mlx5: Add support for DM export DMABUF fd

Add support for DM export DMABUF fd.

Upon the allocation flow of the DM the driver may save the pg_off on its
internal mlx5_dm structure.

This data will be used upon exporting a DMABUF fd for the DM by calling
ibv_cmd_export_dmabuf_fd().

Signed-off-by: Yishai Hadas <yishaih@nvidia.com>

Author: yishaih

providers/mlx5/mlx5.c

@@ -177,6 +177,7 @@ static const struct verbs_context_ops mlx5_ctx_common_ops = {
 	.dealloc_dmah = mlx5_dealloc_dmah,
 	.reg_mr_ex = mlx5_reg_mr_ex,
 	.query_port_speed = mlx5_query_port_speed,
+	.dm_export_dmabuf_fd = mlx5_dm_export_dmabuf_fd,
 };
 
 static const struct verbs_context_ops mlx5_ctx_cqev1_ops = {

providers/mlx5/mlx5.h

@@ -645,6 +645,7 @@ struct mlx5_dm {
 	void			       *mmap_va;
 	void			       *start_va;
 	uint64_t			remote_va;
+	off_t pg_off;
 };
 
 struct mlx5_mr {
@@ -1268,6 +1269,7 @@ int mlx5_modify_flow_action_esp(struct ibv_flow_action *action,
 struct ibv_dm *mlx5_alloc_dm(struct ibv_context *context,
 			     struct ibv_alloc_dm_attr *dm_attr);
 int mlx5_free_dm(struct ibv_dm *ibdm);
+int mlx5_dm_export_dmabuf_fd(struct ibv_dm *dm);
 struct ibv_mr *mlx5_reg_dm_mr(struct ibv_pd *pd, struct ibv_dm *ibdm,
 			      uint64_t dm_offset, size_t length,
 			      unsigned int acc);

providers/mlx5/verbs.c

@@ -5066,8 +5066,10 @@ static void *dm_mmap(struct ibv_context *context, struct mlx5_dm *mdm,
 
 	set_command(MLX5_IB_MMAP_DEVICE_MEM, &offset);
 	set_extended_index(page_idx, &offset);
+	mdm->pg_off = page_size * offset;
+
 	return mmap(NULL, act_size, PROT_READ | PROT_WRITE, MAP_SHARED,
-		    context->cmd_fd, page_size * offset);
+		    context->cmd_fd, mdm->pg_off);
 }
 
 static void *_mlx5dv_dm_map_op_addr(struct ibv_dm *dm, uint8_t op)
@@ -5390,6 +5392,11 @@ struct ibv_dm *mlx5_alloc_dm(struct ibv_context *context,
 	return mlx5dv_alloc_dm(context, dm_attr, &mlx5_attr);
 }
 
+int mlx5_dm_export_dmabuf_fd(struct ibv_dm *ibdm)
+{
+	return ibv_cmd_export_dmabuf_fd(ibdm->context, to_mdm(ibdm)->pg_off);
+}
+
 struct ibv_counters *mlx5_create_counters(struct ibv_context *context,
 					  struct ibv_counters_init_attr *init_attr)
 {