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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// 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