smpboot.c 34 KB

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  1. /*
  2. * x86 SMP booting functions
  3. *
  4. * (c) 1995 Alan Cox, Building #3 <alan@redhat.com>
  5. * (c) 1998, 1999, 2000 Ingo Molnar <mingo@redhat.com>
  6. * Copyright 2001 Andi Kleen, SuSE Labs.
  7. *
  8. * Much of the core SMP work is based on previous work by Thomas Radke, to
  9. * whom a great many thanks are extended.
  10. *
  11. * Thanks to Intel for making available several different Pentium,
  12. * Pentium Pro and Pentium-II/Xeon MP machines.
  13. * Original development of Linux SMP code supported by Caldera.
  14. *
  15. * This code is released under the GNU General Public License version 2 or
  16. * later.
  17. *
  18. * Fixes
  19. * Felix Koop : NR_CPUS used properly
  20. * Jose Renau : Handle single CPU case.
  21. * Alan Cox : By repeated request 8) - Total BogoMIPS report.
  22. * Greg Wright : Fix for kernel stacks panic.
  23. * Erich Boleyn : MP v1.4 and additional changes.
  24. * Matthias Sattler : Changes for 2.1 kernel map.
  25. * Michel Lespinasse : Changes for 2.1 kernel map.
  26. * Michael Chastain : Change trampoline.S to gnu as.
  27. * Alan Cox : Dumb bug: 'B' step PPro's are fine
  28. * Ingo Molnar : Added APIC timers, based on code
  29. * from Jose Renau
  30. * Ingo Molnar : various cleanups and rewrites
  31. * Tigran Aivazian : fixed "0.00 in /proc/uptime on SMP" bug.
  32. * Maciej W. Rozycki : Bits for genuine 82489DX APICs
  33. * Andi Kleen : Changed for SMP boot into long mode.
  34. * Martin J. Bligh : Added support for multi-quad systems
  35. * Dave Jones : Report invalid combinations of Athlon CPUs.
  36. * Rusty Russell : Hacked into shape for new "hotplug" boot process.
  37. * Andi Kleen : Converted to new state machine.
  38. * Ashok Raj : CPU hotplug support
  39. * Glauber Costa : i386 and x86_64 integration
  40. */
  41. #include <linux/init.h>
  42. #include <linux/smp.h>
  43. #include <linux/module.h>
  44. #include <linux/sched.h>
  45. #include <linux/percpu.h>
  46. #include <linux/bootmem.h>
  47. #include <linux/err.h>
  48. #include <linux/nmi.h>
  49. #include <asm/acpi.h>
  50. #include <asm/desc.h>
  51. #include <asm/nmi.h>
  52. #include <asm/irq.h>
  53. #include <asm/smp.h>
  54. #include <asm/trampoline.h>
  55. #include <asm/cpu.h>
  56. #include <asm/numa.h>
  57. #include <asm/pgtable.h>
  58. #include <asm/tlbflush.h>
  59. #include <asm/mtrr.h>
  60. #include <asm/vmi.h>
  61. #include <asm/genapic.h>
  62. #include <linux/mc146818rtc.h>
  63. #include <mach_apic.h>
  64. #include <mach_wakecpu.h>
  65. #include <smpboot_hooks.h>
  66. #ifdef CONFIG_X86_32
  67. u8 apicid_2_node[MAX_APICID];
  68. static int low_mappings;
  69. #endif
  70. /* State of each CPU */
  71. DEFINE_PER_CPU(int, cpu_state) = { 0 };
  72. /* Store all idle threads, this can be reused instead of creating
  73. * a new thread. Also avoids complicated thread destroy functionality
  74. * for idle threads.
  75. */
  76. #ifdef CONFIG_HOTPLUG_CPU
  77. /*
  78. * Needed only for CONFIG_HOTPLUG_CPU because __cpuinitdata is
  79. * removed after init for !CONFIG_HOTPLUG_CPU.
  80. */
  81. static DEFINE_PER_CPU(struct task_struct *, idle_thread_array);
  82. #define get_idle_for_cpu(x) (per_cpu(idle_thread_array, x))
  83. #define set_idle_for_cpu(x, p) (per_cpu(idle_thread_array, x) = (p))
  84. #else
  85. struct task_struct *idle_thread_array[NR_CPUS] __cpuinitdata ;
  86. #define get_idle_for_cpu(x) (idle_thread_array[(x)])
  87. #define set_idle_for_cpu(x, p) (idle_thread_array[(x)] = (p))
  88. #endif
  89. /* Number of siblings per CPU package */
  90. int smp_num_siblings = 1;
  91. EXPORT_SYMBOL(smp_num_siblings);
  92. /* Last level cache ID of each logical CPU */
  93. DEFINE_PER_CPU(u16, cpu_llc_id) = BAD_APICID;
  94. /* bitmap of online cpus */
  95. cpumask_t cpu_online_map __read_mostly;
  96. EXPORT_SYMBOL(cpu_online_map);
  97. cpumask_t cpu_callin_map;
  98. cpumask_t cpu_callout_map;
  99. cpumask_t cpu_possible_map;
  100. EXPORT_SYMBOL(cpu_possible_map);
  101. /* representing HT siblings of each logical CPU */
  102. DEFINE_PER_CPU(cpumask_t, cpu_sibling_map);
  103. EXPORT_PER_CPU_SYMBOL(cpu_sibling_map);
  104. /* representing HT and core siblings of each logical CPU */
  105. DEFINE_PER_CPU(cpumask_t, cpu_core_map);
  106. EXPORT_PER_CPU_SYMBOL(cpu_core_map);
  107. /* Per CPU bogomips and other parameters */
  108. DEFINE_PER_CPU_SHARED_ALIGNED(struct cpuinfo_x86, cpu_info);
  109. EXPORT_PER_CPU_SYMBOL(cpu_info);
  110. static atomic_t init_deasserted;
  111. static int boot_cpu_logical_apicid;
  112. /* representing cpus for which sibling maps can be computed */
  113. static cpumask_t cpu_sibling_setup_map;
  114. /* Set if we find a B stepping CPU */
  115. int __cpuinitdata smp_b_stepping;
  116. #if defined(CONFIG_NUMA) && defined(CONFIG_X86_32)
  117. /* which logical CPUs are on which nodes */
  118. cpumask_t node_to_cpumask_map[MAX_NUMNODES] __read_mostly =
  119. { [0 ... MAX_NUMNODES-1] = CPU_MASK_NONE };
  120. EXPORT_SYMBOL(node_to_cpumask_map);
  121. /* which node each logical CPU is on */
  122. int cpu_to_node_map[NR_CPUS] __read_mostly = { [0 ... NR_CPUS-1] = 0 };
  123. EXPORT_SYMBOL(cpu_to_node_map);
  124. /* set up a mapping between cpu and node. */
  125. static void map_cpu_to_node(int cpu, int node)
  126. {
  127. printk(KERN_INFO "Mapping cpu %d to node %d\n", cpu, node);
  128. cpu_set(cpu, node_to_cpumask_map[node]);
  129. cpu_to_node_map[cpu] = node;
  130. }
  131. /* undo a mapping between cpu and node. */
  132. static void unmap_cpu_to_node(int cpu)
  133. {
  134. int node;
  135. printk(KERN_INFO "Unmapping cpu %d from all nodes\n", cpu);
  136. for (node = 0; node < MAX_NUMNODES; node++)
  137. cpu_clear(cpu, node_to_cpumask_map[node]);
  138. cpu_to_node_map[cpu] = 0;
  139. }
  140. #else /* !(CONFIG_NUMA && CONFIG_X86_32) */
  141. #define map_cpu_to_node(cpu, node) ({})
  142. #define unmap_cpu_to_node(cpu) ({})
  143. #endif
  144. #ifdef CONFIG_X86_32
  145. u8 cpu_2_logical_apicid[NR_CPUS] __read_mostly =
  146. { [0 ... NR_CPUS-1] = BAD_APICID };
  147. static void map_cpu_to_logical_apicid(void)
  148. {
  149. int cpu = smp_processor_id();
  150. int apicid = logical_smp_processor_id();
  151. int node = apicid_to_node(apicid);
  152. if (!node_online(node))
  153. node = first_online_node;
  154. cpu_2_logical_apicid[cpu] = apicid;
  155. map_cpu_to_node(cpu, node);
  156. }
  157. void numa_remove_cpu(int cpu)
  158. {
  159. cpu_2_logical_apicid[cpu] = BAD_APICID;
  160. unmap_cpu_to_node(cpu);
  161. }
  162. #else
  163. #define map_cpu_to_logical_apicid() do {} while (0)
  164. #endif
  165. /*
  166. * Report back to the Boot Processor.
  167. * Running on AP.
  168. */
  169. static void __cpuinit smp_callin(void)
  170. {
  171. int cpuid, phys_id;
  172. unsigned long timeout;
  173. /*
  174. * If waken up by an INIT in an 82489DX configuration
  175. * we may get here before an INIT-deassert IPI reaches
  176. * our local APIC. We have to wait for the IPI or we'll
  177. * lock up on an APIC access.
  178. */
  179. wait_for_init_deassert(&init_deasserted);
  180. /*
  181. * (This works even if the APIC is not enabled.)
  182. */
  183. phys_id = GET_APIC_ID(read_apic_id());
  184. cpuid = smp_processor_id();
  185. if (cpu_isset(cpuid, cpu_callin_map)) {
  186. panic("%s: phys CPU#%d, CPU#%d already present??\n", __func__,
  187. phys_id, cpuid);
  188. }
  189. Dprintk("CPU#%d (phys ID: %d) waiting for CALLOUT\n", cpuid, phys_id);
  190. /*
  191. * STARTUP IPIs are fragile beasts as they might sometimes
  192. * trigger some glue motherboard logic. Complete APIC bus
  193. * silence for 1 second, this overestimates the time the
  194. * boot CPU is spending to send the up to 2 STARTUP IPIs
  195. * by a factor of two. This should be enough.
  196. */
  197. /*
  198. * Waiting 2s total for startup (udelay is not yet working)
  199. */
  200. timeout = jiffies + 2*HZ;
  201. while (time_before(jiffies, timeout)) {
  202. /*
  203. * Has the boot CPU finished it's STARTUP sequence?
  204. */
  205. if (cpu_isset(cpuid, cpu_callout_map))
  206. break;
  207. cpu_relax();
  208. }
  209. if (!time_before(jiffies, timeout)) {
  210. panic("%s: CPU%d started up but did not get a callout!\n",
  211. __func__, cpuid);
  212. }
  213. /*
  214. * the boot CPU has finished the init stage and is spinning
  215. * on callin_map until we finish. We are free to set up this
  216. * CPU, first the APIC. (this is probably redundant on most
  217. * boards)
  218. */
  219. Dprintk("CALLIN, before setup_local_APIC().\n");
  220. smp_callin_clear_local_apic();
  221. setup_local_APIC();
  222. end_local_APIC_setup();
  223. map_cpu_to_logical_apicid();
  224. /*
  225. * Get our bogomips.
  226. *
  227. * Need to enable IRQs because it can take longer and then
  228. * the NMI watchdog might kill us.
  229. */
  230. local_irq_enable();
  231. calibrate_delay();
  232. local_irq_disable();
  233. Dprintk("Stack at about %p\n", &cpuid);
  234. /*
  235. * Save our processor parameters
  236. */
  237. smp_store_cpu_info(cpuid);
  238. /*
  239. * Allow the master to continue.
  240. */
  241. cpu_set(cpuid, cpu_callin_map);
  242. }
  243. /*
  244. * Activate a secondary processor.
  245. */
  246. static void __cpuinit start_secondary(void *unused)
  247. {
  248. /*
  249. * Don't put *anything* before cpu_init(), SMP booting is too
  250. * fragile that we want to limit the things done here to the
  251. * most necessary things.
  252. */
  253. #ifdef CONFIG_VMI
  254. vmi_bringup();
  255. #endif
  256. cpu_init();
  257. preempt_disable();
  258. smp_callin();
  259. /* otherwise gcc will move up smp_processor_id before the cpu_init */
  260. barrier();
  261. /*
  262. * Check TSC synchronization with the BP:
  263. */
  264. check_tsc_sync_target();
  265. if (nmi_watchdog == NMI_IO_APIC) {
  266. disable_8259A_irq(0);
  267. enable_NMI_through_LVT0();
  268. enable_8259A_irq(0);
  269. }
  270. #ifdef CONFIG_X86_32
  271. while (low_mappings)
  272. cpu_relax();
  273. __flush_tlb_all();
  274. #endif
  275. /* This must be done before setting cpu_online_map */
  276. set_cpu_sibling_map(raw_smp_processor_id());
  277. wmb();
  278. /*
  279. * We need to hold call_lock, so there is no inconsistency
  280. * between the time smp_call_function() determines number of
  281. * IPI recipients, and the time when the determination is made
  282. * for which cpus receive the IPI. Holding this
  283. * lock helps us to not include this cpu in a currently in progress
  284. * smp_call_function().
  285. */
  286. lock_ipi_call_lock();
  287. #ifdef CONFIG_X86_IO_APIC
  288. setup_vector_irq(smp_processor_id());
  289. #endif
  290. cpu_set(smp_processor_id(), cpu_online_map);
  291. unlock_ipi_call_lock();
  292. per_cpu(cpu_state, smp_processor_id()) = CPU_ONLINE;
  293. setup_secondary_clock();
  294. wmb();
  295. cpu_idle();
  296. }
  297. static void __cpuinit smp_apply_quirks(struct cpuinfo_x86 *c)
  298. {
  299. /*
  300. * Mask B, Pentium, but not Pentium MMX
  301. */
  302. if (c->x86_vendor == X86_VENDOR_INTEL &&
  303. c->x86 == 5 &&
  304. c->x86_mask >= 1 && c->x86_mask <= 4 &&
  305. c->x86_model <= 3)
  306. /*
  307. * Remember we have B step Pentia with bugs
  308. */
  309. smp_b_stepping = 1;
  310. /*
  311. * Certain Athlons might work (for various values of 'work') in SMP
  312. * but they are not certified as MP capable.
  313. */
  314. if ((c->x86_vendor == X86_VENDOR_AMD) && (c->x86 == 6)) {
  315. if (num_possible_cpus() == 1)
  316. goto valid_k7;
  317. /* Athlon 660/661 is valid. */
  318. if ((c->x86_model == 6) && ((c->x86_mask == 0) ||
  319. (c->x86_mask == 1)))
  320. goto valid_k7;
  321. /* Duron 670 is valid */
  322. if ((c->x86_model == 7) && (c->x86_mask == 0))
  323. goto valid_k7;
  324. /*
  325. * Athlon 662, Duron 671, and Athlon >model 7 have capability
  326. * bit. It's worth noting that the A5 stepping (662) of some
  327. * Athlon XP's have the MP bit set.
  328. * See http://www.heise.de/newsticker/data/jow-18.10.01-000 for
  329. * more.
  330. */
  331. if (((c->x86_model == 6) && (c->x86_mask >= 2)) ||
  332. ((c->x86_model == 7) && (c->x86_mask >= 1)) ||
  333. (c->x86_model > 7))
  334. if (cpu_has_mp)
  335. goto valid_k7;
  336. /* If we get here, not a certified SMP capable AMD system. */
  337. add_taint(TAINT_UNSAFE_SMP);
  338. }
  339. valid_k7:
  340. ;
  341. }
  342. static void __cpuinit smp_checks(void)
  343. {
  344. if (smp_b_stepping)
  345. printk(KERN_WARNING "WARNING: SMP operation may be unreliable"
  346. "with B stepping processors.\n");
  347. /*
  348. * Don't taint if we are running SMP kernel on a single non-MP
  349. * approved Athlon
  350. */
  351. if (tainted & TAINT_UNSAFE_SMP) {
  352. if (num_online_cpus())
  353. printk(KERN_INFO "WARNING: This combination of AMD"
  354. "processors is not suitable for SMP.\n");
  355. else
  356. tainted &= ~TAINT_UNSAFE_SMP;
  357. }
  358. }
  359. /*
  360. * The bootstrap kernel entry code has set these up. Save them for
  361. * a given CPU
  362. */
  363. void __cpuinit smp_store_cpu_info(int id)
  364. {
  365. struct cpuinfo_x86 *c = &cpu_data(id);
  366. *c = boot_cpu_data;
  367. c->cpu_index = id;
  368. if (id != 0)
  369. identify_secondary_cpu(c);
  370. smp_apply_quirks(c);
  371. }
  372. void __cpuinit set_cpu_sibling_map(int cpu)
  373. {
  374. int i;
  375. struct cpuinfo_x86 *c = &cpu_data(cpu);
  376. cpu_set(cpu, cpu_sibling_setup_map);
  377. if (smp_num_siblings > 1) {
  378. for_each_cpu_mask(i, cpu_sibling_setup_map) {
  379. if (c->phys_proc_id == cpu_data(i).phys_proc_id &&
  380. c->cpu_core_id == cpu_data(i).cpu_core_id) {
  381. cpu_set(i, per_cpu(cpu_sibling_map, cpu));
  382. cpu_set(cpu, per_cpu(cpu_sibling_map, i));
  383. cpu_set(i, per_cpu(cpu_core_map, cpu));
  384. cpu_set(cpu, per_cpu(cpu_core_map, i));
  385. cpu_set(i, c->llc_shared_map);
  386. cpu_set(cpu, cpu_data(i).llc_shared_map);
  387. }
  388. }
  389. } else {
  390. cpu_set(cpu, per_cpu(cpu_sibling_map, cpu));
  391. }
  392. cpu_set(cpu, c->llc_shared_map);
  393. if (current_cpu_data.x86_max_cores == 1) {
  394. per_cpu(cpu_core_map, cpu) = per_cpu(cpu_sibling_map, cpu);
  395. c->booted_cores = 1;
  396. return;
  397. }
  398. for_each_cpu_mask(i, cpu_sibling_setup_map) {
  399. if (per_cpu(cpu_llc_id, cpu) != BAD_APICID &&
  400. per_cpu(cpu_llc_id, cpu) == per_cpu(cpu_llc_id, i)) {
  401. cpu_set(i, c->llc_shared_map);
  402. cpu_set(cpu, cpu_data(i).llc_shared_map);
  403. }
  404. if (c->phys_proc_id == cpu_data(i).phys_proc_id) {
  405. cpu_set(i, per_cpu(cpu_core_map, cpu));
  406. cpu_set(cpu, per_cpu(cpu_core_map, i));
  407. /*
  408. * Does this new cpu bringup a new core?
  409. */
  410. if (cpus_weight(per_cpu(cpu_sibling_map, cpu)) == 1) {
  411. /*
  412. * for each core in package, increment
  413. * the booted_cores for this new cpu
  414. */
  415. if (first_cpu(per_cpu(cpu_sibling_map, i)) == i)
  416. c->booted_cores++;
  417. /*
  418. * increment the core count for all
  419. * the other cpus in this package
  420. */
  421. if (i != cpu)
  422. cpu_data(i).booted_cores++;
  423. } else if (i != cpu && !c->booted_cores)
  424. c->booted_cores = cpu_data(i).booted_cores;
  425. }
  426. }
  427. }
  428. /* maps the cpu to the sched domain representing multi-core */
  429. cpumask_t cpu_coregroup_map(int cpu)
  430. {
  431. struct cpuinfo_x86 *c = &cpu_data(cpu);
  432. /*
  433. * For perf, we return last level cache shared map.
  434. * And for power savings, we return cpu_core_map
  435. */
  436. if (sched_mc_power_savings || sched_smt_power_savings)
  437. return per_cpu(cpu_core_map, cpu);
  438. else
  439. return c->llc_shared_map;
  440. }
  441. static void impress_friends(void)
  442. {
  443. int cpu;
  444. unsigned long bogosum = 0;
  445. /*
  446. * Allow the user to impress friends.
  447. */
  448. Dprintk("Before bogomips.\n");
  449. for_each_possible_cpu(cpu)
  450. if (cpu_isset(cpu, cpu_callout_map))
  451. bogosum += cpu_data(cpu).loops_per_jiffy;
  452. printk(KERN_INFO
  453. "Total of %d processors activated (%lu.%02lu BogoMIPS).\n",
  454. num_online_cpus(),
  455. bogosum/(500000/HZ),
  456. (bogosum/(5000/HZ))%100);
  457. Dprintk("Before bogocount - setting activated=1.\n");
  458. }
  459. static inline void __inquire_remote_apic(int apicid)
  460. {
  461. unsigned i, regs[] = { APIC_ID >> 4, APIC_LVR >> 4, APIC_SPIV >> 4 };
  462. char *names[] = { "ID", "VERSION", "SPIV" };
  463. int timeout;
  464. u32 status;
  465. printk(KERN_INFO "Inquiring remote APIC #%d...\n", apicid);
  466. for (i = 0; i < ARRAY_SIZE(regs); i++) {
  467. printk(KERN_INFO "... APIC #%d %s: ", apicid, names[i]);
  468. /*
  469. * Wait for idle.
  470. */
  471. status = safe_apic_wait_icr_idle();
  472. if (status)
  473. printk(KERN_CONT
  474. "a previous APIC delivery may have failed\n");
  475. apic_write_around(APIC_ICR2, SET_APIC_DEST_FIELD(apicid));
  476. apic_write_around(APIC_ICR, APIC_DM_REMRD | regs[i]);
  477. timeout = 0;
  478. do {
  479. udelay(100);
  480. status = apic_read(APIC_ICR) & APIC_ICR_RR_MASK;
  481. } while (status == APIC_ICR_RR_INPROG && timeout++ < 1000);
  482. switch (status) {
  483. case APIC_ICR_RR_VALID:
  484. status = apic_read(APIC_RRR);
  485. printk(KERN_CONT "%08x\n", status);
  486. break;
  487. default:
  488. printk(KERN_CONT "failed\n");
  489. }
  490. }
  491. }
  492. #ifdef WAKE_SECONDARY_VIA_NMI
  493. /*
  494. * Poke the other CPU in the eye via NMI to wake it up. Remember that the normal
  495. * INIT, INIT, STARTUP sequence will reset the chip hard for us, and this
  496. * won't ... remember to clear down the APIC, etc later.
  497. */
  498. static int __devinit
  499. wakeup_secondary_cpu(int logical_apicid, unsigned long start_eip)
  500. {
  501. unsigned long send_status, accept_status = 0;
  502. int maxlvt;
  503. /* Target chip */
  504. apic_write_around(APIC_ICR2, SET_APIC_DEST_FIELD(logical_apicid));
  505. /* Boot on the stack */
  506. /* Kick the second */
  507. apic_write_around(APIC_ICR, APIC_DM_NMI | APIC_DEST_LOGICAL);
  508. Dprintk("Waiting for send to finish...\n");
  509. send_status = safe_apic_wait_icr_idle();
  510. /*
  511. * Give the other CPU some time to accept the IPI.
  512. */
  513. udelay(200);
  514. /*
  515. * Due to the Pentium erratum 3AP.
  516. */
  517. maxlvt = lapic_get_maxlvt();
  518. if (maxlvt > 3) {
  519. apic_read_around(APIC_SPIV);
  520. apic_write(APIC_ESR, 0);
  521. }
  522. accept_status = (apic_read(APIC_ESR) & 0xEF);
  523. Dprintk("NMI sent.\n");
  524. if (send_status)
  525. printk(KERN_ERR "APIC never delivered???\n");
  526. if (accept_status)
  527. printk(KERN_ERR "APIC delivery error (%lx).\n", accept_status);
  528. return (send_status | accept_status);
  529. }
  530. #endif /* WAKE_SECONDARY_VIA_NMI */
  531. #ifdef WAKE_SECONDARY_VIA_INIT
  532. static int __devinit
  533. wakeup_secondary_cpu(int phys_apicid, unsigned long start_eip)
  534. {
  535. unsigned long send_status, accept_status = 0;
  536. int maxlvt, num_starts, j;
  537. if (get_uv_system_type() == UV_NON_UNIQUE_APIC) {
  538. send_status = uv_wakeup_secondary(phys_apicid, start_eip);
  539. atomic_set(&init_deasserted, 1);
  540. return send_status;
  541. }
  542. /*
  543. * Be paranoid about clearing APIC errors.
  544. */
  545. if (APIC_INTEGRATED(apic_version[phys_apicid])) {
  546. apic_read_around(APIC_SPIV);
  547. apic_write(APIC_ESR, 0);
  548. apic_read(APIC_ESR);
  549. }
  550. Dprintk("Asserting INIT.\n");
  551. /*
  552. * Turn INIT on target chip
  553. */
  554. apic_write_around(APIC_ICR2, SET_APIC_DEST_FIELD(phys_apicid));
  555. /*
  556. * Send IPI
  557. */
  558. apic_write_around(APIC_ICR, APIC_INT_LEVELTRIG | APIC_INT_ASSERT
  559. | APIC_DM_INIT);
  560. Dprintk("Waiting for send to finish...\n");
  561. send_status = safe_apic_wait_icr_idle();
  562. mdelay(10);
  563. Dprintk("Deasserting INIT.\n");
  564. /* Target chip */
  565. apic_write_around(APIC_ICR2, SET_APIC_DEST_FIELD(phys_apicid));
  566. /* Send IPI */
  567. apic_write_around(APIC_ICR, APIC_INT_LEVELTRIG | APIC_DM_INIT);
  568. Dprintk("Waiting for send to finish...\n");
  569. send_status = safe_apic_wait_icr_idle();
  570. mb();
  571. atomic_set(&init_deasserted, 1);
  572. /*
  573. * Should we send STARTUP IPIs ?
  574. *
  575. * Determine this based on the APIC version.
  576. * If we don't have an integrated APIC, don't send the STARTUP IPIs.
  577. */
  578. if (APIC_INTEGRATED(apic_version[phys_apicid]))
  579. num_starts = 2;
  580. else
  581. num_starts = 0;
  582. /*
  583. * Paravirt / VMI wants a startup IPI hook here to set up the
  584. * target processor state.
  585. */
  586. startup_ipi_hook(phys_apicid, (unsigned long) start_secondary,
  587. (unsigned long)stack_start.sp);
  588. /*
  589. * Run STARTUP IPI loop.
  590. */
  591. Dprintk("#startup loops: %d.\n", num_starts);
  592. maxlvt = lapic_get_maxlvt();
  593. for (j = 1; j <= num_starts; j++) {
  594. Dprintk("Sending STARTUP #%d.\n", j);
  595. apic_read_around(APIC_SPIV);
  596. apic_write(APIC_ESR, 0);
  597. apic_read(APIC_ESR);
  598. Dprintk("After apic_write.\n");
  599. /*
  600. * STARTUP IPI
  601. */
  602. /* Target chip */
  603. apic_write_around(APIC_ICR2, SET_APIC_DEST_FIELD(phys_apicid));
  604. /* Boot on the stack */
  605. /* Kick the second */
  606. apic_write_around(APIC_ICR, APIC_DM_STARTUP
  607. | (start_eip >> 12));
  608. /*
  609. * Give the other CPU some time to accept the IPI.
  610. */
  611. udelay(300);
  612. Dprintk("Startup point 1.\n");
  613. Dprintk("Waiting for send to finish...\n");
  614. send_status = safe_apic_wait_icr_idle();
  615. /*
  616. * Give the other CPU some time to accept the IPI.
  617. */
  618. udelay(200);
  619. /*
  620. * Due to the Pentium erratum 3AP.
  621. */
  622. if (maxlvt > 3) {
  623. apic_read_around(APIC_SPIV);
  624. apic_write(APIC_ESR, 0);
  625. }
  626. accept_status = (apic_read(APIC_ESR) & 0xEF);
  627. if (send_status || accept_status)
  628. break;
  629. }
  630. Dprintk("After Startup.\n");
  631. if (send_status)
  632. printk(KERN_ERR "APIC never delivered???\n");
  633. if (accept_status)
  634. printk(KERN_ERR "APIC delivery error (%lx).\n", accept_status);
  635. return (send_status | accept_status);
  636. }
  637. #endif /* WAKE_SECONDARY_VIA_INIT */
  638. struct create_idle {
  639. struct work_struct work;
  640. struct task_struct *idle;
  641. struct completion done;
  642. int cpu;
  643. };
  644. static void __cpuinit do_fork_idle(struct work_struct *work)
  645. {
  646. struct create_idle *c_idle =
  647. container_of(work, struct create_idle, work);
  648. c_idle->idle = fork_idle(c_idle->cpu);
  649. complete(&c_idle->done);
  650. }
  651. #ifdef CONFIG_X86_64
  652. /*
  653. * Allocate node local memory for the AP pda.
  654. *
  655. * Must be called after the _cpu_pda pointer table is initialized.
  656. */
  657. static int __cpuinit get_local_pda(int cpu)
  658. {
  659. struct x8664_pda *oldpda, *newpda;
  660. unsigned long size = sizeof(struct x8664_pda);
  661. int node = cpu_to_node(cpu);
  662. if (cpu_pda(cpu) && !cpu_pda(cpu)->in_bootmem)
  663. return 0;
  664. oldpda = cpu_pda(cpu);
  665. newpda = kmalloc_node(size, GFP_ATOMIC, node);
  666. if (!newpda) {
  667. printk(KERN_ERR "Could not allocate node local PDA "
  668. "for CPU %d on node %d\n", cpu, node);
  669. if (oldpda)
  670. return 0; /* have a usable pda */
  671. else
  672. return -1;
  673. }
  674. if (oldpda) {
  675. memcpy(newpda, oldpda, size);
  676. if (!after_bootmem)
  677. free_bootmem((unsigned long)oldpda, size);
  678. }
  679. newpda->in_bootmem = 0;
  680. cpu_pda(cpu) = newpda;
  681. return 0;
  682. }
  683. #endif /* CONFIG_X86_64 */
  684. static int __cpuinit do_boot_cpu(int apicid, int cpu)
  685. /*
  686. * NOTE - on most systems this is a PHYSICAL apic ID, but on multiquad
  687. * (ie clustered apic addressing mode), this is a LOGICAL apic ID.
  688. * Returns zero if CPU booted OK, else error code from wakeup_secondary_cpu.
  689. */
  690. {
  691. unsigned long boot_error = 0;
  692. int timeout;
  693. unsigned long start_ip;
  694. unsigned short nmi_high = 0, nmi_low = 0;
  695. struct create_idle c_idle = {
  696. .cpu = cpu,
  697. .done = COMPLETION_INITIALIZER_ONSTACK(c_idle.done),
  698. };
  699. INIT_WORK(&c_idle.work, do_fork_idle);
  700. #ifdef CONFIG_X86_64
  701. /* Allocate node local memory for AP pdas */
  702. if (cpu > 0) {
  703. boot_error = get_local_pda(cpu);
  704. if (boot_error)
  705. goto restore_state;
  706. /* if can't get pda memory, can't start cpu */
  707. }
  708. #endif
  709. alternatives_smp_switch(1);
  710. c_idle.idle = get_idle_for_cpu(cpu);
  711. /*
  712. * We can't use kernel_thread since we must avoid to
  713. * reschedule the child.
  714. */
  715. if (c_idle.idle) {
  716. c_idle.idle->thread.sp = (unsigned long) (((struct pt_regs *)
  717. (THREAD_SIZE + task_stack_page(c_idle.idle))) - 1);
  718. init_idle(c_idle.idle, cpu);
  719. goto do_rest;
  720. }
  721. if (!keventd_up() || current_is_keventd())
  722. c_idle.work.func(&c_idle.work);
  723. else {
  724. schedule_work(&c_idle.work);
  725. wait_for_completion(&c_idle.done);
  726. }
  727. if (IS_ERR(c_idle.idle)) {
  728. printk("failed fork for CPU %d\n", cpu);
  729. return PTR_ERR(c_idle.idle);
  730. }
  731. set_idle_for_cpu(cpu, c_idle.idle);
  732. do_rest:
  733. #ifdef CONFIG_X86_32
  734. per_cpu(current_task, cpu) = c_idle.idle;
  735. init_gdt(cpu);
  736. /* Stack for startup_32 can be just as for start_secondary onwards */
  737. irq_ctx_init(cpu);
  738. #else
  739. cpu_pda(cpu)->pcurrent = c_idle.idle;
  740. clear_tsk_thread_flag(c_idle.idle, TIF_FORK);
  741. #endif
  742. early_gdt_descr.address = (unsigned long)get_cpu_gdt_table(cpu);
  743. initial_code = (unsigned long)start_secondary;
  744. stack_start.sp = (void *) c_idle.idle->thread.sp;
  745. /* start_ip had better be page-aligned! */
  746. start_ip = setup_trampoline();
  747. /* So we see what's up */
  748. printk(KERN_INFO "Booting processor %d/%d ip %lx\n",
  749. cpu, apicid, start_ip);
  750. /*
  751. * This grunge runs the startup process for
  752. * the targeted processor.
  753. */
  754. atomic_set(&init_deasserted, 0);
  755. if (get_uv_system_type() != UV_NON_UNIQUE_APIC) {
  756. Dprintk("Setting warm reset code and vector.\n");
  757. store_NMI_vector(&nmi_high, &nmi_low);
  758. smpboot_setup_warm_reset_vector(start_ip);
  759. /*
  760. * Be paranoid about clearing APIC errors.
  761. */
  762. apic_write(APIC_ESR, 0);
  763. apic_read(APIC_ESR);
  764. }
  765. /*
  766. * Starting actual IPI sequence...
  767. */
  768. boot_error = wakeup_secondary_cpu(apicid, start_ip);
  769. if (!boot_error) {
  770. /*
  771. * allow APs to start initializing.
  772. */
  773. Dprintk("Before Callout %d.\n", cpu);
  774. cpu_set(cpu, cpu_callout_map);
  775. Dprintk("After Callout %d.\n", cpu);
  776. /*
  777. * Wait 5s total for a response
  778. */
  779. for (timeout = 0; timeout < 50000; timeout++) {
  780. if (cpu_isset(cpu, cpu_callin_map))
  781. break; /* It has booted */
  782. udelay(100);
  783. }
  784. if (cpu_isset(cpu, cpu_callin_map)) {
  785. /* number CPUs logically, starting from 1 (BSP is 0) */
  786. Dprintk("OK.\n");
  787. printk(KERN_INFO "CPU%d: ", cpu);
  788. print_cpu_info(&cpu_data(cpu));
  789. Dprintk("CPU has booted.\n");
  790. } else {
  791. boot_error = 1;
  792. if (*((volatile unsigned char *)trampoline_base)
  793. == 0xA5)
  794. /* trampoline started but...? */
  795. printk(KERN_ERR "Stuck ??\n");
  796. else
  797. /* trampoline code not run */
  798. printk(KERN_ERR "Not responding.\n");
  799. if (get_uv_system_type() != UV_NON_UNIQUE_APIC)
  800. inquire_remote_apic(apicid);
  801. }
  802. }
  803. #ifdef CONFIG_X86_64
  804. restore_state:
  805. #endif
  806. if (boot_error) {
  807. /* Try to put things back the way they were before ... */
  808. numa_remove_cpu(cpu); /* was set by numa_add_cpu */
  809. cpu_clear(cpu, cpu_callout_map); /* was set by do_boot_cpu() */
  810. cpu_clear(cpu, cpu_initialized); /* was set by cpu_init() */
  811. cpu_clear(cpu, cpu_present_map);
  812. per_cpu(x86_cpu_to_apicid, cpu) = BAD_APICID;
  813. }
  814. /* mark "stuck" area as not stuck */
  815. *((volatile unsigned long *)trampoline_base) = 0;
  816. /*
  817. * Cleanup possible dangling ends...
  818. */
  819. smpboot_restore_warm_reset_vector();
  820. return boot_error;
  821. }
  822. int __cpuinit native_cpu_up(unsigned int cpu)
  823. {
  824. int apicid = cpu_present_to_apicid(cpu);
  825. unsigned long flags;
  826. int err;
  827. WARN_ON(irqs_disabled());
  828. Dprintk("++++++++++++++++++++=_---CPU UP %u\n", cpu);
  829. if (apicid == BAD_APICID || apicid == boot_cpu_physical_apicid ||
  830. !physid_isset(apicid, phys_cpu_present_map)) {
  831. printk(KERN_ERR "%s: bad cpu %d\n", __func__, cpu);
  832. return -EINVAL;
  833. }
  834. /*
  835. * Already booted CPU?
  836. */
  837. if (cpu_isset(cpu, cpu_callin_map)) {
  838. Dprintk("do_boot_cpu %d Already started\n", cpu);
  839. return -ENOSYS;
  840. }
  841. /*
  842. * Save current MTRR state in case it was changed since early boot
  843. * (e.g. by the ACPI SMI) to initialize new CPUs with MTRRs in sync:
  844. */
  845. mtrr_save_state();
  846. per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
  847. #ifdef CONFIG_X86_32
  848. /* init low mem mapping */
  849. clone_pgd_range(swapper_pg_dir, swapper_pg_dir + KERNEL_PGD_BOUNDARY,
  850. min_t(unsigned long, KERNEL_PGD_PTRS, KERNEL_PGD_BOUNDARY));
  851. flush_tlb_all();
  852. low_mappings = 1;
  853. err = do_boot_cpu(apicid, cpu);
  854. zap_low_mappings();
  855. low_mappings = 0;
  856. #else
  857. err = do_boot_cpu(apicid, cpu);
  858. #endif
  859. if (err) {
  860. Dprintk("do_boot_cpu failed %d\n", err);
  861. return -EIO;
  862. }
  863. /*
  864. * Check TSC synchronization with the AP (keep irqs disabled
  865. * while doing so):
  866. */
  867. local_irq_save(flags);
  868. check_tsc_sync_source(cpu);
  869. local_irq_restore(flags);
  870. while (!cpu_online(cpu)) {
  871. cpu_relax();
  872. touch_nmi_watchdog();
  873. }
  874. return 0;
  875. }
  876. /*
  877. * Fall back to non SMP mode after errors.
  878. *
  879. * RED-PEN audit/test this more. I bet there is more state messed up here.
  880. */
  881. static __init void disable_smp(void)
  882. {
  883. cpu_present_map = cpumask_of_cpu(0);
  884. cpu_possible_map = cpumask_of_cpu(0);
  885. smpboot_clear_io_apic_irqs();
  886. if (smp_found_config)
  887. physid_set_mask_of_physid(boot_cpu_physical_apicid, &phys_cpu_present_map);
  888. else
  889. physid_set_mask_of_physid(0, &phys_cpu_present_map);
  890. map_cpu_to_logical_apicid();
  891. cpu_set(0, per_cpu(cpu_sibling_map, 0));
  892. cpu_set(0, per_cpu(cpu_core_map, 0));
  893. }
  894. /*
  895. * Various sanity checks.
  896. */
  897. static int __init smp_sanity_check(unsigned max_cpus)
  898. {
  899. preempt_disable();
  900. if (!physid_isset(hard_smp_processor_id(), phys_cpu_present_map)) {
  901. printk(KERN_WARNING "weird, boot CPU (#%d) not listed"
  902. "by the BIOS.\n", hard_smp_processor_id());
  903. physid_set(hard_smp_processor_id(), phys_cpu_present_map);
  904. }
  905. /*
  906. * If we couldn't find an SMP configuration at boot time,
  907. * get out of here now!
  908. */
  909. if (!smp_found_config && !acpi_lapic) {
  910. preempt_enable();
  911. printk(KERN_NOTICE "SMP motherboard not detected.\n");
  912. disable_smp();
  913. if (APIC_init_uniprocessor())
  914. printk(KERN_NOTICE "Local APIC not detected."
  915. " Using dummy APIC emulation.\n");
  916. return -1;
  917. }
  918. /*
  919. * Should not be necessary because the MP table should list the boot
  920. * CPU too, but we do it for the sake of robustness anyway.
  921. */
  922. if (!check_phys_apicid_present(boot_cpu_physical_apicid)) {
  923. printk(KERN_NOTICE
  924. "weird, boot CPU (#%d) not listed by the BIOS.\n",
  925. boot_cpu_physical_apicid);
  926. physid_set(hard_smp_processor_id(), phys_cpu_present_map);
  927. }
  928. preempt_enable();
  929. /*
  930. * If we couldn't find a local APIC, then get out of here now!
  931. */
  932. if (APIC_INTEGRATED(apic_version[boot_cpu_physical_apicid]) &&
  933. !cpu_has_apic) {
  934. printk(KERN_ERR "BIOS bug, local APIC #%d not detected!...\n",
  935. boot_cpu_physical_apicid);
  936. printk(KERN_ERR "... forcing use of dummy APIC emulation."
  937. "(tell your hw vendor)\n");
  938. smpboot_clear_io_apic();
  939. return -1;
  940. }
  941. verify_local_APIC();
  942. /*
  943. * If SMP should be disabled, then really disable it!
  944. */
  945. if (!max_cpus) {
  946. printk(KERN_INFO "SMP mode deactivated.\n");
  947. smpboot_clear_io_apic();
  948. localise_nmi_watchdog();
  949. connect_bsp_APIC();
  950. setup_local_APIC();
  951. end_local_APIC_setup();
  952. return -1;
  953. }
  954. return 0;
  955. }
  956. static void __init smp_cpu_index_default(void)
  957. {
  958. int i;
  959. struct cpuinfo_x86 *c;
  960. for_each_possible_cpu(i) {
  961. c = &cpu_data(i);
  962. /* mark all to hotplug */
  963. c->cpu_index = NR_CPUS;
  964. }
  965. }
  966. /*
  967. * Prepare for SMP bootup. The MP table or ACPI has been read
  968. * earlier. Just do some sanity checking here and enable APIC mode.
  969. */
  970. void __init native_smp_prepare_cpus(unsigned int max_cpus)
  971. {
  972. preempt_disable();
  973. smp_cpu_index_default();
  974. current_cpu_data = boot_cpu_data;
  975. cpu_callin_map = cpumask_of_cpu(0);
  976. mb();
  977. /*
  978. * Setup boot CPU information
  979. */
  980. smp_store_cpu_info(0); /* Final full version of the data */
  981. boot_cpu_logical_apicid = logical_smp_processor_id();
  982. current_thread_info()->cpu = 0; /* needed? */
  983. set_cpu_sibling_map(0);
  984. if (smp_sanity_check(max_cpus) < 0) {
  985. printk(KERN_INFO "SMP disabled\n");
  986. disable_smp();
  987. goto out;
  988. }
  989. preempt_disable();
  990. if (GET_APIC_ID(read_apic_id()) != boot_cpu_physical_apicid) {
  991. panic("Boot APIC ID in local APIC unexpected (%d vs %d)",
  992. GET_APIC_ID(read_apic_id()), boot_cpu_physical_apicid);
  993. /* Or can we switch back to PIC here? */
  994. }
  995. preempt_enable();
  996. connect_bsp_APIC();
  997. /*
  998. * Switch from PIC to APIC mode.
  999. */
  1000. setup_local_APIC();
  1001. #ifdef CONFIG_X86_64
  1002. /*
  1003. * Enable IO APIC before setting up error vector
  1004. */
  1005. if (!skip_ioapic_setup && nr_ioapics)
  1006. enable_IO_APIC();
  1007. #endif
  1008. end_local_APIC_setup();
  1009. map_cpu_to_logical_apicid();
  1010. setup_portio_remap();
  1011. smpboot_setup_io_apic();
  1012. /*
  1013. * Set up local APIC timer on boot CPU.
  1014. */
  1015. printk(KERN_INFO "CPU%d: ", 0);
  1016. print_cpu_info(&cpu_data(0));
  1017. setup_boot_clock();
  1018. out:
  1019. preempt_enable();
  1020. }
  1021. /*
  1022. * Early setup to make printk work.
  1023. */
  1024. void __init native_smp_prepare_boot_cpu(void)
  1025. {
  1026. int me = smp_processor_id();
  1027. #ifdef CONFIG_X86_32
  1028. init_gdt(me);
  1029. #endif
  1030. switch_to_new_gdt();
  1031. /* already set me in cpu_online_map in boot_cpu_init() */
  1032. cpu_set(me, cpu_callout_map);
  1033. per_cpu(cpu_state, me) = CPU_ONLINE;
  1034. }
  1035. void __init native_smp_cpus_done(unsigned int max_cpus)
  1036. {
  1037. Dprintk("Boot done.\n");
  1038. impress_friends();
  1039. smp_checks();
  1040. #ifdef CONFIG_X86_IO_APIC
  1041. setup_ioapic_dest();
  1042. #endif
  1043. check_nmi_watchdog();
  1044. }
  1045. #ifdef CONFIG_HOTPLUG_CPU
  1046. static void remove_siblinginfo(int cpu)
  1047. {
  1048. int sibling;
  1049. struct cpuinfo_x86 *c = &cpu_data(cpu);
  1050. for_each_cpu_mask(sibling, per_cpu(cpu_core_map, cpu)) {
  1051. cpu_clear(cpu, per_cpu(cpu_core_map, sibling));
  1052. /*/
  1053. * last thread sibling in this cpu core going down
  1054. */
  1055. if (cpus_weight(per_cpu(cpu_sibling_map, cpu)) == 1)
  1056. cpu_data(sibling).booted_cores--;
  1057. }
  1058. for_each_cpu_mask(sibling, per_cpu(cpu_sibling_map, cpu))
  1059. cpu_clear(cpu, per_cpu(cpu_sibling_map, sibling));
  1060. cpus_clear(per_cpu(cpu_sibling_map, cpu));
  1061. cpus_clear(per_cpu(cpu_core_map, cpu));
  1062. c->phys_proc_id = 0;
  1063. c->cpu_core_id = 0;
  1064. cpu_clear(cpu, cpu_sibling_setup_map);
  1065. }
  1066. static int additional_cpus __initdata = -1;
  1067. static __init int setup_additional_cpus(char *s)
  1068. {
  1069. return s && get_option(&s, &additional_cpus) ? 0 : -EINVAL;
  1070. }
  1071. early_param("additional_cpus", setup_additional_cpus);
  1072. /*
  1073. * cpu_possible_map should be static, it cannot change as cpu's
  1074. * are onlined, or offlined. The reason is per-cpu data-structures
  1075. * are allocated by some modules at init time, and dont expect to
  1076. * do this dynamically on cpu arrival/departure.
  1077. * cpu_present_map on the other hand can change dynamically.
  1078. * In case when cpu_hotplug is not compiled, then we resort to current
  1079. * behaviour, which is cpu_possible == cpu_present.
  1080. * - Ashok Raj
  1081. *
  1082. * Three ways to find out the number of additional hotplug CPUs:
  1083. * - If the BIOS specified disabled CPUs in ACPI/mptables use that.
  1084. * - The user can overwrite it with additional_cpus=NUM
  1085. * - Otherwise don't reserve additional CPUs.
  1086. * We do this because additional CPUs waste a lot of memory.
  1087. * -AK
  1088. */
  1089. __init void prefill_possible_map(void)
  1090. {
  1091. int i;
  1092. int possible;
  1093. /* no processor from mptable or madt */
  1094. if (!num_processors)
  1095. num_processors = 1;
  1096. #ifdef CONFIG_HOTPLUG_CPU
  1097. if (additional_cpus == -1) {
  1098. if (disabled_cpus > 0)
  1099. additional_cpus = disabled_cpus;
  1100. else
  1101. additional_cpus = 0;
  1102. }
  1103. #else
  1104. additional_cpus = 0;
  1105. #endif
  1106. possible = num_processors + additional_cpus;
  1107. if (possible > NR_CPUS)
  1108. possible = NR_CPUS;
  1109. printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n",
  1110. possible, max_t(int, possible - num_processors, 0));
  1111. for (i = 0; i < possible; i++)
  1112. cpu_set(i, cpu_possible_map);
  1113. nr_cpu_ids = possible;
  1114. }
  1115. static void __ref remove_cpu_from_maps(int cpu)
  1116. {
  1117. cpu_clear(cpu, cpu_online_map);
  1118. cpu_clear(cpu, cpu_callout_map);
  1119. cpu_clear(cpu, cpu_callin_map);
  1120. /* was set by cpu_init() */
  1121. clear_bit(cpu, (unsigned long *)&cpu_initialized);
  1122. numa_remove_cpu(cpu);
  1123. }
  1124. int __cpu_disable(void)
  1125. {
  1126. int cpu = smp_processor_id();
  1127. /*
  1128. * Perhaps use cpufreq to drop frequency, but that could go
  1129. * into generic code.
  1130. *
  1131. * We won't take down the boot processor on i386 due to some
  1132. * interrupts only being able to be serviced by the BSP.
  1133. * Especially so if we're not using an IOAPIC -zwane
  1134. */
  1135. if (cpu == 0)
  1136. return -EBUSY;
  1137. if (nmi_watchdog == NMI_LOCAL_APIC)
  1138. stop_apic_nmi_watchdog(NULL);
  1139. clear_local_APIC();
  1140. /*
  1141. * HACK:
  1142. * Allow any queued timer interrupts to get serviced
  1143. * This is only a temporary solution until we cleanup
  1144. * fixup_irqs as we do for IA64.
  1145. */
  1146. local_irq_enable();
  1147. mdelay(1);
  1148. local_irq_disable();
  1149. remove_siblinginfo(cpu);
  1150. /* It's now safe to remove this processor from the online map */
  1151. remove_cpu_from_maps(cpu);
  1152. fixup_irqs(cpu_online_map);
  1153. return 0;
  1154. }
  1155. void __cpu_die(unsigned int cpu)
  1156. {
  1157. /* We don't do anything here: idle task is faking death itself. */
  1158. unsigned int i;
  1159. for (i = 0; i < 10; i++) {
  1160. /* They ack this in play_dead by setting CPU_DEAD */
  1161. if (per_cpu(cpu_state, cpu) == CPU_DEAD) {
  1162. printk(KERN_INFO "CPU %d is now offline\n", cpu);
  1163. if (1 == num_online_cpus())
  1164. alternatives_smp_switch(0);
  1165. return;
  1166. }
  1167. msleep(100);
  1168. }
  1169. printk(KERN_ERR "CPU %u didn't die...\n", cpu);
  1170. }
  1171. #else /* ... !CONFIG_HOTPLUG_CPU */
  1172. int __cpu_disable(void)
  1173. {
  1174. return -ENOSYS;
  1175. }
  1176. void __cpu_die(unsigned int cpu)
  1177. {
  1178. /* We said "no" in __cpu_disable */
  1179. BUG();
  1180. }
  1181. #endif
  1182. /*
  1183. * If the BIOS enumerates physical processors before logical,
  1184. * maxcpus=N at enumeration-time can be used to disable HT.
  1185. */
  1186. static int __init parse_maxcpus(char *arg)
  1187. {
  1188. extern unsigned int maxcpus;
  1189. maxcpus = simple_strtoul(arg, NULL, 0);
  1190. return 0;
  1191. }
  1192. early_param("maxcpus", parse_maxcpus);