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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * KVM paravirt_ops implementation
4 *
5 * Copyright (C) 2007, Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
6 * Copyright IBM Corporation, 2007
7 * Authors: Anthony Liguori <aliguori@us.ibm.com>
8 */
9
10#include <linux/context_tracking.h>
11#include <linux/init.h>
12#include <linux/kernel.h>
13#include <linux/kvm_para.h>
14#include <linux/cpu.h>
15#include <linux/mm.h>
16#include <linux/highmem.h>
17#include <linux/hardirq.h>
18#include <linux/notifier.h>
19#include <linux/reboot.h>
20#include <linux/hash.h>
21#include <linux/sched.h>
22#include <linux/slab.h>
23#include <linux/kprobes.h>
24#include <linux/debugfs.h>
25#include <linux/nmi.h>
26#include <linux/swait.h>
27#include <asm/timer.h>
28#include <asm/cpu.h>
29#include <asm/traps.h>
30#include <asm/desc.h>
31#include <asm/tlbflush.h>
32#include <asm/apic.h>
33#include <asm/apicdef.h>
34#include <asm/hypervisor.h>
35#include <asm/tlb.h>
36
37static int kvmapf = 1;
38
39static int __init parse_no_kvmapf(char *arg)
40{
41 kvmapf = 0;
42 return 0;
43}
44
45early_param("no-kvmapf", parse_no_kvmapf);
46
47static int steal_acc = 1;
48static int __init parse_no_stealacc(char *arg)
49{
50 steal_acc = 0;
51 return 0;
52}
53
54early_param("no-steal-acc", parse_no_stealacc);
55
56static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
57DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64) __visible;
58static int has_steal_clock = 0;
59
60/*
61 * No need for any "IO delay" on KVM
62 */
63static void kvm_io_delay(void)
64{
65}
66
67#define KVM_TASK_SLEEP_HASHBITS 8
68#define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
69
70struct kvm_task_sleep_node {
71 struct hlist_node link;
72 struct swait_queue_head wq;
73 u32 token;
74 int cpu;
75 bool halted;
76};
77
78static struct kvm_task_sleep_head {
79 raw_spinlock_t lock;
80 struct hlist_head list;
81} async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
82
83static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
84 u32 token)
85{
86 struct hlist_node *p;
87
88 hlist_for_each(p, &b->list) {
89 struct kvm_task_sleep_node *n =
90 hlist_entry(p, typeof(*n), link);
91 if (n->token == token)
92 return n;
93 }
94
95 return NULL;
96}
97
98/*
99 * @interrupt_kernel: Is this called from a routine which interrupts the kernel
100 * (other than user space)?
101 */
102void kvm_async_pf_task_wait(u32 token, int interrupt_kernel)
103{
104 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
105 struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
106 struct kvm_task_sleep_node n, *e;
107 DECLARE_SWAITQUEUE(wait);
108
109 rcu_irq_enter();
110
111 raw_spin_lock(&b->lock);
112 e = _find_apf_task(b, token);
113 if (e) {
114 /* dummy entry exist -> wake up was delivered ahead of PF */
115 hlist_del(&e->link);
116 kfree(e);
117 raw_spin_unlock(&b->lock);
118
119 rcu_irq_exit();
120 return;
121 }
122
123 n.token = token;
124 n.cpu = smp_processor_id();
125 n.halted = is_idle_task(current) ||
126 (IS_ENABLED(CONFIG_PREEMPT_COUNT)
127 ? preempt_count() > 1 || rcu_preempt_depth()
128 : interrupt_kernel);
129 init_swait_queue_head(&n.wq);
130 hlist_add_head(&n.link, &b->list);
131 raw_spin_unlock(&b->lock);
132
133 for (;;) {
134 if (!n.halted)
135 prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
136 if (hlist_unhashed(&n.link))
137 break;
138
139 rcu_irq_exit();
140
141 if (!n.halted) {
142 local_irq_enable();
143 schedule();
144 local_irq_disable();
145 } else {
146 /*
147 * We cannot reschedule. So halt.
148 */
149 native_safe_halt();
150 local_irq_disable();
151 }
152
153 rcu_irq_enter();
154 }
155 if (!n.halted)
156 finish_swait(&n.wq, &wait);
157
158 rcu_irq_exit();
159 return;
160}
161EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait);
162
163static void apf_task_wake_one(struct kvm_task_sleep_node *n)
164{
165 hlist_del_init(&n->link);
166 if (n->halted)
167 smp_send_reschedule(n->cpu);
168 else if (swq_has_sleeper(&n->wq))
169 swake_up_one(&n->wq);
170}
171
172static void apf_task_wake_all(void)
173{
174 int i;
175
176 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
177 struct hlist_node *p, *next;
178 struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
179 raw_spin_lock(&b->lock);
180 hlist_for_each_safe(p, next, &b->list) {
181 struct kvm_task_sleep_node *n =
182 hlist_entry(p, typeof(*n), link);
183 if (n->cpu == smp_processor_id())
184 apf_task_wake_one(n);
185 }
186 raw_spin_unlock(&b->lock);
187 }
188}
189
190void kvm_async_pf_task_wake(u32 token)
191{
192 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
193 struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
194 struct kvm_task_sleep_node *n;
195
196 if (token == ~0) {
197 apf_task_wake_all();
198 return;
199 }
200
201again:
202 raw_spin_lock(&b->lock);
203 n = _find_apf_task(b, token);
204 if (!n) {
205 /*
206 * async PF was not yet handled.
207 * Add dummy entry for the token.
208 */
209 n = kzalloc(sizeof(*n), GFP_ATOMIC);
210 if (!n) {
211 /*
212 * Allocation failed! Busy wait while other cpu
213 * handles async PF.
214 */
215 raw_spin_unlock(&b->lock);
216 cpu_relax();
217 goto again;
218 }
219 n->token = token;
220 n->cpu = smp_processor_id();
221 init_swait_queue_head(&n->wq);
222 hlist_add_head(&n->link, &b->list);
223 } else
224 apf_task_wake_one(n);
225 raw_spin_unlock(&b->lock);
226 return;
227}
228EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
229
230u32 kvm_read_and_reset_pf_reason(void)
231{
232 u32 reason = 0;
233
234 if (__this_cpu_read(apf_reason.enabled)) {
235 reason = __this_cpu_read(apf_reason.reason);
236 __this_cpu_write(apf_reason.reason, 0);
237 }
238
239 return reason;
240}
241EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason);
242NOKPROBE_SYMBOL(kvm_read_and_reset_pf_reason);
243
244dotraplinkage void
245do_async_page_fault(struct pt_regs *regs, unsigned long error_code, unsigned long address)
246{
247 enum ctx_state prev_state;
248
249 switch (kvm_read_and_reset_pf_reason()) {
250 default:
251 do_page_fault(regs, error_code, address);
252 break;
253 case KVM_PV_REASON_PAGE_NOT_PRESENT:
254 /* page is swapped out by the host. */
255 prev_state = exception_enter();
256 kvm_async_pf_task_wait((u32)address, !user_mode(regs));
257 exception_exit(prev_state);
258 break;
259 case KVM_PV_REASON_PAGE_READY:
260 rcu_irq_enter();
261 kvm_async_pf_task_wake((u32)address);
262 rcu_irq_exit();
263 break;
264 }
265}
266NOKPROBE_SYMBOL(do_async_page_fault);
267
268static void __init paravirt_ops_setup(void)
269{
270 pv_info.name = "KVM";
271
272 if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
273 pv_ops.cpu.io_delay = kvm_io_delay;
274
275#ifdef CONFIG_X86_IO_APIC
276 no_timer_check = 1;
277#endif
278}
279
280static void kvm_register_steal_time(void)
281{
282 int cpu = smp_processor_id();
283 struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
284
285 if (!has_steal_clock)
286 return;
287
288 wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
289 pr_info("kvm-stealtime: cpu %d, msr %llx\n",
290 cpu, (unsigned long long) slow_virt_to_phys(st));
291}
292
293static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
294
295static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val)
296{
297 /**
298 * This relies on __test_and_clear_bit to modify the memory
299 * in a way that is atomic with respect to the local CPU.
300 * The hypervisor only accesses this memory from the local CPU so
301 * there's no need for lock or memory barriers.
302 * An optimization barrier is implied in apic write.
303 */
304 if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi)))
305 return;
306 apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK);
307}
308
309static void kvm_guest_cpu_init(void)
310{
311 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) {
312 u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
313
314#ifdef CONFIG_PREEMPTION
315 pa |= KVM_ASYNC_PF_SEND_ALWAYS;
316#endif
317 pa |= KVM_ASYNC_PF_ENABLED;
318
319 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
320 pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
321
322 wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
323 __this_cpu_write(apf_reason.enabled, 1);
324 printk(KERN_INFO"KVM setup async PF for cpu %d\n",
325 smp_processor_id());
326 }
327
328 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
329 unsigned long pa;
330 /* Size alignment is implied but just to make it explicit. */
331 BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
332 __this_cpu_write(kvm_apic_eoi, 0);
333 pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
334 | KVM_MSR_ENABLED;
335 wrmsrl(MSR_KVM_PV_EOI_EN, pa);
336 }
337
338 if (has_steal_clock)
339 kvm_register_steal_time();
340}
341
342static void kvm_pv_disable_apf(void)
343{
344 if (!__this_cpu_read(apf_reason.enabled))
345 return;
346
347 wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
348 __this_cpu_write(apf_reason.enabled, 0);
349
350 printk(KERN_INFO"Unregister pv shared memory for cpu %d\n",
351 smp_processor_id());
352}
353
354static void kvm_pv_guest_cpu_reboot(void *unused)
355{
356 /*
357 * We disable PV EOI before we load a new kernel by kexec,
358 * since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory.
359 * New kernel can re-enable when it boots.
360 */
361 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
362 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
363 kvm_pv_disable_apf();
364 kvm_disable_steal_time();
365}
366
367static int kvm_pv_reboot_notify(struct notifier_block *nb,
368 unsigned long code, void *unused)
369{
370 if (code == SYS_RESTART)
371 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
372 return NOTIFY_DONE;
373}
374
375static struct notifier_block kvm_pv_reboot_nb = {
376 .notifier_call = kvm_pv_reboot_notify,
377};
378
379static u64 kvm_steal_clock(int cpu)
380{
381 u64 steal;
382 struct kvm_steal_time *src;
383 int version;
384
385 src = &per_cpu(steal_time, cpu);
386 do {
387 version = src->version;
388 virt_rmb();
389 steal = src->steal;
390 virt_rmb();
391 } while ((version & 1) || (version != src->version));
392
393 return steal;
394}
395
396void kvm_disable_steal_time(void)
397{
398 if (!has_steal_clock)
399 return;
400
401 wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
402}
403
404static inline void __set_percpu_decrypted(void *ptr, unsigned long size)
405{
406 early_set_memory_decrypted((unsigned long) ptr, size);
407}
408
409/*
410 * Iterate through all possible CPUs and map the memory region pointed
411 * by apf_reason, steal_time and kvm_apic_eoi as decrypted at once.
412 *
413 * Note: we iterate through all possible CPUs to ensure that CPUs
414 * hotplugged will have their per-cpu variable already mapped as
415 * decrypted.
416 */
417static void __init sev_map_percpu_data(void)
418{
419 int cpu;
420
421 if (!sev_active())
422 return;
423
424 for_each_possible_cpu(cpu) {
425 __set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason));
426 __set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time));
427 __set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi));
428 }
429}
430
431#ifdef CONFIG_SMP
432#define KVM_IPI_CLUSTER_SIZE (2 * BITS_PER_LONG)
433
434static void __send_ipi_mask(const struct cpumask *mask, int vector)
435{
436 unsigned long flags;
437 int cpu, apic_id, icr;
438 int min = 0, max = 0;
439#ifdef CONFIG_X86_64
440 __uint128_t ipi_bitmap = 0;
441#else
442 u64 ipi_bitmap = 0;
443#endif
444 long ret;
445
446 if (cpumask_empty(mask))
447 return;
448
449 local_irq_save(flags);
450
451 switch (vector) {
452 default:
453 icr = APIC_DM_FIXED | vector;
454 break;
455 case NMI_VECTOR:
456 icr = APIC_DM_NMI;
457 break;
458 }
459
460 for_each_cpu(cpu, mask) {
461 apic_id = per_cpu(x86_cpu_to_apicid, cpu);
462 if (!ipi_bitmap) {
463 min = max = apic_id;
464 } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) {
465 ipi_bitmap <<= min - apic_id;
466 min = apic_id;
467 } else if (apic_id < min + KVM_IPI_CLUSTER_SIZE) {
468 max = apic_id < max ? max : apic_id;
469 } else {
470 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
471 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
472 WARN_ONCE(ret < 0, "KVM: failed to send PV IPI: %ld", ret);
473 min = max = apic_id;
474 ipi_bitmap = 0;
475 }
476 __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap);
477 }
478
479 if (ipi_bitmap) {
480 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
481 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
482 WARN_ONCE(ret < 0, "KVM: failed to send PV IPI: %ld", ret);
483 }
484
485 local_irq_restore(flags);
486}
487
488static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
489{
490 __send_ipi_mask(mask, vector);
491}
492
493static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
494{
495 unsigned int this_cpu = smp_processor_id();
496 struct cpumask new_mask;
497 const struct cpumask *local_mask;
498
499 cpumask_copy(&new_mask, mask);
500 cpumask_clear_cpu(this_cpu, &new_mask);
501 local_mask = &new_mask;
502 __send_ipi_mask(local_mask, vector);
503}
504
505/*
506 * Set the IPI entry points
507 */
508static void kvm_setup_pv_ipi(void)
509{
510 apic->send_IPI_mask = kvm_send_ipi_mask;
511 apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
512 pr_info("KVM setup pv IPIs\n");
513}
514
515static void kvm_smp_send_call_func_ipi(const struct cpumask *mask)
516{
517 int cpu;
518
519 native_send_call_func_ipi(mask);
520
521 /* Make sure other vCPUs get a chance to run if they need to. */
522 for_each_cpu(cpu, mask) {
523 if (vcpu_is_preempted(cpu)) {
524 kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu));
525 break;
526 }
527 }
528}
529
530static void __init kvm_smp_prepare_cpus(unsigned int max_cpus)
531{
532 native_smp_prepare_cpus(max_cpus);
533 if (kvm_para_has_hint(KVM_HINTS_REALTIME))
534 static_branch_disable(&virt_spin_lock_key);
535}
536
537static void __init kvm_smp_prepare_boot_cpu(void)
538{
539 /*
540 * Map the per-cpu variables as decrypted before kvm_guest_cpu_init()
541 * shares the guest physical address with the hypervisor.
542 */
543 sev_map_percpu_data();
544
545 kvm_guest_cpu_init();
546 native_smp_prepare_boot_cpu();
547 kvm_spinlock_init();
548}
549
550static void kvm_guest_cpu_offline(void)
551{
552 kvm_disable_steal_time();
553 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
554 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
555 kvm_pv_disable_apf();
556 apf_task_wake_all();
557}
558
559static int kvm_cpu_online(unsigned int cpu)
560{
561 local_irq_disable();
562 kvm_guest_cpu_init();
563 local_irq_enable();
564 return 0;
565}
566
567static int kvm_cpu_down_prepare(unsigned int cpu)
568{
569 local_irq_disable();
570 kvm_guest_cpu_offline();
571 local_irq_enable();
572 return 0;
573}
574#endif
575
576static void __init kvm_apf_trap_init(void)
577{
578 update_intr_gate(X86_TRAP_PF, async_page_fault);
579}
580
581static DEFINE_PER_CPU(cpumask_var_t, __pv_tlb_mask);
582
583static void kvm_flush_tlb_others(const struct cpumask *cpumask,
584 const struct flush_tlb_info *info)
585{
586 u8 state;
587 int cpu;
588 struct kvm_steal_time *src;
589 struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_tlb_mask);
590
591 cpumask_copy(flushmask, cpumask);
592 /*
593 * We have to call flush only on online vCPUs. And
594 * queue flush_on_enter for pre-empted vCPUs
595 */
596 for_each_cpu(cpu, flushmask) {
597 src = &per_cpu(steal_time, cpu);
598 state = READ_ONCE(src->preempted);
599 if ((state & KVM_VCPU_PREEMPTED)) {
600 if (try_cmpxchg(&src->preempted, &state,
601 state | KVM_VCPU_FLUSH_TLB))
602 __cpumask_clear_cpu(cpu, flushmask);
603 }
604 }
605
606 native_flush_tlb_others(flushmask, info);
607}
608
609static void __init kvm_guest_init(void)
610{
611 int i;
612
613 paravirt_ops_setup();
614 register_reboot_notifier(&kvm_pv_reboot_nb);
615 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
616 raw_spin_lock_init(&async_pf_sleepers[i].lock);
617 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
618 x86_init.irqs.trap_init = kvm_apf_trap_init;
619
620 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
621 has_steal_clock = 1;
622 pv_ops.time.steal_clock = kvm_steal_clock;
623 }
624
625 if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
626 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
627 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
628 pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;
629 pv_ops.mmu.tlb_remove_table = tlb_remove_table;
630 }
631
632 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
633 apic_set_eoi_write(kvm_guest_apic_eoi_write);
634
635#ifdef CONFIG_SMP
636 smp_ops.smp_prepare_cpus = kvm_smp_prepare_cpus;
637 smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
638 if (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&
639 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
640 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
641 smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi;
642 pr_info("KVM setup pv sched yield\n");
643 }
644 if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
645 kvm_cpu_online, kvm_cpu_down_prepare) < 0)
646 pr_err("kvm_guest: Failed to install cpu hotplug callbacks\n");
647#else
648 sev_map_percpu_data();
649 kvm_guest_cpu_init();
650#endif
651
652 /*
653 * Hard lockup detection is enabled by default. Disable it, as guests
654 * can get false positives too easily, for example if the host is
655 * overcommitted.
656 */
657 hardlockup_detector_disable();
658}
659
660static noinline uint32_t __kvm_cpuid_base(void)
661{
662 if (boot_cpu_data.cpuid_level < 0)
663 return 0; /* So we don't blow up on old processors */
664
665 if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
666 return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0);
667
668 return 0;
669}
670
671static inline uint32_t kvm_cpuid_base(void)
672{
673 static int kvm_cpuid_base = -1;
674
675 if (kvm_cpuid_base == -1)
676 kvm_cpuid_base = __kvm_cpuid_base();
677
678 return kvm_cpuid_base;
679}
680
681bool kvm_para_available(void)
682{
683 return kvm_cpuid_base() != 0;
684}
685EXPORT_SYMBOL_GPL(kvm_para_available);
686
687unsigned int kvm_arch_para_features(void)
688{
689 return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
690}
691
692unsigned int kvm_arch_para_hints(void)
693{
694 return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
695}
696EXPORT_SYMBOL_GPL(kvm_arch_para_hints);
697
698static uint32_t __init kvm_detect(void)
699{
700 return kvm_cpuid_base();
701}
702
703static void __init kvm_apic_init(void)
704{
705#if defined(CONFIG_SMP)
706 if (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI))
707 kvm_setup_pv_ipi();
708#endif
709}
710
711static void __init kvm_init_platform(void)
712{
713 kvmclock_init();
714 x86_platform.apic_post_init = kvm_apic_init;
715}
716
717const __initconst struct hypervisor_x86 x86_hyper_kvm = {
718 .name = "KVM",
719 .detect = kvm_detect,
720 .type = X86_HYPER_KVM,
721 .init.guest_late_init = kvm_guest_init,
722 .init.x2apic_available = kvm_para_available,
723 .init.init_platform = kvm_init_platform,
724};
725
726static __init int activate_jump_labels(void)
727{
728 if (has_steal_clock) {
729 static_key_slow_inc(¶virt_steal_enabled);
730 if (steal_acc)
731 static_key_slow_inc(¶virt_steal_rq_enabled);
732 }
733
734 return 0;
735}
736arch_initcall(activate_jump_labels);
737
738static __init int kvm_setup_pv_tlb_flush(void)
739{
740 int cpu;
741
742 if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
743 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
744 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
745 for_each_possible_cpu(cpu) {
746 zalloc_cpumask_var_node(per_cpu_ptr(&__pv_tlb_mask, cpu),
747 GFP_KERNEL, cpu_to_node(cpu));
748 }
749 pr_info("KVM setup pv remote TLB flush\n");
750 }
751
752 return 0;
753}
754arch_initcall(kvm_setup_pv_tlb_flush);
755
756#ifdef CONFIG_PARAVIRT_SPINLOCKS
757
758/* Kick a cpu by its apicid. Used to wake up a halted vcpu */
759static void kvm_kick_cpu(int cpu)
760{
761 int apicid;
762 unsigned long flags = 0;
763
764 apicid = per_cpu(x86_cpu_to_apicid, cpu);
765 kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
766}
767
768#include <asm/qspinlock.h>
769
770static void kvm_wait(u8 *ptr, u8 val)
771{
772 unsigned long flags;
773
774 if (in_nmi())
775 return;
776
777 local_irq_save(flags);
778
779 if (READ_ONCE(*ptr) != val)
780 goto out;
781
782 /*
783 * halt until it's our turn and kicked. Note that we do safe halt
784 * for irq enabled case to avoid hang when lock info is overwritten
785 * in irq spinlock slowpath and no spurious interrupt occur to save us.
786 */
787 if (arch_irqs_disabled_flags(flags))
788 halt();
789 else
790 safe_halt();
791
792out:
793 local_irq_restore(flags);
794}
795
796#ifdef CONFIG_X86_32
797__visible bool __kvm_vcpu_is_preempted(long cpu)
798{
799 struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
800
801 return !!(src->preempted & KVM_VCPU_PREEMPTED);
802}
803PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
804
805#else
806
807#include <asm/asm-offsets.h>
808
809extern bool __raw_callee_save___kvm_vcpu_is_preempted(long);
810
811/*
812 * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and
813 * restoring to/from the stack.
814 */
815asm(
816".pushsection .text;"
817".global __raw_callee_save___kvm_vcpu_is_preempted;"
818".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"
819"__raw_callee_save___kvm_vcpu_is_preempted:"
820"movq __per_cpu_offset(,%rdi,8), %rax;"
821"cmpb $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);"
822"setne %al;"
823"ret;"
824".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;"
825".popsection");
826
827#endif
828
829/*
830 * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
831 */
832void __init kvm_spinlock_init(void)
833{
834 /* Does host kernel support KVM_FEATURE_PV_UNHALT? */
835 if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
836 return;
837
838 if (kvm_para_has_hint(KVM_HINTS_REALTIME))
839 return;
840
841 /* Don't use the pvqspinlock code if there is only 1 vCPU. */
842 if (num_possible_cpus() == 1)
843 return;
844
845 __pv_init_lock_hash();
846 pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
847 pv_ops.lock.queued_spin_unlock =
848 PV_CALLEE_SAVE(__pv_queued_spin_unlock);
849 pv_ops.lock.wait = kvm_wait;
850 pv_ops.lock.kick = kvm_kick_cpu;
851
852 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
853 pv_ops.lock.vcpu_is_preempted =
854 PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
855 }
856}
857
858#endif /* CONFIG_PARAVIRT_SPINLOCKS */
859
860#ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
861
862static void kvm_disable_host_haltpoll(void *i)
863{
864 wrmsrl(MSR_KVM_POLL_CONTROL, 0);
865}
866
867static void kvm_enable_host_haltpoll(void *i)
868{
869 wrmsrl(MSR_KVM_POLL_CONTROL, 1);
870}
871
872void arch_haltpoll_enable(unsigned int cpu)
873{
874 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {
875 pr_err_once("kvm: host does not support poll control\n");
876 pr_err_once("kvm: host upgrade recommended\n");
877 return;
878 }
879
880 /* Enable guest halt poll disables host halt poll */
881 smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1);
882}
883EXPORT_SYMBOL_GPL(arch_haltpoll_enable);
884
885void arch_haltpoll_disable(unsigned int cpu)
886{
887 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
888 return;
889
890 /* Enable guest halt poll disables host halt poll */
891 smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1);
892}
893EXPORT_SYMBOL_GPL(arch_haltpoll_disable);
894#endif
1/*
2 * KVM paravirt_ops implementation
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
17 *
18 * Copyright (C) 2007, Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
19 * Copyright IBM Corporation, 2007
20 * Authors: Anthony Liguori <aliguori@us.ibm.com>
21 */
22
23#include <linux/context_tracking.h>
24#include <linux/init.h>
25#include <linux/kernel.h>
26#include <linux/kvm_para.h>
27#include <linux/cpu.h>
28#include <linux/mm.h>
29#include <linux/highmem.h>
30#include <linux/hardirq.h>
31#include <linux/notifier.h>
32#include <linux/reboot.h>
33#include <linux/hash.h>
34#include <linux/sched.h>
35#include <linux/slab.h>
36#include <linux/kprobes.h>
37#include <linux/debugfs.h>
38#include <linux/nmi.h>
39#include <linux/swait.h>
40#include <asm/timer.h>
41#include <asm/cpu.h>
42#include <asm/traps.h>
43#include <asm/desc.h>
44#include <asm/tlbflush.h>
45#include <asm/apic.h>
46#include <asm/apicdef.h>
47#include <asm/hypervisor.h>
48#include <asm/kvm_guest.h>
49
50static int kvmapf = 1;
51
52static int parse_no_kvmapf(char *arg)
53{
54 kvmapf = 0;
55 return 0;
56}
57
58early_param("no-kvmapf", parse_no_kvmapf);
59
60static int steal_acc = 1;
61static int parse_no_stealacc(char *arg)
62{
63 steal_acc = 0;
64 return 0;
65}
66
67early_param("no-steal-acc", parse_no_stealacc);
68
69static int kvmclock_vsyscall = 1;
70static int parse_no_kvmclock_vsyscall(char *arg)
71{
72 kvmclock_vsyscall = 0;
73 return 0;
74}
75
76early_param("no-kvmclock-vsyscall", parse_no_kvmclock_vsyscall);
77
78static DEFINE_PER_CPU(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
79static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64);
80static int has_steal_clock = 0;
81
82/*
83 * No need for any "IO delay" on KVM
84 */
85static void kvm_io_delay(void)
86{
87}
88
89#define KVM_TASK_SLEEP_HASHBITS 8
90#define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
91
92struct kvm_task_sleep_node {
93 struct hlist_node link;
94 struct swait_queue_head wq;
95 u32 token;
96 int cpu;
97 bool halted;
98};
99
100static struct kvm_task_sleep_head {
101 raw_spinlock_t lock;
102 struct hlist_head list;
103} async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
104
105static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
106 u32 token)
107{
108 struct hlist_node *p;
109
110 hlist_for_each(p, &b->list) {
111 struct kvm_task_sleep_node *n =
112 hlist_entry(p, typeof(*n), link);
113 if (n->token == token)
114 return n;
115 }
116
117 return NULL;
118}
119
120void kvm_async_pf_task_wait(u32 token)
121{
122 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
123 struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
124 struct kvm_task_sleep_node n, *e;
125 DECLARE_SWAITQUEUE(wait);
126
127 rcu_irq_enter();
128
129 raw_spin_lock(&b->lock);
130 e = _find_apf_task(b, token);
131 if (e) {
132 /* dummy entry exist -> wake up was delivered ahead of PF */
133 hlist_del(&e->link);
134 kfree(e);
135 raw_spin_unlock(&b->lock);
136
137 rcu_irq_exit();
138 return;
139 }
140
141 n.token = token;
142 n.cpu = smp_processor_id();
143 n.halted = is_idle_task(current) || preempt_count() > 1;
144 init_swait_queue_head(&n.wq);
145 hlist_add_head(&n.link, &b->list);
146 raw_spin_unlock(&b->lock);
147
148 for (;;) {
149 if (!n.halted)
150 prepare_to_swait(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
151 if (hlist_unhashed(&n.link))
152 break;
153
154 if (!n.halted) {
155 local_irq_enable();
156 schedule();
157 local_irq_disable();
158 } else {
159 /*
160 * We cannot reschedule. So halt.
161 */
162 rcu_irq_exit();
163 native_safe_halt();
164 rcu_irq_enter();
165 local_irq_disable();
166 }
167 }
168 if (!n.halted)
169 finish_swait(&n.wq, &wait);
170
171 rcu_irq_exit();
172 return;
173}
174EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait);
175
176static void apf_task_wake_one(struct kvm_task_sleep_node *n)
177{
178 hlist_del_init(&n->link);
179 if (n->halted)
180 smp_send_reschedule(n->cpu);
181 else if (swait_active(&n->wq))
182 swake_up(&n->wq);
183}
184
185static void apf_task_wake_all(void)
186{
187 int i;
188
189 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
190 struct hlist_node *p, *next;
191 struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
192 raw_spin_lock(&b->lock);
193 hlist_for_each_safe(p, next, &b->list) {
194 struct kvm_task_sleep_node *n =
195 hlist_entry(p, typeof(*n), link);
196 if (n->cpu == smp_processor_id())
197 apf_task_wake_one(n);
198 }
199 raw_spin_unlock(&b->lock);
200 }
201}
202
203void kvm_async_pf_task_wake(u32 token)
204{
205 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
206 struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
207 struct kvm_task_sleep_node *n;
208
209 if (token == ~0) {
210 apf_task_wake_all();
211 return;
212 }
213
214again:
215 raw_spin_lock(&b->lock);
216 n = _find_apf_task(b, token);
217 if (!n) {
218 /*
219 * async PF was not yet handled.
220 * Add dummy entry for the token.
221 */
222 n = kzalloc(sizeof(*n), GFP_ATOMIC);
223 if (!n) {
224 /*
225 * Allocation failed! Busy wait while other cpu
226 * handles async PF.
227 */
228 raw_spin_unlock(&b->lock);
229 cpu_relax();
230 goto again;
231 }
232 n->token = token;
233 n->cpu = smp_processor_id();
234 init_swait_queue_head(&n->wq);
235 hlist_add_head(&n->link, &b->list);
236 } else
237 apf_task_wake_one(n);
238 raw_spin_unlock(&b->lock);
239 return;
240}
241EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
242
243u32 kvm_read_and_reset_pf_reason(void)
244{
245 u32 reason = 0;
246
247 if (__this_cpu_read(apf_reason.enabled)) {
248 reason = __this_cpu_read(apf_reason.reason);
249 __this_cpu_write(apf_reason.reason, 0);
250 }
251
252 return reason;
253}
254EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason);
255NOKPROBE_SYMBOL(kvm_read_and_reset_pf_reason);
256
257dotraplinkage void
258do_async_page_fault(struct pt_regs *regs, unsigned long error_code)
259{
260 enum ctx_state prev_state;
261
262 switch (kvm_read_and_reset_pf_reason()) {
263 default:
264 trace_do_page_fault(regs, error_code);
265 break;
266 case KVM_PV_REASON_PAGE_NOT_PRESENT:
267 /* page is swapped out by the host. */
268 prev_state = exception_enter();
269 kvm_async_pf_task_wait((u32)read_cr2());
270 exception_exit(prev_state);
271 break;
272 case KVM_PV_REASON_PAGE_READY:
273 rcu_irq_enter();
274 kvm_async_pf_task_wake((u32)read_cr2());
275 rcu_irq_exit();
276 break;
277 }
278}
279NOKPROBE_SYMBOL(do_async_page_fault);
280
281static void __init paravirt_ops_setup(void)
282{
283 pv_info.name = "KVM";
284
285 if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
286 pv_cpu_ops.io_delay = kvm_io_delay;
287
288#ifdef CONFIG_X86_IO_APIC
289 no_timer_check = 1;
290#endif
291}
292
293static void kvm_register_steal_time(void)
294{
295 int cpu = smp_processor_id();
296 struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
297
298 if (!has_steal_clock)
299 return;
300
301 wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
302 pr_info("kvm-stealtime: cpu %d, msr %llx\n",
303 cpu, (unsigned long long) slow_virt_to_phys(st));
304}
305
306static DEFINE_PER_CPU(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
307
308static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val)
309{
310 /**
311 * This relies on __test_and_clear_bit to modify the memory
312 * in a way that is atomic with respect to the local CPU.
313 * The hypervisor only accesses this memory from the local CPU so
314 * there's no need for lock or memory barriers.
315 * An optimization barrier is implied in apic write.
316 */
317 if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi)))
318 return;
319 apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK);
320}
321
322static void kvm_guest_cpu_init(void)
323{
324 if (!kvm_para_available())
325 return;
326
327 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) {
328 u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
329
330#ifdef CONFIG_PREEMPT
331 pa |= KVM_ASYNC_PF_SEND_ALWAYS;
332#endif
333 wrmsrl(MSR_KVM_ASYNC_PF_EN, pa | KVM_ASYNC_PF_ENABLED);
334 __this_cpu_write(apf_reason.enabled, 1);
335 printk(KERN_INFO"KVM setup async PF for cpu %d\n",
336 smp_processor_id());
337 }
338
339 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
340 unsigned long pa;
341 /* Size alignment is implied but just to make it explicit. */
342 BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
343 __this_cpu_write(kvm_apic_eoi, 0);
344 pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
345 | KVM_MSR_ENABLED;
346 wrmsrl(MSR_KVM_PV_EOI_EN, pa);
347 }
348
349 if (has_steal_clock)
350 kvm_register_steal_time();
351}
352
353static void kvm_pv_disable_apf(void)
354{
355 if (!__this_cpu_read(apf_reason.enabled))
356 return;
357
358 wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
359 __this_cpu_write(apf_reason.enabled, 0);
360
361 printk(KERN_INFO"Unregister pv shared memory for cpu %d\n",
362 smp_processor_id());
363}
364
365static void kvm_pv_guest_cpu_reboot(void *unused)
366{
367 /*
368 * We disable PV EOI before we load a new kernel by kexec,
369 * since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory.
370 * New kernel can re-enable when it boots.
371 */
372 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
373 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
374 kvm_pv_disable_apf();
375 kvm_disable_steal_time();
376}
377
378static int kvm_pv_reboot_notify(struct notifier_block *nb,
379 unsigned long code, void *unused)
380{
381 if (code == SYS_RESTART)
382 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
383 return NOTIFY_DONE;
384}
385
386static struct notifier_block kvm_pv_reboot_nb = {
387 .notifier_call = kvm_pv_reboot_notify,
388};
389
390static u64 kvm_steal_clock(int cpu)
391{
392 u64 steal;
393 struct kvm_steal_time *src;
394 int version;
395
396 src = &per_cpu(steal_time, cpu);
397 do {
398 version = src->version;
399 rmb();
400 steal = src->steal;
401 rmb();
402 } while ((version & 1) || (version != src->version));
403
404 return steal;
405}
406
407void kvm_disable_steal_time(void)
408{
409 if (!has_steal_clock)
410 return;
411
412 wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
413}
414
415#ifdef CONFIG_SMP
416static void __init kvm_smp_prepare_boot_cpu(void)
417{
418 kvm_guest_cpu_init();
419 native_smp_prepare_boot_cpu();
420 kvm_spinlock_init();
421}
422
423static void kvm_guest_cpu_offline(void)
424{
425 kvm_disable_steal_time();
426 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
427 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
428 kvm_pv_disable_apf();
429 apf_task_wake_all();
430}
431
432static int kvm_cpu_online(unsigned int cpu)
433{
434 local_irq_disable();
435 kvm_guest_cpu_init();
436 local_irq_enable();
437 return 0;
438}
439
440static int kvm_cpu_down_prepare(unsigned int cpu)
441{
442 local_irq_disable();
443 kvm_guest_cpu_offline();
444 local_irq_enable();
445 return 0;
446}
447#endif
448
449static void __init kvm_apf_trap_init(void)
450{
451 set_intr_gate(14, async_page_fault);
452}
453
454void __init kvm_guest_init(void)
455{
456 int i;
457
458 if (!kvm_para_available())
459 return;
460
461 paravirt_ops_setup();
462 register_reboot_notifier(&kvm_pv_reboot_nb);
463 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
464 raw_spin_lock_init(&async_pf_sleepers[i].lock);
465 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
466 x86_init.irqs.trap_init = kvm_apf_trap_init;
467
468 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
469 has_steal_clock = 1;
470 pv_time_ops.steal_clock = kvm_steal_clock;
471 }
472
473 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
474 apic_set_eoi_write(kvm_guest_apic_eoi_write);
475
476 if (kvmclock_vsyscall)
477 kvm_setup_vsyscall_timeinfo();
478
479#ifdef CONFIG_SMP
480 smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
481 if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
482 kvm_cpu_online, kvm_cpu_down_prepare) < 0)
483 pr_err("kvm_guest: Failed to install cpu hotplug callbacks\n");
484#else
485 kvm_guest_cpu_init();
486#endif
487
488 /*
489 * Hard lockup detection is enabled by default. Disable it, as guests
490 * can get false positives too easily, for example if the host is
491 * overcommitted.
492 */
493 hardlockup_detector_disable();
494}
495
496static noinline uint32_t __kvm_cpuid_base(void)
497{
498 if (boot_cpu_data.cpuid_level < 0)
499 return 0; /* So we don't blow up on old processors */
500
501 if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
502 return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0);
503
504 return 0;
505}
506
507static inline uint32_t kvm_cpuid_base(void)
508{
509 static int kvm_cpuid_base = -1;
510
511 if (kvm_cpuid_base == -1)
512 kvm_cpuid_base = __kvm_cpuid_base();
513
514 return kvm_cpuid_base;
515}
516
517bool kvm_para_available(void)
518{
519 return kvm_cpuid_base() != 0;
520}
521EXPORT_SYMBOL_GPL(kvm_para_available);
522
523unsigned int kvm_arch_para_features(void)
524{
525 return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
526}
527
528static uint32_t __init kvm_detect(void)
529{
530 return kvm_cpuid_base();
531}
532
533const struct hypervisor_x86 x86_hyper_kvm __refconst = {
534 .name = "KVM",
535 .detect = kvm_detect,
536 .x2apic_available = kvm_para_available,
537};
538EXPORT_SYMBOL_GPL(x86_hyper_kvm);
539
540static __init int activate_jump_labels(void)
541{
542 if (has_steal_clock) {
543 static_key_slow_inc(¶virt_steal_enabled);
544 if (steal_acc)
545 static_key_slow_inc(¶virt_steal_rq_enabled);
546 }
547
548 return 0;
549}
550arch_initcall(activate_jump_labels);
551
552#ifdef CONFIG_PARAVIRT_SPINLOCKS
553
554/* Kick a cpu by its apicid. Used to wake up a halted vcpu */
555static void kvm_kick_cpu(int cpu)
556{
557 int apicid;
558 unsigned long flags = 0;
559
560 apicid = per_cpu(x86_cpu_to_apicid, cpu);
561 kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
562}
563
564#include <asm/qspinlock.h>
565
566static void kvm_wait(u8 *ptr, u8 val)
567{
568 unsigned long flags;
569
570 if (in_nmi())
571 return;
572
573 local_irq_save(flags);
574
575 if (READ_ONCE(*ptr) != val)
576 goto out;
577
578 /*
579 * halt until it's our turn and kicked. Note that we do safe halt
580 * for irq enabled case to avoid hang when lock info is overwritten
581 * in irq spinlock slowpath and no spurious interrupt occur to save us.
582 */
583 if (arch_irqs_disabled_flags(flags))
584 halt();
585 else
586 safe_halt();
587
588out:
589 local_irq_restore(flags);
590}
591
592__visible bool __kvm_vcpu_is_preempted(int cpu)
593{
594 struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
595
596 return !!src->preempted;
597}
598PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
599
600/*
601 * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
602 */
603void __init kvm_spinlock_init(void)
604{
605 if (!kvm_para_available())
606 return;
607 /* Does host kernel support KVM_FEATURE_PV_UNHALT? */
608 if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
609 return;
610
611 __pv_init_lock_hash();
612 pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
613 pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock);
614 pv_lock_ops.wait = kvm_wait;
615 pv_lock_ops.kick = kvm_kick_cpu;
616
617 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
618 pv_lock_ops.vcpu_is_preempted =
619 PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
620 }
621}
622
623static __init int kvm_spinlock_init_jump(void)
624{
625 if (!kvm_para_available())
626 return 0;
627 if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
628 return 0;
629
630 static_key_slow_inc(¶virt_ticketlocks_enabled);
631 printk(KERN_INFO "KVM setup paravirtual spinlock\n");
632
633 return 0;
634}
635early_initcall(kvm_spinlock_init_jump);
636
637#endif /* CONFIG_PARAVIRT_SPINLOCKS */