst->backlog.list);
+		spin_lock_init(&inst->backlog.lock);
 	}
 	return 0;
 err:

drivers/crypto/qat/qat_common/qat_crypto.h

@@ -9,9 +9,17 @@
 #include "adf_accel_devices.h"
 #include "icp_qat_fw_la.h"
 
+struct qat_instance_backlog {
+	struct list_head list;
+	spinlock_t lock; /* protects backlog list */
+};
+
 struct qat_alg_req {
 	u32 *fw_req;
 	struct adf_etr_ring_data *tx_ring;
+	struct crypto_async_request *base;
+	struct list_head list;
+	struct qat_instance_backlog *backlog;
 };
 
 struct qat_crypto_instance {
@@ -24,6 +32,7 @@ struct qat_crypto_instance {
 	unsigned long state;
 	int id;
 	atomic_t refctr;
+	struct qat_instance_backlog backlog;
 };
 
 #define QAT_MAX_BUFF_DESC	4
@@ -82,6 +91,7 @@ struct qat_crypto_request {
 		u8 iv[AES_BLOCK_SIZE];
 	};
 	bool encryption;
+	struct qat_alg_req alg_req;
 };
 
 static inline bool adf_hw_dev_has_crypto(struct adf_accel_dev *accel_dev)