xref: /openbmc/linux/arch/x86/xen/smp.c (revision 5104d265)
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 #include <linux/tick.h>
21 
22 #include <asm/paravirt.h>
23 #include <asm/desc.h>
24 #include <asm/pgtable.h>
25 #include <asm/cpu.h>
26 
27 #include <xen/interface/xen.h>
28 #include <xen/interface/vcpu.h>
29 
30 #include <asm/xen/interface.h>
31 #include <asm/xen/hypercall.h>
32 
33 #include <xen/xen.h>
34 #include <xen/page.h>
35 #include <xen/events.h>
36 
37 #include <xen/hvc-console.h>
38 #include "xen-ops.h"
39 #include "mmu.h"
40 
41 cpumask_var_t xen_cpu_initialized_map;
42 
43 struct xen_common_irq {
44 	int irq;
45 	char *name;
46 };
47 static DEFINE_PER_CPU(struct xen_common_irq, xen_resched_irq) = { .irq = -1 };
48 static DEFINE_PER_CPU(struct xen_common_irq, xen_callfunc_irq) = { .irq = -1 };
49 static DEFINE_PER_CPU(struct xen_common_irq, xen_callfuncsingle_irq) = { .irq = -1 };
50 static DEFINE_PER_CPU(struct xen_common_irq, xen_irq_work) = { .irq = -1 };
51 static DEFINE_PER_CPU(struct xen_common_irq, xen_debug_irq) = { .irq = -1 };
52 
53 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id);
54 static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id);
55 static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id);
56 
57 /*
58  * Reschedule call back.
59  */
60 static irqreturn_t xen_reschedule_interrupt(int irq, void *dev_id)
61 {
62 	inc_irq_stat(irq_resched_count);
63 	scheduler_ipi();
64 
65 	return IRQ_HANDLED;
66 }
67 
68 static void cpu_bringup(void)
69 {
70 	int cpu;
71 
72 	cpu_init();
73 	touch_softlockup_watchdog();
74 	preempt_disable();
75 
76 	xen_enable_sysenter();
77 	xen_enable_syscall();
78 
79 	cpu = smp_processor_id();
80 	smp_store_cpu_info(cpu);
81 	cpu_data(cpu).x86_max_cores = 1;
82 	set_cpu_sibling_map(cpu);
83 
84 	xen_setup_cpu_clockevents();
85 
86 	notify_cpu_starting(cpu);
87 
88 	set_cpu_online(cpu, true);
89 
90 	this_cpu_write(cpu_state, CPU_ONLINE);
91 
92 	wmb();
93 
94 	/* We can take interrupts now: we're officially "up". */
95 	local_irq_enable();
96 
97 	wmb();			/* make sure everything is out */
98 }
99 
100 static void cpu_bringup_and_idle(void)
101 {
102 	cpu_bringup();
103 	cpu_startup_entry(CPUHP_ONLINE);
104 }
105 
106 static void xen_smp_intr_free(unsigned int cpu)
107 {
108 	if (per_cpu(xen_resched_irq, cpu).irq >= 0) {
109 		unbind_from_irqhandler(per_cpu(xen_resched_irq, cpu).irq, NULL);
110 		per_cpu(xen_resched_irq, cpu).irq = -1;
111 		kfree(per_cpu(xen_resched_irq, cpu).name);
112 		per_cpu(xen_resched_irq, cpu).name = NULL;
113 	}
114 	if (per_cpu(xen_callfunc_irq, cpu).irq >= 0) {
115 		unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu).irq, NULL);
116 		per_cpu(xen_callfunc_irq, cpu).irq = -1;
117 		kfree(per_cpu(xen_callfunc_irq, cpu).name);
118 		per_cpu(xen_callfunc_irq, cpu).name = NULL;
119 	}
120 	if (per_cpu(xen_debug_irq, cpu).irq >= 0) {
121 		unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu).irq, NULL);
122 		per_cpu(xen_debug_irq, cpu).irq = -1;
123 		kfree(per_cpu(xen_debug_irq, cpu).name);
124 		per_cpu(xen_debug_irq, cpu).name = NULL;
125 	}
126 	if (per_cpu(xen_callfuncsingle_irq, cpu).irq >= 0) {
127 		unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu).irq,
128 				       NULL);
129 		per_cpu(xen_callfuncsingle_irq, cpu).irq = -1;
130 		kfree(per_cpu(xen_callfuncsingle_irq, cpu).name);
131 		per_cpu(xen_callfuncsingle_irq, cpu).name = NULL;
132 	}
133 	if (xen_hvm_domain())
134 		return;
135 
136 	if (per_cpu(xen_irq_work, cpu).irq >= 0) {
137 		unbind_from_irqhandler(per_cpu(xen_irq_work, cpu).irq, NULL);
138 		per_cpu(xen_irq_work, cpu).irq = -1;
139 		kfree(per_cpu(xen_irq_work, cpu).name);
140 		per_cpu(xen_irq_work, cpu).name = NULL;
141 	}
142 };
143 static int xen_smp_intr_init(unsigned int cpu)
144 {
145 	int rc;
146 	char *resched_name, *callfunc_name, *debug_name;
147 
148 	resched_name = kasprintf(GFP_KERNEL, "resched%d", cpu);
149 	rc = bind_ipi_to_irqhandler(XEN_RESCHEDULE_VECTOR,
150 				    cpu,
151 				    xen_reschedule_interrupt,
152 				    IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
153 				    resched_name,
154 				    NULL);
155 	if (rc < 0)
156 		goto fail;
157 	per_cpu(xen_resched_irq, cpu).irq = rc;
158 	per_cpu(xen_resched_irq, cpu).name = resched_name;
159 
160 	callfunc_name = kasprintf(GFP_KERNEL, "callfunc%d", cpu);
161 	rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_VECTOR,
162 				    cpu,
163 				    xen_call_function_interrupt,
164 				    IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
165 				    callfunc_name,
166 				    NULL);
167 	if (rc < 0)
168 		goto fail;
169 	per_cpu(xen_callfunc_irq, cpu).irq = rc;
170 	per_cpu(xen_callfunc_irq, cpu).name = callfunc_name;
171 
172 	debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu);
173 	rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu, xen_debug_interrupt,
174 				     IRQF_DISABLED | IRQF_PERCPU | IRQF_NOBALANCING,
175 				     debug_name, NULL);
176 	if (rc < 0)
177 		goto fail;
178 	per_cpu(xen_debug_irq, cpu).irq = rc;
179 	per_cpu(xen_debug_irq, cpu).name = debug_name;
180 
181 	callfunc_name = kasprintf(GFP_KERNEL, "callfuncsingle%d", cpu);
182 	rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_SINGLE_VECTOR,
183 				    cpu,
184 				    xen_call_function_single_interrupt,
185 				    IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
186 				    callfunc_name,
187 				    NULL);
188 	if (rc < 0)
189 		goto fail;
190 	per_cpu(xen_callfuncsingle_irq, cpu).irq = rc;
191 	per_cpu(xen_callfuncsingle_irq, cpu).name = callfunc_name;
192 
193 	/*
194 	 * The IRQ worker on PVHVM goes through the native path and uses the
195 	 * IPI mechanism.
196 	 */
197 	if (xen_hvm_domain())
198 		return 0;
199 
200 	callfunc_name = kasprintf(GFP_KERNEL, "irqwork%d", cpu);
201 	rc = bind_ipi_to_irqhandler(XEN_IRQ_WORK_VECTOR,
202 				    cpu,
203 				    xen_irq_work_interrupt,
204 				    IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
205 				    callfunc_name,
206 				    NULL);
207 	if (rc < 0)
208 		goto fail;
209 	per_cpu(xen_irq_work, cpu).irq = rc;
210 	per_cpu(xen_irq_work, cpu).name = callfunc_name;
211 
212 	return 0;
213 
214  fail:
215 	xen_smp_intr_free(cpu);
216 	return rc;
217 }
218 
219 static void __init xen_fill_possible_map(void)
220 {
221 	int i, rc;
222 
223 	if (xen_initial_domain())
224 		return;
225 
226 	for (i = 0; i < nr_cpu_ids; i++) {
227 		rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
228 		if (rc >= 0) {
229 			num_processors++;
230 			set_cpu_possible(i, true);
231 		}
232 	}
233 }
234 
235 static void __init xen_filter_cpu_maps(void)
236 {
237 	int i, rc;
238 	unsigned int subtract = 0;
239 
240 	if (!xen_initial_domain())
241 		return;
242 
243 	num_processors = 0;
244 	disabled_cpus = 0;
245 	for (i = 0; i < nr_cpu_ids; i++) {
246 		rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
247 		if (rc >= 0) {
248 			num_processors++;
249 			set_cpu_possible(i, true);
250 		} else {
251 			set_cpu_possible(i, false);
252 			set_cpu_present(i, false);
253 			subtract++;
254 		}
255 	}
256 #ifdef CONFIG_HOTPLUG_CPU
257 	/* This is akin to using 'nr_cpus' on the Linux command line.
258 	 * Which is OK as when we use 'dom0_max_vcpus=X' we can only
259 	 * have up to X, while nr_cpu_ids is greater than X. This
260 	 * normally is not a problem, except when CPU hotplugging
261 	 * is involved and then there might be more than X CPUs
262 	 * in the guest - which will not work as there is no
263 	 * hypercall to expand the max number of VCPUs an already
264 	 * running guest has. So cap it up to X. */
265 	if (subtract)
266 		nr_cpu_ids = nr_cpu_ids - subtract;
267 #endif
268 
269 }
270 
271 static void __init xen_smp_prepare_boot_cpu(void)
272 {
273 	BUG_ON(smp_processor_id() != 0);
274 	native_smp_prepare_boot_cpu();
275 
276 	/* We've switched to the "real" per-cpu gdt, so make sure the
277 	   old memory can be recycled */
278 	make_lowmem_page_readwrite(xen_initial_gdt);
279 
280 	xen_filter_cpu_maps();
281 	xen_setup_vcpu_info_placement();
282 }
283 
284 static void __init xen_smp_prepare_cpus(unsigned int max_cpus)
285 {
286 	unsigned cpu;
287 	unsigned int i;
288 
289 	if (skip_ioapic_setup) {
290 		char *m = (max_cpus == 0) ?
291 			"The nosmp parameter is incompatible with Xen; " \
292 			"use Xen dom0_max_vcpus=1 parameter" :
293 			"The noapic parameter is incompatible with Xen";
294 
295 		xen_raw_printk(m);
296 		panic(m);
297 	}
298 	xen_init_lock_cpu(0);
299 
300 	smp_store_boot_cpu_info();
301 	cpu_data(0).x86_max_cores = 1;
302 
303 	for_each_possible_cpu(i) {
304 		zalloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL);
305 		zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);
306 		zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL);
307 	}
308 	set_cpu_sibling_map(0);
309 
310 	if (xen_smp_intr_init(0))
311 		BUG();
312 
313 	if (!alloc_cpumask_var(&xen_cpu_initialized_map, GFP_KERNEL))
314 		panic("could not allocate xen_cpu_initialized_map\n");
315 
316 	cpumask_copy(xen_cpu_initialized_map, cpumask_of(0));
317 
318 	/* Restrict the possible_map according to max_cpus. */
319 	while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) {
320 		for (cpu = nr_cpu_ids - 1; !cpu_possible(cpu); cpu--)
321 			continue;
322 		set_cpu_possible(cpu, false);
323 	}
324 
325 	for_each_possible_cpu(cpu)
326 		set_cpu_present(cpu, true);
327 }
328 
329 static int
330 cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
331 {
332 	struct vcpu_guest_context *ctxt;
333 	struct desc_struct *gdt;
334 	unsigned long gdt_mfn;
335 
336 	if (cpumask_test_and_set_cpu(cpu, xen_cpu_initialized_map))
337 		return 0;
338 
339 	ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
340 	if (ctxt == NULL)
341 		return -ENOMEM;
342 
343 	gdt = get_cpu_gdt_table(cpu);
344 
345 	ctxt->flags = VGCF_IN_KERNEL;
346 	ctxt->user_regs.ss = __KERNEL_DS;
347 #ifdef CONFIG_X86_32
348 	ctxt->user_regs.fs = __KERNEL_PERCPU;
349 	ctxt->user_regs.gs = __KERNEL_STACK_CANARY;
350 #else
351 	ctxt->gs_base_kernel = per_cpu_offset(cpu);
352 #endif
353 	ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle;
354 
355 	memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));
356 
357 	{
358 		ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
359 		ctxt->user_regs.ds = __USER_DS;
360 		ctxt->user_regs.es = __USER_DS;
361 
362 		xen_copy_trap_info(ctxt->trap_ctxt);
363 
364 		ctxt->ldt_ents = 0;
365 
366 		BUG_ON((unsigned long)gdt & ~PAGE_MASK);
367 
368 		gdt_mfn = arbitrary_virt_to_mfn(gdt);
369 		make_lowmem_page_readonly(gdt);
370 		make_lowmem_page_readonly(mfn_to_virt(gdt_mfn));
371 
372 		ctxt->gdt_frames[0] = gdt_mfn;
373 		ctxt->gdt_ents      = GDT_ENTRIES;
374 
375 		ctxt->kernel_ss = __KERNEL_DS;
376 		ctxt->kernel_sp = idle->thread.sp0;
377 
378 #ifdef CONFIG_X86_32
379 		ctxt->event_callback_cs     = __KERNEL_CS;
380 		ctxt->failsafe_callback_cs  = __KERNEL_CS;
381 #endif
382 		ctxt->event_callback_eip    =
383 					(unsigned long)xen_hypervisor_callback;
384 		ctxt->failsafe_callback_eip =
385 					(unsigned long)xen_failsafe_callback;
386 	}
387 	ctxt->user_regs.cs = __KERNEL_CS;
388 	ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs);
389 
390 	per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir);
391 	ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));
392 
393 	if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt))
394 		BUG();
395 
396 	kfree(ctxt);
397 	return 0;
398 }
399 
400 static int xen_cpu_up(unsigned int cpu, struct task_struct *idle)
401 {
402 	int rc;
403 
404 	per_cpu(current_task, cpu) = idle;
405 #ifdef CONFIG_X86_32
406 	irq_ctx_init(cpu);
407 #else
408 	clear_tsk_thread_flag(idle, TIF_FORK);
409 	per_cpu(kernel_stack, cpu) =
410 		(unsigned long)task_stack_page(idle) -
411 		KERNEL_STACK_OFFSET + THREAD_SIZE;
412 #endif
413 	xen_setup_runstate_info(cpu);
414 	xen_setup_timer(cpu);
415 	xen_init_lock_cpu(cpu);
416 
417 	per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
418 
419 	/* make sure interrupts start blocked */
420 	per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1;
421 
422 	rc = cpu_initialize_context(cpu, idle);
423 	if (rc)
424 		return rc;
425 
426 	if (num_online_cpus() == 1)
427 		/* Just in case we booted with a single CPU. */
428 		alternatives_enable_smp();
429 
430 	rc = xen_smp_intr_init(cpu);
431 	if (rc)
432 		return rc;
433 
434 	rc = HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL);
435 	BUG_ON(rc);
436 
437 	while(per_cpu(cpu_state, cpu) != CPU_ONLINE) {
438 		HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
439 		barrier();
440 	}
441 
442 	return 0;
443 }
444 
445 static void xen_smp_cpus_done(unsigned int max_cpus)
446 {
447 }
448 
449 #ifdef CONFIG_HOTPLUG_CPU
450 static int xen_cpu_disable(void)
451 {
452 	unsigned int cpu = smp_processor_id();
453 	if (cpu == 0)
454 		return -EBUSY;
455 
456 	cpu_disable_common();
457 
458 	load_cr3(swapper_pg_dir);
459 	return 0;
460 }
461 
462 static void xen_cpu_die(unsigned int cpu)
463 {
464 	while (xen_pv_domain() && HYPERVISOR_vcpu_op(VCPUOP_is_up, cpu, NULL)) {
465 		current->state = TASK_UNINTERRUPTIBLE;
466 		schedule_timeout(HZ/10);
467 	}
468 	xen_smp_intr_free(cpu);
469 	xen_uninit_lock_cpu(cpu);
470 	xen_teardown_timer(cpu);
471 }
472 
473 static void xen_play_dead(void) /* used only with HOTPLUG_CPU */
474 {
475 	play_dead_common();
476 	HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
477 	cpu_bringup();
478 	/*
479 	 * commit 4b0c0f294 (tick: Cleanup NOHZ per cpu data on cpu down)
480 	 * clears certain data that the cpu_idle loop (which called us
481 	 * and that we return from) expects. The only way to get that
482 	 * data back is to call:
483 	 */
484 	tick_nohz_idle_enter();
485 }
486 
487 #else /* !CONFIG_HOTPLUG_CPU */
488 static int xen_cpu_disable(void)
489 {
490 	return -ENOSYS;
491 }
492 
493 static void xen_cpu_die(unsigned int cpu)
494 {
495 	BUG();
496 }
497 
498 static void xen_play_dead(void)
499 {
500 	BUG();
501 }
502 
503 #endif
504 static void stop_self(void *v)
505 {
506 	int cpu = smp_processor_id();
507 
508 	/* make sure we're not pinning something down */
509 	load_cr3(swapper_pg_dir);
510 	/* should set up a minimal gdt */
511 
512 	set_cpu_online(cpu, false);
513 
514 	HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL);
515 	BUG();
516 }
517 
518 static void xen_stop_other_cpus(int wait)
519 {
520 	smp_call_function(stop_self, NULL, wait);
521 }
522 
523 static void xen_smp_send_reschedule(int cpu)
524 {
525 	xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR);
526 }
527 
528 static void __xen_send_IPI_mask(const struct cpumask *mask,
529 			      int vector)
530 {
531 	unsigned cpu;
532 
533 	for_each_cpu_and(cpu, mask, cpu_online_mask)
534 		xen_send_IPI_one(cpu, vector);
535 }
536 
537 static void xen_smp_send_call_function_ipi(const struct cpumask *mask)
538 {
539 	int cpu;
540 
541 	__xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR);
542 
543 	/* Make sure other vcpus get a chance to run if they need to. */
544 	for_each_cpu(cpu, mask) {
545 		if (xen_vcpu_stolen(cpu)) {
546 			HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
547 			break;
548 		}
549 	}
550 }
551 
552 static void xen_smp_send_call_function_single_ipi(int cpu)
553 {
554 	__xen_send_IPI_mask(cpumask_of(cpu),
555 			  XEN_CALL_FUNCTION_SINGLE_VECTOR);
556 }
557 
558 static inline int xen_map_vector(int vector)
559 {
560 	int xen_vector;
561 
562 	switch (vector) {
563 	case RESCHEDULE_VECTOR:
564 		xen_vector = XEN_RESCHEDULE_VECTOR;
565 		break;
566 	case CALL_FUNCTION_VECTOR:
567 		xen_vector = XEN_CALL_FUNCTION_VECTOR;
568 		break;
569 	case CALL_FUNCTION_SINGLE_VECTOR:
570 		xen_vector = XEN_CALL_FUNCTION_SINGLE_VECTOR;
571 		break;
572 	case IRQ_WORK_VECTOR:
573 		xen_vector = XEN_IRQ_WORK_VECTOR;
574 		break;
575 	default:
576 		xen_vector = -1;
577 		printk(KERN_ERR "xen: vector 0x%x is not implemented\n",
578 			vector);
579 	}
580 
581 	return xen_vector;
582 }
583 
584 void xen_send_IPI_mask(const struct cpumask *mask,
585 			      int vector)
586 {
587 	int xen_vector = xen_map_vector(vector);
588 
589 	if (xen_vector >= 0)
590 		__xen_send_IPI_mask(mask, xen_vector);
591 }
592 
593 void xen_send_IPI_all(int vector)
594 {
595 	int xen_vector = xen_map_vector(vector);
596 
597 	if (xen_vector >= 0)
598 		__xen_send_IPI_mask(cpu_online_mask, xen_vector);
599 }
600 
601 void xen_send_IPI_self(int vector)
602 {
603 	int xen_vector = xen_map_vector(vector);
604 
605 	if (xen_vector >= 0)
606 		xen_send_IPI_one(smp_processor_id(), xen_vector);
607 }
608 
609 void xen_send_IPI_mask_allbutself(const struct cpumask *mask,
610 				int vector)
611 {
612 	unsigned cpu;
613 	unsigned int this_cpu = smp_processor_id();
614 	int xen_vector = xen_map_vector(vector);
615 
616 	if (!(num_online_cpus() > 1) || (xen_vector < 0))
617 		return;
618 
619 	for_each_cpu_and(cpu, mask, cpu_online_mask) {
620 		if (this_cpu == cpu)
621 			continue;
622 
623 		xen_send_IPI_one(cpu, xen_vector);
624 	}
625 }
626 
627 void xen_send_IPI_allbutself(int vector)
628 {
629 	xen_send_IPI_mask_allbutself(cpu_online_mask, vector);
630 }
631 
632 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id)
633 {
634 	irq_enter();
635 	generic_smp_call_function_interrupt();
636 	inc_irq_stat(irq_call_count);
637 	irq_exit();
638 
639 	return IRQ_HANDLED;
640 }
641 
642 static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id)
643 {
644 	irq_enter();
645 	generic_smp_call_function_single_interrupt();
646 	inc_irq_stat(irq_call_count);
647 	irq_exit();
648 
649 	return IRQ_HANDLED;
650 }
651 
652 static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id)
653 {
654 	irq_enter();
655 	irq_work_run();
656 	inc_irq_stat(apic_irq_work_irqs);
657 	irq_exit();
658 
659 	return IRQ_HANDLED;
660 }
661 
662 static const struct smp_ops xen_smp_ops __initconst = {
663 	.smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu,
664 	.smp_prepare_cpus = xen_smp_prepare_cpus,
665 	.smp_cpus_done = xen_smp_cpus_done,
666 
667 	.cpu_up = xen_cpu_up,
668 	.cpu_die = xen_cpu_die,
669 	.cpu_disable = xen_cpu_disable,
670 	.play_dead = xen_play_dead,
671 
672 	.stop_other_cpus = xen_stop_other_cpus,
673 	.smp_send_reschedule = xen_smp_send_reschedule,
674 
675 	.send_call_func_ipi = xen_smp_send_call_function_ipi,
676 	.send_call_func_single_ipi = xen_smp_send_call_function_single_ipi,
677 };
678 
679 void __init xen_smp_init(void)
680 {
681 	smp_ops = xen_smp_ops;
682 	xen_fill_possible_map();
683 	xen_init_spinlocks();
684 }
685 
686 static void __init xen_hvm_smp_prepare_cpus(unsigned int max_cpus)
687 {
688 	native_smp_prepare_cpus(max_cpus);
689 	WARN_ON(xen_smp_intr_init(0));
690 
691 	xen_init_lock_cpu(0);
692 }
693 
694 static int xen_hvm_cpu_up(unsigned int cpu, struct task_struct *tidle)
695 {
696 	int rc;
697 	rc = native_cpu_up(cpu, tidle);
698 	WARN_ON (xen_smp_intr_init(cpu));
699 	return rc;
700 }
701 
702 static void xen_hvm_cpu_die(unsigned int cpu)
703 {
704 	xen_cpu_die(cpu);
705 	native_cpu_die(cpu);
706 }
707 
708 void __init xen_hvm_smp_init(void)
709 {
710 	if (!xen_have_vector_callback)
711 		return;
712 	smp_ops.smp_prepare_cpus = xen_hvm_smp_prepare_cpus;
713 	smp_ops.smp_send_reschedule = xen_smp_send_reschedule;
714 	smp_ops.cpu_up = xen_hvm_cpu_up;
715 	smp_ops.cpu_die = xen_hvm_cpu_die;
716 	smp_ops.send_call_func_ipi = xen_smp_send_call_function_ipi;
717 	smp_ops.send_call_func_single_ipi = xen_smp_send_call_function_single_ipi;
718 }
719