1 /* 2 * Intel SMP support routines. 3 * 4 * (c) 1995 Alan Cox, Building #3 <alan@lxorguk.ukuu.org.uk> 5 * (c) 1998-99, 2000, 2009 Ingo Molnar <mingo@redhat.com> 6 * (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 14 #include <linux/init.h> 15 16 #include <linux/mm.h> 17 #include <linux/delay.h> 18 #include <linux/spinlock.h> 19 #include <linux/export.h> 20 #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> 25 #include <linux/gfp.h> 26 27 #include <asm/mtrr.h> 28 #include <asm/tlbflush.h> 29 #include <asm/mmu_context.h> 30 #include <asm/proto.h> 31 #include <asm/apic.h> 32 #include <asm/nmi.h> 33 #include <asm/mce.h> 34 #include <asm/trace/irq_vectors.h> 35 /* 36 * Some notes on x86 processor bugs affecting SMP operation: 37 * 38 * Pentium, Pentium Pro, II, III (and all CPUs) have bugs. 39 * The Linux implications for SMP are handled as follows: 40 * 41 * Pentium III / [Xeon] 42 * None of the E1AP-E3AP errata are visible to the user. 43 * 44 * E1AP. see PII A1AP 45 * E2AP. see PII A2AP 46 * E3AP. see PII A3AP 47 * 48 * Pentium II / [Xeon] 49 * None of the A1AP-A3AP errata are visible to the user. 50 * 51 * A1AP. see PPro 1AP 52 * A2AP. see PPro 2AP 53 * A3AP. see PPro 7AP 54 * 55 * Pentium Pro 56 * None of 1AP-9AP errata are visible to the normal user, 57 * except occasional delivery of 'spurious interrupt' as trap #15. 58 * This is very rare and a non-problem. 59 * 60 * 1AP. Linux maps APIC as non-cacheable 61 * 2AP. worked around in hardware 62 * 3AP. fixed in C0 and above steppings microcode update. 63 * Linux does not use excessive STARTUP_IPIs. 64 * 4AP. worked around in hardware 65 * 5AP. symmetric IO mode (normal Linux operation) not affected. 66 * 'noapic' mode has vector 0xf filled out properly. 67 * 6AP. 'noapic' mode might be affected - fixed in later steppings 68 * 7AP. We do not assume writes to the LVT deassering IRQs 69 * 8AP. We do not enable low power mode (deep sleep) during MP bootup 70 * 9AP. We do not use mixed mode 71 * 72 * Pentium 73 * There is a marginal case where REP MOVS on 100MHz SMP 74 * machines with B stepping processors can fail. XXX should provide 75 * an L1cache=Writethrough or L1cache=off option. 76 * 77 * B stepping CPUs may hang. There are hardware work arounds 78 * for this. We warn about it in case your board doesn't have the work 79 * arounds. Basically that's so I can tell anyone with a B stepping 80 * CPU and SMP problems "tough". 81 * 82 * Specific items [From Pentium Processor Specification Update] 83 * 84 * 1AP. Linux doesn't use remote read 85 * 2AP. Linux doesn't trust APIC errors 86 * 3AP. We work around this 87 * 4AP. Linux never generated 3 interrupts of the same priority 88 * to cause a lost local interrupt. 89 * 5AP. Remote read is never used 90 * 6AP. not affected - worked around in hardware 91 * 7AP. not affected - worked around in hardware 92 * 8AP. worked around in hardware - we get explicit CS errors if not 93 * 9AP. only 'noapic' mode affected. Might generate spurious 94 * interrupts, we log only the first one and count the 95 * rest silently. 96 * 10AP. not affected - worked around in hardware 97 * 11AP. Linux reads the APIC between writes to avoid this, as per 98 * the documentation. Make sure you preserve this as it affects 99 * the C stepping chips too. 100 * 12AP. not affected - worked around in hardware 101 * 13AP. not affected - worked around in hardware 102 * 14AP. we always deassert INIT during bootup 103 * 15AP. not affected - worked around in hardware 104 * 16AP. not affected - worked around in hardware 105 * 17AP. not affected - worked around in hardware 106 * 18AP. not affected - worked around in hardware 107 * 19AP. not affected - worked around in BIOS 108 * 109 * If this sounds worrying believe me these bugs are either ___RARE___, 110 * or are signal timing bugs worked around in hardware and there's 111 * about nothing of note with C stepping upwards. 112 */ 113 114 static atomic_t stopping_cpu = ATOMIC_INIT(-1); 115 static bool smp_no_nmi_ipi = false; 116 117 /* 118 * this function sends a 'reschedule' IPI to another CPU. 119 * it goes straight through and wastes no time serializing 120 * anything. Worst case is that we lose a reschedule ... 121 */ 122 static void native_smp_send_reschedule(int cpu) 123 { 124 if (unlikely(cpu_is_offline(cpu))) { 125 WARN_ON(1); 126 return; 127 } 128 apic->send_IPI_mask(cpumask_of(cpu), RESCHEDULE_VECTOR); 129 } 130 131 void native_send_call_func_single_ipi(int cpu) 132 { 133 apic->send_IPI_mask(cpumask_of(cpu), CALL_FUNCTION_SINGLE_VECTOR); 134 } 135 136 void native_send_call_func_ipi(const struct cpumask *mask) 137 { 138 cpumask_var_t allbutself; 139 140 if (!alloc_cpumask_var(&allbutself, GFP_ATOMIC)) { 141 apic->send_IPI_mask(mask, CALL_FUNCTION_VECTOR); 142 return; 143 } 144 145 cpumask_copy(allbutself, cpu_online_mask); 146 cpumask_clear_cpu(smp_processor_id(), allbutself); 147 148 if (cpumask_equal(mask, allbutself) && 149 cpumask_equal(cpu_online_mask, cpu_callout_mask)) 150 apic->send_IPI_allbutself(CALL_FUNCTION_VECTOR); 151 else 152 apic->send_IPI_mask(mask, CALL_FUNCTION_VECTOR); 153 154 free_cpumask_var(allbutself); 155 } 156 157 static int smp_stop_nmi_callback(unsigned int val, struct pt_regs *regs) 158 { 159 /* We are registered on stopping cpu too, avoid spurious NMI */ 160 if (raw_smp_processor_id() == atomic_read(&stopping_cpu)) 161 return NMI_HANDLED; 162 163 stop_this_cpu(NULL); 164 165 return NMI_HANDLED; 166 } 167 168 /* 169 * this function calls the 'stop' function on all other CPUs in the system. 170 */ 171 172 asmlinkage __visible void smp_reboot_interrupt(void) 173 { 174 ipi_entering_ack_irq(); 175 stop_this_cpu(NULL); 176 irq_exit(); 177 } 178 179 static void native_stop_other_cpus(int wait) 180 { 181 unsigned long flags; 182 unsigned long timeout; 183 184 if (reboot_force) 185 return; 186 187 /* 188 * Use an own vector here because smp_call_function 189 * does lots of things not suitable in a panic situation. 190 */ 191 192 /* 193 * We start by using the REBOOT_VECTOR irq. 194 * The irq is treated as a sync point to allow critical 195 * regions of code on other cpus to release their spin locks 196 * and re-enable irqs. Jumping straight to an NMI might 197 * accidentally cause deadlocks with further shutdown/panic 198 * code. By syncing, we give the cpus up to one second to 199 * finish their work before we force them off with the NMI. 200 */ 201 if (num_online_cpus() > 1) { 202 /* did someone beat us here? */ 203 if (atomic_cmpxchg(&stopping_cpu, -1, safe_smp_processor_id()) != -1) 204 return; 205 206 /* sync above data before sending IRQ */ 207 wmb(); 208 209 apic->send_IPI_allbutself(REBOOT_VECTOR); 210 211 /* 212 * Don't wait longer than a second if the caller 213 * didn't ask us to wait. 214 */ 215 timeout = USEC_PER_SEC; 216 while (num_online_cpus() > 1 && (wait || timeout--)) 217 udelay(1); 218 } 219 220 /* if the REBOOT_VECTOR didn't work, try with the NMI */ 221 if ((num_online_cpus() > 1) && (!smp_no_nmi_ipi)) { 222 if (register_nmi_handler(NMI_LOCAL, smp_stop_nmi_callback, 223 NMI_FLAG_FIRST, "smp_stop")) 224 /* Note: we ignore failures here */ 225 /* Hope the REBOOT_IRQ is good enough */ 226 goto finish; 227 228 /* sync above data before sending IRQ */ 229 wmb(); 230 231 pr_emerg("Shutting down cpus with NMI\n"); 232 233 apic->send_IPI_allbutself(NMI_VECTOR); 234 235 /* 236 * Don't wait longer than a 10 ms if the caller 237 * didn't ask us to wait. 238 */ 239 timeout = USEC_PER_MSEC * 10; 240 while (num_online_cpus() > 1 && (wait || timeout--)) 241 udelay(1); 242 } 243 244 finish: 245 local_irq_save(flags); 246 disable_local_APIC(); 247 mcheck_cpu_clear(this_cpu_ptr(&cpu_info)); 248 local_irq_restore(flags); 249 } 250 251 /* 252 * Reschedule call back. 253 */ 254 static inline void __smp_reschedule_interrupt(void) 255 { 256 inc_irq_stat(irq_resched_count); 257 scheduler_ipi(); 258 } 259 260 __visible void smp_reschedule_interrupt(struct pt_regs *regs) 261 { 262 ack_APIC_irq(); 263 __smp_reschedule_interrupt(); 264 /* 265 * KVM uses this interrupt to force a cpu out of guest mode 266 */ 267 } 268 269 __visible void smp_trace_reschedule_interrupt(struct pt_regs *regs) 270 { 271 /* 272 * Need to call irq_enter() before calling the trace point. 273 * __smp_reschedule_interrupt() calls irq_enter/exit() too (in 274 * scheduler_ipi(). This is OK, since those functions are allowed 275 * to nest. 276 */ 277 ipi_entering_ack_irq(); 278 trace_reschedule_entry(RESCHEDULE_VECTOR); 279 __smp_reschedule_interrupt(); 280 trace_reschedule_exit(RESCHEDULE_VECTOR); 281 exiting_irq(); 282 /* 283 * KVM uses this interrupt to force a cpu out of guest mode 284 */ 285 } 286 287 static inline void __smp_call_function_interrupt(void) 288 { 289 generic_smp_call_function_interrupt(); 290 inc_irq_stat(irq_call_count); 291 } 292 293 __visible void smp_call_function_interrupt(struct pt_regs *regs) 294 { 295 ipi_entering_ack_irq(); 296 __smp_call_function_interrupt(); 297 exiting_irq(); 298 } 299 300 __visible void smp_trace_call_function_interrupt(struct pt_regs *regs) 301 { 302 ipi_entering_ack_irq(); 303 trace_call_function_entry(CALL_FUNCTION_VECTOR); 304 __smp_call_function_interrupt(); 305 trace_call_function_exit(CALL_FUNCTION_VECTOR); 306 exiting_irq(); 307 } 308 309 static inline void __smp_call_function_single_interrupt(void) 310 { 311 generic_smp_call_function_single_interrupt(); 312 inc_irq_stat(irq_call_count); 313 } 314 315 __visible void smp_call_function_single_interrupt(struct pt_regs *regs) 316 { 317 ipi_entering_ack_irq(); 318 __smp_call_function_single_interrupt(); 319 exiting_irq(); 320 } 321 322 __visible void smp_trace_call_function_single_interrupt(struct pt_regs *regs) 323 { 324 ipi_entering_ack_irq(); 325 trace_call_function_single_entry(CALL_FUNCTION_SINGLE_VECTOR); 326 __smp_call_function_single_interrupt(); 327 trace_call_function_single_exit(CALL_FUNCTION_SINGLE_VECTOR); 328 exiting_irq(); 329 } 330 331 static int __init nonmi_ipi_setup(char *str) 332 { 333 smp_no_nmi_ipi = true; 334 return 1; 335 } 336 337 __setup("nonmi_ipi", nonmi_ipi_setup); 338 339 struct smp_ops smp_ops = { 340 .smp_prepare_boot_cpu = native_smp_prepare_boot_cpu, 341 .smp_prepare_cpus = native_smp_prepare_cpus, 342 .smp_cpus_done = native_smp_cpus_done, 343 344 .stop_other_cpus = native_stop_other_cpus, 345 .smp_send_reschedule = native_smp_send_reschedule, 346 347 .cpu_up = native_cpu_up, 348 .cpu_die = native_cpu_die, 349 .cpu_disable = native_cpu_disable, 350 .play_dead = native_play_dead, 351 352 .send_call_func_ipi = native_send_call_func_ipi, 353 .send_call_func_single_ipi = native_send_call_func_single_ipi, 354 }; 355 EXPORT_SYMBOL_GPL(smp_ops); 356