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: d370cec32194 ("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>

1 files changed, 15 insertions, 8 deletions

diff --git a/drivers/crypto/qat/qat_common/qat_asym_algs.c b/drivers/crypto/qat/qat_common/qat_asym_algs.c
index 08b8d83e070a..ff7249c093c9 100644
--- a/drivers/crypto/qat/qat_common/qat_asym_algs.c
+++ b/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;