<snip>

+static int vfio_user_device_get_reg_info(struct vfio_user_server *dev,
+	VFIO_USER_MSG *msg)
+{
+	struct vfio_user_reg *reg = &msg->payload.reg_info;
+	struct rte_vfio_user_reg_info *reg_info;
+	struct vfio_region_info *vinfo;
+
+	if (vfio_user_check_msg_fdnum(msg, 0) != 0)
+		return -EINVAL;
+
+	if (msg->size > sizeof(*reg) + VFIO_USER_MSG_HDR_SIZE ||
+		dev->reg->reg_num <= reg->reg_info.index) {
+		VFIO_USER_LOG(ERR, "Invalid message for get dev info\n");

Invalid message for get region info?

+		return -EINVAL;
+	}
+
+	reg_info = &dev->reg->reg_info[reg->reg_info.index];
+	vinfo = reg_info->info;
+	memcpy(reg, vinfo, vinfo->argsz);
+
+	if (reg_info->fd != -1) {
+		msg->fd_num = 1;
+		msg->fds[0] = reg_info->fd;
+	}
+
+	VFIO_USER_LOG(DEBUG, "Region(%u) info: addr(0x%" PRIx64 "),
fd(%d), "
+		"sz(0x%llx), argsz(0x%x), c_off(0x%x), flags(0x%x) "
+		"off(0x%llx)\n", vinfo->index, (uint64_t)reg_info->base,
+		reg_info->fd, vinfo->size, vinfo->argsz, vinfo->cap_offset,
+		vinfo->flags, vinfo->offset);
+
+	return 0;
+}
+

<snip>

+int rte_vfio_user_set_dev_info(const char *sock_addr,
+	struct vfio_device_info *dev_info)
+{
+	struct vfio_user_server *dev;
+	struct vfio_user_server_socket *sk;
+	int dev_id;
+
+	if (!dev_info)
+		return -1;
+
+	pthread_mutex_lock(&vfio_ep_sock.mutex);
+	sk = find_vfio_user_socket(sock_addr);
+	pthread_mutex_unlock(&vfio_ep_sock.mutex);
+
+	if (!sk) {
+		VFIO_USER_LOG(ERR, "Failed to set device info with
sock_addr "
+			"%s: addr not registered.\n", sock_addr);
+		return -1;
+	}
+
+	dev_id = sk->sock.dev_id;
+	dev = vfio_user_get_device(dev_id);
+	if (!dev) {
+		VFIO_USER_LOG(ERR, "Failed to set device info:"
+			"device %d not found.\n", dev_id);
+		return -1;
+	}
+
+	if (dev->started) {
+		VFIO_USER_LOG(ERR, "Failed to set device info for
device %d\n"
+			 ", device already started\n", dev_id);
+		return -1;
+	}
+
+	dev->dev_info = dev_info;
+
+	return 0;
+}
+
+int rte_vfio_user_set_reg_info(const char *sock_addr,
+	struct rte_vfio_user_regions *reg)
+{
+	struct vfio_user_server *dev;
+	struct vfio_user_server_socket *sk;
+	int dev_id;
+
+	if (!reg)
+		return -1;
+
+	pthread_mutex_lock(&vfio_ep_sock.mutex);
+	sk = find_vfio_user_socket(sock_addr);
+	pthread_mutex_unlock(&vfio_ep_sock.mutex);
+
+	if (!sk) {
+		VFIO_USER_LOG(ERR, "Failed to set region info with
sock_addr:"
+			"%s: addr not registered.\n", sock_addr);
+		return -1;
+	}
+
+	dev_id = sk->sock.dev_id;
+	dev = vfio_user_get_device(dev_id);
+	if (!dev) {
+		VFIO_USER_LOG(ERR, "Failed to set region info:"
+			"device %d not found.\n", dev_id);
+		return -1;
+	}
+
+	if (dev->started) {
+		VFIO_USER_LOG(ERR, "Failed to set region info for
device %d\n"
+			 ", device already started\n", dev_id);
+		return -1;
+	}
+
+	dev->reg = reg;
+
+	return 0;
+}

Do you think if we can define a static function to cover the duplicated check part of function rte_vfio_user_set_dev_info and rte_vfio_user_set_reg_info?