net/mlx5: allocate door-bells via DevX

When using DevX API, memory for door-bell records should be allocated
by PMD and registered using DevX API.

This patch implements the utility functions to support it:
- Add struct mlx5_devx_dbr_page, containing door-bells page data.
- Add list of struct mlx5_devx_dbr_page door-bell pages to device
  private data.
- Implement function mlx5_alloc_dbr_page() to allocate page for
  door-bell records, and register it using DevX API.
- Implement function mlx5_get_dbr(). to acquire a door-bell record
  from the door-bells page, allocating a new page if needed.
- Implement function mlx5_release_dbr() to release a door-bell
  record that is no longer needed, freeing the containing page if
  it becomes empty.

Signed-off-by: Dekel Peled <dekelp@mellanox.com>
Acked-by: Matan Azrad <matan@mellanox.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>

drivers/net/mlx5/mlx5.c

@@ -1311,6 +1311,125 @@ mlx5_set_min_inline(struct mlx5_dev_spawn_data *spawn,
 	DRV_LOG(DEBUG, "min tx inline configured: %d", config->txq_inline_min);
 }
 
+/**
+ * Allocate page of door-bells and register it using DevX API.
+ *
+ * @param [in] dev
+ *   Pointer to Ethernet device.
+ *
+ * @return
+ *   Pointer to new page on success, NULL otherwise.
+ */
+static struct mlx5_devx_dbr_page *
+mlx5_alloc_dbr_page(struct rte_eth_dev *dev)
+{
+	struct mlx5_priv *priv = dev->data->dev_private;
+	struct mlx5_devx_dbr_page *page;
+
+	/* Allocate space for door-bell page and management data. */
+	page = rte_calloc_socket(__func__, 1, sizeof(struct mlx5_devx_dbr_page),
+				 RTE_CACHE_LINE_SIZE, dev->device->numa_node);
+	if (!page) {
+		DRV_LOG(ERR, "port %u cannot allocate dbr page",
+			dev->data->port_id);
+		return NULL;
+	}
+	/* Register allocated memory. */
+	page->umem = mlx5_glue->devx_umem_reg(priv->sh->ctx, page->dbrs,
+					      MLX5_DBR_PAGE_SIZE, 0);
+	if (!page->umem) {
+		DRV_LOG(ERR, "port %u cannot umem reg dbr page",
+			dev->data->port_id);
+		rte_free(page);
+		return NULL;
+	}
+	return page;
+}
+
+/**
+ * Find the next available door-bell, allocate new page if needed.
+ *
+ * @param [in] dev
+ *   Pointer to Ethernet device.
+ * @param [out] dbr_page
+ *   Door-bell page containing the page data.
+ *
+ * @return
+ *   Door-bell address offset on success, a negative error value otherwise.
+ */
+int64_t
+mlx5_get_dbr(struct rte_eth_dev *dev, struct mlx5_devx_dbr_page **dbr_page)
+{
+	struct mlx5_priv *priv = dev->data->dev_private;
+	struct mlx5_devx_dbr_page *page = NULL;
+	uint32_t i, j;
+
+	LIST_FOREACH(page, &priv->dbrpgs, next)
+		if (page->dbr_count < MLX5_DBR_PER_PAGE)
+			break;
+	if (!page) { /* No page with free door-bell exists. */
+		page = mlx5_alloc_dbr_page(dev);
+		if (!page) /* Failed to allocate new page. */
+			return (-1);
+		LIST_INSERT_HEAD(&priv->dbrpgs, page, next);
+	}
+	/* Loop to find bitmap part with clear bit. */
+	for (i = 0;
+	     i < MLX5_DBR_BITMAP_SIZE && page->dbr_bitmap[i] == UINT64_MAX;
+	     i++)
+		; /* Empty. */
+	/* Find the first clear bit. */
+	j = rte_bsf64(~page->dbr_bitmap[i]);
+	assert(i < (MLX5_DBR_PER_PAGE / 64));
+	page->dbr_bitmap[i] |= (1 << j);
+	page->dbr_count++;
+	*dbr_page = page;
+	return (((i * 64) + j) * sizeof(uint64_t));
+}
+
+/**
+ * Release a door-bell record.
+ *
+ * @param [in] dev
+ *   Pointer to Ethernet device.
+ * @param [in] umem_id
+ *   UMEM ID of page containing the door-bell record to release.
+ * @param [in] offset
+ *   Offset of door-bell record in page.
+ *
+ * @return
+ *   0 on success, a negative error value otherwise.
+ */
+int32_t
+mlx5_release_dbr(struct rte_eth_dev *dev, uint32_t umem_id, uint64_t offset)
+{
+	struct mlx5_priv *priv = dev->data->dev_private;
+	struct mlx5_devx_dbr_page *page = NULL;
+	int ret = 0;
+
+	LIST_FOREACH(page, &priv->dbrpgs, next)
+		/* Find the page this address belongs to. */
+		if (page->umem->umem_id == umem_id)
+			break;
+	if (!page)
+		return -EINVAL;
+	page->dbr_count--;
+	if (!page->dbr_count) {
+		/* Page not used, free it and remove from list. */
+		LIST_REMOVE(page, next);
+		if (page->umem)
+			ret = -mlx5_glue->devx_umem_dereg(page->umem);
+		rte_free(page);
+	} else {
+		/* Mark in bitmap that this door-bell is not in use. */
+		int i = offset / 64;
+		int j = offset % 64;
+
+		page->dbr_bitmap[i] &= ~(1 << j);
+	}
+	return ret;
+}
+
 /**
  * Spawn an Ethernet device from Verbs information.
  *

drivers/net/mlx5/mlx5.h

@@ -36,6 +36,7 @@
 #include "mlx5_mr.h"
 #include "mlx5_autoconf.h"
 #include "mlx5_defs.h"
+#include "mlx5_glue.h"
 
 enum {
 	PCI_VENDOR_ID_MELLANOX = 0x15b3,
@@ -498,6 +499,21 @@ struct mlx5_flow_tbl_resource {
 #define MLX5_MAX_TABLES_FDB 32
 #define MLX5_GROUP_FACTOR 1
 
+#define MLX5_DBR_PAGE_SIZE 4096 /* Must be >= 512. */
+#define MLX5_DBR_SIZE 8
+#define MLX5_DBR_PER_PAGE (MLX5_DBR_PAGE_SIZE / MLX5_DBR_SIZE)
+#define MLX5_DBR_BITMAP_SIZE (MLX5_DBR_PER_PAGE / 64)
+
+struct mlx5_devx_dbr_page {
+	/* Door-bell records, must be first member in structure. */
+	uint8_t dbrs[MLX5_DBR_PAGE_SIZE];
+	LIST_ENTRY(mlx5_devx_dbr_page) next; /* Pointer to the next element. */
+	struct mlx5dv_devx_umem *umem;
+	uint32_t dbr_count; /* Number of door-bell records in use. */
+	/* 1 bit marks matching door-bell is in use. */
+	uint64_t dbr_bitmap[MLX5_DBR_BITMAP_SIZE];
+};
+
 /*
  * Shared Infiniband device context for Master/Representors
  * which belong to same IB device with multiple IB ports.
@@ -618,6 +634,7 @@ struct mlx5_priv {
 	int nl_socket_rdma; /* Netlink socket (NETLINK_RDMA). */
 	int nl_socket_route; /* Netlink socket (NETLINK_ROUTE). */
 	uint32_t nl_sn; /* Netlink message sequence number. */
+	LIST_HEAD(dbrpage, mlx5_devx_dbr_page) dbrpgs; /* Door-bell pages. */
 #ifndef RTE_ARCH_64
 	rte_spinlock_t uar_lock_cq; /* CQs share a common distinct UAR */
 	rte_spinlock_t uar_lock[MLX5_UAR_PAGE_NUM_MAX];
@@ -632,6 +649,10 @@ struct mlx5_priv {
 
 int mlx5_getenv_int(const char *);
 int mlx5_proc_priv_init(struct rte_eth_dev *dev);
+int64_t mlx5_get_dbr(struct rte_eth_dev *dev,
+		     struct mlx5_devx_dbr_page **dbr_page);
+int32_t mlx5_release_dbr(struct rte_eth_dev *dev, uint32_t umem_id,
+			 uint64_t offset);
 
 /* mlx5_ethdev.c */
 

drivers/net/mlx5/mlx5_glue.h

@@ -61,7 +61,7 @@ enum mlx5dv_flow_table_type { flow_table_type = 0, };
 
 #ifndef HAVE_IBV_DEVX_OBJ
 struct mlx5dv_devx_obj;
-struct mlx5dv_devx_umem;
+struct mlx5dv_devx_umem { uint32_t umem_id; };
 #endif
 
 #ifndef HAVE_IBV_DEVX_ASYNC

drivers/net/mlx5/mlx5_rxtx.h

@@ -29,6 +29,7 @@
 #include <rte_spinlock.h>
 #include <rte_io.h>
 #include <rte_bus_pci.h>
+#include <rte_malloc.h>
 
 #include "mlx5_utils.h"
 #include "mlx5.h"