RDMA/mlx5: Expose UAPI to query DM

Expose UAPI to query MEMIC DM, this will let user space application
that didn't allocate the DM but has access to by owning the matching
command FD to retrieve its information.

Link: https://lore.kernel.org/r/20210411122924.60230-8-leon@kernel.org
Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/hw/mlx5/dm.c

@@ -293,6 +293,7 @@ static struct ib_dm *handle_alloc_dm_memic(struct ib_ucontext *ctx,
 	kref_init(&dm->ref);
 	xa_init(&dm->ops);
 	mutex_init(&dm->ops_xa_lock);
+	dm->req_length = attr->length;
 
 	err = mlx5_cmd_alloc_memic(dm_db, &dm->base.dev_addr,
 				   dm->base.size, attr->alignment);
@@ -473,6 +474,38 @@ static int mlx5_ib_dealloc_dm(struct ib_dm *ibdm,
 	}
 }
 
+static int UVERBS_HANDLER(MLX5_IB_METHOD_DM_QUERY)(
+	struct uverbs_attr_bundle *attrs)
+{
+	struct ib_dm *ibdm =
+		uverbs_attr_get_obj(attrs, MLX5_IB_ATTR_QUERY_DM_REQ_HANDLE);
+	struct mlx5_ib_dm *dm = to_mdm(ibdm);
+	struct mlx5_ib_dm_memic *memic;
+	u64 start_offset;
+	u16 page_idx;
+	int err;
+
+	if (dm->type != MLX5_IB_UAPI_DM_TYPE_MEMIC)
+		return -EOPNOTSUPP;
+
+	memic = to_memic(ibdm);
+	page_idx = memic->mentry.rdma_entry.start_pgoff & 0xFFFF;
+	err = uverbs_copy_to(attrs, MLX5_IB_ATTR_QUERY_DM_RESP_PAGE_INDEX,
+			     &page_idx, sizeof(page_idx));
+	if (err)
+		return err;
+
+	start_offset = memic->base.dev_addr & ~PAGE_MASK;
+	err =  uverbs_copy_to(attrs, MLX5_IB_ATTR_QUERY_DM_RESP_START_OFFSET,
+			      &start_offset, sizeof(start_offset));
+	if (err)
+		return err;
+
+	return uverbs_copy_to(attrs, MLX5_IB_ATTR_QUERY_DM_RESP_LENGTH,
+			      &memic->req_length,
+			      sizeof(memic->req_length));
+}
+
 void mlx5_ib_dm_mmap_free(struct mlx5_ib_dev *dev,
 			  struct mlx5_user_mmap_entry *mentry)
 {
@@ -498,6 +531,17 @@ void mlx5_ib_dm_mmap_free(struct mlx5_ib_dev *dev,
 	}
 }
 
+DECLARE_UVERBS_NAMED_METHOD(
+	MLX5_IB_METHOD_DM_QUERY,
+	UVERBS_ATTR_IDR(MLX5_IB_ATTR_QUERY_DM_REQ_HANDLE, UVERBS_OBJECT_DM,
+			UVERBS_ACCESS_READ, UA_MANDATORY),
+	UVERBS_ATTR_PTR_OUT(MLX5_IB_ATTR_QUERY_DM_RESP_START_OFFSET,
+			    UVERBS_ATTR_TYPE(u64), UA_MANDATORY),
+	UVERBS_ATTR_PTR_OUT(MLX5_IB_ATTR_QUERY_DM_RESP_PAGE_INDEX,
+			    UVERBS_ATTR_TYPE(u16), UA_MANDATORY),
+	UVERBS_ATTR_PTR_OUT(MLX5_IB_ATTR_QUERY_DM_RESP_LENGTH,
+			    UVERBS_ATTR_TYPE(u64), UA_MANDATORY));
+
 ADD_UVERBS_ATTRIBUTES_SIMPLE(
 	mlx5_ib_dm, UVERBS_OBJECT_DM, UVERBS_METHOD_DM_ALLOC,
 	UVERBS_ATTR_PTR_OUT(MLX5_IB_ATTR_ALLOC_DM_RESP_START_OFFSET,
@@ -524,7 +568,8 @@ DECLARE_UVERBS_NAMED_METHOD(
 			    UA_OPTIONAL));
 
 DECLARE_UVERBS_GLOBAL_METHODS(UVERBS_OBJECT_DM,
-			      &UVERBS_METHOD(MLX5_IB_METHOD_DM_MAP_OP_ADDR));
+			      &UVERBS_METHOD(MLX5_IB_METHOD_DM_MAP_OP_ADDR),
+			      &UVERBS_METHOD(MLX5_IB_METHOD_DM_QUERY));
 
 const struct uapi_definition mlx5_ib_dm_defs[] = {
 	UAPI_DEF_CHAIN_OBJ_TREE(UVERBS_OBJECT_DM, &mlx5_ib_dm),

drivers/infiniband/hw/mlx5/dm.h

@@ -31,6 +31,7 @@ struct mlx5_ib_dm_memic {
 	struct xarray               ops;
 	struct mutex                ops_xa_lock;
 	struct kref                 ref;
+	size_t                      req_length;
 };
 
 struct mlx5_ib_dm_icm {

include/uapi/rdma/mlx5_user_ioctl_cmds.h

@@ -43,6 +43,7 @@ enum mlx5_ib_create_flow_action_attrs {
 
 enum mlx5_ib_dm_methods {
 	MLX5_IB_METHOD_DM_MAP_OP_ADDR  = (1U << UVERBS_ID_NS_SHIFT),
+	MLX5_IB_METHOD_DM_QUERY,
 };
 
 enum mlx5_ib_dm_map_op_addr_attrs {
@@ -52,6 +53,13 @@ enum mlx5_ib_dm_map_op_addr_attrs {
 	MLX5_IB_ATTR_DM_MAP_OP_ADDR_RESP_PAGE_INDEX,
 };
 
+enum mlx5_ib_query_dm_attrs {
+	MLX5_IB_ATTR_QUERY_DM_REQ_HANDLE = (1U << UVERBS_ID_NS_SHIFT),
+	MLX5_IB_ATTR_QUERY_DM_RESP_START_OFFSET,
+	MLX5_IB_ATTR_QUERY_DM_RESP_PAGE_INDEX,
+	MLX5_IB_ATTR_QUERY_DM_RESP_LENGTH,
+};
+
 enum mlx5_ib_alloc_dm_attrs {
 	MLX5_IB_ATTR_ALLOC_DM_RESP_START_OFFSET = (1U << UVERBS_ID_NS_SHIFT),
 	MLX5_IB_ATTR_ALLOC_DM_RESP_PAGE_INDEX,