IB/mlx5: Reorder GSI completions

The emulated GSI QP's send completions are generated by multiple hardware
QPs, so their completions could arrive out of order with respect to the
order their work request were submitted.

Reorder the completions by keeping a list of the posted work request and
their completions. A newly received completion from the hardware updates
the list and marks its work request as completed. However, the completions
are only reported to the client according to the list order.

In order to support that, create a new private CQ to handle the hardware
completions.
Signed-off-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/mlx5/gsi.c

@@ -32,6 +32,13 @@
 
 #include "mlx5_ib.h"
 
+struct mlx5_ib_gsi_wr {
+	struct ib_cqe cqe;
+	struct ib_wc wc;
+	int send_flags;
+	bool completed:1;
+};
+
 struct mlx5_ib_gsi_qp {
 	struct ib_qp ibqp;
 	struct ib_qp *rx_qp;
@@ -40,9 +47,13 @@ struct mlx5_ib_gsi_qp {
 	enum ib_sig_type sq_sig_type;
 	/* Serialize qp state modifications */
 	struct mutex mutex;
+	struct ib_cq *cq;
+	struct mlx5_ib_gsi_wr *outstanding_wrs;
+	u32 outstanding_pi, outstanding_ci;
 	int num_qps;
 	/* Protects access to the tx_qps. Post send operations synchronize
-	 * with tx_qp creation in setup_qp().
+	 * with tx_qp creation in setup_qp(). Also protects the
+	 * outstanding_wrs array and indices.
 	 */
 	spinlock_t lock;
 	struct ib_qp **tx_qps;
@@ -58,6 +69,57 @@ static bool mlx5_ib_deth_sqpn_cap(struct mlx5_ib_dev *dev)
 	return MLX5_CAP_GEN(dev->mdev, set_deth_sqpn);
 }
 
+static u32 next_outstanding(struct mlx5_ib_gsi_qp *gsi, u32 index)
+{
+	return ++index % gsi->cap.max_send_wr;
+}
+
+#define for_each_outstanding_wr(gsi, index) \
+	for (index = gsi->outstanding_ci; index != gsi->outstanding_pi; \
+	     index = next_outstanding(gsi, index))
+
+/* Call with gsi->lock locked */
+static void generate_completions(struct mlx5_ib_gsi_qp *gsi)
+{
+	struct ib_cq *gsi_cq = gsi->ibqp.send_cq;
+	struct mlx5_ib_gsi_wr *wr;
+	u32 index;
+
+	for_each_outstanding_wr(gsi, index) {
+		wr = &gsi->outstanding_wrs[index];
+
+		if (!wr->completed)
+			break;
+
+		if (gsi->sq_sig_type == IB_SIGNAL_ALL_WR ||
+		    wr->send_flags & IB_SEND_SIGNALED)
+			WARN_ON_ONCE(mlx5_ib_generate_wc(gsi_cq, &wr->wc));
+
+		wr->completed = false;
+	}
+
+	gsi->outstanding_ci = index;
+}
+
+static void handle_single_completion(struct ib_cq *cq, struct ib_wc *wc)
+{
+	struct mlx5_ib_gsi_qp *gsi = cq->cq_context;
+	struct mlx5_ib_gsi_wr *wr =
+		container_of(wc->wr_cqe, struct mlx5_ib_gsi_wr, cqe);
+	u64 wr_id;
+	unsigned long flags;
+
+	spin_lock_irqsave(&gsi->lock, flags);
+	wr->completed = true;
+	wr_id = wr->wc.wr_id;
+	wr->wc = *wc;
+	wr->wc.wr_id = wr_id;
+	wr->wc.qp = &gsi->ibqp;
+
+	generate_completions(gsi);
+	spin_unlock_irqrestore(&gsi->lock, flags);
+}
+
 struct ib_qp *mlx5_ib_gsi_create_qp(struct ib_pd *pd,
 				    struct ib_qp_init_attr *init_attr)
 {
@@ -88,6 +150,14 @@ struct ib_qp *mlx5_ib_gsi_create_qp(struct ib_pd *pd,
 		goto err_free;
 	}
 
+	gsi->outstanding_wrs = kcalloc(init_attr->cap.max_send_wr,
+				       sizeof(*gsi->outstanding_wrs),
+				       GFP_KERNEL);
+	if (!gsi->outstanding_wrs) {
+		ret = -ENOMEM;
+		goto err_free_tx;
+	}
+
 	mutex_init(&gsi->mutex);
 
 	mutex_lock(&dev->devr.mutex);
@@ -96,7 +166,7 @@ struct ib_qp *mlx5_ib_gsi_create_qp(struct ib_pd *pd,
 		mlx5_ib_warn(dev, "GSI QP already exists on port %d\n",
 			     port_num);
 		ret = -EBUSY;
-		goto err_free_tx;
+		goto err_free_wrs;
 	}
 	gsi->num_qps = num_qps;
 	spin_lock_init(&gsi->lock);
@@ -106,13 +176,23 @@ struct ib_qp *mlx5_ib_gsi_create_qp(struct ib_pd *pd,
 	gsi->ibqp.qp_num = 1;
 	gsi->port_num = port_num;
 
+	gsi->cq = ib_alloc_cq(pd->device, gsi, init_attr->cap.max_send_wr, 0,
+			      IB_POLL_SOFTIRQ);
+	if (IS_ERR(gsi->cq)) {
+		mlx5_ib_warn(dev, "unable to create send CQ for GSI QP. error %ld\n",
+			     PTR_ERR(gsi->cq));
+		ret = PTR_ERR(gsi->cq);
+		goto err_free_wrs;
+	}
+
 	hw_init_attr.qp_type = MLX5_IB_QPT_HW_GSI;
+	hw_init_attr.send_cq = gsi->cq;
 	gsi->rx_qp = ib_create_qp(pd, &hw_init_attr);
 	if (IS_ERR(gsi->rx_qp)) {
 		mlx5_ib_warn(dev, "unable to create hardware GSI QP. error %ld\n",
 			     PTR_ERR(gsi->rx_qp));
 		ret = PTR_ERR(gsi->rx_qp);
-		goto err_free_tx;
+		goto err_destroy_cq;
 	}
 
 	dev->devr.ports[init_attr->port_num - 1].gsi = gsi;
@@ -121,8 +201,12 @@ struct ib_qp *mlx5_ib_gsi_create_qp(struct ib_pd *pd,
 
 	return &gsi->ibqp;
 
-err_free_tx:
+err_destroy_cq:
+	ib_free_cq(gsi->cq);
+err_free_wrs:
 	mutex_unlock(&dev->devr.mutex);
+	kfree(gsi->outstanding_wrs);
+err_free_tx:
 	kfree(gsi->tx_qps);
 err_free:
 	kfree(gsi);
@@ -158,6 +242,9 @@ int mlx5_ib_gsi_destroy_qp(struct ib_qp *qp)
 		gsi->tx_qps[qp_index] = NULL;
 	}
 
+	ib_free_cq(gsi->cq);
+
+	kfree(gsi->outstanding_wrs);
 	kfree(gsi->tx_qps);
 	kfree(gsi);
 
@@ -170,7 +257,7 @@ static struct ib_qp *create_gsi_ud_qp(struct mlx5_ib_gsi_qp *gsi)
 	struct ib_qp_init_attr init_attr = {
 		.event_handler = gsi->rx_qp->event_handler,
 		.qp_context = gsi->rx_qp->qp_context,
-		.send_cq = gsi->rx_qp->send_cq,
+		.send_cq = gsi->cq,
 		.recv_cq = gsi->rx_qp->recv_cq,
 		.cap = {
 			.max_send_wr = gsi->cap.max_send_wr,
@@ -326,12 +413,69 @@ int mlx5_ib_gsi_query_qp(struct ib_qp *qp, struct ib_qp_attr *qp_attr,
 	return ret;
 }
 
+/* Call with gsi->lock locked */
+static int mlx5_ib_add_outstanding_wr(struct mlx5_ib_gsi_qp *gsi,
+				      struct ib_ud_wr *wr, struct ib_wc *wc)
+{
+	struct mlx5_ib_dev *dev = to_mdev(gsi->rx_qp->device);
+	struct mlx5_ib_gsi_wr *gsi_wr;
+
+	if (gsi->outstanding_pi == gsi->outstanding_ci + gsi->cap.max_send_wr) {
+		mlx5_ib_warn(dev, "no available GSI work request.\n");
+		return -ENOMEM;
+	}
+
+	gsi_wr = &gsi->outstanding_wrs[gsi->outstanding_pi];
+	gsi->outstanding_pi = next_outstanding(gsi, gsi->outstanding_pi);
+
+	if (!wc) {
+		memset(&gsi_wr->wc, 0, sizeof(gsi_wr->wc));
+		gsi_wr->wc.pkey_index = wr->pkey_index;
+		gsi_wr->wc.wr_id = wr->wr.wr_id;
+	} else {
+		gsi_wr->wc = *wc;
+		gsi_wr->completed = true;
+	}
+
+	gsi_wr->cqe.done = &handle_single_completion;
+	wr->wr.wr_cqe = &gsi_wr->cqe;
+
+	return 0;
+}
+
 int mlx5_ib_gsi_post_send(struct ib_qp *qp, struct ib_send_wr *wr,
 			  struct ib_send_wr **bad_wr)
 {
 	struct mlx5_ib_gsi_qp *gsi = gsi_qp(qp);
+	unsigned long flags;
+	int ret;
+
+	for (; wr; wr = wr->next) {
+		struct ib_ud_wr cur_wr = *ud_wr(wr);
+
+		cur_wr.wr.next = NULL;
 
-	return ib_post_send(gsi->rx_qp, wr, bad_wr);
+		spin_lock_irqsave(&gsi->lock, flags);
+		ret = mlx5_ib_add_outstanding_wr(gsi, &cur_wr, NULL);
+		if (ret)
+			goto err;
+
+		ret = ib_post_send(gsi->rx_qp, &cur_wr.wr, bad_wr);
+		if (ret) {
+			/* Undo the effect of adding the outstanding wr */
+			gsi->outstanding_pi = (gsi->outstanding_pi - 1) %
+					      gsi->cap.max_send_wr;
+			goto err;
+		}
+		spin_unlock_irqrestore(&gsi->lock, flags);
+	}
+
+	return 0;
+
+err:
+	spin_unlock_irqrestore(&gsi->lock, flags);
+	*bad_wr = wr;
+	return ret;
 }
 
 int mlx5_ib_gsi_post_recv(struct ib_qp *qp, struct ib_recv_wr *wr,