enable SGX in Software Controlled BIOS option

sgx_enable.c

/**
After setting BIOS with "software controlled" option, try to enable SGX in software opt-in way.
The source code comes from https://github.com/intel/linux-sgx/issues/238#issuecomment-377324381.
I just compile and execute it. 

Note that: replace the path with your own, run it with root permission, then reboot the machine

gcc -o sgx_enable sgx_enable.c -I /home/max/data/gitroom/linux-sgx/common/inc/ -L /home/max/data/gitroom/linux-sgx/build/linux/ -lsgx_capable
sudo ./sgx_enable
sudo reboot
**/
#include <stdio.h>
#include "sgx_uae_service.h"
#include "sgx_capable.h"

/* Application entry */
int SGX_CDECL main(int argc, char *argv[])
{
	(void)(argc);
	(void)(argv);

	sgx_device_status_t sgx_device_status;
	sgx_status_t sgx_ret = sgx_cap_enable_device(&sgx_device_status);
	if (sgx_ret != SGX_SUCCESS) {
		printf("Failed to get SGX device status.\n");
		return -1;
	}
	else {
		switch (sgx_device_status) {
			case SGX_ENABLED:
			printf("SGX device is enabled\n");
			return 0;
			case SGX_DISABLED_REBOOT_REQUIRED:
			printf("SGX device has been enabled. Please reboot your machine.\n");
			return -1;
			case SGX_DISABLED_LEGACY_OS:
			printf("SGX device can't be enabled on an OS that doesn't support EFI interface.\n");
			return -1;
			case SGX_DISABLED:
			printf("SGX device not found.\n");
			return -1;
			default:
			printf("Unexpected error.\n");
			return -1;
		}
	}
	return -1;
}