1// SPDX-License-Identifier: GPL-2.0
2/*
3 * arch/x86/kernel/nmi-selftest.c
4 *
5 * Testsuite for NMI: IPIs
6 *
7 * Started by Don Zickus:
8 * (using lib/locking-selftest.c as a guide)
9 *
10 *   Copyright (C) 2011 Red Hat, Inc., Don Zickus <dzickus@redhat.com>
11 */
12
13#include <linux/smp.h>
14#include <linux/cpumask.h>
15#include <linux/delay.h>
16#include <linux/init.h>
17#include <linux/percpu.h>
18
19#include <asm/apic.h>
20#include <asm/nmi.h>
21
22#define SUCCESS		0
23#define FAILURE		1
24#define TIMEOUT		2
25
26static int __initdata nmi_fail;
27
28/* check to see if NMI IPIs work on this machine */
29static DECLARE_BITMAP(nmi_ipi_mask, NR_CPUS) __initdata;
30
31static int __initdata testcase_total;
32static int __initdata testcase_successes;
33static int __initdata expected_testcase_failures;
34static int __initdata unexpected_testcase_failures;
35static int __initdata unexpected_testcase_unknowns;
36
37static int __init nmi_unk_cb(unsigned int val, struct pt_regs *regs)
38{
39	unexpected_testcase_unknowns++;
40	return NMI_HANDLED;
41}
42
43static void __init init_nmi_testsuite(void)
44{
45	/* trap all the unknown NMIs we may generate */
46	register_nmi_handler(NMI_UNKNOWN, nmi_unk_cb, 0, "nmi_selftest_unk",
47			__initdata);
48}
49
50static void __init cleanup_nmi_testsuite(void)
51{
52	unregister_nmi_handler(NMI_UNKNOWN, "nmi_selftest_unk");
53}
54
55static int __init test_nmi_ipi_callback(unsigned int val, struct pt_regs *regs)
56{
57        int cpu = raw_smp_processor_id();
58
59        if (cpumask_test_and_clear_cpu(cpu, to_cpumask(nmi_ipi_mask)))
60                return NMI_HANDLED;
61
62        return NMI_DONE;
63}
64
65static void __init test_nmi_ipi(struct cpumask *mask)
66{
67	unsigned long timeout;
68
69	if (register_nmi_handler(NMI_LOCAL, test_nmi_ipi_callback,
70				 NMI_FLAG_FIRST, "nmi_selftest", __initdata)) {
71		nmi_fail = FAILURE;
72		return;
73	}
74
75	/* sync above data before sending NMI */
76	wmb();
77
78	__apic_send_IPI_mask(mask, NMI_VECTOR);
79
80	/* Don't wait longer than a second */
81	timeout = USEC_PER_SEC;
82	while (!cpumask_empty(mask) && --timeout)
83	        udelay(1);
84
85	/* What happens if we timeout, do we still unregister?? */
86	unregister_nmi_handler(NMI_LOCAL, "nmi_selftest");
87
88	if (!timeout)
89		nmi_fail = TIMEOUT;
90	return;
91}
92
93static void __init remote_ipi(void)
94{
95	cpumask_copy(to_cpumask(nmi_ipi_mask), cpu_online_mask);
96	cpumask_clear_cpu(smp_processor_id(), to_cpumask(nmi_ipi_mask));
97	if (!cpumask_empty(to_cpumask(nmi_ipi_mask)))
98		test_nmi_ipi(to_cpumask(nmi_ipi_mask));
99}
100
101static void __init local_ipi(void)
102{
103	cpumask_clear(to_cpumask(nmi_ipi_mask));
104	cpumask_set_cpu(smp_processor_id(), to_cpumask(nmi_ipi_mask));
105	test_nmi_ipi(to_cpumask(nmi_ipi_mask));
106}
107
108static void __init reset_nmi(void)
109{
110	nmi_fail = 0;
111}
112
113static void __init dotest(void (*testcase_fn)(void), int expected)
114{
115	testcase_fn();
116	/*
117	 * Filter out expected failures:
118	 */
119	if (nmi_fail != expected) {
120		unexpected_testcase_failures++;
121
122		if (nmi_fail == FAILURE)
123			printk(KERN_CONT "FAILED |");
124		else if (nmi_fail == TIMEOUT)
125			printk(KERN_CONT "TIMEOUT|");
126		else
127			printk(KERN_CONT "ERROR  |");
128		dump_stack();
129	} else {
130		testcase_successes++;
131		printk(KERN_CONT "  ok  |");
132	}
133	testcase_total++;
134
135	reset_nmi();
136}
137
138static inline void __init print_testname(const char *testname)
139{
140	printk("%12s:", testname);
141}
142
143void __init nmi_selftest(void)
144{
145	init_nmi_testsuite();
146
147        /*
148	 * Run the testsuite:
149	 */
150	printk("----------------\n");
151	printk("| NMI testsuite:\n");
152	printk("--------------------\n");
153
154	print_testname("remote IPI");
155	dotest(remote_ipi, SUCCESS);
156	printk(KERN_CONT "\n");
157	print_testname("local IPI");
158	dotest(local_ipi, SUCCESS);
159	printk(KERN_CONT "\n");
160
161	cleanup_nmi_testsuite();
162
163	if (unexpected_testcase_failures) {
164		printk("--------------------\n");
165		printk("BUG: %3d unexpected failures (out of %3d) - debugging disabled! |\n",
166			unexpected_testcase_failures, testcase_total);
167		printk("-----------------------------------------------------------------\n");
168	} else if (expected_testcase_failures && testcase_successes) {
169		printk("--------------------\n");
170		printk("%3d out of %3d testcases failed, as expected. |\n",
171			expected_testcase_failures, testcase_total);
172		printk("----------------------------------------------------\n");
173	} else if (expected_testcase_failures && !testcase_successes) {
174		printk("--------------------\n");
175		printk("All %3d testcases failed, as expected. |\n",
176			expected_testcase_failures);
177		printk("----------------------------------------\n");
178	} else {
179		printk("--------------------\n");
180		printk("Good, all %3d testcases passed! |\n",
181			testcase_successes);
182		printk("---------------------------------\n");
183	}
184}
185