]> Pileus Git - ~andy/linux/blob - arch/x86/xen/smp.c
x86-64, reboot: Be more paranoid in 64-bit reboot=bios
[~andy/linux] / arch / x86 / xen / smp.c
1 /*
2  * Xen SMP support
3  *
4  * This file implements the Xen versions of smp_ops.  SMP under Xen is
5  * very straightforward.  Bringing a CPU up is simply a matter of
6  * loading its initial context and setting it running.
7  *
8  * IPIs are handled through the Xen event mechanism.
9  *
10  * Because virtual CPUs can be scheduled onto any real CPU, there's no
11  * useful topology information for the kernel to make use of.  As a
12  * result, all CPUs are treated as if they're single-core and
13  * single-threaded.
14  */
15 #include <linux/sched.h>
16 #include <linux/err.h>
17 #include <linux/slab.h>
18 #include <linux/smp.h>
19 #include <linux/irq_work.h>
20
21 #include <asm/paravirt.h>
22 #include <asm/desc.h>
23 #include <asm/pgtable.h>
24 #include <asm/cpu.h>
25
26 #include <xen/interface/xen.h>
27 #include <xen/interface/vcpu.h>
28
29 #include <asm/xen/interface.h>
30 #include <asm/xen/hypercall.h>
31
32 #include <xen/xen.h>
33 #include <xen/page.h>
34 #include <xen/events.h>
35
36 #include <xen/hvc-console.h>
37 #include "xen-ops.h"
38 #include "mmu.h"
39
40 cpumask_var_t xen_cpu_initialized_map;
41
42 static DEFINE_PER_CPU(int, xen_resched_irq);
43 static DEFINE_PER_CPU(int, xen_callfunc_irq);
44 static DEFINE_PER_CPU(int, xen_callfuncsingle_irq);
45 static DEFINE_PER_CPU(int, xen_irq_work);
46 static DEFINE_PER_CPU(int, xen_debug_irq) = -1;
47
48 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id);
49 static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id);
50 static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id);
51
52 /*
53  * Reschedule call back.
54  */
55 static irqreturn_t xen_reschedule_interrupt(int irq, void *dev_id)
56 {
57         inc_irq_stat(irq_resched_count);
58         scheduler_ipi();
59
60         return IRQ_HANDLED;
61 }
62
63 static void __cpuinit cpu_bringup(void)
64 {
65         int cpu;
66
67         cpu_init();
68         touch_softlockup_watchdog();
69         preempt_disable();
70
71         xen_enable_sysenter();
72         xen_enable_syscall();
73
74         cpu = smp_processor_id();
75         smp_store_cpu_info(cpu);
76         cpu_data(cpu).x86_max_cores = 1;
77         set_cpu_sibling_map(cpu);
78
79         xen_setup_cpu_clockevents();
80
81         notify_cpu_starting(cpu);
82
83         ipi_call_lock();
84         set_cpu_online(cpu, true);
85         ipi_call_unlock();
86
87         this_cpu_write(cpu_state, CPU_ONLINE);
88
89         wmb();
90
91         /* We can take interrupts now: we're officially "up". */
92         local_irq_enable();
93
94         wmb();                  /* make sure everything is out */
95 }
96
97 static void __cpuinit cpu_bringup_and_idle(void)
98 {
99         cpu_bringup();
100         cpu_idle();
101 }
102
103 static int xen_smp_intr_init(unsigned int cpu)
104 {
105         int rc;
106         const char *resched_name, *callfunc_name, *debug_name;
107
108         resched_name = kasprintf(GFP_KERNEL, "resched%d", cpu);
109         rc = bind_ipi_to_irqhandler(XEN_RESCHEDULE_VECTOR,
110                                     cpu,
111                                     xen_reschedule_interrupt,
112                                     IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
113                                     resched_name,
114                                     NULL);
115         if (rc < 0)
116                 goto fail;
117         per_cpu(xen_resched_irq, cpu) = rc;
118
119         callfunc_name = kasprintf(GFP_KERNEL, "callfunc%d", cpu);
120         rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_VECTOR,
121                                     cpu,
122                                     xen_call_function_interrupt,
123                                     IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
124                                     callfunc_name,
125                                     NULL);
126         if (rc < 0)
127                 goto fail;
128         per_cpu(xen_callfunc_irq, cpu) = rc;
129
130         debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu);
131         rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu, xen_debug_interrupt,
132                                      IRQF_DISABLED | IRQF_PERCPU | IRQF_NOBALANCING,
133                                      debug_name, NULL);
134         if (rc < 0)
135                 goto fail;
136         per_cpu(xen_debug_irq, cpu) = rc;
137
138         callfunc_name = kasprintf(GFP_KERNEL, "callfuncsingle%d", cpu);
139         rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_SINGLE_VECTOR,
140                                     cpu,
141                                     xen_call_function_single_interrupt,
142                                     IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
143                                     callfunc_name,
144                                     NULL);
145         if (rc < 0)
146                 goto fail;
147         per_cpu(xen_callfuncsingle_irq, cpu) = rc;
148
149         callfunc_name = kasprintf(GFP_KERNEL, "irqwork%d", cpu);
150         rc = bind_ipi_to_irqhandler(XEN_IRQ_WORK_VECTOR,
151                                     cpu,
152                                     xen_irq_work_interrupt,
153                                     IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
154                                     callfunc_name,
155                                     NULL);
156         if (rc < 0)
157                 goto fail;
158         per_cpu(xen_irq_work, cpu) = rc;
159
160         return 0;
161
162  fail:
163         if (per_cpu(xen_resched_irq, cpu) >= 0)
164                 unbind_from_irqhandler(per_cpu(xen_resched_irq, cpu), NULL);
165         if (per_cpu(xen_callfunc_irq, cpu) >= 0)
166                 unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL);
167         if (per_cpu(xen_debug_irq, cpu) >= 0)
168                 unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL);
169         if (per_cpu(xen_callfuncsingle_irq, cpu) >= 0)
170                 unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu),
171                                        NULL);
172         if (per_cpu(xen_irq_work, cpu) >= 0)
173                 unbind_from_irqhandler(per_cpu(xen_irq_work, cpu), NULL);
174
175         return rc;
176 }
177
178 static void __init xen_fill_possible_map(void)
179 {
180         int i, rc;
181
182         if (xen_initial_domain())
183                 return;
184
185         for (i = 0; i < nr_cpu_ids; i++) {
186                 rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
187                 if (rc >= 0) {
188                         num_processors++;
189                         set_cpu_possible(i, true);
190                 }
191         }
192 }
193
194 static void __init xen_filter_cpu_maps(void)
195 {
196         int i, rc;
197         unsigned int subtract = 0;
198
199         if (!xen_initial_domain())
200                 return;
201
202         num_processors = 0;
203         disabled_cpus = 0;
204         for (i = 0; i < nr_cpu_ids; i++) {
205                 rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
206                 if (rc >= 0) {
207                         num_processors++;
208                         set_cpu_possible(i, true);
209                 } else {
210                         set_cpu_possible(i, false);
211                         set_cpu_present(i, false);
212                         subtract++;
213                 }
214         }
215 #ifdef CONFIG_HOTPLUG_CPU
216         /* This is akin to using 'nr_cpus' on the Linux command line.
217          * Which is OK as when we use 'dom0_max_vcpus=X' we can only
218          * have up to X, while nr_cpu_ids is greater than X. This
219          * normally is not a problem, except when CPU hotplugging
220          * is involved and then there might be more than X CPUs
221          * in the guest - which will not work as there is no
222          * hypercall to expand the max number of VCPUs an already
223          * running guest has. So cap it up to X. */
224         if (subtract)
225                 nr_cpu_ids = nr_cpu_ids - subtract;
226 #endif
227
228 }
229
230 static void __init xen_smp_prepare_boot_cpu(void)
231 {
232         BUG_ON(smp_processor_id() != 0);
233         native_smp_prepare_boot_cpu();
234
235         /* We've switched to the "real" per-cpu gdt, so make sure the
236            old memory can be recycled */
237         make_lowmem_page_readwrite(xen_initial_gdt);
238
239         xen_filter_cpu_maps();
240         xen_setup_vcpu_info_placement();
241 }
242
243 static void __init xen_smp_prepare_cpus(unsigned int max_cpus)
244 {
245         unsigned cpu;
246         unsigned int i;
247
248         if (skip_ioapic_setup) {
249                 char *m = (max_cpus == 0) ?
250                         "The nosmp parameter is incompatible with Xen; " \
251                         "use Xen dom0_max_vcpus=1 parameter" :
252                         "The noapic parameter is incompatible with Xen";
253
254                 xen_raw_printk(m);
255                 panic(m);
256         }
257         xen_init_lock_cpu(0);
258
259         smp_store_cpu_info(0);
260         cpu_data(0).x86_max_cores = 1;
261
262         for_each_possible_cpu(i) {
263                 zalloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL);
264                 zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);
265                 zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL);
266         }
267         set_cpu_sibling_map(0);
268
269         if (xen_smp_intr_init(0))
270                 BUG();
271
272         if (!alloc_cpumask_var(&xen_cpu_initialized_map, GFP_KERNEL))
273                 panic("could not allocate xen_cpu_initialized_map\n");
274
275         cpumask_copy(xen_cpu_initialized_map, cpumask_of(0));
276
277         /* Restrict the possible_map according to max_cpus. */
278         while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) {
279                 for (cpu = nr_cpu_ids - 1; !cpu_possible(cpu); cpu--)
280                         continue;
281                 set_cpu_possible(cpu, false);
282         }
283
284         for_each_possible_cpu(cpu)
285                 set_cpu_present(cpu, true);
286 }
287
288 static int __cpuinit
289 cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
290 {
291         struct vcpu_guest_context *ctxt;
292         struct desc_struct *gdt;
293         unsigned long gdt_mfn;
294
295         if (cpumask_test_and_set_cpu(cpu, xen_cpu_initialized_map))
296                 return 0;
297
298         ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
299         if (ctxt == NULL)
300                 return -ENOMEM;
301
302         gdt = get_cpu_gdt_table(cpu);
303
304         ctxt->flags = VGCF_IN_KERNEL;
305         ctxt->user_regs.ds = __USER_DS;
306         ctxt->user_regs.es = __USER_DS;
307         ctxt->user_regs.ss = __KERNEL_DS;
308 #ifdef CONFIG_X86_32
309         ctxt->user_regs.fs = __KERNEL_PERCPU;
310         ctxt->user_regs.gs = __KERNEL_STACK_CANARY;
311 #else
312         ctxt->gs_base_kernel = per_cpu_offset(cpu);
313 #endif
314         ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle;
315         ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
316
317         memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));
318
319         xen_copy_trap_info(ctxt->trap_ctxt);
320
321         ctxt->ldt_ents = 0;
322
323         BUG_ON((unsigned long)gdt & ~PAGE_MASK);
324
325         gdt_mfn = arbitrary_virt_to_mfn(gdt);
326         make_lowmem_page_readonly(gdt);
327         make_lowmem_page_readonly(mfn_to_virt(gdt_mfn));
328
329         ctxt->gdt_frames[0] = gdt_mfn;
330         ctxt->gdt_ents      = GDT_ENTRIES;
331
332         ctxt->user_regs.cs = __KERNEL_CS;
333         ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs);
334
335         ctxt->kernel_ss = __KERNEL_DS;
336         ctxt->kernel_sp = idle->thread.sp0;
337
338 #ifdef CONFIG_X86_32
339         ctxt->event_callback_cs     = __KERNEL_CS;
340         ctxt->failsafe_callback_cs  = __KERNEL_CS;
341 #endif
342         ctxt->event_callback_eip    = (unsigned long)xen_hypervisor_callback;
343         ctxt->failsafe_callback_eip = (unsigned long)xen_failsafe_callback;
344
345         per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir);
346         ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));
347
348         if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt))
349                 BUG();
350
351         kfree(ctxt);
352         return 0;
353 }
354
355 static int __cpuinit xen_cpu_up(unsigned int cpu, struct task_struct *idle)
356 {
357         int rc;
358
359         per_cpu(current_task, cpu) = idle;
360 #ifdef CONFIG_X86_32
361         irq_ctx_init(cpu);
362 #else
363         clear_tsk_thread_flag(idle, TIF_FORK);
364         per_cpu(kernel_stack, cpu) =
365                 (unsigned long)task_stack_page(idle) -
366                 KERNEL_STACK_OFFSET + THREAD_SIZE;
367 #endif
368         xen_setup_runstate_info(cpu);
369         xen_setup_timer(cpu);
370         xen_init_lock_cpu(cpu);
371
372         per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
373
374         /* make sure interrupts start blocked */
375         per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1;
376
377         rc = cpu_initialize_context(cpu, idle);
378         if (rc)
379                 return rc;
380
381         if (num_online_cpus() == 1)
382                 alternatives_smp_switch(1);
383
384         rc = xen_smp_intr_init(cpu);
385         if (rc)
386                 return rc;
387
388         rc = HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL);
389         BUG_ON(rc);
390
391         while(per_cpu(cpu_state, cpu) != CPU_ONLINE) {
392                 HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
393                 barrier();
394         }
395
396         return 0;
397 }
398
399 static void xen_smp_cpus_done(unsigned int max_cpus)
400 {
401 }
402
403 #ifdef CONFIG_HOTPLUG_CPU
404 static int xen_cpu_disable(void)
405 {
406         unsigned int cpu = smp_processor_id();
407         if (cpu == 0)
408                 return -EBUSY;
409
410         cpu_disable_common();
411
412         load_cr3(swapper_pg_dir);
413         return 0;
414 }
415
416 static void xen_cpu_die(unsigned int cpu)
417 {
418         while (HYPERVISOR_vcpu_op(VCPUOP_is_up, cpu, NULL)) {
419                 current->state = TASK_UNINTERRUPTIBLE;
420                 schedule_timeout(HZ/10);
421         }
422         unbind_from_irqhandler(per_cpu(xen_resched_irq, cpu), NULL);
423         unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL);
424         unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL);
425         unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu), NULL);
426         unbind_from_irqhandler(per_cpu(xen_irq_work, cpu), NULL);
427         xen_uninit_lock_cpu(cpu);
428         xen_teardown_timer(cpu);
429
430         if (num_online_cpus() == 1)
431                 alternatives_smp_switch(0);
432 }
433
434 static void __cpuinit xen_play_dead(void) /* used only with HOTPLUG_CPU */
435 {
436         play_dead_common();
437         HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
438         cpu_bringup();
439         /*
440          * Balance out the preempt calls - as we are running in cpu_idle
441          * loop which has been called at bootup from cpu_bringup_and_idle.
442          * The cpucpu_bringup_and_idle called cpu_bringup which made a
443          * preempt_disable() So this preempt_enable will balance it out.
444          */
445         preempt_enable();
446 }
447
448 #else /* !CONFIG_HOTPLUG_CPU */
449 static int xen_cpu_disable(void)
450 {
451         return -ENOSYS;
452 }
453
454 static void xen_cpu_die(unsigned int cpu)
455 {
456         BUG();
457 }
458
459 static void xen_play_dead(void)
460 {
461         BUG();
462 }
463
464 #endif
465 static void stop_self(void *v)
466 {
467         int cpu = smp_processor_id();
468
469         /* make sure we're not pinning something down */
470         load_cr3(swapper_pg_dir);
471         /* should set up a minimal gdt */
472
473         set_cpu_online(cpu, false);
474
475         HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL);
476         BUG();
477 }
478
479 static void xen_stop_other_cpus(int wait)
480 {
481         smp_call_function(stop_self, NULL, wait);
482 }
483
484 static void xen_smp_send_reschedule(int cpu)
485 {
486         xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR);
487 }
488
489 static void __xen_send_IPI_mask(const struct cpumask *mask,
490                               int vector)
491 {
492         unsigned cpu;
493
494         for_each_cpu_and(cpu, mask, cpu_online_mask)
495                 xen_send_IPI_one(cpu, vector);
496 }
497
498 static void xen_smp_send_call_function_ipi(const struct cpumask *mask)
499 {
500         int cpu;
501
502         __xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR);
503
504         /* Make sure other vcpus get a chance to run if they need to. */
505         for_each_cpu(cpu, mask) {
506                 if (xen_vcpu_stolen(cpu)) {
507                         HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
508                         break;
509                 }
510         }
511 }
512
513 static void xen_smp_send_call_function_single_ipi(int cpu)
514 {
515         __xen_send_IPI_mask(cpumask_of(cpu),
516                           XEN_CALL_FUNCTION_SINGLE_VECTOR);
517 }
518
519 static inline int xen_map_vector(int vector)
520 {
521         int xen_vector;
522
523         switch (vector) {
524         case RESCHEDULE_VECTOR:
525                 xen_vector = XEN_RESCHEDULE_VECTOR;
526                 break;
527         case CALL_FUNCTION_VECTOR:
528                 xen_vector = XEN_CALL_FUNCTION_VECTOR;
529                 break;
530         case CALL_FUNCTION_SINGLE_VECTOR:
531                 xen_vector = XEN_CALL_FUNCTION_SINGLE_VECTOR;
532                 break;
533         case IRQ_WORK_VECTOR:
534                 xen_vector = XEN_IRQ_WORK_VECTOR;
535                 break;
536         default:
537                 xen_vector = -1;
538                 printk(KERN_ERR "xen: vector 0x%x is not implemented\n",
539                         vector);
540         }
541
542         return xen_vector;
543 }
544
545 void xen_send_IPI_mask(const struct cpumask *mask,
546                               int vector)
547 {
548         int xen_vector = xen_map_vector(vector);
549
550         if (xen_vector >= 0)
551                 __xen_send_IPI_mask(mask, xen_vector);
552 }
553
554 void xen_send_IPI_all(int vector)
555 {
556         int xen_vector = xen_map_vector(vector);
557
558         if (xen_vector >= 0)
559                 __xen_send_IPI_mask(cpu_online_mask, xen_vector);
560 }
561
562 void xen_send_IPI_self(int vector)
563 {
564         int xen_vector = xen_map_vector(vector);
565
566         if (xen_vector >= 0)
567                 xen_send_IPI_one(smp_processor_id(), xen_vector);
568 }
569
570 void xen_send_IPI_mask_allbutself(const struct cpumask *mask,
571                                 int vector)
572 {
573         unsigned cpu;
574         unsigned int this_cpu = smp_processor_id();
575
576         if (!(num_online_cpus() > 1))
577                 return;
578
579         for_each_cpu_and(cpu, mask, cpu_online_mask) {
580                 if (this_cpu == cpu)
581                         continue;
582
583                 xen_smp_send_call_function_single_ipi(cpu);
584         }
585 }
586
587 void xen_send_IPI_allbutself(int vector)
588 {
589         int xen_vector = xen_map_vector(vector);
590
591         if (xen_vector >= 0)
592                 xen_send_IPI_mask_allbutself(cpu_online_mask, xen_vector);
593 }
594
595 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id)
596 {
597         irq_enter();
598         generic_smp_call_function_interrupt();
599         inc_irq_stat(irq_call_count);
600         irq_exit();
601
602         return IRQ_HANDLED;
603 }
604
605 static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id)
606 {
607         irq_enter();
608         generic_smp_call_function_single_interrupt();
609         inc_irq_stat(irq_call_count);
610         irq_exit();
611
612         return IRQ_HANDLED;
613 }
614
615 static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id)
616 {
617         irq_enter();
618         irq_work_run();
619         inc_irq_stat(apic_irq_work_irqs);
620         irq_exit();
621
622         return IRQ_HANDLED;
623 }
624
625 static const struct smp_ops xen_smp_ops __initconst = {
626         .smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu,
627         .smp_prepare_cpus = xen_smp_prepare_cpus,
628         .smp_cpus_done = xen_smp_cpus_done,
629
630         .cpu_up = xen_cpu_up,
631         .cpu_die = xen_cpu_die,
632         .cpu_disable = xen_cpu_disable,
633         .play_dead = xen_play_dead,
634
635         .stop_other_cpus = xen_stop_other_cpus,
636         .smp_send_reschedule = xen_smp_send_reschedule,
637
638         .send_call_func_ipi = xen_smp_send_call_function_ipi,
639         .send_call_func_single_ipi = xen_smp_send_call_function_single_ipi,
640 };
641
642 void __init xen_smp_init(void)
643 {
644         smp_ops = xen_smp_ops;
645         xen_fill_possible_map();
646         xen_init_spinlocks();
647 }
648
649 static void __init xen_hvm_smp_prepare_cpus(unsigned int max_cpus)
650 {
651         native_smp_prepare_cpus(max_cpus);
652         WARN_ON(xen_smp_intr_init(0));
653
654         xen_init_lock_cpu(0);
655 }
656
657 static int __cpuinit xen_hvm_cpu_up(unsigned int cpu, struct task_struct *tidle)
658 {
659         int rc;
660         rc = native_cpu_up(cpu, tidle);
661         WARN_ON (xen_smp_intr_init(cpu));
662         return rc;
663 }
664
665 static void xen_hvm_cpu_die(unsigned int cpu)
666 {
667         unbind_from_irqhandler(per_cpu(xen_resched_irq, cpu), NULL);
668         unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL);
669         unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL);
670         unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu), NULL);
671         unbind_from_irqhandler(per_cpu(xen_irq_work, cpu), NULL);
672         native_cpu_die(cpu);
673 }
674
675 void __init xen_hvm_smp_init(void)
676 {
677         if (!xen_have_vector_callback)
678                 return;
679         smp_ops.smp_prepare_cpus = xen_hvm_smp_prepare_cpus;
680         smp_ops.smp_send_reschedule = xen_smp_send_reschedule;
681         smp_ops.cpu_up = xen_hvm_cpu_up;
682         smp_ops.cpu_die = xen_hvm_cpu_die;
683         smp_ops.send_call_func_ipi = xen_smp_send_call_function_ipi;
684         smp_ops.send_call_func_single_ipi = xen_smp_send_call_function_single_ipi;
685 }