nitro_enclaves: Add KUnit tests setup for the misc device functionality

Add the initial setup for the KUnit tests that will target the Nitro
Enclaves misc device functionality.

Reviewed-by: Andra Paraschiv <andraprs@amazon.com>
Signed-off-by: Longpeng <longpeng2@huawei.com>
Link: https://lore.kernel.org/r/20211107140918.2106-4-longpeng2@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/virt/nitro_enclaves/Kconfig

@@ -14,3 +14,12 @@ config NITRO_ENCLAVES
 
 	  To compile this driver as a module, choose M here.
 	  The module will be called nitro_enclaves.
+
+config NITRO_ENCLAVES_MISC_DEV_TEST
+	bool "Tests for the misc device functionality of the Nitro Enclaves"
+	depends on NITRO_ENCLAVES && KUNIT=y
+	help
+	  Enable KUnit tests for the misc device functionality of the Nitro
+	  Enclaves. Select this option only if you will boot the kernel for
+	  the purpose of running unit tests (e.g. under UML or qemu). If
+	  unsure, say N.

drivers/virt/nitro_enclaves/ne_misc_dev.c

@@ -1756,8 +1756,37 @@ static long ne_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	return 0;
 }
 
+#if defined(CONFIG_NITRO_ENCLAVES_MISC_DEV_TEST)
+#include "ne_misc_dev_test.c"
+
+static inline int ne_misc_dev_test_init(void)
+{
+	return __kunit_test_suites_init(ne_misc_dev_test_suites);
+}
+
+static inline void ne_misc_dev_test_exit(void)
+{
+	__kunit_test_suites_exit(ne_misc_dev_test_suites);
+}
+#else
+static inline int ne_misc_dev_test_init(void)
+{
+	return 0;
+}
+
+static inline void ne_misc_dev_test_exit(void)
+{
+}
+#endif
+
 static int __init ne_init(void)
 {
+	int rc = 0;
+
+	rc = ne_misc_dev_test_init();
+	if (rc < 0)
+		return rc;
+
 	mutex_init(&ne_cpu_pool.mutex);
 
 	return pci_register_driver(&ne_pci_driver);
@@ -1768,6 +1797,8 @@ static void __exit ne_exit(void)
 	pci_unregister_driver(&ne_pci_driver);
 
 	ne_teardown_cpu_pool();
+
+	ne_misc_dev_test_exit();
 }
 
 module_init(ne_init);

drivers/virt/nitro_enclaves/ne_misc_dev_test.c

@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <kunit/test.h>
+
+static struct kunit_case ne_misc_dev_test_cases[] = {
+	{}
+};
+
+static struct kunit_suite ne_misc_dev_test_suite = {
+	.name = "ne_misc_dev_test",
+	.test_cases = ne_misc_dev_test_cases,
+};
+
+static struct kunit_suite *ne_misc_dev_test_suites[] = {
+	&ne_misc_dev_test_suite,
+	NULL
+};