2 * Intel specific MCE features.
3 * Copyright 2004 Zwane Mwaikambo <zwane@linuxpower.ca>
4 * Copyright (C) 2008, 2009 Intel Corporation
9 #include <linux/interrupt.h>
10 #include <linux/percpu.h>
11 #include <linux/sched.h>
12 #include <linux/cpumask.h>
14 #include <asm/processor.h>
18 #include "mce-internal.h"
21 * Support for Intel Correct Machine Check Interrupts. This allows
22 * the CPU to raise an interrupt when a corrected machine check happened.
23 * Normally we pick those up using a regular polling timer.
24 * Also supports reliable discovery of shared banks.
28 * CMCI can be delivered to multiple cpus that share a machine check bank
29 * so we need to designate a single cpu to process errors logged in each bank
30 * in the interrupt handler (otherwise we would have many races and potential
31 * double reporting of the same error).
32 * Note that this can change when a cpu is offlined or brought online since
33 * some MCA banks are shared across cpus. When a cpu is offlined, cmci_clear()
34 * disables CMCI on all banks owned by the cpu and clears this bitfield. At
35 * this point, cmci_rediscover() kicks in and a different cpu may end up
36 * taking ownership of some of the shared MCA banks that were previously
37 * owned by the offlined cpu.
39 static DEFINE_PER_CPU(mce_banks_t, mce_banks_owned);
42 * CMCI storm detection backoff counter
44 * During storm, we reset this counter to INITIAL_CHECK_INTERVAL in case we've
45 * encountered an error. If not, we decrement it by one. We signal the end of
46 * the CMCI storm when it reaches 0.
48 static DEFINE_PER_CPU(int, cmci_backoff_cnt);
51 * cmci_discover_lock protects against parallel discovery attempts
52 * which could race against each other.
54 static DEFINE_RAW_SPINLOCK(cmci_discover_lock);
56 #define CMCI_THRESHOLD 1
57 #define CMCI_POLL_INTERVAL (30 * HZ)
58 #define CMCI_STORM_INTERVAL (HZ)
59 #define CMCI_STORM_THRESHOLD 15
61 static DEFINE_PER_CPU(unsigned long, cmci_time_stamp);
62 static DEFINE_PER_CPU(unsigned int, cmci_storm_cnt);
63 static DEFINE_PER_CPU(unsigned int, cmci_storm_state);
71 static atomic_t cmci_storm_on_cpus;
73 static int cmci_supported(int *banks)
77 if (mca_cfg.cmci_disabled || mca_cfg.ignore_ce)
81 * Vendor check is not strictly needed, but the initial
82 * initialization is vendor keyed and this
83 * makes sure none of the backdoors are entered otherwise.
85 if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
87 if (!cpu_has_apic || lapic_get_maxlvt() < 6)
89 rdmsrl(MSR_IA32_MCG_CAP, cap);
90 *banks = min_t(unsigned, MAX_NR_BANKS, cap & 0xff);
91 return !!(cap & MCG_CMCI_P);
94 bool mce_intel_cmci_poll(void)
96 if (__this_cpu_read(cmci_storm_state) == CMCI_STORM_NONE)
100 * Reset the counter if we've logged an error in the last poll
103 if (machine_check_poll(MCP_TIMESTAMP, this_cpu_ptr(&mce_banks_owned)))
104 this_cpu_write(cmci_backoff_cnt, INITIAL_CHECK_INTERVAL);
106 this_cpu_dec(cmci_backoff_cnt);
111 void mce_intel_hcpu_update(unsigned long cpu)
113 if (per_cpu(cmci_storm_state, cpu) == CMCI_STORM_ACTIVE)
114 atomic_dec(&cmci_storm_on_cpus);
116 per_cpu(cmci_storm_state, cpu) = CMCI_STORM_NONE;
119 unsigned long cmci_intel_adjust_timer(unsigned long interval)
121 if ((this_cpu_read(cmci_backoff_cnt) > 0) &&
122 (__this_cpu_read(cmci_storm_state) == CMCI_STORM_ACTIVE)) {
124 return CMCI_STORM_INTERVAL;
127 switch (__this_cpu_read(cmci_storm_state)) {
128 case CMCI_STORM_ACTIVE:
131 * We switch back to interrupt mode once the poll timer has
132 * silenced itself. That means no events recorded and the timer
133 * interval is back to our poll interval.
135 __this_cpu_write(cmci_storm_state, CMCI_STORM_SUBSIDED);
136 if (!atomic_sub_return(1, &cmci_storm_on_cpus))
137 pr_notice("CMCI storm subsided: switching to interrupt mode\n");
141 case CMCI_STORM_SUBSIDED:
143 * We wait for all CPUs to go back to SUBSIDED state. When that
144 * happens we switch back to interrupt mode.
146 if (!atomic_read(&cmci_storm_on_cpus)) {
147 __this_cpu_write(cmci_storm_state, CMCI_STORM_NONE);
151 return CMCI_POLL_INTERVAL;
154 /* We have shiny weather. Let the poll do whatever it thinks. */
159 static void cmci_storm_disable_banks(void)
161 unsigned long flags, *owned;
165 raw_spin_lock_irqsave(&cmci_discover_lock, flags);
166 owned = this_cpu_ptr(mce_banks_owned);
167 for_each_set_bit(bank, owned, MAX_NR_BANKS) {
168 rdmsrl(MSR_IA32_MCx_CTL2(bank), val);
169 val &= ~MCI_CTL2_CMCI_EN;
170 wrmsrl(MSR_IA32_MCx_CTL2(bank), val);
172 raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
175 static bool cmci_storm_detect(void)
177 unsigned int cnt = __this_cpu_read(cmci_storm_cnt);
178 unsigned long ts = __this_cpu_read(cmci_time_stamp);
179 unsigned long now = jiffies;
182 if (__this_cpu_read(cmci_storm_state) != CMCI_STORM_NONE)
185 if (time_before_eq(now, ts + CMCI_STORM_INTERVAL)) {
189 __this_cpu_write(cmci_time_stamp, now);
191 __this_cpu_write(cmci_storm_cnt, cnt);
193 if (cnt <= CMCI_STORM_THRESHOLD)
196 cmci_storm_disable_banks();
197 __this_cpu_write(cmci_storm_state, CMCI_STORM_ACTIVE);
198 r = atomic_add_return(1, &cmci_storm_on_cpus);
199 mce_timer_kick(CMCI_STORM_INTERVAL);
200 this_cpu_write(cmci_backoff_cnt, INITIAL_CHECK_INTERVAL);
203 pr_notice("CMCI storm detected: switching to poll mode\n");
208 * The interrupt handler. This is called on every event.
209 * Just call the poller directly to log any events.
210 * This could in theory increase the threshold under high load,
211 * but doesn't for now.
213 static void intel_threshold_interrupt(void)
215 if (cmci_storm_detect())
218 machine_check_poll(MCP_TIMESTAMP, this_cpu_ptr(&mce_banks_owned));
223 * Enable CMCI (Corrected Machine Check Interrupt) for available MCE banks
224 * on this CPU. Use the algorithm recommended in the SDM to discover shared
227 static void cmci_discover(int banks)
229 unsigned long *owned = (void *)this_cpu_ptr(&mce_banks_owned);
232 int bios_wrong_thresh = 0;
234 raw_spin_lock_irqsave(&cmci_discover_lock, flags);
235 for (i = 0; i < banks; i++) {
237 int bios_zero_thresh = 0;
239 if (test_bit(i, owned))
242 /* Skip banks in firmware first mode */
243 if (test_bit(i, mce_banks_ce_disabled))
246 rdmsrl(MSR_IA32_MCx_CTL2(i), val);
248 /* Already owned by someone else? */
249 if (val & MCI_CTL2_CMCI_EN) {
251 __clear_bit(i, this_cpu_ptr(mce_poll_banks));
255 if (!mca_cfg.bios_cmci_threshold) {
256 val &= ~MCI_CTL2_CMCI_THRESHOLD_MASK;
257 val |= CMCI_THRESHOLD;
258 } else if (!(val & MCI_CTL2_CMCI_THRESHOLD_MASK)) {
260 * If bios_cmci_threshold boot option was specified
261 * but the threshold is zero, we'll try to initialize
264 bios_zero_thresh = 1;
265 val |= CMCI_THRESHOLD;
268 val |= MCI_CTL2_CMCI_EN;
269 wrmsrl(MSR_IA32_MCx_CTL2(i), val);
270 rdmsrl(MSR_IA32_MCx_CTL2(i), val);
272 /* Did the enable bit stick? -- the bank supports CMCI */
273 if (val & MCI_CTL2_CMCI_EN) {
275 __clear_bit(i, this_cpu_ptr(mce_poll_banks));
277 * We are able to set thresholds for some banks that
278 * had a threshold of 0. This means the BIOS has not
279 * set the thresholds properly or does not work with
280 * this boot option. Note down now and report later.
282 if (mca_cfg.bios_cmci_threshold && bios_zero_thresh &&
283 (val & MCI_CTL2_CMCI_THRESHOLD_MASK))
284 bios_wrong_thresh = 1;
286 WARN_ON(!test_bit(i, this_cpu_ptr(mce_poll_banks)));
289 raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
290 if (mca_cfg.bios_cmci_threshold && bios_wrong_thresh) {
292 "bios_cmci_threshold: Some banks do not have valid thresholds set\n");
294 "bios_cmci_threshold: Make sure your BIOS supports this boot option\n");
299 * Just in case we missed an event during initialization check
300 * all the CMCI owned banks.
302 void cmci_recheck(void)
307 if (!mce_available(raw_cpu_ptr(&cpu_info)) || !cmci_supported(&banks))
310 local_irq_save(flags);
311 machine_check_poll(MCP_TIMESTAMP, this_cpu_ptr(&mce_banks_owned));
312 local_irq_restore(flags);
315 /* Caller must hold the lock on cmci_discover_lock */
316 static void __cmci_disable_bank(int bank)
320 if (!test_bit(bank, this_cpu_ptr(mce_banks_owned)))
322 rdmsrl(MSR_IA32_MCx_CTL2(bank), val);
323 val &= ~MCI_CTL2_CMCI_EN;
324 wrmsrl(MSR_IA32_MCx_CTL2(bank), val);
325 __clear_bit(bank, this_cpu_ptr(mce_banks_owned));
329 * Disable CMCI on this CPU for all banks it owns when it goes down.
330 * This allows other CPUs to claim the banks on rediscovery.
332 void cmci_clear(void)
338 if (!cmci_supported(&banks))
340 raw_spin_lock_irqsave(&cmci_discover_lock, flags);
341 for (i = 0; i < banks; i++)
342 __cmci_disable_bank(i);
343 raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
346 static void cmci_rediscover_work_func(void *arg)
350 /* Recheck banks in case CPUs don't all have the same */
351 if (cmci_supported(&banks))
352 cmci_discover(banks);
355 /* After a CPU went down cycle through all the others and rediscover */
356 void cmci_rediscover(void)
360 if (!cmci_supported(&banks))
363 on_each_cpu(cmci_rediscover_work_func, NULL, 1);
367 * Reenable CMCI on this CPU in case a CPU down failed.
369 void cmci_reenable(void)
372 if (cmci_supported(&banks))
373 cmci_discover(banks);
376 void cmci_disable_bank(int bank)
381 if (!cmci_supported(&banks))
384 raw_spin_lock_irqsave(&cmci_discover_lock, flags);
385 __cmci_disable_bank(bank);
386 raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
389 static void intel_init_cmci(void)
393 if (!cmci_supported(&banks))
396 mce_threshold_vector = intel_threshold_interrupt;
397 cmci_discover(banks);
399 * For CPU #0 this runs with still disabled APIC, but that's
400 * ok because only the vector is set up. We still do another
401 * check for the banks later for CPU #0 just to make sure
402 * to not miss any events.
404 apic_write(APIC_LVTCMCI, THRESHOLD_APIC_VECTOR|APIC_DM_FIXED);
408 void mce_intel_feature_init(struct cpuinfo_x86 *c)
410 intel_init_thermal(c);