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Glauber Costa0941ecb2008-03-03 14:12:55 -03001/*
2 * Intel SMP support routines.
3 *
Alan Cox87c6fe22009-01-05 14:08:04 +00004 * (c) 1995 Alan Cox, Building #3 <alan@lxorguk.ukuu.org.uk>
Ingo Molnar8f47e162009-01-31 02:03:42 +01005 * (c) 1998-99, 2000, 2009 Ingo Molnar <mingo@redhat.com>
Glauber Costa0941ecb2008-03-03 14:12:55 -03006 * (c) 2002,2003 Andi Kleen, SuSE Labs.
7 *
8 * i386 and x86_64 integration by Glauber Costa <gcosta@redhat.com>
9 *
10 * This code is released under the GNU General Public License version 2 or
11 * later.
12 */
13
Glauber Costaf9e47a12008-03-03 14:12:52 -030014#include <linux/init.h>
15
16#include <linux/mm.h>
17#include <linux/delay.h>
18#include <linux/spinlock.h>
Paul Gortmaker69c60c82011-05-26 12:22:53 -040019#include <linux/export.h>
Glauber Costaf9e47a12008-03-03 14:12:52 -030020#include <linux/kernel_stat.h>
21#include <linux/mc146818rtc.h>
22#include <linux/cache.h>
23#include <linux/interrupt.h>
24#include <linux/cpu.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090025#include <linux/gfp.h>
Glauber Costaf9e47a12008-03-03 14:12:52 -030026
27#include <asm/mtrr.h>
28#include <asm/tlbflush.h>
29#include <asm/mmu_context.h>
30#include <asm/proto.h>
Ingo Molnar7b6aa332009-02-17 13:58:15 +010031#include <asm/apic.h>
Don Zickus3603a252011-10-13 15:14:25 -040032#include <asm/nmi.h>
Glauber Costa0941ecb2008-03-03 14:12:55 -030033/*
34 * Some notes on x86 processor bugs affecting SMP operation:
35 *
36 * Pentium, Pentium Pro, II, III (and all CPUs) have bugs.
37 * The Linux implications for SMP are handled as follows:
38 *
39 * Pentium III / [Xeon]
40 * None of the E1AP-E3AP errata are visible to the user.
41 *
42 * E1AP. see PII A1AP
43 * E2AP. see PII A2AP
44 * E3AP. see PII A3AP
45 *
46 * Pentium II / [Xeon]
47 * None of the A1AP-A3AP errata are visible to the user.
48 *
49 * A1AP. see PPro 1AP
50 * A2AP. see PPro 2AP
51 * A3AP. see PPro 7AP
52 *
53 * Pentium Pro
54 * None of 1AP-9AP errata are visible to the normal user,
55 * except occasional delivery of 'spurious interrupt' as trap #15.
56 * This is very rare and a non-problem.
57 *
58 * 1AP. Linux maps APIC as non-cacheable
59 * 2AP. worked around in hardware
60 * 3AP. fixed in C0 and above steppings microcode update.
61 * Linux does not use excessive STARTUP_IPIs.
62 * 4AP. worked around in hardware
63 * 5AP. symmetric IO mode (normal Linux operation) not affected.
64 * 'noapic' mode has vector 0xf filled out properly.
65 * 6AP. 'noapic' mode might be affected - fixed in later steppings
66 * 7AP. We do not assume writes to the LVT deassering IRQs
67 * 8AP. We do not enable low power mode (deep sleep) during MP bootup
68 * 9AP. We do not use mixed mode
69 *
70 * Pentium
71 * There is a marginal case where REP MOVS on 100MHz SMP
72 * machines with B stepping processors can fail. XXX should provide
73 * an L1cache=Writethrough or L1cache=off option.
74 *
75 * B stepping CPUs may hang. There are hardware work arounds
76 * for this. We warn about it in case your board doesn't have the work
77 * arounds. Basically that's so I can tell anyone with a B stepping
78 * CPU and SMP problems "tough".
79 *
80 * Specific items [From Pentium Processor Specification Update]
81 *
82 * 1AP. Linux doesn't use remote read
83 * 2AP. Linux doesn't trust APIC errors
84 * 3AP. We work around this
85 * 4AP. Linux never generated 3 interrupts of the same priority
86 * to cause a lost local interrupt.
87 * 5AP. Remote read is never used
88 * 6AP. not affected - worked around in hardware
89 * 7AP. not affected - worked around in hardware
90 * 8AP. worked around in hardware - we get explicit CS errors if not
91 * 9AP. only 'noapic' mode affected. Might generate spurious
92 * interrupts, we log only the first one and count the
93 * rest silently.
94 * 10AP. not affected - worked around in hardware
95 * 11AP. Linux reads the APIC between writes to avoid this, as per
96 * the documentation. Make sure you preserve this as it affects
97 * the C stepping chips too.
98 * 12AP. not affected - worked around in hardware
99 * 13AP. not affected - worked around in hardware
100 * 14AP. we always deassert INIT during bootup
101 * 15AP. not affected - worked around in hardware
102 * 16AP. not affected - worked around in hardware
103 * 17AP. not affected - worked around in hardware
104 * 18AP. not affected - worked around in hardware
105 * 19AP. not affected - worked around in BIOS
106 *
107 * If this sounds worrying believe me these bugs are either ___RARE___,
108 * or are signal timing bugs worked around in hardware and there's
109 * about nothing of note with C stepping upwards.
110 */
Glauber Costaf9e47a12008-03-03 14:12:52 -0300111
112/*
113 * this function sends a 'reschedule' IPI to another CPU.
114 * it goes straight through and wastes no time serializing
115 * anything. Worst case is that we lose a reschedule ...
116 */
117static void native_smp_send_reschedule(int cpu)
118{
Gautham R Shenoyf6940102008-03-10 17:44:03 +0530119 if (unlikely(cpu_is_offline(cpu))) {
120 WARN_ON(1);
121 return;
122 }
Ingo Molnardac5f412009-01-28 15:42:24 +0100123 apic->send_IPI_mask(cpumask_of(cpu), RESCHEDULE_VECTOR);
Glauber Costaf9e47a12008-03-03 14:12:52 -0300124}
125
Jens Axboe3b16cf82008-06-26 11:21:54 +0200126void native_send_call_func_single_ipi(int cpu)
Glauber Costaf9e47a12008-03-03 14:12:52 -0300127{
Ingo Molnardac5f412009-01-28 15:42:24 +0100128 apic->send_IPI_mask(cpumask_of(cpu), CALL_FUNCTION_SINGLE_VECTOR);
Glauber Costaf9e47a12008-03-03 14:12:52 -0300129}
130
Mike Travisbcda0162008-12-16 17:33:59 -0800131void native_send_call_func_ipi(const struct cpumask *mask)
Glauber Costaf9e47a12008-03-03 14:12:52 -0300132{
Mike Travisc2d1cec2009-01-04 05:18:03 -0800133 cpumask_var_t allbutself;
Glauber Costaf9e47a12008-03-03 14:12:52 -0300134
Mike Travisc2d1cec2009-01-04 05:18:03 -0800135 if (!alloc_cpumask_var(&allbutself, GFP_ATOMIC)) {
Ingo Molnardac5f412009-01-28 15:42:24 +0100136 apic->send_IPI_mask(mask, CALL_FUNCTION_VECTOR);
Mike Travisc2d1cec2009-01-04 05:18:03 -0800137 return;
138 }
Glauber Costaf9e47a12008-03-03 14:12:52 -0300139
Mike Travisc2d1cec2009-01-04 05:18:03 -0800140 cpumask_copy(allbutself, cpu_online_mask);
141 cpumask_clear_cpu(smp_processor_id(), allbutself);
142
143 if (cpumask_equal(mask, allbutself) &&
144 cpumask_equal(cpu_online_mask, cpu_callout_mask))
Ingo Molnardac5f412009-01-28 15:42:24 +0100145 apic->send_IPI_allbutself(CALL_FUNCTION_VECTOR);
Glauber Costaf9e47a12008-03-03 14:12:52 -0300146 else
Ingo Molnardac5f412009-01-28 15:42:24 +0100147 apic->send_IPI_mask(mask, CALL_FUNCTION_VECTOR);
Mike Travisc2d1cec2009-01-04 05:18:03 -0800148
149 free_cpumask_var(allbutself);
Glauber Costaf9e47a12008-03-03 14:12:52 -0300150}
151
Don Zickus3603a252011-10-13 15:14:25 -0400152static atomic_t stopping_cpu = ATOMIC_INIT(-1);
153
154static int smp_stop_nmi_callback(unsigned int val, struct pt_regs *regs)
155{
156 /* We are registered on stopping cpu too, avoid spurious NMI */
157 if (raw_smp_processor_id() == atomic_read(&stopping_cpu))
158 return NMI_HANDLED;
159
160 stop_this_cpu(NULL);
161
162 return NMI_HANDLED;
163}
164
165static void native_nmi_stop_other_cpus(int wait)
166{
167 unsigned long flags;
168 unsigned long timeout;
169
170 if (reboot_force)
171 return;
172
173 /*
174 * Use an own vector here because smp_call_function
175 * does lots of things not suitable in a panic situation.
176 */
177 if (num_online_cpus() > 1) {
178 /* did someone beat us here? */
Don Zickuse58d4292012-01-06 11:17:51 -0500179 if (atomic_cmpxchg(&stopping_cpu, -1, safe_smp_processor_id()) != -1)
Don Zickus3603a252011-10-13 15:14:25 -0400180 return;
181
182 if (register_nmi_handler(NMI_LOCAL, smp_stop_nmi_callback,
183 NMI_FLAG_FIRST, "smp_stop"))
184 /* Note: we ignore failures here */
185 return;
186
187 /* sync above data before sending NMI */
188 wmb();
189
190 apic->send_IPI_allbutself(NMI_VECTOR);
191
192 /*
193 * Don't wait longer than a second if the caller
194 * didn't ask us to wait.
195 */
196 timeout = USEC_PER_SEC;
197 while (num_online_cpus() > 1 && (wait || timeout--))
198 udelay(1);
199 }
200
201 local_irq_save(flags);
202 disable_local_APIC();
203 local_irq_restore(flags);
204}
205
Glauber Costaf9e47a12008-03-03 14:12:52 -0300206/*
207 * this function calls the 'stop' function on all other CPUs in the system.
208 */
209
Andi Kleen4ef702c2009-05-27 21:56:52 +0200210asmlinkage void smp_reboot_interrupt(void)
211{
212 ack_APIC_irq();
213 irq_enter();
214 stop_this_cpu(NULL);
215 irq_exit();
216}
217
Don Zickus3603a252011-10-13 15:14:25 -0400218static void native_irq_stop_other_cpus(int wait)
Glauber Costaf9e47a12008-03-03 14:12:52 -0300219{
Glauber Costaf9e47a12008-03-03 14:12:52 -0300220 unsigned long flags;
Alok Kataria76fac072010-10-11 14:37:08 -0700221 unsigned long timeout;
Glauber Costaf9e47a12008-03-03 14:12:52 -0300222
223 if (reboot_force)
224 return;
225
Andi Kleen4ef702c2009-05-27 21:56:52 +0200226 /*
227 * Use an own vector here because smp_call_function
228 * does lots of things not suitable in a panic situation.
229 * On most systems we could also use an NMI here,
230 * but there are a few systems around where NMI
231 * is problematic so stay with an non NMI for now
232 * (this implies we cannot stop CPUs spinning with irq off
233 * currently)
234 */
235 if (num_online_cpus() > 1) {
236 apic->send_IPI_allbutself(REBOOT_VECTOR);
237
Alok Kataria76fac072010-10-11 14:37:08 -0700238 /*
239 * Don't wait longer than a second if the caller
240 * didn't ask us to wait.
241 */
242 timeout = USEC_PER_SEC;
243 while (num_online_cpus() > 1 && (wait || timeout--))
Andi Kleen4ef702c2009-05-27 21:56:52 +0200244 udelay(1);
245 }
246
Glauber Costaf9e47a12008-03-03 14:12:52 -0300247 local_irq_save(flags);
Glauber Costaf9e47a12008-03-03 14:12:52 -0300248 disable_local_APIC();
249 local_irq_restore(flags);
250}
251
Don Zickusbda62632011-10-13 15:14:27 -0400252static void native_smp_disable_nmi_ipi(void)
253{
254 smp_ops.stop_other_cpus = native_irq_stop_other_cpus;
255}
256
Glauber Costaf9e47a12008-03-03 14:12:52 -0300257/*
Peter Zijlstra184748c2011-04-05 17:23:39 +0200258 * Reschedule call back.
Glauber Costaf9e47a12008-03-03 14:12:52 -0300259 */
260void smp_reschedule_interrupt(struct pt_regs *regs)
261{
262 ack_APIC_irq();
Hiroshi Shimamoto915b0d02008-12-08 19:19:26 -0800263 inc_irq_stat(irq_resched_count);
Peter Zijlstra184748c2011-04-05 17:23:39 +0200264 scheduler_ipi();
Marcelo Tosatti32f88402009-05-07 17:55:12 -0300265 /*
266 * KVM uses this interrupt to force a cpu out of guest mode
267 */
Glauber Costaf9e47a12008-03-03 14:12:52 -0300268}
269
270void smp_call_function_interrupt(struct pt_regs *regs)
271{
Glauber Costaf9e47a12008-03-03 14:12:52 -0300272 ack_APIC_irq();
Glauber Costaf9e47a12008-03-03 14:12:52 -0300273 irq_enter();
Jens Axboe3b16cf82008-06-26 11:21:54 +0200274 generic_smp_call_function_interrupt();
Hiroshi Shimamoto915b0d02008-12-08 19:19:26 -0800275 inc_irq_stat(irq_call_count);
Glauber Costaf9e47a12008-03-03 14:12:52 -0300276 irq_exit();
Jens Axboe3b16cf82008-06-26 11:21:54 +0200277}
Glauber Costaf9e47a12008-03-03 14:12:52 -0300278
Jens Axboe5e374fb2008-07-01 13:12:04 +0200279void smp_call_function_single_interrupt(struct pt_regs *regs)
Jens Axboe3b16cf82008-06-26 11:21:54 +0200280{
281 ack_APIC_irq();
282 irq_enter();
283 generic_smp_call_function_single_interrupt();
Hiroshi Shimamoto915b0d02008-12-08 19:19:26 -0800284 inc_irq_stat(irq_call_count);
Jens Axboe3b16cf82008-06-26 11:21:54 +0200285 irq_exit();
Glauber Costaf9e47a12008-03-03 14:12:52 -0300286}
287
Don Zickusbda62632011-10-13 15:14:27 -0400288static int __init nonmi_ipi_setup(char *str)
289{
290 native_smp_disable_nmi_ipi();
291 return 1;
292}
293
294__setup("nonmi_ipi", nonmi_ipi_setup);
295
Glauber Costaf9e47a12008-03-03 14:12:52 -0300296struct smp_ops smp_ops = {
Cyrill Gorcunovb9b34f22009-04-12 20:47:42 +0400297 .smp_prepare_boot_cpu = native_smp_prepare_boot_cpu,
298 .smp_prepare_cpus = native_smp_prepare_cpus,
299 .smp_cpus_done = native_smp_cpus_done,
Glauber Costaf9e47a12008-03-03 14:12:52 -0300300
Don Zickus3603a252011-10-13 15:14:25 -0400301 .stop_other_cpus = native_nmi_stop_other_cpus,
Cyrill Gorcunovb9b34f22009-04-12 20:47:42 +0400302 .smp_send_reschedule = native_smp_send_reschedule,
Jens Axboe3b16cf82008-06-26 11:21:54 +0200303
Cyrill Gorcunovb9b34f22009-04-12 20:47:42 +0400304 .cpu_up = native_cpu_up,
305 .cpu_die = native_cpu_die,
306 .cpu_disable = native_cpu_disable,
307 .play_dead = native_play_dead,
Alex Nixon93be71b2008-08-22 11:52:11 +0100308
Cyrill Gorcunovb9b34f22009-04-12 20:47:42 +0400309 .send_call_func_ipi = native_send_call_func_ipi,
Jens Axboe3b16cf82008-06-26 11:21:54 +0200310 .send_call_func_single_ipi = native_send_call_func_single_ipi,
Glauber Costaf9e47a12008-03-03 14:12:52 -0300311};
312EXPORT_SYMBOL_GPL(smp_ops);