1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Intel specific MCE features.
4 * Copyright 2004 Zwane Mwaikambo <zwane@linuxpower.ca>
5 * Copyright (C) 2008, 2009 Intel Corporation
6 * Author: Andi Kleen
7 */
8
9#include <linux/gfp.h>
10#include <linux/interrupt.h>
11#include <linux/percpu.h>
12#include <linux/sched.h>
13#include <linux/cpumask.h>
14#include <asm/apic.h>
15#include <asm/cpufeature.h>
16#include <asm/intel-family.h>
17#include <asm/processor.h>
18#include <asm/msr.h>
19#include <asm/mce.h>
20
21#include "internal.h"
22
23/*
24 * Support for Intel Correct Machine Check Interrupts. This allows
25 * the CPU to raise an interrupt when a corrected machine check happened.
26 * Normally we pick those up using a regular polling timer.
27 * Also supports reliable discovery of shared banks.
28 */
29
30/*
31 * CMCI can be delivered to multiple cpus that share a machine check bank
32 * so we need to designate a single cpu to process errors logged in each bank
33 * in the interrupt handler (otherwise we would have many races and potential
34 * double reporting of the same error).
35 * Note that this can change when a cpu is offlined or brought online since
36 * some MCA banks are shared across cpus. When a cpu is offlined, cmci_clear()
37 * disables CMCI on all banks owned by the cpu and clears this bitfield. At
38 * this point, cmci_rediscover() kicks in and a different cpu may end up
39 * taking ownership of some of the shared MCA banks that were previously
40 * owned by the offlined cpu.
41 */
42static DEFINE_PER_CPU(mce_banks_t, mce_banks_owned);
43
44/*
45 * CMCI storm detection backoff counter
46 *
47 * During storm, we reset this counter to INITIAL_CHECK_INTERVAL in case we've
48 * encountered an error. If not, we decrement it by one. We signal the end of
49 * the CMCI storm when it reaches 0.
50 */
51static DEFINE_PER_CPU(int, cmci_backoff_cnt);
52
53/*
54 * cmci_discover_lock protects against parallel discovery attempts
55 * which could race against each other.
56 */
57static DEFINE_RAW_SPINLOCK(cmci_discover_lock);
58
59/*
60 * On systems that do support CMCI but it's disabled, polling for MCEs can
61 * cause the same event to be reported multiple times because IA32_MCi_STATUS
62 * is shared by the same package.
63 */
64static DEFINE_SPINLOCK(cmci_poll_lock);
65
66#define CMCI_THRESHOLD 1
67#define CMCI_POLL_INTERVAL (30 * HZ)
68#define CMCI_STORM_INTERVAL (HZ)
69#define CMCI_STORM_THRESHOLD 15
70
71static DEFINE_PER_CPU(unsigned long, cmci_time_stamp);
72static DEFINE_PER_CPU(unsigned int, cmci_storm_cnt);
73static DEFINE_PER_CPU(unsigned int, cmci_storm_state);
74
75enum {
76 CMCI_STORM_NONE,
77 CMCI_STORM_ACTIVE,
78 CMCI_STORM_SUBSIDED,
79};
80
81static atomic_t cmci_storm_on_cpus;
82
83static int cmci_supported(int *banks)
84{
85 u64 cap;
86
87 if (mca_cfg.cmci_disabled || mca_cfg.ignore_ce)
88 return 0;
89
90 /*
91 * Vendor check is not strictly needed, but the initial
92 * initialization is vendor keyed and this
93 * makes sure none of the backdoors are entered otherwise.
94 */
95 if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL &&
96 boot_cpu_data.x86_vendor != X86_VENDOR_ZHAOXIN)
97 return 0;
98
99 if (!boot_cpu_has(X86_FEATURE_APIC) || lapic_get_maxlvt() < 6)
100 return 0;
101 rdmsrl(MSR_IA32_MCG_CAP, cap);
102 *banks = min_t(unsigned, MAX_NR_BANKS, cap & 0xff);
103 return !!(cap & MCG_CMCI_P);
104}
105
106static bool lmce_supported(void)
107{
108 u64 tmp;
109
110 if (mca_cfg.lmce_disabled)
111 return false;
112
113 rdmsrl(MSR_IA32_MCG_CAP, tmp);
114
115 /*
116 * LMCE depends on recovery support in the processor. Hence both
117 * MCG_SER_P and MCG_LMCE_P should be present in MCG_CAP.
118 */
119 if ((tmp & (MCG_SER_P | MCG_LMCE_P)) !=
120 (MCG_SER_P | MCG_LMCE_P))
121 return false;
122
123 /*
124 * BIOS should indicate support for LMCE by setting bit 20 in
125 * IA32_FEAT_CTL without which touching MCG_EXT_CTL will generate a #GP
126 * fault. The MSR must also be locked for LMCE_ENABLED to take effect.
127 * WARN if the MSR isn't locked as init_ia32_feat_ctl() unconditionally
128 * locks the MSR in the event that it wasn't already locked by BIOS.
129 */
130 rdmsrl(MSR_IA32_FEAT_CTL, tmp);
131 if (WARN_ON_ONCE(!(tmp & FEAT_CTL_LOCKED)))
132 return false;
133
134 return tmp & FEAT_CTL_LMCE_ENABLED;
135}
136
137bool mce_intel_cmci_poll(void)
138{
139 if (__this_cpu_read(cmci_storm_state) == CMCI_STORM_NONE)
140 return false;
141
142 /*
143 * Reset the counter if we've logged an error in the last poll
144 * during the storm.
145 */
146 if (machine_check_poll(flags: 0, this_cpu_ptr(&mce_banks_owned)))
147 this_cpu_write(cmci_backoff_cnt, INITIAL_CHECK_INTERVAL);
148 else
149 this_cpu_dec(cmci_backoff_cnt);
150
151 return true;
152}
153
154void mce_intel_hcpu_update(unsigned long cpu)
155{
156 if (per_cpu(cmci_storm_state, cpu) == CMCI_STORM_ACTIVE)
157 atomic_dec(v: &cmci_storm_on_cpus);
158
159 per_cpu(cmci_storm_state, cpu) = CMCI_STORM_NONE;
160}
161
162static void cmci_toggle_interrupt_mode(bool on)
163{
164 unsigned long flags, *owned;
165 int bank;
166 u64 val;
167
168 raw_spin_lock_irqsave(&cmci_discover_lock, flags);
169 owned = this_cpu_ptr(mce_banks_owned);
170 for_each_set_bit(bank, owned, MAX_NR_BANKS) {
171 rdmsrl(MSR_IA32_MCx_CTL2(bank), val);
172
173 if (on)
174 val |= MCI_CTL2_CMCI_EN;
175 else
176 val &= ~MCI_CTL2_CMCI_EN;
177
178 wrmsrl(MSR_IA32_MCx_CTL2(bank), val);
179 }
180 raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
181}
182
183unsigned long cmci_intel_adjust_timer(unsigned long interval)
184{
185 if ((this_cpu_read(cmci_backoff_cnt) > 0) &&
186 (__this_cpu_read(cmci_storm_state) == CMCI_STORM_ACTIVE)) {
187 mce_notify_irq();
188 return CMCI_STORM_INTERVAL;
189 }
190
191 switch (__this_cpu_read(cmci_storm_state)) {
192 case CMCI_STORM_ACTIVE:
193
194 /*
195 * We switch back to interrupt mode once the poll timer has
196 * silenced itself. That means no events recorded and the timer
197 * interval is back to our poll interval.
198 */
199 __this_cpu_write(cmci_storm_state, CMCI_STORM_SUBSIDED);
200 if (!atomic_sub_return(i: 1, v: &cmci_storm_on_cpus))
201 pr_notice("CMCI storm subsided: switching to interrupt mode\n");
202
203 fallthrough;
204
205 case CMCI_STORM_SUBSIDED:
206 /*
207 * We wait for all CPUs to go back to SUBSIDED state. When that
208 * happens we switch back to interrupt mode.
209 */
210 if (!atomic_read(v: &cmci_storm_on_cpus)) {
211 __this_cpu_write(cmci_storm_state, CMCI_STORM_NONE);
212 cmci_toggle_interrupt_mode(on: true);
213 cmci_recheck();
214 }
215 return CMCI_POLL_INTERVAL;
216 default:
217
218 /* We have shiny weather. Let the poll do whatever it thinks. */
219 return interval;
220 }
221}
222
223static bool cmci_storm_detect(void)
224{
225 unsigned int cnt = __this_cpu_read(cmci_storm_cnt);
226 unsigned long ts = __this_cpu_read(cmci_time_stamp);
227 unsigned long now = jiffies;
228 int r;
229
230 if (__this_cpu_read(cmci_storm_state) != CMCI_STORM_NONE)
231 return true;
232
233 if (time_before_eq(now, ts + CMCI_STORM_INTERVAL)) {
234 cnt++;
235 } else {
236 cnt = 1;
237 __this_cpu_write(cmci_time_stamp, now);
238 }
239 __this_cpu_write(cmci_storm_cnt, cnt);
240
241 if (cnt <= CMCI_STORM_THRESHOLD)
242 return false;
243
244 cmci_toggle_interrupt_mode(on: false);
245 __this_cpu_write(cmci_storm_state, CMCI_STORM_ACTIVE);
246 r = atomic_add_return(i: 1, v: &cmci_storm_on_cpus);
247 mce_timer_kick(CMCI_STORM_INTERVAL);
248 this_cpu_write(cmci_backoff_cnt, INITIAL_CHECK_INTERVAL);
249
250 if (r == 1)
251 pr_notice("CMCI storm detected: switching to poll mode\n");
252 return true;
253}
254
255/*
256 * The interrupt handler. This is called on every event.
257 * Just call the poller directly to log any events.
258 * This could in theory increase the threshold under high load,
259 * but doesn't for now.
260 */
261static void intel_threshold_interrupt(void)
262{
263 if (cmci_storm_detect())
264 return;
265
266 machine_check_poll(flags: MCP_TIMESTAMP, this_cpu_ptr(&mce_banks_owned));
267}
268
269/*
270 * Enable CMCI (Corrected Machine Check Interrupt) for available MCE banks
271 * on this CPU. Use the algorithm recommended in the SDM to discover shared
272 * banks.
273 */
274static void cmci_discover(int banks)
275{
276 unsigned long *owned = (void *)this_cpu_ptr(&mce_banks_owned);
277 unsigned long flags;
278 int i;
279 int bios_wrong_thresh = 0;
280
281 raw_spin_lock_irqsave(&cmci_discover_lock, flags);
282 for (i = 0; i < banks; i++) {
283 u64 val;
284 int bios_zero_thresh = 0;
285
286 if (test_bit(i, owned))
287 continue;
288
289 /* Skip banks in firmware first mode */
290 if (test_bit(i, mce_banks_ce_disabled))
291 continue;
292
293 rdmsrl(MSR_IA32_MCx_CTL2(i), val);
294
295 /* Already owned by someone else? */
296 if (val & MCI_CTL2_CMCI_EN) {
297 clear_bit(nr: i, addr: owned);
298 __clear_bit(i, this_cpu_ptr(mce_poll_banks));
299 continue;
300 }
301
302 if (!mca_cfg.bios_cmci_threshold) {
303 val &= ~MCI_CTL2_CMCI_THRESHOLD_MASK;
304 val |= CMCI_THRESHOLD;
305 } else if (!(val & MCI_CTL2_CMCI_THRESHOLD_MASK)) {
306 /*
307 * If bios_cmci_threshold boot option was specified
308 * but the threshold is zero, we'll try to initialize
309 * it to 1.
310 */
311 bios_zero_thresh = 1;
312 val |= CMCI_THRESHOLD;
313 }
314
315 val |= MCI_CTL2_CMCI_EN;
316 wrmsrl(MSR_IA32_MCx_CTL2(i), val);
317 rdmsrl(MSR_IA32_MCx_CTL2(i), val);
318
319 /* Did the enable bit stick? -- the bank supports CMCI */
320 if (val & MCI_CTL2_CMCI_EN) {
321 set_bit(nr: i, addr: owned);
322 __clear_bit(i, this_cpu_ptr(mce_poll_banks));
323 /*
324 * We are able to set thresholds for some banks that
325 * had a threshold of 0. This means the BIOS has not
326 * set the thresholds properly or does not work with
327 * this boot option. Note down now and report later.
328 */
329 if (mca_cfg.bios_cmci_threshold && bios_zero_thresh &&
330 (val & MCI_CTL2_CMCI_THRESHOLD_MASK))
331 bios_wrong_thresh = 1;
332 } else {
333 WARN_ON(!test_bit(i, this_cpu_ptr(mce_poll_banks)));
334 }
335 }
336 raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
337 if (mca_cfg.bios_cmci_threshold && bios_wrong_thresh) {
338 pr_info_once(
339 "bios_cmci_threshold: Some banks do not have valid thresholds set\n");
340 pr_info_once(
341 "bios_cmci_threshold: Make sure your BIOS supports this boot option\n");
342 }
343}
344
345/*
346 * Just in case we missed an event during initialization check
347 * all the CMCI owned banks.
348 */
349void cmci_recheck(void)
350{
351 unsigned long flags;
352 int banks;
353
354 if (!mce_available(raw_cpu_ptr(&cpu_info)) || !cmci_supported(banks: &banks))
355 return;
356
357 local_irq_save(flags);
358 machine_check_poll(flags: 0, this_cpu_ptr(&mce_banks_owned));
359 local_irq_restore(flags);
360}
361
362/* Caller must hold the lock on cmci_discover_lock */
363static void __cmci_disable_bank(int bank)
364{
365 u64 val;
366
367 if (!test_bit(bank, this_cpu_ptr(mce_banks_owned)))
368 return;
369 rdmsrl(MSR_IA32_MCx_CTL2(bank), val);
370 val &= ~MCI_CTL2_CMCI_EN;
371 wrmsrl(MSR_IA32_MCx_CTL2(bank), val);
372 __clear_bit(bank, this_cpu_ptr(mce_banks_owned));
373}
374
375/*
376 * Disable CMCI on this CPU for all banks it owns when it goes down.
377 * This allows other CPUs to claim the banks on rediscovery.
378 */
379void cmci_clear(void)
380{
381 unsigned long flags;
382 int i;
383 int banks;
384
385 if (!cmci_supported(banks: &banks))
386 return;
387 raw_spin_lock_irqsave(&cmci_discover_lock, flags);
388 for (i = 0; i < banks; i++)
389 __cmci_disable_bank(bank: i);
390 raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
391}
392
393static void cmci_rediscover_work_func(void *arg)
394{
395 int banks;
396
397 /* Recheck banks in case CPUs don't all have the same */
398 if (cmci_supported(banks: &banks))
399 cmci_discover(banks);
400}
401
402/* After a CPU went down cycle through all the others and rediscover */
403void cmci_rediscover(void)
404{
405 int banks;
406
407 if (!cmci_supported(banks: &banks))
408 return;
409
410 on_each_cpu(func: cmci_rediscover_work_func, NULL, wait: 1);
411}
412
413/*
414 * Reenable CMCI on this CPU in case a CPU down failed.
415 */
416void cmci_reenable(void)
417{
418 int banks;
419 if (cmci_supported(banks: &banks))
420 cmci_discover(banks);
421}
422
423void cmci_disable_bank(int bank)
424{
425 int banks;
426 unsigned long flags;
427
428 if (!cmci_supported(banks: &banks))
429 return;
430
431 raw_spin_lock_irqsave(&cmci_discover_lock, flags);
432 __cmci_disable_bank(bank);
433 raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
434}
435
436/* Bank polling function when CMCI is disabled. */
437static void cmci_mc_poll_banks(void)
438{
439 spin_lock(lock: &cmci_poll_lock);
440 machine_check_poll(flags: 0, this_cpu_ptr(&mce_poll_banks));
441 spin_unlock(lock: &cmci_poll_lock);
442}
443
444void intel_init_cmci(void)
445{
446 int banks;
447
448 if (!cmci_supported(banks: &banks)) {
449 mc_poll_banks = cmci_mc_poll_banks;
450 return;
451 }
452
453 mce_threshold_vector = intel_threshold_interrupt;
454 cmci_discover(banks);
455 /*
456 * For CPU #0 this runs with still disabled APIC, but that's
457 * ok because only the vector is set up. We still do another
458 * check for the banks later for CPU #0 just to make sure
459 * to not miss any events.
460 */
461 apic_write(APIC_LVTCMCI, THRESHOLD_APIC_VECTOR|APIC_DM_FIXED);
462 cmci_recheck();
463}
464
465void intel_init_lmce(void)
466{
467 u64 val;
468
469 if (!lmce_supported())
470 return;
471
472 rdmsrl(MSR_IA32_MCG_EXT_CTL, val);
473
474 if (!(val & MCG_EXT_CTL_LMCE_EN))
475 wrmsrl(MSR_IA32_MCG_EXT_CTL, val: val | MCG_EXT_CTL_LMCE_EN);
476}
477
478void intel_clear_lmce(void)
479{
480 u64 val;
481
482 if (!lmce_supported())
483 return;
484
485 rdmsrl(MSR_IA32_MCG_EXT_CTL, val);
486 val &= ~MCG_EXT_CTL_LMCE_EN;
487 wrmsrl(MSR_IA32_MCG_EXT_CTL, val);
488}
489
490/*
491 * Enable additional error logs from the integrated
492 * memory controller on processors that support this.
493 */
494static void intel_imc_init(struct cpuinfo_x86 *c)
495{
496 u64 error_control;
497
498 switch (c->x86_model) {
499 case INTEL_FAM6_SANDYBRIDGE_X:
500 case INTEL_FAM6_IVYBRIDGE_X:
501 case INTEL_FAM6_HASWELL_X:
502 if (rdmsrl_safe(MSR_ERROR_CONTROL, p: &error_control))
503 return;
504 error_control |= 2;
505 wrmsrl_safe(MSR_ERROR_CONTROL, val: error_control);
506 break;
507 }
508}
509
510void mce_intel_feature_init(struct cpuinfo_x86 *c)
511{
512 intel_init_cmci();
513 intel_init_lmce();
514 intel_imc_init(c);
515}
516
517void mce_intel_feature_clear(struct cpuinfo_x86 *c)
518{
519 intel_clear_lmce();
520}
521
522bool intel_filter_mce(struct mce *m)
523{
524 struct cpuinfo_x86 *c = &boot_cpu_data;
525
526 /* MCE errata HSD131, HSM142, HSW131, BDM48, HSM142 and SKX37 */
527 if ((c->x86 == 6) &&
528 ((c->x86_model == INTEL_FAM6_HASWELL) ||
529 (c->x86_model == INTEL_FAM6_HASWELL_L) ||
530 (c->x86_model == INTEL_FAM6_BROADWELL) ||
531 (c->x86_model == INTEL_FAM6_HASWELL_G) ||
532 (c->x86_model == INTEL_FAM6_SKYLAKE_X)) &&
533 (m->bank == 0) &&
534 ((m->status & 0xa0000000ffffffff) == 0x80000000000f0005))
535 return true;
536
537 return false;
538}
539
540/*
541 * Check if the address reported by the CPU is in a format we can parse.
542 * It would be possible to add code for most other cases, but all would
543 * be somewhat complicated (e.g. segment offset would require an instruction
544 * parser). So only support physical addresses up to page granularity for now.
545 */
546bool intel_mce_usable_address(struct mce *m)
547{
548 if (!(m->status & MCI_STATUS_MISCV))
549 return false;
550
551 if (MCI_MISC_ADDR_LSB(m->misc) > PAGE_SHIFT)
552 return false;
553
554 if (MCI_MISC_ADDR_MODE(m->misc) != MCI_MISC_ADDR_PHYS)
555 return false;
556
557 return true;
558}
559

source code of linux/arch/x86/kernel/cpu/mce/intel.c