ipc: turn ipc_msg_reply() into a system call

Make ipc_msg_reply() a system call, so it can be called from
audio thread even when audio thread is running in a user-space
thread.

Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>

Author: kv2019i

src/include/sof/ipc/common.h

@@ -310,7 +310,7 @@ int ipc_process_on_core(uint32_t core, bool blocking);
  * \brief reply to an IPC message.
  * @param[in] reply pointer to the reply structure.
  */
-void ipc_msg_reply(struct sof_ipc_reply *reply);
+#include <sof/ipc/ipc_reply.h>
 
 /**
  * \brief Call platform-specific IPC completion function.

src/include/sof/ipc/ipc_reply.h

@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright(c) 2026 Intel Corporation. All rights reserved.
+ */
+
+#ifndef __SOF_IPC_IPC_REPLY_H__
+#define __SOF_IPC_IPC_REPLY_H__
+
+#include <ipc/header.h>
+
+struct sof_ipc_reply;
+
+/**
+ * \brief reply to an IPC message.
+ * @param[in] reply pointer to the reply structure.
+ */
+#if defined(__ZEPHYR__) && defined(CONFIG_SOF_USERSPACE_LL)
+__syscall void ipc_msg_reply(struct sof_ipc_reply *reply);
+#else
+void z_impl_ipc_msg_reply(struct sof_ipc_reply *reply);
+#define ipc_msg_reply z_impl_ipc_msg_reply
+#endif
+
+#if defined(__ZEPHYR__) && defined(CONFIG_SOF_USERSPACE_LL)
+#include <zephyr/syscalls/ipc_reply.h>
+#endif
+
+#endif /* __SOF_IPC_IPC_REPLY_H__ */

src/ipc/ipc3/helper.c

@@ -710,7 +710,7 @@ int ipc_comp_new(struct ipc *ipc, ipc_comp *_comp)
 	return 0;
 }
 
-void ipc_msg_reply(struct sof_ipc_reply *reply)
+void z_impl_ipc_msg_reply(struct sof_ipc_reply *reply)
 {
 	struct ipc *ipc = ipc_get();
 	k_spinlock_key_t key;

src/ipc/ipc4/handler-kernel.c

@@ -40,6 +40,11 @@
 #include <rtos/string.h>
 #include <sof/lib_manager.h>
 
+#ifdef __ZEPHYR__
+#include <zephyr/kernel.h>
+#include <zephyr/internal/syscall_handler.h>
+#endif
+
 #if CONFIG_SOF_BOOT_TEST
 /* CONFIG_SOF_BOOT_TEST depends on Zephyr */
 #include <zephyr/ztest.h>
@@ -524,14 +529,23 @@ void ipc_send_buffer_status_notify(void)
 }
 #endif
 
-void ipc_msg_reply(struct sof_ipc_reply *reply)
+void z_impl_ipc_msg_reply(struct sof_ipc_reply *reply)
 {
 	struct ipc4_message_request in;
 
 	in.primary.dat = msg_data.msg_in.pri;
 	ipc_compound_msg_done(in.primary.r.type, reply->error);
 }
 
+#ifdef CONFIG_USERSPACE
+void z_vrfy_ipc_msg_reply(struct sof_ipc_reply *reply)
+{
+	K_OOPS(K_SYSCALL_MEMORY_READ(reply, sizeof(*reply)));
+	z_impl_ipc_msg_reply(reply);
+}
+#include <zephyr/syscalls/ipc_msg_reply_mrsh.c>
+#endif
+
 void ipc_cmd(struct ipc_cmd_hdr *_hdr)
 {
 	struct ipc4_message_request *in = ipc4_get_message_request();

zephyr/CMakeLists.txt

@@ -545,6 +545,7 @@ zephyr_library_sources_ifdef(CONFIG_SHELL
 
 zephyr_syscall_header(${SOF_SRC_PATH}/include/sof/audio/module_adapter/module/generic.h)
 zephyr_syscall_header(${SOF_SRC_PATH}/include/sof/lib/fast-get.h)
+zephyr_syscall_header(${SOF_SRC_PATH}/include/sof/ipc/ipc_reply.h)
 zephyr_syscall_header(include/rtos/alloc.h)
 zephyr_library_sources(syscall/alloc.c)