net/mlx5: Add interface to get reference to a UAR

A reference to a UAR is required to generate CQ or EQ doorbells. Since
CQ or EQ doorbells can all be generated using the same UAR area without
any effect on performance, we are just getting a reference to any
available UAR, If one is not available we allocate it but we don't waste
the blue flame registers it can provide and we will use them for
subsequent allocations.
We get a reference to such UAR and put in mlx5_priv so any kernel
consumer can make use of it.

Signed-off-by: Eli Cohen <eli@mellanox.com>
Reviewed-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/eq.c

@@ -512,7 +512,7 @@ static void init_eq_buf(struct mlx5_eq *eq)
 
 int mlx5_create_map_eq(struct mlx5_core_dev *dev, struct mlx5_eq *eq, u8 vecidx,
 		       int nent, u64 mask, const char *name,
-		       struct mlx5_uar *uar, enum mlx5_eq_type type)
+		       enum mlx5_eq_type type)
 {
 	u32 out[MLX5_ST_SZ_DW(create_eq_out)] = {0};
 	struct mlx5_priv *priv = &dev->priv;
@@ -556,7 +556,7 @@ int mlx5_create_map_eq(struct mlx5_core_dev *dev, struct mlx5_eq *eq, u8 vecidx,
 
 	eqc = MLX5_ADDR_OF(create_eq_in, in, eq_context_entry);
 	MLX5_SET(eqc, eqc, log_eq_size, ilog2(eq->nent));
-	MLX5_SET(eqc, eqc, uar_page, uar->index);
+	MLX5_SET(eqc, eqc, uar_page, priv->uar->index);
 	MLX5_SET(eqc, eqc, intr, vecidx);
 	MLX5_SET(eqc, eqc, log_page_size,
 		 eq->buf.page_shift - MLX5_ADAPTER_PAGE_SHIFT);
@@ -571,7 +571,7 @@ int mlx5_create_map_eq(struct mlx5_core_dev *dev, struct mlx5_eq *eq, u8 vecidx,
 	eq->eqn = MLX5_GET(create_eq_out, out, eq_number);
 	eq->irqn = priv->msix_arr[vecidx].vector;
 	eq->dev = dev;
-	eq->doorbell = uar->map + MLX5_EQ_DOORBEL_OFFSET;
+	eq->doorbell = priv->uar->map + MLX5_EQ_DOORBEL_OFFSET;
 	err = request_irq(eq->irqn, handler, 0,
 			  priv->irq_info[vecidx].name, eq);
 	if (err)
@@ -686,8 +686,7 @@ int mlx5_start_eqs(struct mlx5_core_dev *dev)
 
 	err = mlx5_create_map_eq(dev, &table->cmd_eq, MLX5_EQ_VEC_CMD,
 				 MLX5_NUM_CMD_EQE, 1ull << MLX5_EVENT_TYPE_CMD,
-				 "mlx5_cmd_eq", &dev->priv.bfregi.uars[0],
-				 MLX5_EQ_TYPE_ASYNC);
+				 "mlx5_cmd_eq", MLX5_EQ_TYPE_ASYNC);
 	if (err) {
 		mlx5_core_warn(dev, "failed to create cmd EQ %d\n", err);
 		return err;
@@ -697,8 +696,7 @@ int mlx5_start_eqs(struct mlx5_core_dev *dev)
 
 	err = mlx5_create_map_eq(dev, &table->async_eq, MLX5_EQ_VEC_ASYNC,
 				 MLX5_NUM_ASYNC_EQE, async_event_mask,
-				 "mlx5_async_eq", &dev->priv.bfregi.uars[0],
-				 MLX5_EQ_TYPE_ASYNC);
+				 "mlx5_async_eq", MLX5_EQ_TYPE_ASYNC);
 	if (err) {
 		mlx5_core_warn(dev, "failed to create async EQ %d\n", err);
 		goto err1;
@@ -708,7 +706,6 @@ int mlx5_start_eqs(struct mlx5_core_dev *dev)
 				 MLX5_EQ_VEC_PAGES,
 				 /* TODO: sriov max_vf + */ 1,
 				 1 << MLX5_EVENT_TYPE_PAGE_REQUEST, "mlx5_pages_eq",
-				 &dev->priv.bfregi.uars[0],
 				 MLX5_EQ_TYPE_ASYNC);
 	if (err) {
 		mlx5_core_warn(dev, "failed to create pages EQ %d\n", err);
@@ -722,7 +719,6 @@ int mlx5_start_eqs(struct mlx5_core_dev *dev)
 					 MLX5_NUM_ASYNC_EQE,
 					 1 << MLX5_EVENT_TYPE_PAGE_FAULT,
 					 "mlx5_page_fault_eq",
-					 &dev->priv.bfregi.uars[0],
 					 MLX5_EQ_TYPE_PF);
 		if (err) {
 			mlx5_core_warn(dev, "failed to create page fault EQ %d\n",

drivers/net/ethernet/mellanox/mlx5/core/main.c

@@ -753,8 +753,7 @@ static int alloc_comp_eqs(struct mlx5_core_dev *dev)
 		snprintf(name, MLX5_MAX_IRQ_NAME, "mlx5_comp%d", i);
 		err = mlx5_create_map_eq(dev, eq,
 					 i + MLX5_EQ_VEC_COMP_BASE, nent, 0,
-					 name, &dev->priv.bfregi.uars[0],
-					 MLX5_EQ_TYPE_COMP);
+					 name, MLX5_EQ_TYPE_COMP);
 		if (err) {
 			kfree(eq);
 			goto clean;
@@ -1094,12 +1093,18 @@ static int mlx5_load_one(struct mlx5_core_dev *dev, struct mlx5_priv *priv,
 		goto err_cleanup_once;
 	}
 
-	err = mlx5_alloc_bfregs(dev, &priv->bfregi);
-	if (err) {
+	dev->priv.uar = mlx5_get_uars_page(dev);
+	if (!dev->priv.uar) {
 		dev_err(&pdev->dev, "Failed allocating uar, aborting\n");
 		goto err_disable_msix;
 	}
 
+	err = mlx5_alloc_bfregs(dev, &priv->bfregi);
+	if (err) {
+		dev_err(&pdev->dev, "Failed allocating uuars, aborting\n");
+		goto err_uar_cleanup;
+	}
+
 	err = mlx5_start_eqs(dev);
 	if (err) {
 		dev_err(&pdev->dev, "Failed to start pages and async EQs\n");
@@ -1172,6 +1177,9 @@ err_stop_eqs:
 err_free_uar:
 	mlx5_free_bfregs(dev, &priv->bfregi);
 
+err_uar_cleanup:
+	mlx5_put_uars_page(dev, priv->uar);
+
 err_disable_msix:
 	mlx5_disable_msix(dev);
 
@@ -1231,6 +1239,7 @@ static int mlx5_unload_one(struct mlx5_core_dev *dev, struct mlx5_priv *priv,
 	free_comp_eqs(dev);
 	mlx5_stop_eqs(dev);
 	mlx5_free_bfregs(dev, &priv->bfregi);
+	mlx5_put_uars_page(dev, priv->uar);
 	mlx5_disable_msix(dev);
 	if (cleanup)
 		mlx5_cleanup_once(dev);
@@ -1305,6 +1314,11 @@ static int init_one(struct pci_dev *pdev,
 		goto clean_dev;
 	}
 #endif
+	mutex_init(&priv->bfregs.reg_head.lock);
+	mutex_init(&priv->bfregs.wc_head.lock);
+	INIT_LIST_HEAD(&priv->bfregs.reg_head.list);
+	INIT_LIST_HEAD(&priv->bfregs.wc_head.list);
+
 	err = mlx5_pci_init(dev, priv);
 	if (err) {
 		dev_err(&pdev->dev, "mlx5_pci_init failed with error code %d\n", err);

drivers/net/ethernet/mellanox/mlx5/core/uar.c

@@ -332,6 +332,38 @@ error1:
 	return ERR_PTR(err);
 }
 
+struct mlx5_uars_page *mlx5_get_uars_page(struct mlx5_core_dev *mdev)
+{
+	struct mlx5_uars_page *ret;
+
+	mutex_lock(&mdev->priv.bfregs.reg_head.lock);
+	if (list_empty(&mdev->priv.bfregs.reg_head.list)) {
+		ret = alloc_uars_page(mdev, false);
+		if (IS_ERR(ret)) {
+			ret = NULL;
+			goto out;
+		}
+		list_add(&ret->list, &mdev->priv.bfregs.reg_head.list);
+	} else {
+		ret = list_first_entry(&mdev->priv.bfregs.reg_head.list,
+				       struct mlx5_uars_page, list);
+		kref_get(&ret->ref_count);
+	}
+out:
+	mutex_unlock(&mdev->priv.bfregs.reg_head.lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(mlx5_get_uars_page);
+
+void mlx5_put_uars_page(struct mlx5_core_dev *mdev, struct mlx5_uars_page *up)
+{
+	mutex_lock(&mdev->priv.bfregs.reg_head.lock);
+	kref_put(&up->ref_count, up_rel_func);
+	mutex_unlock(&mdev->priv.bfregs.reg_head.lock);
+}
+EXPORT_SYMBOL(mlx5_put_uars_page);
+
 static unsigned long map_offset(struct mlx5_core_dev *mdev, int dbi)
 {
 	/* return the offset in bytes from the start of the page to the

include/linux/mlx5/driver.h

@@ -679,6 +679,7 @@ struct mlx5_priv {
 	struct srcu_struct      pfault_srcu;
 #endif
 	struct mlx5_bfreg_data		bfregs;
+	struct mlx5_uars_page	       *uar;
 };
 
 enum mlx5_device_state {
@@ -1007,7 +1008,7 @@ void mlx5_cmd_comp_handler(struct mlx5_core_dev *dev, u64 vec);
 void mlx5_cq_event(struct mlx5_core_dev *dev, u32 cqn, int event_type);
 int mlx5_create_map_eq(struct mlx5_core_dev *dev, struct mlx5_eq *eq, u8 vecidx,
 		       int nent, u64 mask, const char *name,
-		       struct mlx5_uar *uar, enum mlx5_eq_type type);
+		       enum mlx5_eq_type type);
 int mlx5_destroy_unmap_eq(struct mlx5_core_dev *dev, struct mlx5_eq *eq);
 int mlx5_start_eqs(struct mlx5_core_dev *dev);
 int mlx5_stop_eqs(struct mlx5_core_dev *dev);
@@ -1118,6 +1119,8 @@ int mlx5_cmd_create_vport_lag(struct mlx5_core_dev *dev);
 int mlx5_cmd_destroy_vport_lag(struct mlx5_core_dev *dev);
 bool mlx5_lag_is_active(struct mlx5_core_dev *dev);
 struct net_device *mlx5_lag_get_roce_netdev(struct mlx5_core_dev *dev);
+struct mlx5_uars_page *mlx5_get_uars_page(struct mlx5_core_dev *mdev);
+void mlx5_put_uars_page(struct mlx5_core_dev *mdev, struct mlx5_uars_page *up);
 
 struct mlx5_profile {
 	u64	mask;