net/mlx5: DR, Add buddy allocator utilities

Add implementation of SW Steering variation of buddy allocator.

The buddy system for ICM memory uses 2 main data structures:
- Bitmap per order, that keeps the current state of allocated
  blocks for this order
- Indicator for the number of available blocks per each order
Signed-off-by: Erez Shitrit <erezsh@nvidia.com>
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/Makefile

@@ -81,7 +81,7 @@ mlx5_core-$(CONFIG_MLX5_EN_TLS) += en_accel/tls.o en_accel/tls_rxtx.o en_accel/t
 
 mlx5_core-$(CONFIG_MLX5_SW_STEERING) += steering/dr_domain.o steering/dr_table.o \
 					steering/dr_matcher.o steering/dr_rule.o \
-					steering/dr_icm_pool.o \
+					steering/dr_icm_pool.o steering/dr_buddy.o \
 					steering/dr_ste.o steering/dr_send.o \
 					steering/dr_cmd.o steering/dr_fw.o \
 					steering/dr_action.o steering/fs_dr.o

drivers/net/ethernet/mellanox/mlx5/core/steering/dr_buddy.c

+// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
+/* Copyright (c) 2004 Topspin Communications. All rights reserved.
+ * Copyright (c) 2005 - 2008 Mellanox Technologies. All rights reserved.
+ * Copyright (c) 2006 - 2007 Cisco Systems, Inc. All rights reserved.
+ * Copyright (c) 2020 NVIDIA CORPORATION. All rights reserved.
+ */
+
+#include "dr_types.h"
+
+int mlx5dr_buddy_init(struct mlx5dr_icm_buddy_mem *buddy,
+		      unsigned int max_order)
+{
+	int i;
+
+	buddy->max_order = max_order;
+
+	INIT_LIST_HEAD(&buddy->list_node);
+	INIT_LIST_HEAD(&buddy->used_list);
+	INIT_LIST_HEAD(&buddy->hot_list);
+
+	buddy->bitmap = kcalloc(buddy->max_order + 1,
+				sizeof(*buddy->bitmap),
+				GFP_KERNEL);
+	buddy->num_free = kcalloc(buddy->max_order + 1,
+				  sizeof(*buddy->num_free),
+				  GFP_KERNEL);
+
+	if (!buddy->bitmap || !buddy->num_free)
+		goto err_free_all;
+
+	/* Allocating max_order bitmaps, one for each order */
+
+	for (i = 0; i <= buddy->max_order; ++i) {
+		unsigned int size = 1 << (buddy->max_order - i);
+
+		buddy->bitmap[i] = bitmap_zalloc(size, GFP_KERNEL);
+		if (!buddy->bitmap[i])
+			goto err_out_free_each_bit_per_order;
+	}
+
+	/* In the beginning, we have only one order that is available for
+	 * use (the biggest one), so mark the first bit in both bitmaps.
+	 */
+
+	bitmap_set(buddy->bitmap[buddy->max_order], 0, 1);
+
+	buddy->num_free[buddy->max_order] = 1;
+
+	return 0;
+
+err_out_free_each_bit_per_order:
+	for (i = 0; i <= buddy->max_order; ++i)
+		bitmap_free(buddy->bitmap[i]);
+
+err_free_all:
+	kfree(buddy->num_free);
+	kfree(buddy->bitmap);
+	return -ENOMEM;
+}
+
+void mlx5dr_buddy_cleanup(struct mlx5dr_icm_buddy_mem *buddy)
+{
+	int i;
+
+	list_del(&buddy->list_node);
+
+	for (i = 0; i <= buddy->max_order; ++i)
+		bitmap_free(buddy->bitmap[i]);
+
+	kfree(buddy->num_free);
+	kfree(buddy->bitmap);
+}
+
+static int dr_buddy_find_free_seg(struct mlx5dr_icm_buddy_mem *buddy,
+				  unsigned int start_order,
+				  unsigned int *segment,
+				  unsigned int *order)
+{
+	unsigned int seg, order_iter, m;
+
+	for (order_iter = start_order;
+	     order_iter <= buddy->max_order; ++order_iter) {
+		if (!buddy->num_free[order_iter])
+			continue;
+
+		m = 1 << (buddy->max_order - order_iter);
+		seg = find_first_bit(buddy->bitmap[order_iter], m);
+
+		if (WARN(seg >= m,
+			 "ICM Buddy: failed finding free mem for order %d\n",
+			 order_iter))
+			return -ENOMEM;
+
+		break;
+	}
+
+	if (order_iter > buddy->max_order)
+		return -ENOMEM;
+
+	*segment = seg;
+	*order = order_iter;
+	return 0;
+}
+
+/**
+ * mlx5dr_buddy_alloc_mem() - Update second level bitmap.
+ * @buddy: Buddy to update.
+ * @order: Order of the buddy to update.
+ * @segment: Segment number.
+ *
+ * This function finds the first area of the ICM memory managed by this buddy.
+ * It uses the data structures of the buddy system in order to find the first
+ * area of free place, starting from the current order till the maximum order
+ * in the system.
+ *
+ * Return: 0 when segment is set, non-zero error status otherwise.
+ *
+ * The function returns the location (segment) in the whole buddy ICM memory
+ * area - the index of the memory segment that is available for use.
+ */
+int mlx5dr_buddy_alloc_mem(struct mlx5dr_icm_buddy_mem *buddy,
+			   unsigned int order,
+			   unsigned int *segment)
+{
+	unsigned int seg, order_iter;
+	int err;
+
+	err = dr_buddy_find_free_seg(buddy, order, &seg, &order_iter);
+	if (err)
+		return err;
+
+	bitmap_clear(buddy->bitmap[order_iter], seg, 1);
+	--buddy->num_free[order_iter];
+
+	/* If we found free memory in some order that is bigger than the
+	 * required order, we need to split every order between the required
+	 * order and the order that we found into two parts, and mark accordingly.
+	 */
+	while (order_iter > order) {
+		--order_iter;
+		seg <<= 1;
+		bitmap_set(buddy->bitmap[order_iter], seg ^ 1, 1);
+		++buddy->num_free[order_iter];
+	}
+
+	seg <<= order;
+	*segment = seg;
+
+	return 0;
+}
+
+void mlx5dr_buddy_free_mem(struct mlx5dr_icm_buddy_mem *buddy,
+			   unsigned int seg, unsigned int order)
+{
+	seg >>= order;
+
+	/* Whenever a segment is free,
+	 * the mem is added to the buddy that gave it.
+	 */
+	while (test_bit(seg ^ 1, buddy->bitmap[order])) {
+		bitmap_clear(buddy->bitmap[order], seg ^ 1, 1);
+		--buddy->num_free[order];
+		seg >>= 1;
+		++order;
+	}
+	bitmap_set(buddy->bitmap[order], seg, 1);
+
+	++buddy->num_free[order];
+}
+

drivers/net/ethernet/mellanox/mlx5/core/steering/mlx5dr.h

@@ -127,4 +127,37 @@ mlx5dr_is_supported(struct mlx5_core_dev *dev)
 	return MLX5_CAP_ESW_FLOWTABLE_FDB(dev, sw_owner);
 }
 
+/* buddy functions & structure */
+
+struct mlx5dr_icm_mr;
+
+struct mlx5dr_icm_buddy_mem {
+	unsigned long		**bitmap;
+	unsigned int		*num_free;
+	u32			max_order;
+	struct list_head	list_node;
+	struct mlx5dr_icm_mr	*icm_mr;
+	struct mlx5dr_icm_pool	*pool;
+
+	/* This is the list of used chunks. HW may be accessing this memory */
+	struct list_head	used_list;
+
+	/* Hardware may be accessing this memory but at some future,
+	 * undetermined time, it might cease to do so.
+	 * sync_ste command sets them free.
+	 */
+	struct list_head	hot_list;
+	/* indicates the byte size of hot mem */
+	unsigned int		hot_memory_size;
+};
+
+int mlx5dr_buddy_init(struct mlx5dr_icm_buddy_mem *buddy,
+		      unsigned int max_order);
+void mlx5dr_buddy_cleanup(struct mlx5dr_icm_buddy_mem *buddy);
+int mlx5dr_buddy_alloc_mem(struct mlx5dr_icm_buddy_mem *buddy,
+			   unsigned int order,
+			   unsigned int *segment);
+void mlx5dr_buddy_free_mem(struct mlx5dr_icm_buddy_mem *buddy,
+			   unsigned int seg, unsigned int order);
+
 #endif /* _MLX5DR_H_ */