diff --git a/drivers/infiniband/core/Makefile b/drivers/infiniband/core/Makefile
index 781b3172e596..fc1d5adfb24b 100644
--- a/drivers/infiniband/core/Makefile
+++ b/drivers/infiniband/core/Makefile
@@ -38,4 +38,4 @@ ib_uverbs-y :=			uverbs_main.o uverbs_cmd.o uverbs_marshall.o \
 				uverbs_std_types_cq.o \
 				uverbs_std_types_flow_action.o uverbs_std_types_dm.o \
 				uverbs_std_types_mr.o uverbs_std_types_counters.o \
-				uverbs_uapi.o
+				uverbs_uapi.o uverbs_std_types_device.o
diff --git a/drivers/infiniband/core/rdma_core.h b/drivers/infiniband/core/rdma_core.h
index b3ca7457ac42..be6b8e1257d0 100644
--- a/drivers/infiniband/core/rdma_core.h
+++ b/drivers/infiniband/core/rdma_core.h
@@ -188,6 +188,7 @@ void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile);
 
 extern const struct uapi_definition uverbs_def_obj_counters[];
 extern const struct uapi_definition uverbs_def_obj_cq[];
+extern const struct uapi_definition uverbs_def_obj_device[];
 extern const struct uapi_definition uverbs_def_obj_dm[];
 extern const struct uapi_definition uverbs_def_obj_flow_action[];
 extern const struct uapi_definition uverbs_def_obj_intf[];
@@ -214,4 +215,8 @@ uapi_get_method(const struct uverbs_api *uapi, u32 command)
 	return uapi->write_methods[cmd_idx];
 }
 
+void uverbs_fill_udata(struct uverbs_attr_bundle *bundle,
+		       struct ib_udata *udata, unsigned int attr_in,
+		       unsigned int attr_out);
+
 #endif /* RDMA_CORE_H */
diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h
index 8b41c95300c6..88029f3b6853 100644
--- a/drivers/infiniband/core/uverbs.h
+++ b/drivers/infiniband/core/uverbs.h
@@ -246,7 +246,6 @@ int uverbs_dealloc_mw(struct ib_mw *mw);
 void ib_uverbs_detach_umcast(struct ib_qp *qp,
 			     struct ib_uqp_object *uobj);
 
-void create_udata(struct uverbs_attr_bundle *ctx, struct ib_udata *udata);
 long ib_uverbs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
 
 struct ib_uverbs_flow_spec {
diff --git a/drivers/infiniband/core/uverbs_ioctl.c b/drivers/infiniband/core/uverbs_ioctl.c
index e643a43dce8d..3cc46447240e 100644
--- a/drivers/infiniband/core/uverbs_ioctl.c
+++ b/drivers/infiniband/core/uverbs_ioctl.c
@@ -436,7 +436,9 @@ static int ib_uverbs_run_method(struct bundle_priv *pbundle,
 		return -EINVAL;
 
 	if (pbundle->method_elm->has_udata)
-		create_udata(&pbundle->bundle, &pbundle->bundle.driver_udata);
+		uverbs_fill_udata(&pbundle->bundle,
+				  &pbundle->bundle.driver_udata,
+				  UVERBS_ATTR_UHW_IN, UVERBS_ATTR_UHW_OUT);
 
 	if (destroy_bkey != UVERBS_API_ATTR_BKEY_LEN) {
 		struct uverbs_obj_attr *destroy_attr =
@@ -664,35 +666,37 @@ int uverbs_get_flags32(u32 *to, const struct uverbs_attr_bundle *attrs_bundle,
 EXPORT_SYMBOL(uverbs_get_flags32);
 
 /*
- * This is for ease of conversion. The purpose is to convert all drivers to
- * use uverbs_attr_bundle instead of ib_udata.  Assume attr == 0 is input and
- * attr == 1 is output.
+ * Fill a ib_udata struct (core or uhw) using the given attribute IDs.
+ * This is primarily used to convert the UVERBS_ATTR_UHW() into the
+ * ib_udata format used by the drivers.
  */
-void create_udata(struct uverbs_attr_bundle *bundle, struct ib_udata *udata)
+void uverbs_fill_udata(struct uverbs_attr_bundle *bundle,
+		       struct ib_udata *udata, unsigned int attr_in,
+		       unsigned int attr_out)
 {
 	struct bundle_priv *pbundle =
 		container_of(bundle, struct bundle_priv, bundle);
-	const struct uverbs_attr *uhw_in =
-		uverbs_attr_get(bundle, UVERBS_ATTR_UHW_IN);
-	const struct uverbs_attr *uhw_out =
-		uverbs_attr_get(bundle, UVERBS_ATTR_UHW_OUT);
-
-	if (!IS_ERR(uhw_in)) {
-		udata->inlen = uhw_in->ptr_attr.len;
-		if (uverbs_attr_ptr_is_inline(uhw_in))
+	const struct uverbs_attr *in =
+		uverbs_attr_get(&pbundle->bundle, attr_in);
+	const struct uverbs_attr *out =
+		uverbs_attr_get(&pbundle->bundle, attr_out);
+
+	if (!IS_ERR(in)) {
+		udata->inlen = in->ptr_attr.len;
+		if (uverbs_attr_ptr_is_inline(in))
 			udata->inbuf =
-				&pbundle->user_attrs[uhw_in->ptr_attr.uattr_idx]
+				&pbundle->user_attrs[in->ptr_attr.uattr_idx]
 					 .data;
 		else
-			udata->inbuf = u64_to_user_ptr(uhw_in->ptr_attr.data);
+			udata->inbuf = u64_to_user_ptr(in->ptr_attr.data);
 	} else {
 		udata->inbuf = NULL;
 		udata->inlen = 0;
 	}
 
-	if (!IS_ERR(uhw_out)) {
-		udata->outbuf = u64_to_user_ptr(uhw_out->ptr_attr.data);
-		udata->outlen = uhw_out->ptr_attr.len;
+	if (!IS_ERR(out)) {
+		udata->outbuf = u64_to_user_ptr(out->ptr_attr.data);
+		udata->outlen = out->ptr_attr.len;
 	} else {
 		udata->outbuf = NULL;
 		udata->outlen = 0;
diff --git a/drivers/infiniband/core/uverbs_std_types.c b/drivers/infiniband/core/uverbs_std_types.c
index 063aff9e7a04..8db5d23ca087 100644
--- a/drivers/infiniband/core/uverbs_std_types.c
+++ b/drivers/infiniband/core/uverbs_std_types.c
@@ -259,10 +259,7 @@ DECLARE_UVERBS_NAMED_OBJECT(
 DECLARE_UVERBS_NAMED_OBJECT(UVERBS_OBJECT_PD,
 			    UVERBS_TYPE_ALLOC_IDR(uverbs_free_pd));
 
-DECLARE_UVERBS_GLOBAL_METHODS(UVERBS_OBJECT_DEVICE);
-
 const struct uapi_definition uverbs_def_obj_intf[] = {
-	UAPI_DEF_CHAIN_OBJ_TREE_NAMED(UVERBS_OBJECT_DEVICE),
 	UAPI_DEF_CHAIN_OBJ_TREE_NAMED(UVERBS_OBJECT_PD,
 				      UAPI_DEF_OBJ_NEEDS_FN(dealloc_pd)),
 	UAPI_DEF_CHAIN_OBJ_TREE_NAMED(UVERBS_OBJECT_COMP_CHANNEL,
diff --git a/drivers/infiniband/core/uverbs_std_types_device.c b/drivers/infiniband/core/uverbs_std_types_device.c
new file mode 100644
index 000000000000..aafb251b7d37
--- /dev/null
+++ b/drivers/infiniband/core/uverbs_std_types_device.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
+/*
+ * Copyright (c) 2018, Mellanox Technologies inc.  All rights reserved.
+ */
+
+#include <rdma/uverbs_std_types.h>
+#include "rdma_core.h"
+#include "uverbs.h"
+
+/*
+ * This ioctl method allows calling any defined write or write_ex
+ * handler. This essentially replaces the hdr/ex_hdr system with the ioctl
+ * marshalling, and brings the non-ex path into the same marshalling as the ex
+ * path.
+ */
+static int UVERBS_HANDLER(UVERBS_METHOD_INVOKE_WRITE)(
+	struct uverbs_attr_bundle *attrs)
+{
+	struct uverbs_api *uapi = attrs->ufile->device->uapi;
+	const struct uverbs_api_write_method *method_elm;
+	u32 cmd;
+	int rc;
+
+	rc = uverbs_get_const(&cmd, attrs, UVERBS_ATTR_WRITE_CMD);
+	if (rc)
+		return rc;
+
+	method_elm = uapi_get_method(uapi, cmd);
+	if (IS_ERR(method_elm))
+		return PTR_ERR(method_elm);
+
+	uverbs_fill_udata(attrs, &attrs->ucore, UVERBS_ATTR_CORE_IN,
+			  UVERBS_ATTR_CORE_OUT);
+
+	if (attrs->ucore.inlen < method_elm->req_size ||
+	    attrs->ucore.outlen < method_elm->resp_size)
+		return -ENOSPC;
+
+	return method_elm->handler(attrs);
+}
+
+DECLARE_UVERBS_NAMED_METHOD(UVERBS_METHOD_INVOKE_WRITE,
+			    UVERBS_ATTR_CONST_IN(UVERBS_ATTR_WRITE_CMD,
+						 enum ib_uverbs_write_cmds,
+						 UA_MANDATORY),
+			    UVERBS_ATTR_PTR_IN(UVERBS_ATTR_CORE_IN,
+					       UVERBS_ATTR_MIN_SIZE(sizeof(u32)),
+					       UA_OPTIONAL),
+			    UVERBS_ATTR_PTR_OUT(UVERBS_ATTR_CORE_OUT,
+						UVERBS_ATTR_MIN_SIZE(0),
+						UA_OPTIONAL),
+			    UVERBS_ATTR_UHW());
+
+DECLARE_UVERBS_GLOBAL_METHODS(UVERBS_OBJECT_DEVICE,
+			      &UVERBS_METHOD(UVERBS_METHOD_INVOKE_WRITE));
+
+const struct uapi_definition uverbs_def_obj_device[] = {
+	UAPI_DEF_CHAIN_OBJ_TREE_NAMED(UVERBS_OBJECT_DEVICE),
+	{},
+};
diff --git a/drivers/infiniband/core/uverbs_uapi.c b/drivers/infiniband/core/uverbs_uapi.c
index 0136c1d78a0f..7097cae8d2b7 100644
--- a/drivers/infiniband/core/uverbs_uapi.c
+++ b/drivers/infiniband/core/uverbs_uapi.c
@@ -620,6 +620,7 @@ void uverbs_destroy_api(struct uverbs_api *uapi)
 static const struct uapi_definition uverbs_core_api[] = {
 	UAPI_DEF_CHAIN(uverbs_def_obj_counters),
 	UAPI_DEF_CHAIN(uverbs_def_obj_cq),
+	UAPI_DEF_CHAIN(uverbs_def_obj_device),
 	UAPI_DEF_CHAIN(uverbs_def_obj_dm),
 	UAPI_DEF_CHAIN(uverbs_def_obj_flow_action),
 	UAPI_DEF_CHAIN(uverbs_def_obj_intf),
diff --git a/include/uapi/rdma/ib_user_ioctl_cmds.h b/include/uapi/rdma/ib_user_ioctl_cmds.h
index 2c881aaf05c2..34e71994f4a5 100644
--- a/include/uapi/rdma/ib_user_ioctl_cmds.h
+++ b/include/uapi/rdma/ib_user_ioctl_cmds.h
@@ -63,6 +63,16 @@ enum {
 	UVERBS_ATTR_UHW_OUT,
 };
 
+enum uverbs_methods_device {
+	UVERBS_METHOD_INVOKE_WRITE,
+};
+
+enum uverbs_attrs_invoke_write_cmd_attr_ids {
+	UVERBS_ATTR_CORE_IN,
+	UVERBS_ATTR_CORE_OUT,
+	UVERBS_ATTR_WRITE_CMD,
+};
+
 enum uverbs_attrs_create_cq_cmd_attr_ids {
 	UVERBS_ATTR_CREATE_CQ_HANDLE,
 	UVERBS_ATTR_CREATE_CQ_CQE,
diff --git a/include/uapi/rdma/ib_user_verbs.h b/include/uapi/rdma/ib_user_verbs.h
index c586fc43739c..480d9a60b68e 100644
--- a/include/uapi/rdma/ib_user_verbs.h
+++ b/include/uapi/rdma/ib_user_verbs.h
@@ -46,7 +46,7 @@
 #define IB_USER_VERBS_ABI_VERSION	6
 #define IB_USER_VERBS_CMD_THRESHOLD    50
 
-enum {
+enum ib_uverbs_write_cmds {
 	IB_USER_VERBS_CMD_GET_CONTEXT,
 	IB_USER_VERBS_CMD_QUERY_DEVICE,
 	IB_USER_VERBS_CMD_QUERY_PORT,
