DM: add command handler for command monitor

The command handler is to implement handlers for each command,
currently, two handler is implemented for command monitor:
user_vm_destroy_handler: the handler is for user VM destroy command,
which shuts down to standard post-launched user VM forcefully.
user_vm_blkrescan_handler: the handler is for user VM blkrescan
command, which rescan virtio-blk device to revalidate and update
the backend file for user VM.

v1--v2:
	Update log message format.
	Generate JSON format ack message using libcjson lib APIs.
v2-->v3:
	Update ACK message to {"ack": 0} or {"ack": -1}

Tracked-On: #5921

Signed-off-by: Xiangyang Wu <xiangyang.wu@intel.com>
Acked-by: Wang, Yu1 <yu1.wang@intel.com>

devicemodel/Makefile

@@ -81,6 +81,7 @@ LIBS += -lpciaccess
 LIBS += -luuid
 LIBS += -lusb-1.0
 LIBS += -lacrn-mngr
+LIBS += -lcjson
 
 # lib
 SRCS += lib/dm_string.c

devicemodel/core/cmd_monitor/command_handler.c

@@ -0,0 +1,124 @@
+/*
+ * Copyright (C) 2022 Intel Corporation
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <unistd.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <sys/un.h>
+#include <libgen.h>
+#include <cjson/cJSON.h>
+#include "command.h"
+#include "socket.h"
+#include "command_handler.h"
+#include "dm.h"
+#include "pm.h"
+#include "vmmapi.h"
+#include "log.h"
+#include "monitor.h"
+
+#define SUCCEEDED 0
+#define FAILED -1
+
+static char *generate_ack_message(int ret_val)
+{
+	char *ack_msg;
+	cJSON *val;
+	cJSON *ret_obj = cJSON_CreateObject();
+
+	if (ret_obj == NULL)
+		return NULL;
+	val = cJSON_CreateNumber(ret_val);
+	if (val == NULL)
+		return NULL;
+	cJSON_AddItemToObject(ret_obj, "ack", val);
+	ack_msg = cJSON_Print(ret_obj);
+	if (ack_msg == NULL)
+		fprintf(stderr, "Failed to generate ACK message.\n");
+	cJSON_Delete(ret_obj);
+	return ack_msg;
+}
+static int send_socket_ack(struct socket_dev *sock, int fd, bool normal)
+{
+	int ret = 0, val;
+	char *ack_message;
+	struct socket_client *client = NULL;
+
+	client = find_socket_client(sock, fd);
+	if (client == NULL)
+		return -1;
+	val = normal ? SUCCEEDED : FAILED;
+	ack_message = generate_ack_message(val);
+
+	if (ack_message != NULL) {
+		memset(client->buf, 0, CLIENT_BUF_LEN);
+		memcpy(client->buf, ack_message, strlen(ack_message));
+		client->len = strlen(ack_message);
+		ret = write_socket_char(client);
+		free(ack_message);
+	} else {
+		pr_err("Failed to generate ACK message.\n");
+		ret = -1;
+	}
+	return ret;
+}
+
+int user_vm_destroy_handler(void *arg, void *command_para)
+{
+	int ret;
+	struct command_parameters *cmd_para = (struct command_parameters *)command_para;
+	struct handler_args *hdl_arg = (struct handler_args *)arg;
+	struct socket_dev *sock = (struct socket_dev *)hdl_arg->channel_arg;
+	struct socket_client *client = NULL;
+	bool cmd_completed = false;
+
+	client = find_socket_client(sock, cmd_para->fd);
+	if (client == NULL)
+		return -1;
+
+	if (!is_rtvm) {
+		pr_info("%s: setting VM state to %s.\n", __func__, vm_state_to_str(VM_SUSPEND_POWEROFF));
+		vm_set_suspend_mode(VM_SUSPEND_POWEROFF);
+		cmd_completed = true;
+	} else {
+		pr_err("Failed to destroy post-launched RTVM.\n");
+		ret = -1;
+	}
+
+	ret = send_socket_ack(sock, cmd_para->fd, cmd_completed);
+	if (ret < 0) {
+		pr_err("Failed to send ACK message by socket.\n");
+	}
+	return ret;
+}
+
+int user_vm_blkrescan_handler(void *arg, void *command_para)
+{
+	int ret = 0;
+	struct command_parameters *cmd_para = (struct command_parameters *)command_para;
+	struct handler_args *hdl_arg = (struct handler_args *)arg;
+	struct socket_dev *sock = (struct socket_dev *)hdl_arg->channel_arg;
+	struct socket_client *client = NULL;
+	bool cmd_completed = false;
+
+	client = find_socket_client(sock, cmd_para->fd);
+	if (client == NULL)
+		return -1;
+
+	ret = vm_monitor_blkrescan(hdl_arg->ctx_arg, cmd_para->option);
+	if (ret >= 0) {
+		cmd_completed = true;
+	} else {
+		pr_err("Failed to rescan virtio-blk device.\n");
+	}
+
+	ret = send_socket_ack(sock, cmd_para->fd, cmd_completed);
+	if (ret < 0) {
+		pr_err("Failed to send ACK by socket.\n");
+	}
+	return ret;
+}

devicemodel/core/cmd_monitor/command_handler.h

@@ -0,0 +1,12 @@
+/*
+ * Copyright (C) 2022 Intel Corporation
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+#ifndef _COMMAND_HANDLER_H_
+#define _COMMAND_HANDLER_H_
+
+extern struct socket_dev *sock_server;
+
+int user_vm_destroy_handler(void *arg, void *command_para);
+int user_vm_blkrescan_handler(void *arg, void *command_para);
+#endif