--- /dev/null
+// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
+// Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+
+#include "dr_types.h"
+#include "dr_ste.h"
+
+struct dr_definer_object {
+       u32 id;
+       u16 format_id;
+       u8 dw_selectors[MLX5_IFC_DEFINER_DW_SELECTORS_NUM];
+       u8 byte_selectors[MLX5_IFC_DEFINER_BYTE_SELECTORS_NUM];
+       u8 match_mask[DR_STE_SIZE_MATCH_TAG];
+       refcount_t refcount;
+};
+
+static bool dr_definer_compare(struct dr_definer_object *definer,
+                              u16 format_id, u8 *dw_selectors,
+                              u8 *byte_selectors, u8 *match_mask)
+{
+       int i;
+
+       if (definer->format_id != format_id)
+               return false;
+
+       for (i = 0; i < MLX5_IFC_DEFINER_DW_SELECTORS_NUM; i++)
+               if (definer->dw_selectors[i] != dw_selectors[i])
+                       return false;
+
+       for (i = 0; i < MLX5_IFC_DEFINER_BYTE_SELECTORS_NUM; i++)
+               if (definer->byte_selectors[i] != byte_selectors[i])
+                       return false;
+
+       if (memcmp(definer->match_mask, match_mask, DR_STE_SIZE_MATCH_TAG))
+               return false;
+
+       return true;
+}
+
+static struct dr_definer_object *
+dr_definer_find_obj(struct mlx5dr_domain *dmn, u16 format_id,
+                   u8 *dw_selectors, u8 *byte_selectors, u8 *match_mask)
+{
+       struct dr_definer_object *definer_obj;
+       unsigned long id;
+
+       xa_for_each(&dmn->definers_xa, id, definer_obj) {
+               if (dr_definer_compare(definer_obj, format_id,
+                                      dw_selectors, byte_selectors,
+                                      match_mask))
+                       return definer_obj;
+       }
+
+       return NULL;
+}
+
+static struct dr_definer_object *
+dr_definer_create_obj(struct mlx5dr_domain *dmn, u16 format_id,
+                     u8 *dw_selectors, u8 *byte_selectors, u8 *match_mask)
+{
+       struct dr_definer_object *definer_obj;
+       int ret = 0;
+
+       definer_obj = kzalloc(sizeof(*definer_obj), GFP_KERNEL);
+       if (!definer_obj)
+               return NULL;
+
+       ret = mlx5dr_cmd_create_definer(dmn->mdev,
+                                       format_id,
+                                       dw_selectors,
+                                       byte_selectors,
+                                       match_mask,
+                                       &definer_obj->id);
+       if (ret)
+               goto err_free_definer_obj;
+
+       /* Definer ID can have 32 bits, but STE format
+        * supports only definers with 8 bit IDs.
+        */
+       if (definer_obj->id > 0xff) {
+               mlx5dr_err(dmn, "Unsupported definer ID (%d)\n", definer_obj->id);
+               goto err_destroy_definer;
+       }
+
+       definer_obj->format_id = format_id;
+       memcpy(definer_obj->dw_selectors, dw_selectors, sizeof(definer_obj->dw_selectors));
+       memcpy(definer_obj->byte_selectors, byte_selectors, sizeof(definer_obj->byte_selectors));
+       memcpy(definer_obj->match_mask, match_mask, sizeof(definer_obj->match_mask));
+
+       refcount_set(&definer_obj->refcount, 1);
+
+       ret = xa_insert(&dmn->definers_xa, definer_obj->id, definer_obj, GFP_KERNEL);
+       if (ret) {
+               mlx5dr_dbg(dmn, "Couldn't insert new definer into xarray (%d)\n", ret);
+               goto err_destroy_definer;
+       }
+
+       return definer_obj;
+
+err_destroy_definer:
+       mlx5dr_cmd_destroy_definer(dmn->mdev, definer_obj->id);
+err_free_definer_obj:
+       kfree(definer_obj);
+
+       return NULL;
+}
+
+static void dr_definer_destroy_obj(struct mlx5dr_domain *dmn,
+                                  struct dr_definer_object *definer_obj)
+{
+       mlx5dr_cmd_destroy_definer(dmn->mdev, definer_obj->id);
+       xa_erase(&dmn->definers_xa, definer_obj->id);
+       kfree(definer_obj);
+}
+
+int mlx5dr_definer_get(struct mlx5dr_domain *dmn, u16 format_id,
+                      u8 *dw_selectors, u8 *byte_selectors,
+                      u8 *match_mask, u32 *definer_id)
+{
+       struct dr_definer_object *definer_obj;
+       int ret = 0;
+
+       definer_obj = dr_definer_find_obj(dmn, format_id, dw_selectors,
+                                         byte_selectors, match_mask);
+       if (!definer_obj) {
+               definer_obj = dr_definer_create_obj(dmn, format_id,
+                                                   dw_selectors, byte_selectors,
+                                                   match_mask);
+               if (!definer_obj)
+                       return -ENOMEM;
+       } else {
+               refcount_inc(&definer_obj->refcount);
+       }
+
+       *definer_id = definer_obj->id;
+
+       return ret;
+}
+
+void mlx5dr_definer_put(struct mlx5dr_domain *dmn, u32 definer_id)
+{
+       struct dr_definer_object *definer_obj;
+
+       definer_obj = xa_load(&dmn->definers_xa, definer_id);
+       if (!definer_obj) {
+               mlx5dr_err(dmn, "Definer ID %d not found\n", definer_id);
+               return;
+       }
+
+       if (refcount_dec_and_test(&definer_obj->refcount))
+               dr_definer_destroy_obj(dmn, definer_obj);
+}