cpu.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * CPU subsystem support
  4 */
  5
  6#include <linux/kernel.h>
  7#include <linux/module.h>
  8#include <linux/init.h>
  9#include <linux/sched.h>
 10#include <linux/cpu.h>
 11#include <linux/topology.h>
 12#include <linux/device.h>
 13#include <linux/node.h>
 14#include <linux/gfp.h>
 15#include <linux/slab.h>
 16#include <linux/percpu.h>
 17#include <linux/acpi.h>
 18#include <linux/of.h>
 19#include <linux/cpufeature.h>
 20#include <linux/tick.h>
 21#include <linux/pm_qos.h>
 22#include <linux/delay.h>
 23#include <linux/sched/isolation.h>
 24
 25#include "base.h"
 26
 27static DEFINE_PER_CPU(struct device *, cpu_sys_devices);
 28
 29static int cpu_subsys_match(struct device *dev, const struct device_driver *drv)
 30{
 31	/* ACPI style match is the only one that may succeed. */
 32	if (acpi_driver_match_device(dev, drv))
 33		return 1;
 34
 35	return 0;
 36}
 37
 38#ifdef CONFIG_HOTPLUG_CPU
 39static void change_cpu_under_node(struct cpu *cpu,
 40			unsigned int from_nid, unsigned int to_nid)
 41{
 42	int cpuid = cpu->dev.id;
 43	unregister_cpu_under_node(cpuid, from_nid);
 44	register_cpu_under_node(cpuid, to_nid);
 45	cpu->node_id = to_nid;
 46}
 47
 48static int cpu_subsys_online(struct device *dev)
 49{
 50	struct cpu *cpu = container_of(dev, struct cpu, dev);
 51	int cpuid = dev->id;
 52	int from_nid, to_nid;
 53	int ret;
 54	int retries = 0;
 55
 56	from_nid = cpu_to_node(cpuid);
 57	if (from_nid == NUMA_NO_NODE)
 58		return -ENODEV;
 59
 60retry:
 61	ret = cpu_device_up(dev);
 62
 63	/*
 64	 * If -EBUSY is returned, it is likely that hotplug is temporarily
 65	 * disabled when cpu_hotplug_disable() was called. This condition is
 66	 * transient. So we retry after waiting for an exponentially
 67	 * increasing delay up to a total of at least 620ms as some PCI
 68	 * device initialization can take quite a while.
 69	 */
 70	if (ret == -EBUSY) {
 71		retries++;
 72		if (retries > 5)
 73			return ret;
 74		msleep(10 * (1 << retries));
 75		goto retry;
 76	}
 77
 78	/*
 79	 * When hot adding memory to memoryless node and enabling a cpu
 80	 * on the node, node number of the cpu may internally change.
 81	 */
 82	to_nid = cpu_to_node(cpuid);
 83	if (from_nid != to_nid)
 84		change_cpu_under_node(cpu, from_nid, to_nid);
 85
 86	return ret;
 87}
 88
 89static int cpu_subsys_offline(struct device *dev)
 90{
 91	return cpu_device_down(dev);
 92}
 93
 94void unregister_cpu(struct cpu *cpu)
 95{
 96	int logical_cpu = cpu->dev.id;
 97
 98	set_cpu_enabled(logical_cpu, false);
 99	unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
100
101	device_unregister(&cpu->dev);
102	per_cpu(cpu_sys_devices, logical_cpu) = NULL;
103	return;
104}
105
106#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
107static ssize_t cpu_probe_store(struct device *dev,
108			       struct device_attribute *attr,
109			       const char *buf,
110			       size_t count)
111{
112	ssize_t cnt;
113	int ret;
114
115	ret = lock_device_hotplug_sysfs();
116	if (ret)
117		return ret;
118
119	cnt = arch_cpu_probe(buf, count);
120
121	unlock_device_hotplug();
122	return cnt;
123}
124
125static ssize_t cpu_release_store(struct device *dev,
126				 struct device_attribute *attr,
127				 const char *buf,
128				 size_t count)
129{
130	ssize_t cnt;
131	int ret;
132
133	ret = lock_device_hotplug_sysfs();
134	if (ret)
135		return ret;
136
137	cnt = arch_cpu_release(buf, count);
138
139	unlock_device_hotplug();
140	return cnt;
141}
142
143static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
144static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
145#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
146#endif /* CONFIG_HOTPLUG_CPU */
147
148#ifdef CONFIG_CRASH_DUMP
149#include <linux/kexec.h>
150
151static ssize_t crash_notes_show(struct device *dev,
152				struct device_attribute *attr,
153				char *buf)
154{
155	struct cpu *cpu = container_of(dev, struct cpu, dev);
156	unsigned long long addr;
157	int cpunum;
158
159	cpunum = cpu->dev.id;
160
161	/*
162	 * Might be reading other cpu's data based on which cpu read thread
163	 * has been scheduled. But cpu data (memory) is allocated once during
164	 * boot up and this data does not change there after. Hence this
165	 * operation should be safe. No locking required.
166	 */
167	addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));
168
169	return sysfs_emit(buf, "%llx\n", addr);
170}
171static DEVICE_ATTR_ADMIN_RO(crash_notes);
172
173static ssize_t crash_notes_size_show(struct device *dev,
174				     struct device_attribute *attr,
175				     char *buf)
176{
177	return sysfs_emit(buf, "%zu\n", sizeof(note_buf_t));
178}
179static DEVICE_ATTR_ADMIN_RO(crash_notes_size);
180
181static struct attribute *crash_note_cpu_attrs[] = {
182	&dev_attr_crash_notes.attr,
183	&dev_attr_crash_notes_size.attr,
184	NULL
185};
186
187static const struct attribute_group crash_note_cpu_attr_group = {
188	.attrs = crash_note_cpu_attrs,
189};
190#endif
191
192static const struct attribute_group *common_cpu_attr_groups[] = {
193#ifdef CONFIG_CRASH_DUMP
194	&crash_note_cpu_attr_group,
195#endif
196	NULL
197};
198
199static const struct attribute_group *hotplugable_cpu_attr_groups[] = {
200#ifdef CONFIG_CRASH_DUMP
201	&crash_note_cpu_attr_group,
202#endif
203	NULL
204};
205
206/*
207 * Print cpu online, possible, present, and system maps
208 */
209
210struct cpu_attr {
211	struct device_attribute attr;
212	const struct cpumask *const map;
213};
214
215static ssize_t show_cpus_attr(struct device *dev,
216			      struct device_attribute *attr,
217			      char *buf)
218{
219	struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
220
221	return cpumap_print_to_pagebuf(true, buf, ca->map);
222}
223
224#define _CPU_ATTR(name, map) \
225	{ __ATTR(name, 0444, show_cpus_attr, NULL), map }
226
227/* Keep in sync with cpu_subsys_attrs */
228static struct cpu_attr cpu_attrs[] = {
229	_CPU_ATTR(online, &__cpu_online_mask),
230	_CPU_ATTR(possible, &__cpu_possible_mask),
231	_CPU_ATTR(present, &__cpu_present_mask),
232};
233
234/*
235 * Print values for NR_CPUS and offlined cpus
236 */
237static ssize_t print_cpus_kernel_max(struct device *dev,
238				     struct device_attribute *attr, char *buf)
239{
240	return sysfs_emit(buf, "%d\n", NR_CPUS - 1);
241}
242static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
243
244/* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
245unsigned int total_cpus;
246
247static ssize_t print_cpus_offline(struct device *dev,
248				  struct device_attribute *attr, char *buf)
249{
250	int len = 0;
251	cpumask_var_t offline;
252
253	/* display offline cpus < nr_cpu_ids */
254	if (!alloc_cpumask_var(&offline, GFP_KERNEL))
255		return -ENOMEM;
256	cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);
257	len += sysfs_emit_at(buf, len, "%*pbl", cpumask_pr_args(offline));
258	free_cpumask_var(offline);
259
260	/* display offline cpus >= nr_cpu_ids */
261	if (total_cpus && nr_cpu_ids < total_cpus) {
262		len += sysfs_emit_at(buf, len, ",");
263
264		if (nr_cpu_ids == total_cpus-1)
265			len += sysfs_emit_at(buf, len, "%u", nr_cpu_ids);
266		else
267			len += sysfs_emit_at(buf, len, "%u-%d",
268					     nr_cpu_ids, total_cpus - 1);
269	}
270
271	len += sysfs_emit_at(buf, len, "\n");
272
273	return len;
274}
275static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
276
277static ssize_t print_cpus_enabled(struct device *dev,
278				  struct device_attribute *attr, char *buf)
279{
280	return sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(cpu_enabled_mask));
281}
282static DEVICE_ATTR(enabled, 0444, print_cpus_enabled, NULL);
283
284static ssize_t print_cpus_isolated(struct device *dev,
285				  struct device_attribute *attr, char *buf)
286{
287	int len;
288	cpumask_var_t isolated;
289
290	if (!alloc_cpumask_var(&isolated, GFP_KERNEL))
291		return -ENOMEM;
292
293	cpumask_andnot(isolated, cpu_possible_mask,
294		       housekeeping_cpumask(HK_TYPE_DOMAIN));
295	len = sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(isolated));
296
297	free_cpumask_var(isolated);
298
299	return len;
300}
301static DEVICE_ATTR(isolated, 0444, print_cpus_isolated, NULL);
302
303static ssize_t housekeeping_show(struct device *dev,
304			     struct device_attribute *attr, char *buf)
305{
306	const struct cpumask *hk_mask;
307
308	hk_mask = housekeeping_cpumask(HK_TYPE_KERNEL_NOISE);
309
310	if (housekeeping_enabled(HK_TYPE_KERNEL_NOISE))
311		return sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(hk_mask));
312	return sysfs_emit(buf, "\n");
313}
314static DEVICE_ATTR_RO(housekeeping);
315
316#ifdef CONFIG_NO_HZ_FULL
317static ssize_t nohz_full_show(struct device *dev,
318				    struct device_attribute *attr,
319				    char *buf)
320{
321	if (cpumask_available(tick_nohz_full_mask))
322		return sysfs_emit(buf, "%*pbl\n",
323				  cpumask_pr_args(tick_nohz_full_mask));
324	return sysfs_emit(buf, "\n");
325}
326static DEVICE_ATTR_RO(nohz_full);
327#endif
328
329#ifdef CONFIG_CRASH_HOTPLUG
330static ssize_t crash_hotplug_show(struct device *dev,
331				     struct device_attribute *attr,
332				     char *buf)
333{
334	return sysfs_emit(buf, "%d\n", crash_check_hotplug_support());
335}
336static DEVICE_ATTR_RO(crash_hotplug);
337#endif
338
339static void cpu_device_release(struct device *dev)
340{
341	/*
342	 * This is an empty function to prevent the driver core from spitting a
343	 * warning at us.  Yes, I know this is directly opposite of what the
344	 * documentation for the driver core and kobjects say, and the author
345	 * of this code has already been publicly ridiculed for doing
346	 * something as foolish as this.  However, at this point in time, it is
347	 * the only way to handle the issue of statically allocated cpu
348	 * devices.  The different architectures will have their cpu device
349	 * code reworked to properly handle this in the near future, so this
350	 * function will then be changed to correctly free up the memory held
351	 * by the cpu device.
352	 *
353	 * Never copy this way of doing things, or you too will be made fun of
354	 * on the linux-kernel list, you have been warned.
355	 */
356}
357
358#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
359static ssize_t print_cpu_modalias(struct device *dev,
360				  struct device_attribute *attr,
361				  char *buf)
362{
363	int len = 0;
364	u32 i;
365
366	len += sysfs_emit_at(buf, len,
367			     "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:",
368			     CPU_FEATURE_TYPEVAL);
369
370	for (i = 0; i < MAX_CPU_FEATURES; i++)
371		if (cpu_have_feature(i)) {
372			if (len + sizeof(",XXXX\n") >= PAGE_SIZE) {
373				WARN(1, "CPU features overflow page\n");
374				break;
375			}
376			len += sysfs_emit_at(buf, len, ",%04X", i);
377		}
378	len += sysfs_emit_at(buf, len, "\n");
379	return len;
380}
381
382static int cpu_uevent(const struct device *dev, struct kobj_uevent_env *env)
383{
384	char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
385	if (buf) {
386		print_cpu_modalias(NULL, NULL, buf);
387		add_uevent_var(env, "MODALIAS=%s", buf);
388		kfree(buf);
389	}
390	return 0;
391}
392#endif
393
394const struct bus_type cpu_subsys = {
395	.name = "cpu",
396	.dev_name = "cpu",
397	.match = cpu_subsys_match,
398#ifdef CONFIG_HOTPLUG_CPU
399	.online = cpu_subsys_online,
400	.offline = cpu_subsys_offline,
401#endif
402#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
403	.uevent = cpu_uevent,
404#endif
405};
406EXPORT_SYMBOL_GPL(cpu_subsys);
407
408/*
409 * register_cpu - Setup a sysfs device for a CPU.
410 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
411 *	  sysfs for this CPU.
412 * @num - CPU number to use when creating the device.
413 *
414 * Initialize and register the CPU device.
415 */
416int register_cpu(struct cpu *cpu, int num)
417{
418	int error;
419
420	cpu->node_id = cpu_to_node(num);
421	memset(&cpu->dev, 0x00, sizeof(struct device));
422	cpu->dev.id = num;
423	cpu->dev.bus = &cpu_subsys;
424	cpu->dev.release = cpu_device_release;
425	cpu->dev.offline_disabled = !cpu->hotpluggable;
426	cpu->dev.offline = !cpu_online(num);
427	cpu->dev.of_node = of_get_cpu_node(num, NULL);
428	cpu->dev.groups = common_cpu_attr_groups;
429	if (cpu->hotpluggable)
430		cpu->dev.groups = hotplugable_cpu_attr_groups;
431	error = device_register(&cpu->dev);
432	if (error) {
433		put_device(&cpu->dev);
434		return error;
435	}
436
437	per_cpu(cpu_sys_devices, num) = &cpu->dev;
438	register_cpu_under_node(num, cpu_to_node(num));
439	dev_pm_qos_expose_latency_limit(&cpu->dev,
440					PM_QOS_RESUME_LATENCY_NO_CONSTRAINT);
441	set_cpu_enabled(num, true);
442
443	return 0;
444}
445
446struct device *get_cpu_device(unsigned int cpu)
447{
448	if (cpu < nr_cpu_ids && cpu_possible(cpu))
449		return per_cpu(cpu_sys_devices, cpu);
450	else
451		return NULL;
452}
453EXPORT_SYMBOL_GPL(get_cpu_device);
454
455static void device_create_release(struct device *dev)
456{
457	kfree(dev);
458}
459
460__printf(4, 0)
461static struct device *
462__cpu_device_create(struct device *parent, void *drvdata,
463		    const struct attribute_group **groups,
464		    const char *fmt, va_list args)
465{
466	struct device *dev = NULL;
467	int retval = -ENOMEM;
468
469	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
470	if (!dev)
471		goto error;
472
473	device_initialize(dev);
474	dev->parent = parent;
475	dev->groups = groups;
476	dev->release = device_create_release;
477	device_set_pm_not_required(dev);
478	dev_set_drvdata(dev, drvdata);
479
480	retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
481	if (retval)
482		goto error;
483
484	retval = device_add(dev);
485	if (retval)
486		goto error;
487
488	return dev;
489
490error:
491	put_device(dev);
492	return ERR_PTR(retval);
493}
494
495struct device *cpu_device_create(struct device *parent, void *drvdata,
496				 const struct attribute_group **groups,
497				 const char *fmt, ...)
498{
499	va_list vargs;
500	struct device *dev;
501
502	va_start(vargs, fmt);
503	dev = __cpu_device_create(parent, drvdata, groups, fmt, vargs);
504	va_end(vargs);
505	return dev;
506}
507EXPORT_SYMBOL_GPL(cpu_device_create);
508
509#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
510static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL);
511#endif
512
513static struct attribute *cpu_root_attrs[] = {
514#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
515	&dev_attr_probe.attr,
516	&dev_attr_release.attr,
517#endif
518	&cpu_attrs[0].attr.attr,
519	&cpu_attrs[1].attr.attr,
520	&cpu_attrs[2].attr.attr,
521	&dev_attr_kernel_max.attr,
522	&dev_attr_offline.attr,
523	&dev_attr_enabled.attr,
524	&dev_attr_isolated.attr,
525	&dev_attr_housekeeping.attr,
526#ifdef CONFIG_NO_HZ_FULL
527	&dev_attr_nohz_full.attr,
528#endif
529#ifdef CONFIG_CRASH_HOTPLUG
530	&dev_attr_crash_hotplug.attr,
531#endif
532#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
533	&dev_attr_modalias.attr,
534#endif
535	NULL
536};
537
538static const struct attribute_group cpu_root_attr_group = {
539	.attrs = cpu_root_attrs,
540};
541
542static const struct attribute_group *cpu_root_attr_groups[] = {
543	&cpu_root_attr_group,
544	NULL,
545};
546
547bool cpu_is_hotpluggable(unsigned int cpu)
548{
549	struct device *dev = get_cpu_device(cpu);
550	return dev && container_of(dev, struct cpu, dev)->hotpluggable
551		&& tick_nohz_cpu_hotpluggable(cpu);
552}
553EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
554
555#ifdef CONFIG_GENERIC_CPU_DEVICES
556DEFINE_PER_CPU(struct cpu, cpu_devices);
557
558bool __weak arch_cpu_is_hotpluggable(int cpu)
559{
560	return false;
561}
562
563int __weak arch_register_cpu(int cpu)
564{
565	struct cpu *c = &per_cpu(cpu_devices, cpu);
566
567	c->hotpluggable = arch_cpu_is_hotpluggable(cpu);
568
569	return register_cpu(c, cpu);
570}
571
572#ifdef CONFIG_HOTPLUG_CPU
573void __weak arch_unregister_cpu(int num)
574{
575	unregister_cpu(&per_cpu(cpu_devices, num));
576}
577#endif /* CONFIG_HOTPLUG_CPU */
578#endif /* CONFIG_GENERIC_CPU_DEVICES */
579
580static void __init cpu_dev_register_generic(void)
581{
582	int i, ret;
583
584	if (!IS_ENABLED(CONFIG_GENERIC_CPU_DEVICES))
585		return;
586
587	for_each_present_cpu(i) {
588		ret = arch_register_cpu(i);
589		if (ret && ret != -EPROBE_DEFER)
590			pr_warn("register_cpu %d failed (%d)\n", i, ret);
591	}
592}
593
594#ifdef CONFIG_GENERIC_CPU_VULNERABILITIES
595static ssize_t cpu_show_not_affected(struct device *dev,
596			      struct device_attribute *attr, char *buf)
597{
598	return sysfs_emit(buf, "Not affected\n");
599}
600
601#define CPU_SHOW_VULN_FALLBACK(func)					\
602	ssize_t cpu_show_##func(struct device *,			\
603				  struct device_attribute *, char *)	\
604		 __attribute__((weak, alias("cpu_show_not_affected")))
605
606CPU_SHOW_VULN_FALLBACK(meltdown);
607CPU_SHOW_VULN_FALLBACK(spectre_v1);
608CPU_SHOW_VULN_FALLBACK(spectre_v2);
609CPU_SHOW_VULN_FALLBACK(spec_store_bypass);
610CPU_SHOW_VULN_FALLBACK(l1tf);
611CPU_SHOW_VULN_FALLBACK(mds);
612CPU_SHOW_VULN_FALLBACK(tsx_async_abort);
613CPU_SHOW_VULN_FALLBACK(itlb_multihit);
614CPU_SHOW_VULN_FALLBACK(srbds);
615CPU_SHOW_VULN_FALLBACK(mmio_stale_data);
616CPU_SHOW_VULN_FALLBACK(retbleed);
617CPU_SHOW_VULN_FALLBACK(spec_rstack_overflow);
618CPU_SHOW_VULN_FALLBACK(gds);
619CPU_SHOW_VULN_FALLBACK(reg_file_data_sampling);
620CPU_SHOW_VULN_FALLBACK(ghostwrite);
621CPU_SHOW_VULN_FALLBACK(old_microcode);
622CPU_SHOW_VULN_FALLBACK(indirect_target_selection);
623CPU_SHOW_VULN_FALLBACK(tsa);
624CPU_SHOW_VULN_FALLBACK(vmscape);
625
626static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL);
627static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL);
628static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL);
629static DEVICE_ATTR(spec_store_bypass, 0444, cpu_show_spec_store_bypass, NULL);
630static DEVICE_ATTR(l1tf, 0444, cpu_show_l1tf, NULL);
631static DEVICE_ATTR(mds, 0444, cpu_show_mds, NULL);
632static DEVICE_ATTR(tsx_async_abort, 0444, cpu_show_tsx_async_abort, NULL);
633static DEVICE_ATTR(itlb_multihit, 0444, cpu_show_itlb_multihit, NULL);
634static DEVICE_ATTR(srbds, 0444, cpu_show_srbds, NULL);
635static DEVICE_ATTR(mmio_stale_data, 0444, cpu_show_mmio_stale_data, NULL);
636static DEVICE_ATTR(retbleed, 0444, cpu_show_retbleed, NULL);
637static DEVICE_ATTR(spec_rstack_overflow, 0444, cpu_show_spec_rstack_overflow, NULL);
638static DEVICE_ATTR(gather_data_sampling, 0444, cpu_show_gds, NULL);
639static DEVICE_ATTR(reg_file_data_sampling, 0444, cpu_show_reg_file_data_sampling, NULL);
640static DEVICE_ATTR(ghostwrite, 0444, cpu_show_ghostwrite, NULL);
641static DEVICE_ATTR(old_microcode, 0444, cpu_show_old_microcode, NULL);
642static DEVICE_ATTR(indirect_target_selection, 0444, cpu_show_indirect_target_selection, NULL);
643static DEVICE_ATTR(tsa, 0444, cpu_show_tsa, NULL);
644static DEVICE_ATTR(vmscape, 0444, cpu_show_vmscape, NULL);
645
646static struct attribute *cpu_root_vulnerabilities_attrs[] = {
647	&dev_attr_meltdown.attr,
648	&dev_attr_spectre_v1.attr,
649	&dev_attr_spectre_v2.attr,
650	&dev_attr_spec_store_bypass.attr,
651	&dev_attr_l1tf.attr,
652	&dev_attr_mds.attr,
653	&dev_attr_tsx_async_abort.attr,
654	&dev_attr_itlb_multihit.attr,
655	&dev_attr_srbds.attr,
656	&dev_attr_mmio_stale_data.attr,
657	&dev_attr_retbleed.attr,
658	&dev_attr_spec_rstack_overflow.attr,
659	&dev_attr_gather_data_sampling.attr,
660	&dev_attr_reg_file_data_sampling.attr,
661	&dev_attr_ghostwrite.attr,
662	&dev_attr_old_microcode.attr,
663	&dev_attr_indirect_target_selection.attr,
664	&dev_attr_tsa.attr,
665	&dev_attr_vmscape.attr,
666	NULL
667};
668
669static const struct attribute_group cpu_root_vulnerabilities_group = {
670	.name  = "vulnerabilities",
671	.attrs = cpu_root_vulnerabilities_attrs,
672};
673
674static void __init cpu_register_vulnerabilities(void)
675{
676	struct device *dev = bus_get_dev_root(&cpu_subsys);
677
678	if (dev) {
679		if (sysfs_create_group(&dev->kobj, &cpu_root_vulnerabilities_group))
680			pr_err("Unable to register CPU vulnerabilities\n");
681		put_device(dev);
682	}
683}
684
685#else
686static inline void cpu_register_vulnerabilities(void) { }
687#endif
688
689void __init cpu_dev_init(void)
690{
691	if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
692		panic("Failed to register CPU subsystem");
693
694	cpu_dev_register_generic();
695	cpu_register_vulnerabilities();
696}