2 * Intel specific MCE features.
3 * Copyright 2004 Zwane Mwaikambo <zwane@linuxpower.ca>
4 * Copyright (C) 2008, 2009 Intel Corporation
9 #include <linux/init.h>
10 #include <linux/interrupt.h>
11 #include <linux/percpu.h>
12 #include <linux/sched.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_discover_lock protects against parallel discovery attempts
43 * which could race against each other.
45 static DEFINE_RAW_SPINLOCK(cmci_discover_lock);
47 #define CMCI_THRESHOLD 1
48 #define CMCI_POLL_INTERVAL (30 * HZ)
49 #define CMCI_STORM_INTERVAL (1 * HZ)
50 #define CMCI_STORM_THRESHOLD 15
52 static DEFINE_PER_CPU(unsigned long, cmci_time_stamp);
53 static DEFINE_PER_CPU(unsigned int, cmci_storm_cnt);
54 static DEFINE_PER_CPU(unsigned int, cmci_storm_state);
62 static atomic_t cmci_storm_on_cpus;
64 static int cmci_supported(int *banks)
68 if (mca_cfg.cmci_disabled || mca_cfg.ignore_ce)
72 * Vendor check is not strictly needed, but the initial
73 * initialization is vendor keyed and this
74 * makes sure none of the backdoors are entered otherwise.
76 if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
78 if (!cpu_has_apic || lapic_get_maxlvt() < 6)
80 rdmsrl(MSR_IA32_MCG_CAP, cap);
81 *banks = min_t(unsigned, MAX_NR_BANKS, cap & 0xff);
82 return !!(cap & MCG_CMCI_P);
85 void mce_intel_cmci_poll(void)
87 if (__this_cpu_read(cmci_storm_state) == CMCI_STORM_NONE)
89 machine_check_poll(MCP_TIMESTAMP, &__get_cpu_var(mce_banks_owned));
92 void mce_intel_hcpu_update(unsigned long cpu)
94 if (per_cpu(cmci_storm_state, cpu) == CMCI_STORM_ACTIVE)
95 atomic_dec(&cmci_storm_on_cpus);
97 per_cpu(cmci_storm_state, cpu) = CMCI_STORM_NONE;
100 unsigned long mce_intel_adjust_timer(unsigned long interval)
104 if (interval < CMCI_POLL_INTERVAL)
107 switch (__this_cpu_read(cmci_storm_state)) {
108 case CMCI_STORM_ACTIVE:
110 * We switch back to interrupt mode once the poll timer has
111 * silenced itself. That means no events recorded and the
112 * timer interval is back to our poll interval.
114 __this_cpu_write(cmci_storm_state, CMCI_STORM_SUBSIDED);
115 r = atomic_sub_return(1, &cmci_storm_on_cpus);
117 pr_notice("CMCI storm subsided: switching to interrupt mode\n");
120 case CMCI_STORM_SUBSIDED:
122 * We wait for all cpus to go back to SUBSIDED
123 * state. When that happens we switch back to
126 if (!atomic_read(&cmci_storm_on_cpus)) {
127 __this_cpu_write(cmci_storm_state, CMCI_STORM_NONE);
131 return CMCI_POLL_INTERVAL;
134 * We have shiny weather. Let the poll do whatever it
141 static bool cmci_storm_detect(void)
143 unsigned int cnt = __this_cpu_read(cmci_storm_cnt);
144 unsigned long ts = __this_cpu_read(cmci_time_stamp);
145 unsigned long now = jiffies;
148 if (__this_cpu_read(cmci_storm_state) != CMCI_STORM_NONE)
151 if (time_before_eq(now, ts + CMCI_STORM_INTERVAL)) {
155 __this_cpu_write(cmci_time_stamp, now);
157 __this_cpu_write(cmci_storm_cnt, cnt);
159 if (cnt <= CMCI_STORM_THRESHOLD)
163 __this_cpu_write(cmci_storm_state, CMCI_STORM_ACTIVE);
164 r = atomic_add_return(1, &cmci_storm_on_cpus);
165 mce_timer_kick(CMCI_POLL_INTERVAL);
168 pr_notice("CMCI storm detected: switching to poll mode\n");
173 * The interrupt handler. This is called on every event.
174 * Just call the poller directly to log any events.
175 * This could in theory increase the threshold under high load,
176 * but doesn't for now.
178 static void intel_threshold_interrupt(void)
180 if (cmci_storm_detect())
182 machine_check_poll(MCP_TIMESTAMP, &__get_cpu_var(mce_banks_owned));
187 * Enable CMCI (Corrected Machine Check Interrupt) for available MCE banks
188 * on this CPU. Use the algorithm recommended in the SDM to discover shared
191 static void cmci_discover(int banks)
193 unsigned long *owned = (void *)&__get_cpu_var(mce_banks_owned);
196 int bios_wrong_thresh = 0;
198 raw_spin_lock_irqsave(&cmci_discover_lock, flags);
199 for (i = 0; i < banks; i++) {
201 int bios_zero_thresh = 0;
203 if (test_bit(i, owned))
206 rdmsrl(MSR_IA32_MCx_CTL2(i), val);
208 /* Already owned by someone else? */
209 if (val & MCI_CTL2_CMCI_EN) {
211 __clear_bit(i, __get_cpu_var(mce_poll_banks));
215 if (!mca_cfg.bios_cmci_threshold) {
216 val &= ~MCI_CTL2_CMCI_THRESHOLD_MASK;
217 val |= CMCI_THRESHOLD;
218 } else if (!(val & MCI_CTL2_CMCI_THRESHOLD_MASK)) {
220 * If bios_cmci_threshold boot option was specified
221 * but the threshold is zero, we'll try to initialize
224 bios_zero_thresh = 1;
225 val |= CMCI_THRESHOLD;
228 val |= MCI_CTL2_CMCI_EN;
229 wrmsrl(MSR_IA32_MCx_CTL2(i), val);
230 rdmsrl(MSR_IA32_MCx_CTL2(i), val);
232 /* Did the enable bit stick? -- the bank supports CMCI */
233 if (val & MCI_CTL2_CMCI_EN) {
235 __clear_bit(i, __get_cpu_var(mce_poll_banks));
237 * We are able to set thresholds for some banks that
238 * had a threshold of 0. This means the BIOS has not
239 * set the thresholds properly or does not work with
240 * this boot option. Note down now and report later.
242 if (mca_cfg.bios_cmci_threshold && bios_zero_thresh &&
243 (val & MCI_CTL2_CMCI_THRESHOLD_MASK))
244 bios_wrong_thresh = 1;
246 WARN_ON(!test_bit(i, __get_cpu_var(mce_poll_banks)));
249 raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
250 if (mca_cfg.bios_cmci_threshold && bios_wrong_thresh) {
252 "bios_cmci_threshold: Some banks do not have valid thresholds set\n");
254 "bios_cmci_threshold: Make sure your BIOS supports this boot option\n");
259 * Just in case we missed an event during initialization check
260 * all the CMCI owned banks.
262 void cmci_recheck(void)
267 if (!mce_available(__this_cpu_ptr(&cpu_info)) || !cmci_supported(&banks))
269 local_irq_save(flags);
270 machine_check_poll(MCP_TIMESTAMP, &__get_cpu_var(mce_banks_owned));
271 local_irq_restore(flags);
275 * Disable CMCI on this CPU for all banks it owns when it goes down.
276 * This allows other CPUs to claim the banks on rediscovery.
278 void cmci_clear(void)
285 if (!cmci_supported(&banks))
287 raw_spin_lock_irqsave(&cmci_discover_lock, flags);
288 for (i = 0; i < banks; i++) {
289 if (!test_bit(i, __get_cpu_var(mce_banks_owned)))
292 rdmsrl(MSR_IA32_MCx_CTL2(i), val);
293 val &= ~MCI_CTL2_CMCI_EN;
294 wrmsrl(MSR_IA32_MCx_CTL2(i), val);
295 __clear_bit(i, __get_cpu_var(mce_banks_owned));
297 raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
300 static void cmci_rediscover_work_func(void *arg)
304 /* Recheck banks in case CPUs don't all have the same */
305 if (cmci_supported(&banks))
306 cmci_discover(banks);
309 /* After a CPU went down cycle through all the others and rediscover */
310 void cmci_rediscover(void)
314 if (!cmci_supported(&banks))
317 on_each_cpu(cmci_rediscover_work_func, NULL, 1);
321 * Reenable CMCI on this CPU in case a CPU down failed.
323 void cmci_reenable(void)
326 if (cmci_supported(&banks))
327 cmci_discover(banks);
330 static void intel_init_cmci(void)
334 if (!cmci_supported(&banks))
337 mce_threshold_vector = intel_threshold_interrupt;
338 cmci_discover(banks);
340 * For CPU #0 this runs with still disabled APIC, but that's
341 * ok because only the vector is set up. We still do another
342 * check for the banks later for CPU #0 just to make sure
343 * to not miss any events.
345 apic_write(APIC_LVTCMCI, THRESHOLD_APIC_VECTOR|APIC_DM_FIXED);
349 void mce_intel_feature_init(struct cpuinfo_x86 *c)
351 intel_init_thermal(c);