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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#define pr_fmt(fmt) "kvm-guest: " fmt
11
12#include <linux/context_tracking.h>
13#include <linux/init.h>
14#include <linux/irq.h>
15#include <linux/kernel.h>
16#include <linux/kvm_para.h>
17#include <linux/cpu.h>
18#include <linux/mm.h>
19#include <linux/highmem.h>
20#include <linux/hardirq.h>
21#include <linux/notifier.h>
22#include <linux/reboot.h>
23#include <linux/hash.h>
24#include <linux/sched.h>
25#include <linux/slab.h>
26#include <linux/kprobes.h>
27#include <linux/nmi.h>
28#include <linux/swait.h>
29#include <linux/syscore_ops.h>
30#include <linux/cc_platform.h>
31#include <linux/efi.h>
32#include <asm/timer.h>
33#include <asm/cpu.h>
34#include <asm/traps.h>
35#include <asm/desc.h>
36#include <asm/tlbflush.h>
37#include <asm/apic.h>
38#include <asm/apicdef.h>
39#include <asm/hypervisor.h>
40#include <asm/mtrr.h>
41#include <asm/tlb.h>
42#include <asm/cpuidle_haltpoll.h>
43#include <asm/ptrace.h>
44#include <asm/reboot.h>
45#include <asm/svm.h>
46#include <asm/e820/api.h>
47
48DEFINE_STATIC_KEY_FALSE_RO(kvm_async_pf_enabled);
49
50static int kvmapf = 1;
51
52static int __init 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 __init 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 DEFINE_PER_CPU_READ_MOSTLY(bool, async_pf_enabled);
70static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
71DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64) __visible;
72static int has_steal_clock = 0;
73
74static int has_guest_poll = 0;
75/*
76 * No need for any "IO delay" on KVM
77 */
78static void kvm_io_delay(void)
79{
80}
81
82#define KVM_TASK_SLEEP_HASHBITS 8
83#define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
84
85struct kvm_task_sleep_node {
86 struct hlist_node link;
87 struct swait_queue_head wq;
88 u32 token;
89 int cpu;
90};
91
92static struct kvm_task_sleep_head {
93 raw_spinlock_t lock;
94 struct hlist_head list;
95} async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
96
97static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
98 u32 token)
99{
100 struct hlist_node *p;
101
102 hlist_for_each(p, &b->list) {
103 struct kvm_task_sleep_node *n =
104 hlist_entry(p, typeof(*n), link);
105 if (n->token == token)
106 return n;
107 }
108
109 return NULL;
110}
111
112static bool kvm_async_pf_queue_task(u32 token, struct kvm_task_sleep_node *n)
113{
114 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
115 struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
116 struct kvm_task_sleep_node *e;
117
118 raw_spin_lock(&b->lock);
119 e = _find_apf_task(b, token);
120 if (e) {
121 /* dummy entry exist -> wake up was delivered ahead of PF */
122 hlist_del(&e->link);
123 raw_spin_unlock(&b->lock);
124 kfree(e);
125 return false;
126 }
127
128 n->token = token;
129 n->cpu = smp_processor_id();
130 init_swait_queue_head(&n->wq);
131 hlist_add_head(&n->link, &b->list);
132 raw_spin_unlock(&b->lock);
133 return true;
134}
135
136/*
137 * kvm_async_pf_task_wait_schedule - Wait for pagefault to be handled
138 * @token: Token to identify the sleep node entry
139 *
140 * Invoked from the async pagefault handling code or from the VM exit page
141 * fault handler. In both cases RCU is watching.
142 */
143void kvm_async_pf_task_wait_schedule(u32 token)
144{
145 struct kvm_task_sleep_node n;
146 DECLARE_SWAITQUEUE(wait);
147
148 lockdep_assert_irqs_disabled();
149
150 if (!kvm_async_pf_queue_task(token, &n))
151 return;
152
153 for (;;) {
154 prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
155 if (hlist_unhashed(&n.link))
156 break;
157
158 local_irq_enable();
159 schedule();
160 local_irq_disable();
161 }
162 finish_swait(&n.wq, &wait);
163}
164EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait_schedule);
165
166static void apf_task_wake_one(struct kvm_task_sleep_node *n)
167{
168 hlist_del_init(&n->link);
169 if (swq_has_sleeper(&n->wq))
170 swake_up_one(&n->wq);
171}
172
173static void apf_task_wake_all(void)
174{
175 int i;
176
177 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
178 struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
179 struct kvm_task_sleep_node *n;
180 struct hlist_node *p, *next;
181
182 raw_spin_lock(&b->lock);
183 hlist_for_each_safe(p, next, &b->list) {
184 n = hlist_entry(p, typeof(*n), link);
185 if (n->cpu == smp_processor_id())
186 apf_task_wake_one(n);
187 }
188 raw_spin_unlock(&b->lock);
189 }
190}
191
192void kvm_async_pf_task_wake(u32 token)
193{
194 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
195 struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
196 struct kvm_task_sleep_node *n, *dummy = NULL;
197
198 if (token == ~0) {
199 apf_task_wake_all();
200 return;
201 }
202
203again:
204 raw_spin_lock(&b->lock);
205 n = _find_apf_task(b, token);
206 if (!n) {
207 /*
208 * Async #PF not yet handled, add a dummy entry for the token.
209 * Allocating the token must be down outside of the raw lock
210 * as the allocator is preemptible on PREEMPT_RT kernels.
211 */
212 if (!dummy) {
213 raw_spin_unlock(&b->lock);
214 dummy = kzalloc(sizeof(*dummy), GFP_ATOMIC);
215
216 /*
217 * Continue looping on allocation failure, eventually
218 * the async #PF will be handled and allocating a new
219 * node will be unnecessary.
220 */
221 if (!dummy)
222 cpu_relax();
223
224 /*
225 * Recheck for async #PF completion before enqueueing
226 * the dummy token to avoid duplicate list entries.
227 */
228 goto again;
229 }
230 dummy->token = token;
231 dummy->cpu = smp_processor_id();
232 init_swait_queue_head(&dummy->wq);
233 hlist_add_head(&dummy->link, &b->list);
234 dummy = NULL;
235 } else {
236 apf_task_wake_one(n);
237 }
238 raw_spin_unlock(&b->lock);
239
240 /* A dummy token might be allocated and ultimately not used. */
241 kfree(dummy);
242}
243EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
244
245noinstr u32 kvm_read_and_reset_apf_flags(void)
246{
247 u32 flags = 0;
248
249 if (__this_cpu_read(async_pf_enabled)) {
250 flags = __this_cpu_read(apf_reason.flags);
251 __this_cpu_write(apf_reason.flags, 0);
252 }
253
254 return flags;
255}
256EXPORT_SYMBOL_GPL(kvm_read_and_reset_apf_flags);
257
258noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token)
259{
260 u32 flags = kvm_read_and_reset_apf_flags();
261 irqentry_state_t state;
262
263 if (!flags)
264 return false;
265
266 state = irqentry_enter(regs);
267 instrumentation_begin();
268
269 /*
270 * If the host managed to inject an async #PF into an interrupt
271 * disabled region, then die hard as this is not going to end well
272 * and the host side is seriously broken.
273 */
274 if (unlikely(!(regs->flags & X86_EFLAGS_IF)))
275 panic("Host injected async #PF in interrupt disabled region\n");
276
277 if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) {
278 if (unlikely(!(user_mode(regs))))
279 panic("Host injected async #PF in kernel mode\n");
280 /* Page is swapped out by the host. */
281 kvm_async_pf_task_wait_schedule(token);
282 } else {
283 WARN_ONCE(1, "Unexpected async PF flags: %x\n", flags);
284 }
285
286 instrumentation_end();
287 irqentry_exit(regs, state);
288 return true;
289}
290
291DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)
292{
293 struct pt_regs *old_regs = set_irq_regs(regs);
294 u32 token;
295
296 apic_eoi();
297
298 inc_irq_stat(irq_hv_callback_count);
299
300 if (__this_cpu_read(async_pf_enabled)) {
301 token = __this_cpu_read(apf_reason.token);
302 kvm_async_pf_task_wake(token);
303 __this_cpu_write(apf_reason.token, 0);
304 wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1);
305 }
306
307 set_irq_regs(old_regs);
308}
309
310static void __init paravirt_ops_setup(void)
311{
312 pv_info.name = "KVM";
313
314 if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
315 pv_ops.cpu.io_delay = kvm_io_delay;
316
317#ifdef CONFIG_X86_IO_APIC
318 no_timer_check = 1;
319#endif
320}
321
322static void kvm_register_steal_time(void)
323{
324 int cpu = smp_processor_id();
325 struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
326
327 if (!has_steal_clock)
328 return;
329
330 wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
331 pr_debug("stealtime: cpu %d, msr %llx\n", cpu,
332 (unsigned long long) slow_virt_to_phys(st));
333}
334
335static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
336
337static notrace __maybe_unused void kvm_guest_apic_eoi_write(void)
338{
339 /**
340 * This relies on __test_and_clear_bit to modify the memory
341 * in a way that is atomic with respect to the local CPU.
342 * The hypervisor only accesses this memory from the local CPU so
343 * there's no need for lock or memory barriers.
344 * An optimization barrier is implied in apic write.
345 */
346 if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi)))
347 return;
348 apic_native_eoi();
349}
350
351static void kvm_guest_cpu_init(void)
352{
353 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
354 u64 pa;
355
356 WARN_ON_ONCE(!static_branch_likely(&kvm_async_pf_enabled));
357
358 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
359 pa |= KVM_ASYNC_PF_ENABLED | KVM_ASYNC_PF_DELIVERY_AS_INT;
360
361 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
362 pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
363
364 wrmsrl(MSR_KVM_ASYNC_PF_INT, HYPERVISOR_CALLBACK_VECTOR);
365
366 wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
367 __this_cpu_write(async_pf_enabled, true);
368 pr_debug("setup async PF for cpu %d\n", smp_processor_id());
369 }
370
371 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
372 unsigned long pa;
373
374 /* Size alignment is implied but just to make it explicit. */
375 BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
376 __this_cpu_write(kvm_apic_eoi, 0);
377 pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
378 | KVM_MSR_ENABLED;
379 wrmsrl(MSR_KVM_PV_EOI_EN, pa);
380 }
381
382 if (has_steal_clock)
383 kvm_register_steal_time();
384}
385
386static void kvm_pv_disable_apf(void)
387{
388 if (!__this_cpu_read(async_pf_enabled))
389 return;
390
391 wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
392 __this_cpu_write(async_pf_enabled, false);
393
394 pr_debug("disable async PF for cpu %d\n", smp_processor_id());
395}
396
397static void kvm_disable_steal_time(void)
398{
399 if (!has_steal_clock)
400 return;
401
402 wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
403}
404
405static u64 kvm_steal_clock(int cpu)
406{
407 u64 steal;
408 struct kvm_steal_time *src;
409 int version;
410
411 src = &per_cpu(steal_time, cpu);
412 do {
413 version = src->version;
414 virt_rmb();
415 steal = src->steal;
416 virt_rmb();
417 } while ((version & 1) || (version != src->version));
418
419 return steal;
420}
421
422static inline void __set_percpu_decrypted(void *ptr, unsigned long size)
423{
424 early_set_memory_decrypted((unsigned long) ptr, size);
425}
426
427/*
428 * Iterate through all possible CPUs and map the memory region pointed
429 * by apf_reason, steal_time and kvm_apic_eoi as decrypted at once.
430 *
431 * Note: we iterate through all possible CPUs to ensure that CPUs
432 * hotplugged will have their per-cpu variable already mapped as
433 * decrypted.
434 */
435static void __init sev_map_percpu_data(void)
436{
437 int cpu;
438
439 if (cc_vendor != CC_VENDOR_AMD ||
440 !cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
441 return;
442
443 for_each_possible_cpu(cpu) {
444 __set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason));
445 __set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time));
446 __set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi));
447 }
448}
449
450static void kvm_guest_cpu_offline(bool shutdown)
451{
452 kvm_disable_steal_time();
453 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
454 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
455 if (kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL))
456 wrmsrl(MSR_KVM_MIGRATION_CONTROL, 0);
457 kvm_pv_disable_apf();
458 if (!shutdown)
459 apf_task_wake_all();
460 kvmclock_disable();
461}
462
463static int kvm_cpu_online(unsigned int cpu)
464{
465 unsigned long flags;
466
467 local_irq_save(flags);
468 kvm_guest_cpu_init();
469 local_irq_restore(flags);
470 return 0;
471}
472
473#ifdef CONFIG_SMP
474
475static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask);
476
477static bool pv_tlb_flush_supported(void)
478{
479 return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
480 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
481 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&
482 !boot_cpu_has(X86_FEATURE_MWAIT) &&
483 (num_possible_cpus() != 1));
484}
485
486static bool pv_ipi_supported(void)
487{
488 return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) &&
489 (num_possible_cpus() != 1));
490}
491
492static bool pv_sched_yield_supported(void)
493{
494 return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&
495 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
496 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&
497 !boot_cpu_has(X86_FEATURE_MWAIT) &&
498 (num_possible_cpus() != 1));
499}
500
501#define KVM_IPI_CLUSTER_SIZE (2 * BITS_PER_LONG)
502
503static void __send_ipi_mask(const struct cpumask *mask, int vector)
504{
505 unsigned long flags;
506 int cpu, min = 0, max = 0;
507#ifdef CONFIG_X86_64
508 __uint128_t ipi_bitmap = 0;
509#else
510 u64 ipi_bitmap = 0;
511#endif
512 u32 apic_id, icr;
513 long ret;
514
515 if (cpumask_empty(mask))
516 return;
517
518 local_irq_save(flags);
519
520 switch (vector) {
521 default:
522 icr = APIC_DM_FIXED | vector;
523 break;
524 case NMI_VECTOR:
525 icr = APIC_DM_NMI;
526 break;
527 }
528
529 for_each_cpu(cpu, mask) {
530 apic_id = per_cpu(x86_cpu_to_apicid, cpu);
531 if (!ipi_bitmap) {
532 min = max = apic_id;
533 } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) {
534 ipi_bitmap <<= min - apic_id;
535 min = apic_id;
536 } else if (apic_id > min && apic_id < min + KVM_IPI_CLUSTER_SIZE) {
537 max = apic_id < max ? max : apic_id;
538 } else {
539 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
540 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
541 WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
542 ret);
543 min = max = apic_id;
544 ipi_bitmap = 0;
545 }
546 __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap);
547 }
548
549 if (ipi_bitmap) {
550 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
551 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
552 WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
553 ret);
554 }
555
556 local_irq_restore(flags);
557}
558
559static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
560{
561 __send_ipi_mask(mask, vector);
562}
563
564static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
565{
566 unsigned int this_cpu = smp_processor_id();
567 struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
568 const struct cpumask *local_mask;
569
570 cpumask_copy(new_mask, mask);
571 cpumask_clear_cpu(this_cpu, new_mask);
572 local_mask = new_mask;
573 __send_ipi_mask(local_mask, vector);
574}
575
576static int __init setup_efi_kvm_sev_migration(void)
577{
578 efi_char16_t efi_sev_live_migration_enabled[] = L"SevLiveMigrationEnabled";
579 efi_guid_t efi_variable_guid = AMD_SEV_MEM_ENCRYPT_GUID;
580 efi_status_t status;
581 unsigned long size;
582 bool enabled;
583
584 if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) ||
585 !kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL))
586 return 0;
587
588 if (!efi_enabled(EFI_BOOT))
589 return 0;
590
591 if (!efi_enabled(EFI_RUNTIME_SERVICES)) {
592 pr_info("%s : EFI runtime services are not enabled\n", __func__);
593 return 0;
594 }
595
596 size = sizeof(enabled);
597
598 /* Get variable contents into buffer */
599 status = efi.get_variable(efi_sev_live_migration_enabled,
600 &efi_variable_guid, NULL, &size, &enabled);
601
602 if (status == EFI_NOT_FOUND) {
603 pr_info("%s : EFI live migration variable not found\n", __func__);
604 return 0;
605 }
606
607 if (status != EFI_SUCCESS) {
608 pr_info("%s : EFI variable retrieval failed\n", __func__);
609 return 0;
610 }
611
612 if (enabled == 0) {
613 pr_info("%s: live migration disabled in EFI\n", __func__);
614 return 0;
615 }
616
617 pr_info("%s : live migration enabled in EFI\n", __func__);
618 wrmsrl(MSR_KVM_MIGRATION_CONTROL, KVM_MIGRATION_READY);
619
620 return 1;
621}
622
623late_initcall(setup_efi_kvm_sev_migration);
624
625/*
626 * Set the IPI entry points
627 */
628static __init void kvm_setup_pv_ipi(void)
629{
630 apic_update_callback(send_IPI_mask, kvm_send_ipi_mask);
631 apic_update_callback(send_IPI_mask_allbutself, kvm_send_ipi_mask_allbutself);
632 pr_info("setup PV IPIs\n");
633}
634
635static void kvm_smp_send_call_func_ipi(const struct cpumask *mask)
636{
637 int cpu;
638
639 native_send_call_func_ipi(mask);
640
641 /* Make sure other vCPUs get a chance to run if they need to. */
642 for_each_cpu(cpu, mask) {
643 if (!idle_cpu(cpu) && vcpu_is_preempted(cpu)) {
644 kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu));
645 break;
646 }
647 }
648}
649
650static void kvm_flush_tlb_multi(const struct cpumask *cpumask,
651 const struct flush_tlb_info *info)
652{
653 u8 state;
654 int cpu;
655 struct kvm_steal_time *src;
656 struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
657
658 cpumask_copy(flushmask, cpumask);
659 /*
660 * We have to call flush only on online vCPUs. And
661 * queue flush_on_enter for pre-empted vCPUs
662 */
663 for_each_cpu(cpu, flushmask) {
664 /*
665 * The local vCPU is never preempted, so we do not explicitly
666 * skip check for local vCPU - it will never be cleared from
667 * flushmask.
668 */
669 src = &per_cpu(steal_time, cpu);
670 state = READ_ONCE(src->preempted);
671 if ((state & KVM_VCPU_PREEMPTED)) {
672 if (try_cmpxchg(&src->preempted, &state,
673 state | KVM_VCPU_FLUSH_TLB))
674 __cpumask_clear_cpu(cpu, flushmask);
675 }
676 }
677
678 native_flush_tlb_multi(flushmask, info);
679}
680
681static __init int kvm_alloc_cpumask(void)
682{
683 int cpu;
684
685 if (!kvm_para_available() || nopv)
686 return 0;
687
688 if (pv_tlb_flush_supported() || pv_ipi_supported())
689 for_each_possible_cpu(cpu) {
690 zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu),
691 GFP_KERNEL, cpu_to_node(cpu));
692 }
693
694 return 0;
695}
696arch_initcall(kvm_alloc_cpumask);
697
698static void __init kvm_smp_prepare_boot_cpu(void)
699{
700 /*
701 * Map the per-cpu variables as decrypted before kvm_guest_cpu_init()
702 * shares the guest physical address with the hypervisor.
703 */
704 sev_map_percpu_data();
705
706 kvm_guest_cpu_init();
707 native_smp_prepare_boot_cpu();
708 kvm_spinlock_init();
709}
710
711static int kvm_cpu_down_prepare(unsigned int cpu)
712{
713 unsigned long flags;
714
715 local_irq_save(flags);
716 kvm_guest_cpu_offline(false);
717 local_irq_restore(flags);
718 return 0;
719}
720
721#endif
722
723static int kvm_suspend(void)
724{
725 u64 val = 0;
726
727 kvm_guest_cpu_offline(false);
728
729#ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
730 if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
731 rdmsrl(MSR_KVM_POLL_CONTROL, val);
732 has_guest_poll = !(val & 1);
733#endif
734 return 0;
735}
736
737static void kvm_resume(void)
738{
739 kvm_cpu_online(raw_smp_processor_id());
740
741#ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
742 if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL) && has_guest_poll)
743 wrmsrl(MSR_KVM_POLL_CONTROL, 0);
744#endif
745}
746
747static struct syscore_ops kvm_syscore_ops = {
748 .suspend = kvm_suspend,
749 .resume = kvm_resume,
750};
751
752static void kvm_pv_guest_cpu_reboot(void *unused)
753{
754 kvm_guest_cpu_offline(true);
755}
756
757static int kvm_pv_reboot_notify(struct notifier_block *nb,
758 unsigned long code, void *unused)
759{
760 if (code == SYS_RESTART)
761 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
762 return NOTIFY_DONE;
763}
764
765static struct notifier_block kvm_pv_reboot_nb = {
766 .notifier_call = kvm_pv_reboot_notify,
767};
768
769/*
770 * After a PV feature is registered, the host will keep writing to the
771 * registered memory location. If the guest happens to shutdown, this memory
772 * won't be valid. In cases like kexec, in which you install a new kernel, this
773 * means a random memory location will be kept being written.
774 */
775#ifdef CONFIG_CRASH_DUMP
776static void kvm_crash_shutdown(struct pt_regs *regs)
777{
778 kvm_guest_cpu_offline(true);
779 native_machine_crash_shutdown(regs);
780}
781#endif
782
783#if defined(CONFIG_X86_32) || !defined(CONFIG_SMP)
784bool __kvm_vcpu_is_preempted(long cpu);
785
786__visible bool __kvm_vcpu_is_preempted(long cpu)
787{
788 struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
789
790 return !!(src->preempted & KVM_VCPU_PREEMPTED);
791}
792PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
793
794#else
795
796#include <asm/asm-offsets.h>
797
798extern bool __raw_callee_save___kvm_vcpu_is_preempted(long);
799
800/*
801 * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and
802 * restoring to/from the stack.
803 */
804#define PV_VCPU_PREEMPTED_ASM \
805 "movq __per_cpu_offset(,%rdi,8), %rax\n\t" \
806 "cmpb $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax)\n\t" \
807 "setne %al\n\t"
808
809DEFINE_ASM_FUNC(__raw_callee_save___kvm_vcpu_is_preempted,
810 PV_VCPU_PREEMPTED_ASM, .text);
811#endif
812
813static void __init kvm_guest_init(void)
814{
815 int i;
816
817 paravirt_ops_setup();
818 register_reboot_notifier(&kvm_pv_reboot_nb);
819 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
820 raw_spin_lock_init(&async_pf_sleepers[i].lock);
821
822 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
823 has_steal_clock = 1;
824 static_call_update(pv_steal_clock, kvm_steal_clock);
825
826 pv_ops.lock.vcpu_is_preempted =
827 PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
828 }
829
830 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
831 apic_update_callback(eoi, kvm_guest_apic_eoi_write);
832
833 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
834 static_branch_enable(&kvm_async_pf_enabled);
835 sysvec_install(HYPERVISOR_CALLBACK_VECTOR, sysvec_kvm_asyncpf_interrupt);
836 }
837
838#ifdef CONFIG_SMP
839 if (pv_tlb_flush_supported()) {
840 pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi;
841 pv_ops.mmu.tlb_remove_table = tlb_remove_table;
842 pr_info("KVM setup pv remote TLB flush\n");
843 }
844
845 smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
846 if (pv_sched_yield_supported()) {
847 smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi;
848 pr_info("setup PV sched yield\n");
849 }
850 if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
851 kvm_cpu_online, kvm_cpu_down_prepare) < 0)
852 pr_err("failed to install cpu hotplug callbacks\n");
853#else
854 sev_map_percpu_data();
855 kvm_guest_cpu_init();
856#endif
857
858#ifdef CONFIG_CRASH_DUMP
859 machine_ops.crash_shutdown = kvm_crash_shutdown;
860#endif
861
862 register_syscore_ops(&kvm_syscore_ops);
863
864 /*
865 * Hard lockup detection is enabled by default. Disable it, as guests
866 * can get false positives too easily, for example if the host is
867 * overcommitted.
868 */
869 hardlockup_detector_disable();
870}
871
872static noinline uint32_t __kvm_cpuid_base(void)
873{
874 if (boot_cpu_data.cpuid_level < 0)
875 return 0; /* So we don't blow up on old processors */
876
877 if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
878 return hypervisor_cpuid_base(KVM_SIGNATURE, 0);
879
880 return 0;
881}
882
883static inline uint32_t kvm_cpuid_base(void)
884{
885 static int kvm_cpuid_base = -1;
886
887 if (kvm_cpuid_base == -1)
888 kvm_cpuid_base = __kvm_cpuid_base();
889
890 return kvm_cpuid_base;
891}
892
893bool kvm_para_available(void)
894{
895 return kvm_cpuid_base() != 0;
896}
897EXPORT_SYMBOL_GPL(kvm_para_available);
898
899unsigned int kvm_arch_para_features(void)
900{
901 return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
902}
903
904unsigned int kvm_arch_para_hints(void)
905{
906 return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
907}
908EXPORT_SYMBOL_GPL(kvm_arch_para_hints);
909
910static uint32_t __init kvm_detect(void)
911{
912 return kvm_cpuid_base();
913}
914
915static void __init kvm_apic_init(void)
916{
917#ifdef CONFIG_SMP
918 if (pv_ipi_supported())
919 kvm_setup_pv_ipi();
920#endif
921}
922
923static bool __init kvm_msi_ext_dest_id(void)
924{
925 return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID);
926}
927
928static void kvm_sev_hc_page_enc_status(unsigned long pfn, int npages, bool enc)
929{
930 kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, pfn << PAGE_SHIFT, npages,
931 KVM_MAP_GPA_RANGE_ENC_STAT(enc) | KVM_MAP_GPA_RANGE_PAGE_SZ_4K);
932}
933
934static void __init kvm_init_platform(void)
935{
936 if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) &&
937 kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) {
938 unsigned long nr_pages;
939 int i;
940
941 pv_ops.mmu.notify_page_enc_status_changed =
942 kvm_sev_hc_page_enc_status;
943
944 /*
945 * Reset the host's shared pages list related to kernel
946 * specific page encryption status settings before we load a
947 * new kernel by kexec. Reset the page encryption status
948 * during early boot instead of just before kexec to avoid SMP
949 * races during kvm_pv_guest_cpu_reboot().
950 * NOTE: We cannot reset the complete shared pages list
951 * here as we need to retain the UEFI/OVMF firmware
952 * specific settings.
953 */
954
955 for (i = 0; i < e820_table->nr_entries; i++) {
956 struct e820_entry *entry = &e820_table->entries[i];
957
958 if (entry->type != E820_TYPE_RAM)
959 continue;
960
961 nr_pages = DIV_ROUND_UP(entry->size, PAGE_SIZE);
962
963 kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, entry->addr,
964 nr_pages,
965 KVM_MAP_GPA_RANGE_ENCRYPTED | KVM_MAP_GPA_RANGE_PAGE_SZ_4K);
966 }
967
968 /*
969 * Ensure that _bss_decrypted section is marked as decrypted in the
970 * shared pages list.
971 */
972 early_set_mem_enc_dec_hypercall((unsigned long)__start_bss_decrypted,
973 __end_bss_decrypted - __start_bss_decrypted, 0);
974
975 /*
976 * If not booted using EFI, enable Live migration support.
977 */
978 if (!efi_enabled(EFI_BOOT))
979 wrmsrl(MSR_KVM_MIGRATION_CONTROL,
980 KVM_MIGRATION_READY);
981 }
982 kvmclock_init();
983 x86_platform.apic_post_init = kvm_apic_init;
984
985 /* Set WB as the default cache mode for SEV-SNP and TDX */
986 mtrr_overwrite_state(NULL, 0, MTRR_TYPE_WRBACK);
987}
988
989#if defined(CONFIG_AMD_MEM_ENCRYPT)
990static void kvm_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs)
991{
992 /* RAX and CPL are already in the GHCB */
993 ghcb_set_rbx(ghcb, regs->bx);
994 ghcb_set_rcx(ghcb, regs->cx);
995 ghcb_set_rdx(ghcb, regs->dx);
996 ghcb_set_rsi(ghcb, regs->si);
997}
998
999static bool kvm_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs)
1000{
1001 /* No checking of the return state needed */
1002 return true;
1003}
1004#endif
1005
1006const __initconst struct hypervisor_x86 x86_hyper_kvm = {
1007 .name = "KVM",
1008 .detect = kvm_detect,
1009 .type = X86_HYPER_KVM,
1010 .init.guest_late_init = kvm_guest_init,
1011 .init.x2apic_available = kvm_para_available,
1012 .init.msi_ext_dest_id = kvm_msi_ext_dest_id,
1013 .init.init_platform = kvm_init_platform,
1014#if defined(CONFIG_AMD_MEM_ENCRYPT)
1015 .runtime.sev_es_hcall_prepare = kvm_sev_es_hcall_prepare,
1016 .runtime.sev_es_hcall_finish = kvm_sev_es_hcall_finish,
1017#endif
1018};
1019
1020static __init int activate_jump_labels(void)
1021{
1022 if (has_steal_clock) {
1023 static_key_slow_inc(¶virt_steal_enabled);
1024 if (steal_acc)
1025 static_key_slow_inc(¶virt_steal_rq_enabled);
1026 }
1027
1028 return 0;
1029}
1030arch_initcall(activate_jump_labels);
1031
1032#ifdef CONFIG_PARAVIRT_SPINLOCKS
1033
1034/* Kick a cpu by its apicid. Used to wake up a halted vcpu */
1035static void kvm_kick_cpu(int cpu)
1036{
1037 unsigned long flags = 0;
1038 u32 apicid;
1039
1040 apicid = per_cpu(x86_cpu_to_apicid, cpu);
1041 kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
1042}
1043
1044#include <asm/qspinlock.h>
1045
1046static void kvm_wait(u8 *ptr, u8 val)
1047{
1048 if (in_nmi())
1049 return;
1050
1051 /*
1052 * halt until it's our turn and kicked. Note that we do safe halt
1053 * for irq enabled case to avoid hang when lock info is overwritten
1054 * in irq spinlock slowpath and no spurious interrupt occur to save us.
1055 */
1056 if (irqs_disabled()) {
1057 if (READ_ONCE(*ptr) == val)
1058 halt();
1059 } else {
1060 local_irq_disable();
1061
1062 /* safe_halt() will enable IRQ */
1063 if (READ_ONCE(*ptr) == val)
1064 safe_halt();
1065 else
1066 local_irq_enable();
1067 }
1068}
1069
1070/*
1071 * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
1072 */
1073void __init kvm_spinlock_init(void)
1074{
1075 /*
1076 * In case host doesn't support KVM_FEATURE_PV_UNHALT there is still an
1077 * advantage of keeping virt_spin_lock_key enabled: virt_spin_lock() is
1078 * preferred over native qspinlock when vCPU is preempted.
1079 */
1080 if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) {
1081 pr_info("PV spinlocks disabled, no host support\n");
1082 return;
1083 }
1084
1085 /*
1086 * Disable PV spinlocks and use native qspinlock when dedicated pCPUs
1087 * are available.
1088 */
1089 if (kvm_para_has_hint(KVM_HINTS_REALTIME)) {
1090 pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n");
1091 goto out;
1092 }
1093
1094 if (num_possible_cpus() == 1) {
1095 pr_info("PV spinlocks disabled, single CPU\n");
1096 goto out;
1097 }
1098
1099 if (nopvspin) {
1100 pr_info("PV spinlocks disabled, forced by \"nopvspin\" parameter\n");
1101 goto out;
1102 }
1103
1104 pr_info("PV spinlocks enabled\n");
1105
1106 __pv_init_lock_hash();
1107 pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
1108 pv_ops.lock.queued_spin_unlock =
1109 PV_CALLEE_SAVE(__pv_queued_spin_unlock);
1110 pv_ops.lock.wait = kvm_wait;
1111 pv_ops.lock.kick = kvm_kick_cpu;
1112
1113 /*
1114 * When PV spinlock is enabled which is preferred over
1115 * virt_spin_lock(), virt_spin_lock_key's value is meaningless.
1116 * Just disable it anyway.
1117 */
1118out:
1119 static_branch_disable(&virt_spin_lock_key);
1120}
1121
1122#endif /* CONFIG_PARAVIRT_SPINLOCKS */
1123
1124#ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
1125
1126static void kvm_disable_host_haltpoll(void *i)
1127{
1128 wrmsrl(MSR_KVM_POLL_CONTROL, 0);
1129}
1130
1131static void kvm_enable_host_haltpoll(void *i)
1132{
1133 wrmsrl(MSR_KVM_POLL_CONTROL, 1);
1134}
1135
1136void arch_haltpoll_enable(unsigned int cpu)
1137{
1138 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {
1139 pr_err_once("host does not support poll control\n");
1140 pr_err_once("host upgrade recommended\n");
1141 return;
1142 }
1143
1144 /* Enable guest halt poll disables host halt poll */
1145 smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1);
1146}
1147EXPORT_SYMBOL_GPL(arch_haltpoll_enable);
1148
1149void arch_haltpoll_disable(unsigned int cpu)
1150{
1151 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
1152 return;
1153
1154 /* Disable guest halt poll enables host halt poll */
1155 smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1);
1156}
1157EXPORT_SYMBOL_GPL(arch_haltpoll_disable);
1158#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/module.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 <asm/timer.h>
39#include <asm/cpu.h>
40#include <asm/traps.h>
41#include <asm/desc.h>
42#include <asm/tlbflush.h>
43#include <asm/idle.h>
44#include <asm/apic.h>
45#include <asm/apicdef.h>
46#include <asm/hypervisor.h>
47#include <asm/kvm_guest.h>
48
49static int kvmapf = 1;
50
51static int parse_no_kvmapf(char *arg)
52{
53 kvmapf = 0;
54 return 0;
55}
56
57early_param("no-kvmapf", parse_no_kvmapf);
58
59static int steal_acc = 1;
60static int parse_no_stealacc(char *arg)
61{
62 steal_acc = 0;
63 return 0;
64}
65
66early_param("no-steal-acc", parse_no_stealacc);
67
68static int kvmclock_vsyscall = 1;
69static int parse_no_kvmclock_vsyscall(char *arg)
70{
71 kvmclock_vsyscall = 0;
72 return 0;
73}
74
75early_param("no-kvmclock-vsyscall", parse_no_kvmclock_vsyscall);
76
77static DEFINE_PER_CPU(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
78static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64);
79static int has_steal_clock = 0;
80
81/*
82 * No need for any "IO delay" on KVM
83 */
84static void kvm_io_delay(void)
85{
86}
87
88#define KVM_TASK_SLEEP_HASHBITS 8
89#define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
90
91struct kvm_task_sleep_node {
92 struct hlist_node link;
93 wait_queue_head_t wq;
94 u32 token;
95 int cpu;
96 bool halted;
97};
98
99static struct kvm_task_sleep_head {
100 spinlock_t lock;
101 struct hlist_head list;
102} async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
103
104static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
105 u32 token)
106{
107 struct hlist_node *p;
108
109 hlist_for_each(p, &b->list) {
110 struct kvm_task_sleep_node *n =
111 hlist_entry(p, typeof(*n), link);
112 if (n->token == token)
113 return n;
114 }
115
116 return NULL;
117}
118
119void kvm_async_pf_task_wait(u32 token)
120{
121 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
122 struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
123 struct kvm_task_sleep_node n, *e;
124 DEFINE_WAIT(wait);
125
126 rcu_irq_enter();
127
128 spin_lock(&b->lock);
129 e = _find_apf_task(b, token);
130 if (e) {
131 /* dummy entry exist -> wake up was delivered ahead of PF */
132 hlist_del(&e->link);
133 kfree(e);
134 spin_unlock(&b->lock);
135
136 rcu_irq_exit();
137 return;
138 }
139
140 n.token = token;
141 n.cpu = smp_processor_id();
142 n.halted = is_idle_task(current) || preempt_count() > 1;
143 init_waitqueue_head(&n.wq);
144 hlist_add_head(&n.link, &b->list);
145 spin_unlock(&b->lock);
146
147 for (;;) {
148 if (!n.halted)
149 prepare_to_wait(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
150 if (hlist_unhashed(&n.link))
151 break;
152
153 if (!n.halted) {
154 local_irq_enable();
155 schedule();
156 local_irq_disable();
157 } else {
158 /*
159 * We cannot reschedule. So halt.
160 */
161 rcu_irq_exit();
162 native_safe_halt();
163 rcu_irq_enter();
164 local_irq_disable();
165 }
166 }
167 if (!n.halted)
168 finish_wait(&n.wq, &wait);
169
170 rcu_irq_exit();
171 return;
172}
173EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait);
174
175static void apf_task_wake_one(struct kvm_task_sleep_node *n)
176{
177 hlist_del_init(&n->link);
178 if (n->halted)
179 smp_send_reschedule(n->cpu);
180 else if (waitqueue_active(&n->wq))
181 wake_up(&n->wq);
182}
183
184static void apf_task_wake_all(void)
185{
186 int i;
187
188 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
189 struct hlist_node *p, *next;
190 struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
191 spin_lock(&b->lock);
192 hlist_for_each_safe(p, next, &b->list) {
193 struct kvm_task_sleep_node *n =
194 hlist_entry(p, typeof(*n), link);
195 if (n->cpu == smp_processor_id())
196 apf_task_wake_one(n);
197 }
198 spin_unlock(&b->lock);
199 }
200}
201
202void kvm_async_pf_task_wake(u32 token)
203{
204 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
205 struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
206 struct kvm_task_sleep_node *n;
207
208 if (token == ~0) {
209 apf_task_wake_all();
210 return;
211 }
212
213again:
214 spin_lock(&b->lock);
215 n = _find_apf_task(b, token);
216 if (!n) {
217 /*
218 * async PF was not yet handled.
219 * Add dummy entry for the token.
220 */
221 n = kzalloc(sizeof(*n), GFP_ATOMIC);
222 if (!n) {
223 /*
224 * Allocation failed! Busy wait while other cpu
225 * handles async PF.
226 */
227 spin_unlock(&b->lock);
228 cpu_relax();
229 goto again;
230 }
231 n->token = token;
232 n->cpu = smp_processor_id();
233 init_waitqueue_head(&n->wq);
234 hlist_add_head(&n->link, &b->list);
235 } else
236 apf_task_wake_one(n);
237 spin_unlock(&b->lock);
238 return;
239}
240EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
241
242u32 kvm_read_and_reset_pf_reason(void)
243{
244 u32 reason = 0;
245
246 if (__get_cpu_var(apf_reason).enabled) {
247 reason = __get_cpu_var(apf_reason).reason;
248 __get_cpu_var(apf_reason).reason = 0;
249 }
250
251 return reason;
252}
253EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason);
254
255dotraplinkage void __kprobes
256do_async_page_fault(struct pt_regs *regs, unsigned long error_code)
257{
258 enum ctx_state prev_state;
259
260 switch (kvm_read_and_reset_pf_reason()) {
261 default:
262 do_page_fault(regs, error_code);
263 break;
264 case KVM_PV_REASON_PAGE_NOT_PRESENT:
265 /* page is swapped out by the host. */
266 prev_state = exception_enter();
267 exit_idle();
268 kvm_async_pf_task_wait((u32)read_cr2());
269 exception_exit(prev_state);
270 break;
271 case KVM_PV_REASON_PAGE_READY:
272 rcu_irq_enter();
273 exit_idle();
274 kvm_async_pf_task_wake((u32)read_cr2());
275 rcu_irq_exit();
276 break;
277 }
278}
279
280static void __init paravirt_ops_setup(void)
281{
282 pv_info.name = "KVM";
283 pv_info.paravirt_enabled = 1;
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 memset(st, 0, sizeof(*st));
302
303 wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
304 pr_info("kvm-stealtime: cpu %d, msr %llx\n",
305 cpu, (unsigned long long) slow_virt_to_phys(st));
306}
307
308static DEFINE_PER_CPU(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
309
310static void kvm_guest_apic_eoi_write(u32 reg, u32 val)
311{
312 /**
313 * This relies on __test_and_clear_bit to modify the memory
314 * in a way that is atomic with respect to the local CPU.
315 * The hypervisor only accesses this memory from the local CPU so
316 * there's no need for lock or memory barriers.
317 * An optimization barrier is implied in apic write.
318 */
319 if (__test_and_clear_bit(KVM_PV_EOI_BIT, &__get_cpu_var(kvm_apic_eoi)))
320 return;
321 apic_write(APIC_EOI, APIC_EOI_ACK);
322}
323
324void kvm_guest_cpu_init(void)
325{
326 if (!kvm_para_available())
327 return;
328
329 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) {
330 u64 pa = slow_virt_to_phys(&__get_cpu_var(apf_reason));
331
332#ifdef CONFIG_PREEMPT
333 pa |= KVM_ASYNC_PF_SEND_ALWAYS;
334#endif
335 wrmsrl(MSR_KVM_ASYNC_PF_EN, pa | KVM_ASYNC_PF_ENABLED);
336 __get_cpu_var(apf_reason).enabled = 1;
337 printk(KERN_INFO"KVM setup async PF for cpu %d\n",
338 smp_processor_id());
339 }
340
341 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
342 unsigned long pa;
343 /* Size alignment is implied but just to make it explicit. */
344 BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
345 __get_cpu_var(kvm_apic_eoi) = 0;
346 pa = slow_virt_to_phys(&__get_cpu_var(kvm_apic_eoi))
347 | KVM_MSR_ENABLED;
348 wrmsrl(MSR_KVM_PV_EOI_EN, pa);
349 }
350
351 if (has_steal_clock)
352 kvm_register_steal_time();
353}
354
355static void kvm_pv_disable_apf(void)
356{
357 if (!__get_cpu_var(apf_reason).enabled)
358 return;
359
360 wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
361 __get_cpu_var(apf_reason).enabled = 0;
362
363 printk(KERN_INFO"Unregister pv shared memory for cpu %d\n",
364 smp_processor_id());
365}
366
367static void kvm_pv_guest_cpu_reboot(void *unused)
368{
369 /*
370 * We disable PV EOI before we load a new kernel by kexec,
371 * since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory.
372 * New kernel can re-enable when it boots.
373 */
374 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
375 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
376 kvm_pv_disable_apf();
377 kvm_disable_steal_time();
378}
379
380static int kvm_pv_reboot_notify(struct notifier_block *nb,
381 unsigned long code, void *unused)
382{
383 if (code == SYS_RESTART)
384 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
385 return NOTIFY_DONE;
386}
387
388static struct notifier_block kvm_pv_reboot_nb = {
389 .notifier_call = kvm_pv_reboot_notify,
390};
391
392static u64 kvm_steal_clock(int cpu)
393{
394 u64 steal;
395 struct kvm_steal_time *src;
396 int version;
397
398 src = &per_cpu(steal_time, cpu);
399 do {
400 version = src->version;
401 rmb();
402 steal = src->steal;
403 rmb();
404 } while ((version & 1) || (version != src->version));
405
406 return steal;
407}
408
409void kvm_disable_steal_time(void)
410{
411 if (!has_steal_clock)
412 return;
413
414 wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
415}
416
417#ifdef CONFIG_SMP
418static void __init kvm_smp_prepare_boot_cpu(void)
419{
420 kvm_guest_cpu_init();
421 native_smp_prepare_boot_cpu();
422 kvm_spinlock_init();
423}
424
425static void kvm_guest_cpu_online(void *dummy)
426{
427 kvm_guest_cpu_init();
428}
429
430static void kvm_guest_cpu_offline(void *dummy)
431{
432 kvm_disable_steal_time();
433 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
434 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
435 kvm_pv_disable_apf();
436 apf_task_wake_all();
437}
438
439static int kvm_cpu_notify(struct notifier_block *self, unsigned long action,
440 void *hcpu)
441{
442 int cpu = (unsigned long)hcpu;
443 switch (action) {
444 case CPU_ONLINE:
445 case CPU_DOWN_FAILED:
446 case CPU_ONLINE_FROZEN:
447 smp_call_function_single(cpu, kvm_guest_cpu_online, NULL, 0);
448 break;
449 case CPU_DOWN_PREPARE:
450 case CPU_DOWN_PREPARE_FROZEN:
451 smp_call_function_single(cpu, kvm_guest_cpu_offline, NULL, 1);
452 break;
453 default:
454 break;
455 }
456 return NOTIFY_OK;
457}
458
459static struct notifier_block kvm_cpu_notifier = {
460 .notifier_call = kvm_cpu_notify,
461};
462#endif
463
464static void __init kvm_apf_trap_init(void)
465{
466 set_intr_gate(14, async_page_fault);
467}
468
469void __init kvm_guest_init(void)
470{
471 int i;
472
473 if (!kvm_para_available())
474 return;
475
476 paravirt_ops_setup();
477 register_reboot_notifier(&kvm_pv_reboot_nb);
478 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
479 spin_lock_init(&async_pf_sleepers[i].lock);
480 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
481 x86_init.irqs.trap_init = kvm_apf_trap_init;
482
483 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
484 has_steal_clock = 1;
485 pv_time_ops.steal_clock = kvm_steal_clock;
486 }
487
488 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
489 apic_set_eoi_write(kvm_guest_apic_eoi_write);
490
491 if (kvmclock_vsyscall)
492 kvm_setup_vsyscall_timeinfo();
493
494#ifdef CONFIG_SMP
495 smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
496 register_cpu_notifier(&kvm_cpu_notifier);
497#else
498 kvm_guest_cpu_init();
499#endif
500}
501
502static noinline uint32_t __kvm_cpuid_base(void)
503{
504 if (boot_cpu_data.cpuid_level < 0)
505 return 0; /* So we don't blow up on old processors */
506
507 if (cpu_has_hypervisor)
508 return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0);
509
510 return 0;
511}
512
513static inline uint32_t kvm_cpuid_base(void)
514{
515 static int kvm_cpuid_base = -1;
516
517 if (kvm_cpuid_base == -1)
518 kvm_cpuid_base = __kvm_cpuid_base();
519
520 return kvm_cpuid_base;
521}
522
523bool kvm_para_available(void)
524{
525 return kvm_cpuid_base() != 0;
526}
527EXPORT_SYMBOL_GPL(kvm_para_available);
528
529unsigned int kvm_arch_para_features(void)
530{
531 return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
532}
533
534static uint32_t __init kvm_detect(void)
535{
536 return kvm_cpuid_base();
537}
538
539const struct hypervisor_x86 x86_hyper_kvm __refconst = {
540 .name = "KVM",
541 .detect = kvm_detect,
542 .x2apic_available = kvm_para_available,
543};
544EXPORT_SYMBOL_GPL(x86_hyper_kvm);
545
546static __init int activate_jump_labels(void)
547{
548 if (has_steal_clock) {
549 static_key_slow_inc(¶virt_steal_enabled);
550 if (steal_acc)
551 static_key_slow_inc(¶virt_steal_rq_enabled);
552 }
553
554 return 0;
555}
556arch_initcall(activate_jump_labels);
557
558#ifdef CONFIG_PARAVIRT_SPINLOCKS
559
560/* Kick a cpu by its apicid. Used to wake up a halted vcpu */
561static void kvm_kick_cpu(int cpu)
562{
563 int apicid;
564 unsigned long flags = 0;
565
566 apicid = per_cpu(x86_cpu_to_apicid, cpu);
567 kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
568}
569
570enum kvm_contention_stat {
571 TAKEN_SLOW,
572 TAKEN_SLOW_PICKUP,
573 RELEASED_SLOW,
574 RELEASED_SLOW_KICKED,
575 NR_CONTENTION_STATS
576};
577
578#ifdef CONFIG_KVM_DEBUG_FS
579#define HISTO_BUCKETS 30
580
581static struct kvm_spinlock_stats
582{
583 u32 contention_stats[NR_CONTENTION_STATS];
584 u32 histo_spin_blocked[HISTO_BUCKETS+1];
585 u64 time_blocked;
586} spinlock_stats;
587
588static u8 zero_stats;
589
590static inline void check_zero(void)
591{
592 u8 ret;
593 u8 old;
594
595 old = ACCESS_ONCE(zero_stats);
596 if (unlikely(old)) {
597 ret = cmpxchg(&zero_stats, old, 0);
598 /* This ensures only one fellow resets the stat */
599 if (ret == old)
600 memset(&spinlock_stats, 0, sizeof(spinlock_stats));
601 }
602}
603
604static inline void add_stats(enum kvm_contention_stat var, u32 val)
605{
606 check_zero();
607 spinlock_stats.contention_stats[var] += val;
608}
609
610
611static inline u64 spin_time_start(void)
612{
613 return sched_clock();
614}
615
616static void __spin_time_accum(u64 delta, u32 *array)
617{
618 unsigned index;
619
620 index = ilog2(delta);
621 check_zero();
622
623 if (index < HISTO_BUCKETS)
624 array[index]++;
625 else
626 array[HISTO_BUCKETS]++;
627}
628
629static inline void spin_time_accum_blocked(u64 start)
630{
631 u32 delta;
632
633 delta = sched_clock() - start;
634 __spin_time_accum(delta, spinlock_stats.histo_spin_blocked);
635 spinlock_stats.time_blocked += delta;
636}
637
638static struct dentry *d_spin_debug;
639static struct dentry *d_kvm_debug;
640
641struct dentry *kvm_init_debugfs(void)
642{
643 d_kvm_debug = debugfs_create_dir("kvm-guest", NULL);
644 if (!d_kvm_debug)
645 printk(KERN_WARNING "Could not create 'kvm' debugfs directory\n");
646
647 return d_kvm_debug;
648}
649
650static int __init kvm_spinlock_debugfs(void)
651{
652 struct dentry *d_kvm;
653
654 d_kvm = kvm_init_debugfs();
655 if (d_kvm == NULL)
656 return -ENOMEM;
657
658 d_spin_debug = debugfs_create_dir("spinlocks", d_kvm);
659
660 debugfs_create_u8("zero_stats", 0644, d_spin_debug, &zero_stats);
661
662 debugfs_create_u32("taken_slow", 0444, d_spin_debug,
663 &spinlock_stats.contention_stats[TAKEN_SLOW]);
664 debugfs_create_u32("taken_slow_pickup", 0444, d_spin_debug,
665 &spinlock_stats.contention_stats[TAKEN_SLOW_PICKUP]);
666
667 debugfs_create_u32("released_slow", 0444, d_spin_debug,
668 &spinlock_stats.contention_stats[RELEASED_SLOW]);
669 debugfs_create_u32("released_slow_kicked", 0444, d_spin_debug,
670 &spinlock_stats.contention_stats[RELEASED_SLOW_KICKED]);
671
672 debugfs_create_u64("time_blocked", 0444, d_spin_debug,
673 &spinlock_stats.time_blocked);
674
675 debugfs_create_u32_array("histo_blocked", 0444, d_spin_debug,
676 spinlock_stats.histo_spin_blocked, HISTO_BUCKETS + 1);
677
678 return 0;
679}
680fs_initcall(kvm_spinlock_debugfs);
681#else /* !CONFIG_KVM_DEBUG_FS */
682static inline void add_stats(enum kvm_contention_stat var, u32 val)
683{
684}
685
686static inline u64 spin_time_start(void)
687{
688 return 0;
689}
690
691static inline void spin_time_accum_blocked(u64 start)
692{
693}
694#endif /* CONFIG_KVM_DEBUG_FS */
695
696struct kvm_lock_waiting {
697 struct arch_spinlock *lock;
698 __ticket_t want;
699};
700
701/* cpus 'waiting' on a spinlock to become available */
702static cpumask_t waiting_cpus;
703
704/* Track spinlock on which a cpu is waiting */
705static DEFINE_PER_CPU(struct kvm_lock_waiting, klock_waiting);
706
707__visible void kvm_lock_spinning(struct arch_spinlock *lock, __ticket_t want)
708{
709 struct kvm_lock_waiting *w;
710 int cpu;
711 u64 start;
712 unsigned long flags;
713
714 if (in_nmi())
715 return;
716
717 w = &__get_cpu_var(klock_waiting);
718 cpu = smp_processor_id();
719 start = spin_time_start();
720
721 /*
722 * Make sure an interrupt handler can't upset things in a
723 * partially setup state.
724 */
725 local_irq_save(flags);
726
727 /*
728 * The ordering protocol on this is that the "lock" pointer
729 * may only be set non-NULL if the "want" ticket is correct.
730 * If we're updating "want", we must first clear "lock".
731 */
732 w->lock = NULL;
733 smp_wmb();
734 w->want = want;
735 smp_wmb();
736 w->lock = lock;
737
738 add_stats(TAKEN_SLOW, 1);
739
740 /*
741 * This uses set_bit, which is atomic but we should not rely on its
742 * reordering gurantees. So barrier is needed after this call.
743 */
744 cpumask_set_cpu(cpu, &waiting_cpus);
745
746 barrier();
747
748 /*
749 * Mark entry to slowpath before doing the pickup test to make
750 * sure we don't deadlock with an unlocker.
751 */
752 __ticket_enter_slowpath(lock);
753
754 /*
755 * check again make sure it didn't become free while
756 * we weren't looking.
757 */
758 if (ACCESS_ONCE(lock->tickets.head) == want) {
759 add_stats(TAKEN_SLOW_PICKUP, 1);
760 goto out;
761 }
762
763 /*
764 * halt until it's our turn and kicked. Note that we do safe halt
765 * for irq enabled case to avoid hang when lock info is overwritten
766 * in irq spinlock slowpath and no spurious interrupt occur to save us.
767 */
768 if (arch_irqs_disabled_flags(flags))
769 halt();
770 else
771 safe_halt();
772
773out:
774 cpumask_clear_cpu(cpu, &waiting_cpus);
775 w->lock = NULL;
776 local_irq_restore(flags);
777 spin_time_accum_blocked(start);
778}
779PV_CALLEE_SAVE_REGS_THUNK(kvm_lock_spinning);
780
781/* Kick vcpu waiting on @lock->head to reach value @ticket */
782static void kvm_unlock_kick(struct arch_spinlock *lock, __ticket_t ticket)
783{
784 int cpu;
785
786 add_stats(RELEASED_SLOW, 1);
787 for_each_cpu(cpu, &waiting_cpus) {
788 const struct kvm_lock_waiting *w = &per_cpu(klock_waiting, cpu);
789 if (ACCESS_ONCE(w->lock) == lock &&
790 ACCESS_ONCE(w->want) == ticket) {
791 add_stats(RELEASED_SLOW_KICKED, 1);
792 kvm_kick_cpu(cpu);
793 break;
794 }
795 }
796}
797
798/*
799 * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
800 */
801void __init kvm_spinlock_init(void)
802{
803 if (!kvm_para_available())
804 return;
805 /* Does host kernel support KVM_FEATURE_PV_UNHALT? */
806 if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
807 return;
808
809 pv_lock_ops.lock_spinning = PV_CALLEE_SAVE(kvm_lock_spinning);
810 pv_lock_ops.unlock_kick = kvm_unlock_kick;
811}
812
813static __init int kvm_spinlock_init_jump(void)
814{
815 if (!kvm_para_available())
816 return 0;
817 if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
818 return 0;
819
820 static_key_slow_inc(¶virt_ticketlocks_enabled);
821 printk(KERN_INFO "KVM setup paravirtual spinlock\n");
822
823 return 0;
824}
825early_initcall(kvm_spinlock_init_jump);
826
827#endif /* CONFIG_PARAVIRT_SPINLOCKS */