nitro_enclaves: Add sample for ioctl interface usage

Add a user space sample for the usage of the ioctl interface provided by
the Nitro Enclaves driver.

Changelog

v9 -> v10

* Update commit message to include the changelog before the SoB tag(s).

v8 -> v9

* No changes.

v7 -> v8

* Track NE custom error codes for invalid page size, invalid flags and
enclave CID.
* Update the heartbeat logic to have a listener fd first, then start the
enclave and then accept connection to get the heartbeat.
* Update the reference link to the hugetlb documentation.

v6 -> v7

* Track POLLNVAL as poll event in addition to POLLHUP.

v5 -> v6

* Remove "rc" mentioning when printing errno string.
* Remove the ioctl to query API version.
* Include usage info for NUMA-aware hugetlb configuration.
* Update documentation to kernel-doc format.
* Add logic for enclave image loading.

v4 -> v5

* Print enclave vCPU ids when they are created.
* Update logic to map the modified vCPU ioctl call.
* Add check for the path to the enclave image to be less than PATH_MAX.
* Update the ioctl calls error checking logic to match the NE specific
error codes.

v3 -> v4

* Update usage details to match the updates in v4.
* Update NE ioctl interface usage.

v2 -> v3

* Remove the include directory to use the uapi from the kernel.
* Remove the GPL additional wording as SPDX-License-Identifier is
already in place.

v1 -> v2

* New in v2.

Reviewed-by: Alexander Graf <[e-mail]>
Signed-off-by: Alexandru Vasile <[e-mail]>
Signed-off-by: Andra Paraschiv <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

samples/nitro_enclaves/.gitignore

···
+# SPDX-License-Identifier: GPL-2.0
+ne_ioctl_sample

samples/nitro_enclaves/Makefile

···
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+
+# Enclave lifetime management support for Nitro Enclaves (NE) - ioctl sample
+# usage.
+
+.PHONY: all clean
+
+CFLAGS += -Wall
+
+all:
+	$(CC) $(CFLAGS) -o ne_ioctl_sample ne_ioctl_sample.c -lpthread
+
+clean:
+	rm -f ne_ioctl_sample

samples/nitro_enclaves/ne_ioctl_sample.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ */
+
+/**
+ * DOC: Sample flow of using the ioctl interface provided by the Nitro Enclaves (NE)
+ * kernel driver.
+ *
+ * Usage
+ * -----
+ *
+ * Load the nitro_enclaves module, setting also the enclave CPU pool. The
+ * enclave CPUs need to be full cores from the same NUMA node. CPU 0 and its
+ * siblings have to remain available for the primary / parent VM, so they
+ * cannot be included in the enclave CPU pool.
+ *
+ * See the cpu list section from the kernel documentation.
+ * https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html#cpu-lists
+ *
+ *	insmod drivers/virt/nitro_enclaves/nitro_enclaves.ko
+ *	lsmod
+ *
+ *	The CPU pool can be set at runtime, after the kernel module is loaded.
+ *
+ *	echo <cpu-list> > /sys/module/nitro_enclaves/parameters/ne_cpus
+ *
+ *	NUMA and CPU siblings information can be found using:
+ *
+ *	lscpu
+ *	/proc/cpuinfo
+ *
+ * Check the online / offline CPU list. The CPUs from the pool should be
+ * offlined.
+ *
+ *	lscpu
+ *
+ * Check dmesg for any warnings / errors through the NE driver lifetime / usage.
+ * The NE logs contain the "nitro_enclaves" or "pci 0000:00:02.0" pattern.
+ *
+ *	dmesg
+ *
+ * Setup hugetlbfs huge pages. The memory needs to be from the same NUMA node as
+ * the enclave CPUs.
+ *
+ * https://www.kernel.org/doc/html/latest/admin-guide/mm/hugetlbpage.html
+ *
+ * By default, the allocation of hugetlb pages are distributed on all possible
+ * NUMA nodes. Use the following configuration files to set the number of huge
+ * pages from a NUMA node:
+ *
+ *	/sys/devices/system/node/node<X>/hugepages/hugepages-2048kB/nr_hugepages
+ *	/sys/devices/system/node/node<X>/hugepages/hugepages-1048576kB/nr_hugepages
+ *
+ *	or, if not on a system with multiple NUMA nodes, can also set the number
+ *	of 2 MiB / 1 GiB huge pages using
+ *
+ *	/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
+ *	/sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages
+ *
+ *	In this example 256 hugepages of 2 MiB are used.
+ *
+ * Build and run the NE sample.
+ *
+ *	make -C samples/nitro_enclaves clean
+ *	make -C samples/nitro_enclaves
+ *	./samples/nitro_enclaves/ne_ioctl_sample <path_to_enclave_image>
+ *
+ * Unload the nitro_enclaves module.
+ *
+ *	rmmod nitro_enclaves
+ *	lsmod
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <poll.h>
+#include <pthread.h>
+#include <string.h>
+#include <sys/eventfd.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <linux/mman.h>
+#include <linux/nitro_enclaves.h>
+#include <linux/vm_sockets.h>
+
+/**
+ * NE_DEV_NAME - Nitro Enclaves (NE) misc device that provides the ioctl interface.
+ */
+#define NE_DEV_NAME			"/dev/nitro_enclaves"
+
+/**
+ * NE_POLL_WAIT_TIME - Timeout in seconds for each poll event.
+ */
+#define NE_POLL_WAIT_TIME		(60)
+/**
+ * NE_POLL_WAIT_TIME_MS - Timeout in milliseconds for each poll event.
+ */
+#define NE_POLL_WAIT_TIME_MS		(NE_POLL_WAIT_TIME * 1000)
+
+/**
+ * NE_SLEEP_TIME - Amount of time in seconds for the process to keep the enclave alive.
+ */
+#define NE_SLEEP_TIME			(300)
+
+/**
+ * NE_DEFAULT_NR_VCPUS - Default number of vCPUs set for an enclave.
+ */
+#define NE_DEFAULT_NR_VCPUS		(2)
+
+/**
+ * NE_MIN_MEM_REGION_SIZE - Minimum size of a memory region - 2 MiB.
+ */
+#define NE_MIN_MEM_REGION_SIZE		(2 * 1024 * 1024)
+
+/**
+ * NE_DEFAULT_NR_MEM_REGIONS - Default number of memory regions of 2 MiB set for
+ *			       an enclave.
+ */
+#define NE_DEFAULT_NR_MEM_REGIONS	(256)
+
+/**
+ * NE_IMAGE_LOAD_HEARTBEAT_CID - Vsock CID for enclave image loading heartbeat logic.
+ */
+#define NE_IMAGE_LOAD_HEARTBEAT_CID	(3)
+/**
+ * NE_IMAGE_LOAD_HEARTBEAT_PORT - Vsock port for enclave image loading heartbeat logic.
+ */
+#define NE_IMAGE_LOAD_HEARTBEAT_PORT	(9000)
+/**
+ * NE_IMAGE_LOAD_HEARTBEAT_VALUE - Heartbeat value for enclave image loading.
+ */
+#define NE_IMAGE_LOAD_HEARTBEAT_VALUE	(0xb7)
+
+/**
+ * struct ne_user_mem_region - User space memory region set for an enclave.
+ * @userspace_addr:	Address of the user space memory region.
+ * @memory_size:	Size of the user space memory region.
+ */
+struct ne_user_mem_region {
+	void	*userspace_addr;
+	size_t	memory_size;
+};
+
+/**
+ * ne_create_vm() - Create a slot for the enclave VM.
+ * @ne_dev_fd:		The file descriptor of the NE misc device.
+ * @slot_uid:		The generated slot uid for the enclave.
+ * @enclave_fd :	The generated file descriptor for the enclave.
+ *
+ * Context: Process context.
+ * Return:
+ * * 0 on success.
+ * * Negative return value on failure.
+ */
+static int ne_create_vm(int ne_dev_fd, unsigned long *slot_uid, int *enclave_fd)
+{
+	int rc = -EINVAL;
+	*enclave_fd = ioctl(ne_dev_fd, NE_CREATE_VM, slot_uid);
+
+	if (*enclave_fd < 0) {
+		rc = *enclave_fd;
+		switch (errno) {
+		case NE_ERR_NO_CPUS_AVAIL_IN_POOL: {
+			printf("Error in create VM, no CPUs available in the NE CPU pool\n");
+
+			break;
+		}
+
+		default:
+			printf("Error in create VM [%m]\n");
+		}
+
+		return rc;
+	}
+
+	return 0;
+}
+
+
+/**
+ * ne_poll_enclave_fd() - Thread function for polling the enclave fd.
+ * @data:	Argument provided for the polling function.
+ *
+ * Context: Process context.
+ * Return:
+ * * NULL on success / failure.
+ */
+void *ne_poll_enclave_fd(void *data)
+{
+	int enclave_fd = *(int *)data;
+	struct pollfd fds[1] = {};
+	int i = 0;
+	int rc = -EINVAL;
+
+	printf("Running from poll thread, enclave fd %d\n", enclave_fd);
+
+	fds[0].fd = enclave_fd;
+	fds[0].events = POLLIN | POLLERR | POLLHUP;
+
+	/* Keep on polling until the current process is terminated. */
+	while (1) {
+		printf("[iter %d] Polling ...\n", i);
+
+		rc = poll(fds, 1, NE_POLL_WAIT_TIME_MS);
+		if (rc < 0) {
+			printf("Error in poll [%m]\n");
+
+			return NULL;
+		}
+
+		i++;
+
+		if (!rc) {
+			printf("Poll: %d seconds elapsed\n",
+			       i * NE_POLL_WAIT_TIME);
+
+			continue;
+		}
+
+		printf("Poll received value 0x%x\n", fds[0].revents);
+
+		if (fds[0].revents & POLLHUP) {
+			printf("Received POLLHUP\n");
+
+			return NULL;
+		}
+
+		if (fds[0].revents & POLLNVAL) {
+			printf("Received POLLNVAL\n");
+
+			return NULL;
+		}
+	}
+
+	return NULL;
+}
+
+/**
+ * ne_alloc_user_mem_region() - Allocate a user space memory region for an enclave.
+ * @ne_user_mem_region:	User space memory region allocated using hugetlbfs.
+ *
+ * Context: Process context.
+ * Return:
+ * * 0 on success.
+ * * Negative return value on failure.
+ */
+static int ne_alloc_user_mem_region(struct ne_user_mem_region *ne_user_mem_region)
+{
+	/**
+	 * Check available hugetlb encodings for different huge page sizes in
+	 * include/uapi/linux/mman.h.
+	 */
+	ne_user_mem_region->userspace_addr = mmap(NULL, ne_user_mem_region->memory_size,
+						  PROT_READ | PROT_WRITE,
+						  MAP_PRIVATE | MAP_ANONYMOUS |
+						  MAP_HUGETLB | MAP_HUGE_2MB, -1, 0);
+	if (ne_user_mem_region->userspace_addr == MAP_FAILED) {
+		printf("Error in mmap memory [%m]\n");
+
+		return -1;
+	}
+
+	return 0;
+}
+
+/**
+ * ne_load_enclave_image() - Place the enclave image in the enclave memory.
+ * @enclave_fd :		The file descriptor associated with the enclave.
+ * @ne_user_mem_regions:	User space memory regions allocated for the enclave.
+ * @enclave_image_path :	The file path of the enclave image.
+ *
+ * Context: Process context.
+ * Return:
+ * * 0 on success.
+ * * Negative return value on failure.
+ */
+static int ne_load_enclave_image(int enclave_fd, struct ne_user_mem_region ne_user_mem_regions[],
+				 char *enclave_image_path)
+{
+	unsigned char *enclave_image = NULL;
+	int enclave_image_fd = -1;
+	size_t enclave_image_size = 0;
+	size_t enclave_memory_size = 0;
+	unsigned long i = 0;
+	size_t image_written_bytes = 0;
+	struct ne_image_load_info image_load_info = {
+		.flags = NE_EIF_IMAGE,
+	};
+	struct stat image_stat_buf = {};
+	int rc = -EINVAL;
+	size_t temp_image_offset = 0;
+
+	for (i = 0; i < NE_DEFAULT_NR_MEM_REGIONS; i++)
+		enclave_memory_size += ne_user_mem_regions[i].memory_size;
+
+	rc = stat(enclave_image_path, &image_stat_buf);
+	if (rc < 0) {
+		printf("Error in get image stat info [%m]\n");
+
+		return rc;
+	}
+
+	enclave_image_size = image_stat_buf.st_size;
+
+	if (enclave_memory_size < enclave_image_size) {
+		printf("The enclave memory is smaller than the enclave image size\n");
+
+		return -ENOMEM;
+	}
+
+	rc = ioctl(enclave_fd, NE_GET_IMAGE_LOAD_INFO, &image_load_info);
+	if (rc < 0) {
+		switch (errno) {
+		case NE_ERR_NOT_IN_INIT_STATE: {
+			printf("Error in get image load info, enclave not in init state\n");
+
+			break;
+		}
+
+		case NE_ERR_INVALID_FLAG_VALUE: {
+			printf("Error in get image load info, provided invalid flag\n");
+
+			break;
+		}
+
+		default:
+			printf("Error in get image load info [%m]\n");
+		}
+
+		return rc;
+	}
+
+	printf("Enclave image offset in enclave memory is %lld\n",
+	       image_load_info.memory_offset);
+
+	enclave_image_fd = open(enclave_image_path, O_RDONLY);
+	if (enclave_image_fd < 0) {
+		printf("Error in open enclave image file [%m]\n");
+
+		return enclave_image_fd;
+	}
+
+	enclave_image = mmap(NULL, enclave_image_size, PROT_READ,
+			     MAP_PRIVATE, enclave_image_fd, 0);
+	if (enclave_image == MAP_FAILED) {
+		printf("Error in mmap enclave image [%m]\n");
+
+		return -1;
+	}
+
+	temp_image_offset = image_load_info.memory_offset;
+
+	for (i = 0; i < NE_DEFAULT_NR_MEM_REGIONS; i++) {
+		size_t bytes_to_write = 0;
+		size_t memory_offset = 0;
+		size_t memory_size = ne_user_mem_regions[i].memory_size;
+		size_t remaining_bytes = 0;
+		void *userspace_addr = ne_user_mem_regions[i].userspace_addr;
+
+		if (temp_image_offset >= memory_size) {
+			temp_image_offset -= memory_size;
+
+			continue;
+		} else if (temp_image_offset != 0) {
+			memory_offset = temp_image_offset;
+			memory_size -= temp_image_offset;
+			temp_image_offset = 0;
+		}
+
+		remaining_bytes = enclave_image_size - image_written_bytes;
+		bytes_to_write = memory_size < remaining_bytes ?
+				 memory_size : remaining_bytes;
+
+		memcpy(userspace_addr + memory_offset,
+		       enclave_image + image_written_bytes, bytes_to_write);
+
+		image_written_bytes += bytes_to_write;
+
+		if (image_written_bytes == enclave_image_size)
+			break;
+	}
+
+	munmap(enclave_image, enclave_image_size);
+
+	close(enclave_image_fd);
+
+	return 0;
+}
+
+/**
+ * ne_set_user_mem_region() - Set a user space memory region for the given enclave.
+ * @enclave_fd :		The file descriptor associated with the enclave.
+ * @ne_user_mem_region :	User space memory region to be set for the enclave.
+ *
+ * Context: Process context.
+ * Return:
+ * * 0 on success.
+ * * Negative return value on failure.
+ */
+static int ne_set_user_mem_region(int enclave_fd, struct ne_user_mem_region ne_user_mem_region)
+{
+	struct ne_user_memory_region mem_region = {
+		.flags = NE_DEFAULT_MEMORY_REGION,
+		.memory_size = ne_user_mem_region.memory_size,
+		.userspace_addr = (__u64)ne_user_mem_region.userspace_addr,
+	};
+	int rc = -EINVAL;
+
+	rc = ioctl(enclave_fd, NE_SET_USER_MEMORY_REGION, &mem_region);
+	if (rc < 0) {
+		switch (errno) {
+		case NE_ERR_NOT_IN_INIT_STATE: {
+			printf("Error in set user memory region, enclave not in init state\n");
+
+			break;
+		}
+
+		case NE_ERR_INVALID_MEM_REGION_SIZE: {
+			printf("Error in set user memory region, mem size not multiple of 2 MiB\n");
+
+			break;
+		}
+
+		case NE_ERR_INVALID_MEM_REGION_ADDR: {
+			printf("Error in set user memory region, invalid user space address\n");
+
+			break;
+		}
+
+		case NE_ERR_UNALIGNED_MEM_REGION_ADDR: {
+			printf("Error in set user memory region, unaligned user space address\n");
+
+			break;
+		}
+
+		case NE_ERR_MEM_REGION_ALREADY_USED: {
+			printf("Error in set user memory region, memory region already used\n");
+
+			break;
+		}
+
+		case NE_ERR_MEM_NOT_HUGE_PAGE: {
+			printf("Error in set user memory region, not backed by huge pages\n");
+
+			break;
+		}
+
+		case NE_ERR_MEM_DIFFERENT_NUMA_NODE: {
+			printf("Error in set user memory region, different NUMA node than CPUs\n");
+
+			break;
+		}
+
+		case NE_ERR_MEM_MAX_REGIONS: {
+			printf("Error in set user memory region, max memory regions reached\n");
+
+			break;
+		}
+
+		case NE_ERR_INVALID_PAGE_SIZE: {
+			printf("Error in set user memory region, has page not multiple of 2 MiB\n");
+
+			break;
+		}
+
+		case NE_ERR_INVALID_FLAG_VALUE: {
+			printf("Error in set user memory region, provided invalid flag\n");
+
+			break;
+		}
+
+		default:
+			printf("Error in set user memory region [%m]\n");
+		}
+
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * ne_free_mem_regions() - Unmap all the user space memory regions that were set
+ *			   aside for the enclave.
+ * @ne_user_mem_regions:	The user space memory regions associated with an enclave.
+ *
+ * Context: Process context.
+ */
+static void ne_free_mem_regions(struct ne_user_mem_region ne_user_mem_regions[])
+{
+	unsigned int i = 0;
+
+	for (i = 0; i < NE_DEFAULT_NR_MEM_REGIONS; i++)
+		munmap(ne_user_mem_regions[i].userspace_addr,
+		       ne_user_mem_regions[i].memory_size);
+}
+
+/**
+ * ne_add_vcpu() - Add a vCPU to the given enclave.
+ * @enclave_fd :	The file descriptor associated with the enclave.
+ * @vcpu_id:		vCPU id to be set for the enclave, either provided or
+ *			auto-generated (if provided vCPU id is 0).
+ *
+ * Context: Process context.
+ * Return:
+ * * 0 on success.
+ * * Negative return value on failure.
+ */
+static int ne_add_vcpu(int enclave_fd, unsigned int *vcpu_id)
+{
+	int rc = -EINVAL;
+
+	rc = ioctl(enclave_fd, NE_ADD_VCPU, vcpu_id);
+	if (rc < 0) {
+		switch (errno) {
+		case NE_ERR_NO_CPUS_AVAIL_IN_POOL: {
+			printf("Error in add vcpu, no CPUs available in the NE CPU pool\n");
+
+			break;
+		}
+
+		case NE_ERR_VCPU_ALREADY_USED: {
+			printf("Error in add vcpu, the provided vCPU is already used\n");
+
+			break;
+		}
+
+		case NE_ERR_VCPU_NOT_IN_CPU_POOL: {
+			printf("Error in add vcpu, the provided vCPU is not in the NE CPU pool\n");
+
+			break;
+		}
+
+		case NE_ERR_VCPU_INVALID_CPU_CORE: {
+			printf("Error in add vcpu, the core id of the provided vCPU is invalid\n");
+
+			break;
+		}
+
+		case NE_ERR_NOT_IN_INIT_STATE: {
+			printf("Error in add vcpu, enclave not in init state\n");
+
+			break;
+		}
+
+		case NE_ERR_INVALID_VCPU: {
+			printf("Error in add vcpu, the provided vCPU is out of avail CPUs range\n");
+
+			break;
+		}
+
+		default:
+			printf("Error in add vcpu [%m]\n");
+
+		}
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * ne_start_enclave() - Start the given enclave.
+ * @enclave_fd :		The file descriptor associated with the enclave.
+ * @enclave_start_info :	Enclave metadata used for starting e.g. vsock CID.
+ *
+ * Context: Process context.
+ * Return:
+ * * 0 on success.
+ * * Negative return value on failure.
+ */
+static int ne_start_enclave(int enclave_fd,  struct ne_enclave_start_info *enclave_start_info)
+{
+	int rc = -EINVAL;
+
+	rc = ioctl(enclave_fd, NE_START_ENCLAVE, enclave_start_info);
+	if (rc < 0) {
+		switch (errno) {
+		case NE_ERR_NOT_IN_INIT_STATE: {
+			printf("Error in start enclave, enclave not in init state\n");
+
+			break;
+		}
+
+		case NE_ERR_NO_MEM_REGIONS_ADDED: {
+			printf("Error in start enclave, no memory regions have been added\n");
+
+			break;
+		}
+
+		case NE_ERR_NO_VCPUS_ADDED: {
+			printf("Error in start enclave, no vCPUs have been added\n");
+
+			break;
+		}
+
+		case NE_ERR_FULL_CORES_NOT_USED: {
+			printf("Error in start enclave, enclave has no full cores set\n");
+
+			break;
+		}
+
+		case NE_ERR_ENCLAVE_MEM_MIN_SIZE: {
+			printf("Error in start enclave, enclave memory is less than min size\n");
+
+			break;
+		}
+
+		case NE_ERR_INVALID_FLAG_VALUE: {
+			printf("Error in start enclave, provided invalid flag\n");
+
+			break;
+		}
+
+		case NE_ERR_INVALID_ENCLAVE_CID: {
+			printf("Error in start enclave, provided invalid enclave CID\n");
+
+			break;
+		}
+
+		default:
+			printf("Error in start enclave [%m]\n");
+		}
+
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * ne_start_enclave_check_booted() - Start the enclave and wait for a hearbeat
+ *				     from it, on a newly created vsock channel,
+ *				     to check it has booted.
+ * @enclave_fd :	The file descriptor associated with the enclave.
+ *
+ * Context: Process context.
+ * Return:
+ * * 0 on success.
+ * * Negative return value on failure.
+ */
+static int ne_start_enclave_check_booted(int enclave_fd)
+{
+	struct sockaddr_vm client_vsock_addr = {};
+	int client_vsock_fd = -1;
+	socklen_t client_vsock_len = sizeof(client_vsock_addr);
+	struct ne_enclave_start_info enclave_start_info = {};
+	struct pollfd fds[1] = {};
+	int rc = -EINVAL;
+	unsigned char recv_buf = 0;
+	struct sockaddr_vm server_vsock_addr = {
+		.svm_family = AF_VSOCK,
+		.svm_cid = NE_IMAGE_LOAD_HEARTBEAT_CID,
+		.svm_port = NE_IMAGE_LOAD_HEARTBEAT_PORT,
+	};
+	int server_vsock_fd = -1;
+
+	server_vsock_fd = socket(AF_VSOCK, SOCK_STREAM, 0);
+	if (server_vsock_fd < 0) {
+		rc = server_vsock_fd;
+
+		printf("Error in socket [%m]\n");
+
+		return rc;
+	}
+
+	rc = bind(server_vsock_fd, (struct sockaddr *)&server_vsock_addr,
+		  sizeof(server_vsock_addr));
+	if (rc < 0) {
+		printf("Error in bind [%m]\n");
+
+		goto out;
+	}
+
+	rc = listen(server_vsock_fd, 1);
+	if (rc < 0) {
+		printf("Error in listen [%m]\n");
+
+		goto out;
+	}
+
+	rc = ne_start_enclave(enclave_fd, &enclave_start_info);
+	if (rc < 0)
+		goto out;
+
+	printf("Enclave started, CID %llu\n", enclave_start_info.enclave_cid);
+
+	fds[0].fd = server_vsock_fd;
+	fds[0].events = POLLIN;
+
+	rc = poll(fds, 1, NE_POLL_WAIT_TIME_MS);
+	if (rc < 0) {
+		printf("Error in poll [%m]\n");
+
+		goto out;
+	}
+
+	if (!rc) {
+		printf("Poll timeout, %d seconds elapsed\n", NE_POLL_WAIT_TIME);
+
+		rc = -ETIMEDOUT;
+
+		goto out;
+	}
+
+	if ((fds[0].revents & POLLIN) == 0) {
+		printf("Poll received value %d\n", fds[0].revents);
+
+		rc = -EINVAL;
+
+		goto out;
+	}
+
+	rc = accept(server_vsock_fd, (struct sockaddr *)&client_vsock_addr,
+		    &client_vsock_len);
+	if (rc < 0) {
+		printf("Error in accept [%m]\n");
+
+		goto out;
+	}
+
+	client_vsock_fd = rc;
+
+	/*
+	 * Read the heartbeat value that the init process in the enclave sends
+	 * after vsock connect.
+	 */
+	rc = read(client_vsock_fd, &recv_buf, sizeof(recv_buf));
+	if (rc < 0) {
+		printf("Error in read [%m]\n");
+
+		goto out;
+	}
+
+	if (rc != sizeof(recv_buf) || recv_buf != NE_IMAGE_LOAD_HEARTBEAT_VALUE) {
+		printf("Read %d instead of %d\n", recv_buf,
+		       NE_IMAGE_LOAD_HEARTBEAT_VALUE);
+
+		goto out;
+	}
+
+	/* Write the heartbeat value back. */
+	rc = write(client_vsock_fd, &recv_buf, sizeof(recv_buf));
+	if (rc < 0) {
+		printf("Error in write [%m]\n");
+
+		goto out;
+	}
+
+	rc = 0;
+
+out:
+	close(server_vsock_fd);
+
+	return rc;
+}
+
+int main(int argc, char *argv[])
+{
+	int enclave_fd = -1;
+	unsigned int i = 0;
+	int ne_dev_fd = -1;
+	struct ne_user_mem_region ne_user_mem_regions[NE_DEFAULT_NR_MEM_REGIONS] = {};
+	unsigned int ne_vcpus[NE_DEFAULT_NR_VCPUS] = {};
+	int rc = -EINVAL;
+	pthread_t thread_id = 0;
+	unsigned long slot_uid = 0;
+
+	if (argc != 2) {
+		printf("Usage: %s <path_to_enclave_image>\n", argv[0]);
+
+		exit(EXIT_FAILURE);
+	}
+
+	if (strlen(argv[1]) >= PATH_MAX) {
+		printf("The size of the path to enclave image is higher than max path\n");
+
+		exit(EXIT_FAILURE);
+	}
+
+	ne_dev_fd = open(NE_DEV_NAME, O_RDWR | O_CLOEXEC);
+	if (ne_dev_fd < 0) {
+		printf("Error in open NE device [%m]\n");
+
+		exit(EXIT_FAILURE);
+	}
+
+	printf("Creating enclave slot ...\n");
+
+	rc = ne_create_vm(ne_dev_fd, &slot_uid, &enclave_fd);
+
+	close(ne_dev_fd);
+
+	if (rc < 0)
+		exit(EXIT_FAILURE);
+
+	printf("Enclave fd %d\n", enclave_fd);
+
+	rc = pthread_create(&thread_id, NULL, ne_poll_enclave_fd, (void *)&enclave_fd);
+	if (rc < 0) {
+		printf("Error in thread create [%m]\n");
+
+		close(enclave_fd);
+
+		exit(EXIT_FAILURE);
+	}
+
+	for (i = 0; i < NE_DEFAULT_NR_MEM_REGIONS; i++) {
+		ne_user_mem_regions[i].memory_size = NE_MIN_MEM_REGION_SIZE;
+
+		rc = ne_alloc_user_mem_region(&ne_user_mem_regions[i]);
+		if (rc < 0) {
+			printf("Error in alloc userspace memory region, iter %d\n", i);
+
+			goto release_enclave_fd;
+		}
+	}
+
+	rc = ne_load_enclave_image(enclave_fd, ne_user_mem_regions, argv[1]);
+	if (rc < 0)
+		goto release_enclave_fd;
+
+	for (i = 0; i < NE_DEFAULT_NR_MEM_REGIONS; i++) {
+		rc = ne_set_user_mem_region(enclave_fd, ne_user_mem_regions[i]);
+		if (rc < 0) {
+			printf("Error in set memory region, iter %d\n", i);
+
+			goto release_enclave_fd;
+		}
+	}
+
+	printf("Enclave memory regions were added\n");
+
+	for (i = 0; i < NE_DEFAULT_NR_VCPUS; i++) {
+		/*
+		 * The vCPU is chosen from the enclave vCPU pool, if the value
+		 * of the vcpu_id is 0.
+		 */
+		ne_vcpus[i] = 0;
+		rc = ne_add_vcpu(enclave_fd, &ne_vcpus[i]);
+		if (rc < 0) {
+			printf("Error in add vcpu, iter %d\n", i);
+
+			goto release_enclave_fd;
+		}
+
+		printf("Added vCPU %d to the enclave\n", ne_vcpus[i]);
+	}
+
+	printf("Enclave vCPUs were added\n");
+
+	rc = ne_start_enclave_check_booted(enclave_fd);
+	if (rc < 0) {
+		printf("Error in the enclave start / image loading heartbeat logic [rc=%d]\n", rc);
+
+		goto release_enclave_fd;
+	}
+
+	printf("Entering sleep for %d seconds ...\n", NE_SLEEP_TIME);
+
+	sleep(NE_SLEEP_TIME);
+
+	close(enclave_fd);
+
+	ne_free_mem_regions(ne_user_mem_regions);
+
+	exit(EXIT_SUCCESS);
+
+release_enclave_fd:
+	close(enclave_fd);
+	ne_free_mem_regions(ne_user_mem_regions);
+
+	exit(EXIT_FAILURE);
+}