diff --git a/drivers/gpu/drm/i915/gt/uc/abi/guc_actions_abi.h b/drivers/gpu/drm/i915/gt/uc/abi/guc_actions_abi.h
index 90efef8a73e4..dfaea0b54370 100644
--- a/drivers/gpu/drm/i915/gt/uc/abi/guc_actions_abi.h
+++ b/drivers/gpu/drm/i915/gt/uc/abi/guc_actions_abi.h
@@ -6,6 +6,113 @@
 #ifndef _ABI_GUC_ACTIONS_ABI_H
 #define _ABI_GUC_ACTIONS_ABI_H
 
+/**
+ * DOC: HOST2GUC_REGISTER_CTB
+ *
+ * This message is used as part of the `CTB based communication`_ setup.
+ *
+ * This message must be sent as `MMIO HXG Message`_.
+ *
+ *  +---+-------+--------------------------------------------------------------+
+ *  |   | Bits  | Description                                                  |
+ *  +===+=======+==============================================================+
+ *  | 0 |    31 | ORIGIN = GUC_HXG_ORIGIN_HOST_                                |
+ *  |   +-------+--------------------------------------------------------------+
+ *  |   | 30:28 | TYPE = GUC_HXG_TYPE_REQUEST_                                 |
+ *  |   +-------+--------------------------------------------------------------+
+ *  |   | 27:16 | DATA0 = MBZ                                                  |
+ *  |   +-------+--------------------------------------------------------------+
+ *  |   |  15:0 | ACTION = _`GUC_ACTION_HOST2GUC_REGISTER_CTB`                 |
+ *  +---+-------+--------------------------------------------------------------+
+ *  | 1 | 31:12 | RESERVED = MBZ                                               |
+ *  |   +-------+--------------------------------------------------------------+
+ *  |   |  11:8 | **TYPE** - type for the `CT Buffer`_                         |
+ *  |   |       |                                                              |
+ *  |   |       |   - _`GUC_CTB_TYPE_HOST2GUC` = 0                             |
+ *  |   |       |   - _`GUC_CTB_TYPE_GUC2HOST` = 1                             |
+ *  |   +-------+--------------------------------------------------------------+
+ *  |   |   7:0 | **SIZE** - size of the `CT Buffer`_ in 4K units minus 1      |
+ *  +---+-------+--------------------------------------------------------------+
+ *  | 2 |  31:0 | **DESC_ADDR** - GGTT address of the `CTB Descriptor`_        |
+ *  +---+-------+--------------------------------------------------------------+
+ *  | 3 |  31:0 | **BUFF_ADDF** - GGTT address of the `CT Buffer`_             |
+ *  +---+-------+--------------------------------------------------------------+
+ *
+ *  +---+-------+--------------------------------------------------------------+
+ *  |   | Bits  | Description                                                  |
+ *  +===+=======+==============================================================+
+ *  | 0 |    31 | ORIGIN = GUC_HXG_ORIGIN_GUC_                                 |
+ *  |   +-------+--------------------------------------------------------------+
+ *  |   | 30:28 | TYPE = GUC_HXG_TYPE_RESPONSE_SUCCESS_                        |
+ *  |   +-------+--------------------------------------------------------------+
+ *  |   |  27:0 | DATA0 = MBZ                                                  |
+ *  +---+-------+--------------------------------------------------------------+
+ */
+#define GUC_ACTION_HOST2GUC_REGISTER_CTB		0x4505
+
+#define HOST2GUC_REGISTER_CTB_REQUEST_MSG_LEN		(GUC_HXG_REQUEST_MSG_MIN_LEN + 3u)
+#define HOST2GUC_REGISTER_CTB_REQUEST_MSG_0_MBZ		GUC_HXG_REQUEST_MSG_0_DATA0
+#define HOST2GUC_REGISTER_CTB_REQUEST_MSG_1_MBZ		(0xfffff << 12)
+#define HOST2GUC_REGISTER_CTB_REQUEST_MSG_1_TYPE	(0xf << 8)
+#define   GUC_CTB_TYPE_HOST2GUC				0u
+#define   GUC_CTB_TYPE_GUC2HOST				1u
+#define HOST2GUC_REGISTER_CTB_REQUEST_MSG_1_SIZE	(0xff << 0)
+#define HOST2GUC_REGISTER_CTB_REQUEST_MSG_2_DESC_ADDR	GUC_HXG_REQUEST_MSG_n_DATAn
+#define HOST2GUC_REGISTER_CTB_REQUEST_MSG_3_BUFF_ADDR	GUC_HXG_REQUEST_MSG_n_DATAn
+
+#define HOST2GUC_REGISTER_CTB_RESPONSE_MSG_LEN		GUC_HXG_RESPONSE_MSG_MIN_LEN
+#define HOST2GUC_REGISTER_CTB_RESPONSE_MSG_0_MBZ	GUC_HXG_RESPONSE_MSG_0_DATA0
+
+/**
+ * DOC: HOST2GUC_DEREGISTER_CTB
+ *
+ * This message is used as part of the `CTB based communication`_ teardown.
+ *
+ * This message must be sent as `MMIO HXG Message`_.
+ *
+ *  +---+-------+--------------------------------------------------------------+
+ *  |   | Bits  | Description                                                  |
+ *  +===+=======+==============================================================+
+ *  | 0 |    31 | ORIGIN = GUC_HXG_ORIGIN_HOST_                                |
+ *  |   +-------+--------------------------------------------------------------+
+ *  |   | 30:28 | TYPE = GUC_HXG_TYPE_REQUEST_                                 |
+ *  |   +-------+--------------------------------------------------------------+
+ *  |   | 27:16 | DATA0 = MBZ                                                  |
+ *  |   +-------+--------------------------------------------------------------+
+ *  |   |  15:0 | ACTION = _`GUC_ACTION_HOST2GUC_DEREGISTER_CTB`               |
+ *  +---+-------+--------------------------------------------------------------+
+ *  | 1 | 31:12 | RESERVED = MBZ                                               |
+ *  |   +-------+--------------------------------------------------------------+
+ *  |   |  11:8 | **TYPE** - type of the `CT Buffer`_                          |
+ *  |   |       |                                                              |
+ *  |   |       | see `GUC_ACTION_HOST2GUC_REGISTER_CTB`_                      |
+ *  |   +-------+--------------------------------------------------------------+
+ *  |   |   7:0 | RESERVED = MBZ                                               |
+ *  +---+-------+--------------------------------------------------------------+
+ *
+ *  +---+-------+--------------------------------------------------------------+
+ *  |   | Bits  | Description                                                  |
+ *  +===+=======+==============================================================+
+ *  | 0 |    31 | ORIGIN = GUC_HXG_ORIGIN_GUC_                                 |
+ *  |   +-------+--------------------------------------------------------------+
+ *  |   | 30:28 | TYPE = GUC_HXG_TYPE_RESPONSE_SUCCESS_                        |
+ *  |   +-------+--------------------------------------------------------------+
+ *  |   |  27:0 | DATA0 = MBZ                                                  |
+ *  +---+-------+--------------------------------------------------------------+
+ */
+#define GUC_ACTION_HOST2GUC_DEREGISTER_CTB		0x4506
+
+#define HOST2GUC_DEREGISTER_CTB_REQUEST_MSG_LEN		(GUC_HXG_REQUEST_MSG_MIN_LEN + 1u)
+#define HOST2GUC_DEREGISTER_CTB_REQUEST_MSG_0_MBZ	GUC_HXG_REQUEST_MSG_0_DATA0
+#define HOST2GUC_DEREGISTER_CTB_REQUEST_MSG_1_MBZ	(0xfffff << 12)
+#define HOST2GUC_DEREGISTER_CTB_REQUEST_MSG_1_TYPE	(0xf << 8)
+#define HOST2GUC_DEREGISTER_CTB_REQUEST_MSG_1_MBZ2	(0xff << 0)
+
+#define HOST2GUC_DEREGISTER_CTB_RESPONSE_MSG_LEN	GUC_HXG_RESPONSE_MSG_MIN_LEN
+#define HOST2GUC_DEREGISTER_CTB_RESPONSE_MSG_0_MBZ	GUC_HXG_RESPONSE_MSG_0_DATA0
+
+/* legacy definitions */
+
 enum intel_guc_action {
 	INTEL_GUC_ACTION_DEFAULT = 0x0,
 	INTEL_GUC_ACTION_REQUEST_PREEMPTION = 0x2,
diff --git a/drivers/gpu/drm/i915/gt/uc/abi/guc_communication_ctb_abi.h b/drivers/gpu/drm/i915/gt/uc/abi/guc_communication_ctb_abi.h
index 88f1fc2a19e0..6735f1fdaa2a 100644
--- a/drivers/gpu/drm/i915/gt/uc/abi/guc_communication_ctb_abi.h
+++ b/drivers/gpu/drm/i915/gt/uc/abi/guc_communication_ctb_abi.h
@@ -110,10 +110,6 @@ static_assert(sizeof(struct guc_ct_buffer_desc) == 64);
  * - **flags**, holds various bits to control message handling
  */
 
-/* Type of command transport buffer */
-#define INTEL_GUC_CT_BUFFER_TYPE_SEND	0x0u
-#define INTEL_GUC_CT_BUFFER_TYPE_RECV	0x1u
-
 /*
  * Definition of the command transport message header (DW0)
  *
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
index 3241a477196f..6a29be779cc9 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
@@ -103,9 +103,9 @@ void intel_guc_ct_init_early(struct intel_guc_ct *ct)
 static inline const char *guc_ct_buffer_type_to_str(u32 type)
 {
 	switch (type) {
-	case INTEL_GUC_CT_BUFFER_TYPE_SEND:
+	case GUC_CTB_TYPE_HOST2GUC:
 		return "SEND";
-	case INTEL_GUC_CT_BUFFER_TYPE_RECV:
+	case GUC_CTB_TYPE_GUC2HOST:
 		return "RECV";
 	default:
 		return "<invalid>";
@@ -136,25 +136,33 @@ static void guc_ct_buffer_init(struct intel_guc_ct_buffer *ctb,
 	guc_ct_buffer_reset(ctb);
 }
 
-static int guc_action_register_ct_buffer(struct intel_guc *guc,
-					 u32 desc_addr,
-					 u32 type)
+static int guc_action_register_ct_buffer(struct intel_guc *guc, u32 type,
+					 u32 desc_addr, u32 buff_addr, u32 size)
 {
-	u32 action[] = {
-		INTEL_GUC_ACTION_REGISTER_COMMAND_TRANSPORT_BUFFER,
-		desc_addr,
-		sizeof(struct guc_ct_buffer_desc),
-		type
+	u32 request[HOST2GUC_REGISTER_CTB_REQUEST_MSG_LEN] = {
+		FIELD_PREP(GUC_HXG_MSG_0_ORIGIN, GUC_HXG_ORIGIN_HOST) |
+		FIELD_PREP(GUC_HXG_MSG_0_TYPE, GUC_HXG_TYPE_REQUEST) |
+		FIELD_PREP(GUC_HXG_REQUEST_MSG_0_ACTION, GUC_ACTION_HOST2GUC_REGISTER_CTB),
+		FIELD_PREP(HOST2GUC_REGISTER_CTB_REQUEST_MSG_1_SIZE, size / SZ_4K - 1) |
+		FIELD_PREP(HOST2GUC_REGISTER_CTB_REQUEST_MSG_1_TYPE, type),
+		FIELD_PREP(HOST2GUC_REGISTER_CTB_REQUEST_MSG_2_DESC_ADDR, desc_addr),
+		FIELD_PREP(HOST2GUC_REGISTER_CTB_REQUEST_MSG_3_BUFF_ADDR, buff_addr),
 	};
 
-	/* Can't use generic send(), CT registration must go over MMIO */
-	return intel_guc_send_mmio(guc, action, ARRAY_SIZE(action), NULL, 0);
+	GEM_BUG_ON(type != GUC_CTB_TYPE_HOST2GUC && type != GUC_CTB_TYPE_GUC2HOST);
+	GEM_BUG_ON(size % SZ_4K);
+
+	/* CT registration must go over MMIO */
+	return intel_guc_send_mmio(guc, request, ARRAY_SIZE(request), NULL, 0);
 }
 
-static int ct_register_buffer(struct intel_guc_ct *ct, u32 desc_addr, u32 type)
+static int ct_register_buffer(struct intel_guc_ct *ct, u32 type,
+			      u32 desc_addr, u32 buff_addr, u32 size)
 {
-	int err = guc_action_register_ct_buffer(ct_to_guc(ct), desc_addr, type);
+	int err;
 
+	err = guc_action_register_ct_buffer(ct_to_guc(ct), type,
+					    desc_addr, buff_addr, size);
 	if (unlikely(err))
 		CT_ERROR(ct, "Failed to register %s buffer (err=%d)\n",
 			 guc_ct_buffer_type_to_str(type), err);
@@ -163,14 +171,17 @@ static int ct_register_buffer(struct intel_guc_ct *ct, u32 desc_addr, u32 type)
 
 static int guc_action_deregister_ct_buffer(struct intel_guc *guc, u32 type)
 {
-	u32 action[] = {
-		INTEL_GUC_ACTION_DEREGISTER_COMMAND_TRANSPORT_BUFFER,
-		CTB_OWNER_HOST,
-		type
+	u32 request[HOST2GUC_DEREGISTER_CTB_REQUEST_MSG_LEN] = {
+		FIELD_PREP(GUC_HXG_MSG_0_ORIGIN, GUC_HXG_ORIGIN_HOST) |
+		FIELD_PREP(GUC_HXG_MSG_0_TYPE, GUC_HXG_TYPE_REQUEST) |
+		FIELD_PREP(GUC_HXG_REQUEST_MSG_0_ACTION, GUC_ACTION_HOST2GUC_DEREGISTER_CTB),
+		FIELD_PREP(HOST2GUC_DEREGISTER_CTB_REQUEST_MSG_1_TYPE, type),
 	};
 
-	/* Can't use generic send(), CT deregistration must go over MMIO */
-	return intel_guc_send_mmio(guc, action, ARRAY_SIZE(action), NULL, 0);
+	GEM_BUG_ON(type != GUC_CTB_TYPE_HOST2GUC && type != GUC_CTB_TYPE_GUC2HOST);
+
+	/* CT deregistration must go over MMIO */
+	return intel_guc_send_mmio(guc, request, ARRAY_SIZE(request), NULL, 0);
 }
 
 static int ct_deregister_buffer(struct intel_guc_ct *ct, u32 type)
@@ -258,7 +269,7 @@ void intel_guc_ct_fini(struct intel_guc_ct *ct)
 int intel_guc_ct_enable(struct intel_guc_ct *ct)
 {
 	struct intel_guc *guc = ct_to_guc(ct);
-	u32 base, cmds;
+	u32 base, desc, cmds;
 	void *blob;
 	int err;
 
@@ -274,23 +285,26 @@ int intel_guc_ct_enable(struct intel_guc_ct *ct)
 	GEM_BUG_ON(blob != ct->ctbs.send.desc);
 
 	/* (re)initialize descriptors */
-	cmds = base + ptrdiff(ct->ctbs.send.cmds, blob);
 	guc_ct_buffer_reset(&ct->ctbs.send);
-
-	cmds = base + ptrdiff(ct->ctbs.recv.cmds, blob);
 	guc_ct_buffer_reset(&ct->ctbs.recv);
 
 	/*
 	 * Register both CT buffers starting with RECV buffer.
 	 * Descriptors are in first half of the blob.
 	 */
-	err = ct_register_buffer(ct, base + ptrdiff(ct->ctbs.recv.desc, blob),
-				 INTEL_GUC_CT_BUFFER_TYPE_RECV);
+	desc = base + ptrdiff(ct->ctbs.recv.desc, blob);
+	cmds = base + ptrdiff(ct->ctbs.recv.cmds, blob);
+	err = ct_register_buffer(ct, GUC_CTB_TYPE_GUC2HOST,
+				 desc, cmds, ct->ctbs.recv.size * 4);
+
 	if (unlikely(err))
 		goto err_out;
 
-	err = ct_register_buffer(ct, base + ptrdiff(ct->ctbs.send.desc, blob),
-				 INTEL_GUC_CT_BUFFER_TYPE_SEND);
+	desc = base + ptrdiff(ct->ctbs.send.desc, blob);
+	cmds = base + ptrdiff(ct->ctbs.send.cmds, blob);
+	err = ct_register_buffer(ct, GUC_CTB_TYPE_HOST2GUC,
+				 desc, cmds, ct->ctbs.send.size * 4);
+
 	if (unlikely(err))
 		goto err_deregister;
 
@@ -299,7 +313,7 @@ int intel_guc_ct_enable(struct intel_guc_ct *ct)
 	return 0;
 
 err_deregister:
-	ct_deregister_buffer(ct, INTEL_GUC_CT_BUFFER_TYPE_RECV);
+	ct_deregister_buffer(ct, GUC_CTB_TYPE_GUC2HOST);
 err_out:
 	CT_PROBE_ERROR(ct, "Failed to enable CTB (%pe)\n", ERR_PTR(err));
 	return err;
@@ -318,8 +332,8 @@ void intel_guc_ct_disable(struct intel_guc_ct *ct)
 	ct->enabled = false;
 
 	if (intel_guc_is_fw_running(guc)) {
-		ct_deregister_buffer(ct, INTEL_GUC_CT_BUFFER_TYPE_SEND);
-		ct_deregister_buffer(ct, INTEL_GUC_CT_BUFFER_TYPE_RECV);
+		ct_deregister_buffer(ct, GUC_CTB_TYPE_HOST2GUC);
+		ct_deregister_buffer(ct, GUC_CTB_TYPE_GUC2HOST);
 	}
 }
 
