Line data Source code
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 <asm/timer.h>
30 : #include <asm/cpu.h>
31 : #include <asm/traps.h>
32 : #include <asm/desc.h>
33 : #include <asm/tlbflush.h>
34 : #include <asm/apic.h>
35 : #include <asm/apicdef.h>
36 : #include <asm/hypervisor.h>
37 : #include <asm/tlb.h>
38 : #include <asm/cpuidle_haltpoll.h>
39 : #include <asm/ptrace.h>
40 : #include <asm/svm.h>
41 :
42 : DEFINE_STATIC_KEY_FALSE(kvm_async_pf_enabled);
43 :
44 : static int kvmapf = 1;
45 :
46 0 : static int __init parse_no_kvmapf(char *arg)
47 : {
48 0 : kvmapf = 0;
49 0 : return 0;
50 : }
51 :
52 : early_param("no-kvmapf", parse_no_kvmapf);
53 :
54 : static int steal_acc = 1;
55 0 : static int __init parse_no_stealacc(char *arg)
56 : {
57 0 : steal_acc = 0;
58 0 : return 0;
59 : }
60 :
61 : early_param("no-steal-acc", parse_no_stealacc);
62 :
63 : static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
64 : DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64) __visible;
65 : static int has_steal_clock = 0;
66 :
67 : /*
68 : * No need for any "IO delay" on KVM
69 : */
70 0 : static void kvm_io_delay(void)
71 : {
72 0 : }
73 :
74 : #define KVM_TASK_SLEEP_HASHBITS 8
75 : #define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
76 :
77 : struct kvm_task_sleep_node {
78 : struct hlist_node link;
79 : struct swait_queue_head wq;
80 : u32 token;
81 : int cpu;
82 : };
83 :
84 : static struct kvm_task_sleep_head {
85 : raw_spinlock_t lock;
86 : struct hlist_head list;
87 : } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
88 :
89 0 : static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
90 : u32 token)
91 : {
92 0 : struct hlist_node *p;
93 :
94 0 : hlist_for_each(p, &b->list) {
95 0 : struct kvm_task_sleep_node *n =
96 0 : hlist_entry(p, typeof(*n), link);
97 0 : if (n->token == token)
98 : return n;
99 : }
100 :
101 : return NULL;
102 : }
103 :
104 0 : static bool kvm_async_pf_queue_task(u32 token, struct kvm_task_sleep_node *n)
105 : {
106 0 : u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
107 0 : struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
108 0 : struct kvm_task_sleep_node *e;
109 :
110 0 : raw_spin_lock(&b->lock);
111 0 : e = _find_apf_task(b, token);
112 0 : if (e) {
113 : /* dummy entry exist -> wake up was delivered ahead of PF */
114 0 : hlist_del(&e->link);
115 0 : raw_spin_unlock(&b->lock);
116 0 : kfree(e);
117 0 : return false;
118 : }
119 :
120 0 : n->token = token;
121 0 : n->cpu = smp_processor_id();
122 0 : init_swait_queue_head(&n->wq);
123 0 : hlist_add_head(&n->link, &b->list);
124 0 : raw_spin_unlock(&b->lock);
125 0 : return true;
126 : }
127 :
128 : /*
129 : * kvm_async_pf_task_wait_schedule - Wait for pagefault to be handled
130 : * @token: Token to identify the sleep node entry
131 : *
132 : * Invoked from the async pagefault handling code or from the VM exit page
133 : * fault handler. In both cases RCU is watching.
134 : */
135 0 : void kvm_async_pf_task_wait_schedule(u32 token)
136 : {
137 0 : struct kvm_task_sleep_node n;
138 0 : DECLARE_SWAITQUEUE(wait);
139 :
140 0 : lockdep_assert_irqs_disabled();
141 :
142 0 : if (!kvm_async_pf_queue_task(token, &n))
143 0 : return;
144 :
145 0 : for (;;) {
146 0 : prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
147 0 : if (hlist_unhashed(&n.link))
148 : break;
149 :
150 0 : local_irq_enable();
151 0 : schedule();
152 0 : local_irq_disable();
153 : }
154 0 : finish_swait(&n.wq, &wait);
155 : }
156 : EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait_schedule);
157 :
158 0 : static void apf_task_wake_one(struct kvm_task_sleep_node *n)
159 : {
160 0 : hlist_del_init(&n->link);
161 0 : if (swq_has_sleeper(&n->wq))
162 0 : swake_up_one(&n->wq);
163 0 : }
164 :
165 0 : static void apf_task_wake_all(void)
166 : {
167 0 : int i;
168 :
169 0 : for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
170 0 : struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
171 0 : struct kvm_task_sleep_node *n;
172 0 : struct hlist_node *p, *next;
173 :
174 0 : raw_spin_lock(&b->lock);
175 0 : hlist_for_each_safe(p, next, &b->list) {
176 0 : n = hlist_entry(p, typeof(*n), link);
177 0 : if (n->cpu == smp_processor_id())
178 0 : apf_task_wake_one(n);
179 : }
180 0 : raw_spin_unlock(&b->lock);
181 : }
182 0 : }
183 :
184 0 : void kvm_async_pf_task_wake(u32 token)
185 : {
186 0 : u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
187 0 : struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
188 0 : struct kvm_task_sleep_node *n;
189 :
190 0 : if (token == ~0) {
191 0 : apf_task_wake_all();
192 0 : return;
193 : }
194 :
195 0 : again:
196 0 : raw_spin_lock(&b->lock);
197 0 : n = _find_apf_task(b, token);
198 0 : if (!n) {
199 : /*
200 : * async PF was not yet handled.
201 : * Add dummy entry for the token.
202 : */
203 0 : n = kzalloc(sizeof(*n), GFP_ATOMIC);
204 0 : if (!n) {
205 : /*
206 : * Allocation failed! Busy wait while other cpu
207 : * handles async PF.
208 : */
209 0 : raw_spin_unlock(&b->lock);
210 0 : cpu_relax();
211 0 : goto again;
212 : }
213 0 : n->token = token;
214 0 : n->cpu = smp_processor_id();
215 0 : init_swait_queue_head(&n->wq);
216 0 : hlist_add_head(&n->link, &b->list);
217 : } else {
218 0 : apf_task_wake_one(n);
219 : }
220 0 : raw_spin_unlock(&b->lock);
221 0 : return;
222 : }
223 : EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
224 :
225 0 : noinstr u32 kvm_read_and_reset_apf_flags(void)
226 : {
227 0 : u32 flags = 0;
228 :
229 0 : if (__this_cpu_read(apf_reason.enabled)) {
230 0 : flags = __this_cpu_read(apf_reason.flags);
231 0 : __this_cpu_write(apf_reason.flags, 0);
232 : }
233 :
234 0 : return flags;
235 : }
236 : EXPORT_SYMBOL_GPL(kvm_read_and_reset_apf_flags);
237 :
238 0 : noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token)
239 : {
240 0 : u32 flags = kvm_read_and_reset_apf_flags();
241 0 : irqentry_state_t state;
242 :
243 0 : if (!flags)
244 : return false;
245 :
246 0 : state = irqentry_enter(regs);
247 0 : instrumentation_begin();
248 :
249 : /*
250 : * If the host managed to inject an async #PF into an interrupt
251 : * disabled region, then die hard as this is not going to end well
252 : * and the host side is seriously broken.
253 : */
254 0 : if (unlikely(!(regs->flags & X86_EFLAGS_IF)))
255 0 : panic("Host injected async #PF in interrupt disabled region\n");
256 :
257 0 : if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) {
258 0 : if (unlikely(!(user_mode(regs))))
259 0 : panic("Host injected async #PF in kernel mode\n");
260 : /* Page is swapped out by the host. */
261 0 : kvm_async_pf_task_wait_schedule(token);
262 : } else {
263 0 : WARN_ONCE(1, "Unexpected async PF flags: %x\n", flags);
264 : }
265 :
266 0 : instrumentation_end();
267 0 : irqentry_exit(regs, state);
268 0 : return true;
269 : }
270 :
271 0 : DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)
272 : {
273 0 : struct pt_regs *old_regs = set_irq_regs(regs);
274 0 : u32 token;
275 :
276 0 : ack_APIC_irq();
277 :
278 0 : inc_irq_stat(irq_hv_callback_count);
279 :
280 0 : if (__this_cpu_read(apf_reason.enabled)) {
281 0 : token = __this_cpu_read(apf_reason.token);
282 0 : kvm_async_pf_task_wake(token);
283 0 : __this_cpu_write(apf_reason.token, 0);
284 0 : wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1);
285 : }
286 :
287 0 : set_irq_regs(old_regs);
288 0 : }
289 :
290 1 : static void __init paravirt_ops_setup(void)
291 : {
292 1 : pv_info.name = "KVM";
293 :
294 2 : if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
295 1 : pv_ops.cpu.io_delay = kvm_io_delay;
296 :
297 : #ifdef CONFIG_X86_IO_APIC
298 1 : no_timer_check = 1;
299 : #endif
300 1 : }
301 :
302 4 : static void kvm_register_steal_time(void)
303 : {
304 4 : int cpu = smp_processor_id();
305 4 : struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
306 :
307 4 : if (!has_steal_clock)
308 : return;
309 :
310 4 : wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
311 4 : pr_info("stealtime: cpu %d, msr %llx\n", cpu,
312 : (unsigned long long) slow_virt_to_phys(st));
313 : }
314 :
315 : static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
316 :
317 89323 : static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val)
318 : {
319 : /**
320 : * This relies on __test_and_clear_bit to modify the memory
321 : * in a way that is atomic with respect to the local CPU.
322 : * The hypervisor only accesses this memory from the local CPU so
323 : * there's no need for lock or memory barriers.
324 : * An optimization barrier is implied in apic write.
325 : */
326 181008 : if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi)))
327 : return;
328 2149 : apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK);
329 : }
330 :
331 4 : static void kvm_guest_cpu_init(void)
332 : {
333 8 : if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
334 0 : u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
335 :
336 0 : WARN_ON_ONCE(!static_branch_likely(&kvm_async_pf_enabled));
337 :
338 0 : pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
339 0 : pa |= KVM_ASYNC_PF_ENABLED | KVM_ASYNC_PF_DELIVERY_AS_INT;
340 :
341 0 : if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
342 0 : pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
343 :
344 0 : wrmsrl(MSR_KVM_ASYNC_PF_INT, HYPERVISOR_CALLBACK_VECTOR);
345 :
346 0 : wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
347 0 : __this_cpu_write(apf_reason.enabled, 1);
348 0 : pr_info("KVM setup async PF for cpu %d\n", smp_processor_id());
349 : }
350 :
351 8 : if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
352 4 : unsigned long pa;
353 :
354 : /* Size alignment is implied but just to make it explicit. */
355 4 : BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
356 4 : __this_cpu_write(kvm_apic_eoi, 0);
357 4 : pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
358 : | KVM_MSR_ENABLED;
359 4 : wrmsrl(MSR_KVM_PV_EOI_EN, pa);
360 : }
361 :
362 4 : if (has_steal_clock)
363 4 : kvm_register_steal_time();
364 4 : }
365 :
366 0 : static void kvm_pv_disable_apf(void)
367 : {
368 0 : if (!__this_cpu_read(apf_reason.enabled))
369 : return;
370 :
371 0 : wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
372 0 : __this_cpu_write(apf_reason.enabled, 0);
373 :
374 0 : pr_info("Unregister pv shared memory for cpu %d\n", smp_processor_id());
375 : }
376 :
377 0 : static void kvm_pv_guest_cpu_reboot(void *unused)
378 : {
379 : /*
380 : * We disable PV EOI before we load a new kernel by kexec,
381 : * since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory.
382 : * New kernel can re-enable when it boots.
383 : */
384 0 : if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
385 0 : wrmsrl(MSR_KVM_PV_EOI_EN, 0);
386 0 : kvm_pv_disable_apf();
387 0 : kvm_disable_steal_time();
388 0 : }
389 :
390 0 : static int kvm_pv_reboot_notify(struct notifier_block *nb,
391 : unsigned long code, void *unused)
392 : {
393 0 : if (code == SYS_RESTART)
394 0 : on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
395 0 : return NOTIFY_DONE;
396 : }
397 :
398 : static struct notifier_block kvm_pv_reboot_nb = {
399 : .notifier_call = kvm_pv_reboot_notify,
400 : };
401 :
402 264445 : static u64 kvm_steal_clock(int cpu)
403 : {
404 264445 : u64 steal;
405 264445 : struct kvm_steal_time *src;
406 264445 : int version;
407 :
408 264445 : src = &per_cpu(steal_time, cpu);
409 264446 : do {
410 264446 : version = src->version;
411 264446 : virt_rmb();
412 264400 : steal = src->steal;
413 264400 : virt_rmb();
414 264962 : } while ((version & 1) || (version != src->version));
415 :
416 264961 : return steal;
417 : }
418 :
419 0 : void kvm_disable_steal_time(void)
420 : {
421 0 : if (!has_steal_clock)
422 : return;
423 :
424 0 : wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
425 : }
426 :
427 : static inline void __set_percpu_decrypted(void *ptr, unsigned long size)
428 : {
429 : early_set_memory_decrypted((unsigned long) ptr, size);
430 : }
431 :
432 : /*
433 : * Iterate through all possible CPUs and map the memory region pointed
434 : * by apf_reason, steal_time and kvm_apic_eoi as decrypted at once.
435 : *
436 : * Note: we iterate through all possible CPUs to ensure that CPUs
437 : * hotplugged will have their per-cpu variable already mapped as
438 : * decrypted.
439 : */
440 1 : static void __init sev_map_percpu_data(void)
441 : {
442 1 : int cpu;
443 :
444 1 : if (!sev_active())
445 1 : return;
446 :
447 : for_each_possible_cpu(cpu) {
448 : __set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason));
449 : __set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time));
450 : __set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi));
451 : }
452 : }
453 :
454 2 : static bool pv_tlb_flush_supported(void)
455 : {
456 2 : return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
457 4 : !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
458 2 : kvm_para_has_feature(KVM_FEATURE_STEAL_TIME));
459 : }
460 :
461 : static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask);
462 :
463 : #ifdef CONFIG_SMP
464 :
465 2 : static bool pv_ipi_supported(void)
466 : {
467 4 : return kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI);
468 : }
469 :
470 1 : static bool pv_sched_yield_supported(void)
471 : {
472 1 : return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&
473 2 : !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
474 1 : kvm_para_has_feature(KVM_FEATURE_STEAL_TIME));
475 : }
476 :
477 : #define KVM_IPI_CLUSTER_SIZE (2 * BITS_PER_LONG)
478 :
479 14431 : static void __send_ipi_mask(const struct cpumask *mask, int vector)
480 : {
481 14431 : unsigned long flags;
482 14431 : int cpu, apic_id, icr;
483 14431 : int min = 0, max = 0;
484 : #ifdef CONFIG_X86_64
485 14431 : __uint128_t ipi_bitmap = 0;
486 : #else
487 : u64 ipi_bitmap = 0;
488 : #endif
489 14431 : long ret;
490 :
491 14431 : if (cpumask_empty(mask))
492 14 : return;
493 :
494 28834 : local_irq_save(flags);
495 :
496 14417 : switch (vector) {
497 : default:
498 : icr = APIC_DM_FIXED | vector;
499 : break;
500 0 : case NMI_VECTOR:
501 0 : icr = APIC_DM_NMI;
502 0 : break;
503 : }
504 :
505 28836 : for_each_cpu(cpu, mask) {
506 14419 : apic_id = per_cpu(x86_cpu_to_apicid, cpu);
507 14419 : if (!ipi_bitmap) {
508 : min = max = apic_id;
509 2 : } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) {
510 0 : ipi_bitmap <<= min - apic_id;
511 0 : min = apic_id;
512 2 : } else if (apic_id < min + KVM_IPI_CLUSTER_SIZE) {
513 2 : max = apic_id < max ? max : apic_id;
514 : } else {
515 0 : ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
516 0 : (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
517 0 : WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
518 : ret);
519 0 : min = max = apic_id;
520 0 : ipi_bitmap = 0;
521 : }
522 14419 : __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap);
523 : }
524 :
525 14417 : if (ipi_bitmap) {
526 28834 : ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
527 14417 : (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
528 14417 : WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
529 : ret);
530 : }
531 :
532 14862 : local_irq_restore(flags);
533 : }
534 :
535 14430 : static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
536 : {
537 14430 : __send_ipi_mask(mask, vector);
538 14431 : }
539 :
540 0 : static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
541 : {
542 0 : unsigned int this_cpu = smp_processor_id();
543 0 : struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
544 0 : const struct cpumask *local_mask;
545 :
546 0 : cpumask_copy(new_mask, mask);
547 0 : cpumask_clear_cpu(this_cpu, new_mask);
548 0 : local_mask = new_mask;
549 0 : __send_ipi_mask(local_mask, vector);
550 0 : }
551 :
552 : /*
553 : * Set the IPI entry points
554 : */
555 1 : static void kvm_setup_pv_ipi(void)
556 : {
557 1 : apic->send_IPI_mask = kvm_send_ipi_mask;
558 1 : apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
559 1 : pr_info("setup PV IPIs\n");
560 1 : }
561 :
562 62 : static void kvm_smp_send_call_func_ipi(const struct cpumask *mask)
563 : {
564 62 : int cpu;
565 :
566 62 : native_send_call_func_ipi(mask);
567 :
568 : /* Make sure other vCPUs get a chance to run if they need to. */
569 181 : for_each_cpu(cpu, mask) {
570 89 : if (vcpu_is_preempted(cpu)) {
571 32 : kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu));
572 32 : break;
573 : }
574 : }
575 62 : }
576 :
577 1 : static void __init kvm_smp_prepare_boot_cpu(void)
578 : {
579 : /*
580 : * Map the per-cpu variables as decrypted before kvm_guest_cpu_init()
581 : * shares the guest physical address with the hypervisor.
582 : */
583 1 : sev_map_percpu_data();
584 :
585 1 : kvm_guest_cpu_init();
586 1 : native_smp_prepare_boot_cpu();
587 1 : kvm_spinlock_init();
588 1 : }
589 :
590 0 : static void kvm_guest_cpu_offline(void)
591 : {
592 0 : kvm_disable_steal_time();
593 0 : if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
594 0 : wrmsrl(MSR_KVM_PV_EOI_EN, 0);
595 0 : kvm_pv_disable_apf();
596 0 : apf_task_wake_all();
597 0 : }
598 :
599 3 : static int kvm_cpu_online(unsigned int cpu)
600 : {
601 3 : local_irq_disable();
602 3 : kvm_guest_cpu_init();
603 3 : local_irq_enable();
604 3 : return 0;
605 : }
606 :
607 0 : static int kvm_cpu_down_prepare(unsigned int cpu)
608 : {
609 0 : local_irq_disable();
610 0 : kvm_guest_cpu_offline();
611 0 : local_irq_enable();
612 0 : return 0;
613 : }
614 : #endif
615 :
616 3240 : static void kvm_flush_tlb_others(const struct cpumask *cpumask,
617 : const struct flush_tlb_info *info)
618 : {
619 3240 : u8 state;
620 3240 : int cpu;
621 3240 : struct kvm_steal_time *src;
622 3240 : struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
623 :
624 3240 : cpumask_copy(flushmask, cpumask);
625 : /*
626 : * We have to call flush only on online vCPUs. And
627 : * queue flush_on_enter for pre-empted vCPUs
628 : */
629 12619 : for_each_cpu(cpu, flushmask) {
630 6139 : src = &per_cpu(steal_time, cpu);
631 6139 : state = READ_ONCE(src->preempted);
632 6139 : if ((state & KVM_VCPU_PREEMPTED)) {
633 2677 : if (try_cmpxchg(&src->preempted, &state,
634 : state | KVM_VCPU_FLUSH_TLB))
635 12056 : __cpumask_clear_cpu(cpu, flushmask);
636 : }
637 : }
638 :
639 3240 : native_flush_tlb_others(flushmask, info);
640 3240 : }
641 :
642 1 : static void __init kvm_guest_init(void)
643 : {
644 1 : int i;
645 :
646 1 : paravirt_ops_setup();
647 1 : register_reboot_notifier(&kvm_pv_reboot_nb);
648 258 : for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
649 256 : raw_spin_lock_init(&async_pf_sleepers[i].lock);
650 :
651 2 : if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
652 1 : has_steal_clock = 1;
653 1 : pv_ops.time.steal_clock = kvm_steal_clock;
654 : }
655 :
656 1 : if (pv_tlb_flush_supported()) {
657 1 : pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;
658 1 : pv_ops.mmu.tlb_remove_table = tlb_remove_table;
659 1 : pr_info("KVM setup pv remote TLB flush\n");
660 : }
661 :
662 2 : if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
663 1 : apic_set_eoi_write(kvm_guest_apic_eoi_write);
664 :
665 2 : if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
666 0 : static_branch_enable(&kvm_async_pf_enabled);
667 0 : alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_kvm_asyncpf_interrupt);
668 : }
669 :
670 : #ifdef CONFIG_SMP
671 1 : smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
672 1 : if (pv_sched_yield_supported()) {
673 1 : smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi;
674 1 : pr_info("setup PV sched yield\n");
675 : }
676 1 : if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
677 : kvm_cpu_online, kvm_cpu_down_prepare) < 0)
678 0 : pr_err("failed to install cpu hotplug callbacks\n");
679 : #else
680 : sev_map_percpu_data();
681 : kvm_guest_cpu_init();
682 : #endif
683 :
684 : /*
685 : * Hard lockup detection is enabled by default. Disable it, as guests
686 : * can get false positives too easily, for example if the host is
687 : * overcommitted.
688 : */
689 1 : hardlockup_detector_disable();
690 1 : }
691 :
692 1 : static noinline uint32_t __kvm_cpuid_base(void)
693 : {
694 1 : if (boot_cpu_data.cpuid_level < 0)
695 : return 0; /* So we don't blow up on old processors */
696 :
697 1 : if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
698 1 : return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0);
699 :
700 : return 0;
701 : }
702 :
703 31 : static inline uint32_t kvm_cpuid_base(void)
704 : {
705 31 : static int kvm_cpuid_base = -1;
706 :
707 31 : if (kvm_cpuid_base == -1)
708 1 : kvm_cpuid_base = __kvm_cpuid_base();
709 :
710 31 : return kvm_cpuid_base;
711 : }
712 :
713 2 : bool kvm_para_available(void)
714 : {
715 1 : return kvm_cpuid_base() != 0;
716 : }
717 : EXPORT_SYMBOL_GPL(kvm_para_available);
718 :
719 24 : unsigned int kvm_arch_para_features(void)
720 : {
721 20 : return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
722 : }
723 :
724 4 : unsigned int kvm_arch_para_hints(void)
725 : {
726 4 : return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
727 : }
728 : EXPORT_SYMBOL_GPL(kvm_arch_para_hints);
729 :
730 1 : static uint32_t __init kvm_detect(void)
731 : {
732 1 : return kvm_cpuid_base();
733 : }
734 :
735 1 : static void __init kvm_apic_init(void)
736 : {
737 : #if defined(CONFIG_SMP)
738 2 : if (pv_ipi_supported())
739 1 : kvm_setup_pv_ipi();
740 : #endif
741 1 : }
742 :
743 0 : static bool __init kvm_msi_ext_dest_id(void)
744 : {
745 0 : return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID);
746 : }
747 :
748 1 : static void __init kvm_init_platform(void)
749 : {
750 1 : kvmclock_init();
751 1 : x86_platform.apic_post_init = kvm_apic_init;
752 1 : }
753 :
754 : #if defined(CONFIG_AMD_MEM_ENCRYPT)
755 : static void kvm_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs)
756 : {
757 : /* RAX and CPL are already in the GHCB */
758 : ghcb_set_rbx(ghcb, regs->bx);
759 : ghcb_set_rcx(ghcb, regs->cx);
760 : ghcb_set_rdx(ghcb, regs->dx);
761 : ghcb_set_rsi(ghcb, regs->si);
762 : }
763 :
764 : static bool kvm_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs)
765 : {
766 : /* No checking of the return state needed */
767 : return true;
768 : }
769 : #endif
770 :
771 : const __initconst struct hypervisor_x86 x86_hyper_kvm = {
772 : .name = "KVM",
773 : .detect = kvm_detect,
774 : .type = X86_HYPER_KVM,
775 : .init.guest_late_init = kvm_guest_init,
776 : .init.x2apic_available = kvm_para_available,
777 : .init.msi_ext_dest_id = kvm_msi_ext_dest_id,
778 : .init.init_platform = kvm_init_platform,
779 : #if defined(CONFIG_AMD_MEM_ENCRYPT)
780 : .runtime.sev_es_hcall_prepare = kvm_sev_es_hcall_prepare,
781 : .runtime.sev_es_hcall_finish = kvm_sev_es_hcall_finish,
782 : #endif
783 : };
784 :
785 1 : static __init int activate_jump_labels(void)
786 : {
787 1 : if (has_steal_clock) {
788 1 : static_key_slow_inc(¶virt_steal_enabled);
789 1 : if (steal_acc)
790 1 : static_key_slow_inc(¶virt_steal_rq_enabled);
791 : }
792 :
793 1 : return 0;
794 : }
795 : arch_initcall(activate_jump_labels);
796 :
797 1 : static __init int kvm_alloc_cpumask(void)
798 : {
799 1 : int cpu;
800 1 : bool alloc = false;
801 :
802 1 : if (!kvm_para_available() || nopv)
803 : return 0;
804 :
805 1 : if (pv_tlb_flush_supported())
806 1 : alloc = true;
807 :
808 : #if defined(CONFIG_SMP)
809 2 : if (pv_ipi_supported())
810 : alloc = true;
811 : #endif
812 :
813 0 : if (alloc)
814 5 : for_each_possible_cpu(cpu) {
815 5 : zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu),
816 : GFP_KERNEL, cpu_to_node(cpu));
817 : }
818 :
819 : return 0;
820 : }
821 : arch_initcall(kvm_alloc_cpumask);
822 :
823 : #ifdef CONFIG_PARAVIRT_SPINLOCKS
824 :
825 : /* Kick a cpu by its apicid. Used to wake up a halted vcpu */
826 76 : static void kvm_kick_cpu(int cpu)
827 : {
828 76 : int apicid;
829 76 : unsigned long flags = 0;
830 :
831 76 : apicid = per_cpu(x86_cpu_to_apicid, cpu);
832 76 : kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
833 76 : }
834 :
835 : #include <asm/qspinlock.h>
836 :
837 76 : static void kvm_wait(u8 *ptr, u8 val)
838 : {
839 76 : unsigned long flags;
840 :
841 76 : if (in_nmi())
842 : return;
843 :
844 152 : local_irq_save(flags);
845 :
846 76 : if (READ_ONCE(*ptr) != val)
847 0 : goto out;
848 :
849 : /*
850 : * halt until it's our turn and kicked. Note that we do safe halt
851 : * for irq enabled case to avoid hang when lock info is overwritten
852 : * in irq spinlock slowpath and no spurious interrupt occur to save us.
853 : */
854 76 : if (arch_irqs_disabled_flags(flags))
855 72 : halt();
856 : else
857 4 : safe_halt();
858 :
859 76 : out:
860 76 : local_irq_restore(flags);
861 : }
862 :
863 : #ifdef CONFIG_X86_32
864 : __visible bool __kvm_vcpu_is_preempted(long cpu)
865 : {
866 : struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
867 :
868 : return !!(src->preempted & KVM_VCPU_PREEMPTED);
869 : }
870 : PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
871 :
872 : #else
873 :
874 : #include <asm/asm-offsets.h>
875 :
876 : extern bool __raw_callee_save___kvm_vcpu_is_preempted(long);
877 :
878 : /*
879 : * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and
880 : * restoring to/from the stack.
881 : */
882 : asm(
883 : ".pushsection .text;"
884 : ".global __raw_callee_save___kvm_vcpu_is_preempted;"
885 : ".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"
886 : "__raw_callee_save___kvm_vcpu_is_preempted:"
887 : "movq __per_cpu_offset(,%rdi,8), %rax;"
888 : "cmpb $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);"
889 : "setne %al;"
890 : "ret;"
891 : ".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;"
892 : ".popsection");
893 :
894 : #endif
895 :
896 : /*
897 : * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
898 : */
899 1 : void __init kvm_spinlock_init(void)
900 : {
901 : /*
902 : * In case host doesn't support KVM_FEATURE_PV_UNHALT there is still an
903 : * advantage of keeping virt_spin_lock_key enabled: virt_spin_lock() is
904 : * preferred over native qspinlock when vCPU is preempted.
905 : */
906 2 : if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) {
907 0 : pr_info("PV spinlocks disabled, no host support\n");
908 0 : return;
909 : }
910 :
911 : /*
912 : * Disable PV spinlocks and use native qspinlock when dedicated pCPUs
913 : * are available.
914 : */
915 2 : if (kvm_para_has_hint(KVM_HINTS_REALTIME)) {
916 0 : pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n");
917 0 : goto out;
918 : }
919 :
920 1 : if (num_possible_cpus() == 1) {
921 0 : pr_info("PV spinlocks disabled, single CPU\n");
922 0 : goto out;
923 : }
924 :
925 1 : if (nopvspin) {
926 0 : pr_info("PV spinlocks disabled, forced by \"nopvspin\" parameter\n");
927 0 : goto out;
928 : }
929 :
930 1 : pr_info("PV spinlocks enabled\n");
931 :
932 1 : __pv_init_lock_hash();
933 1 : pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
934 1 : pv_ops.lock.queued_spin_unlock =
935 : PV_CALLEE_SAVE(__pv_queued_spin_unlock);
936 1 : pv_ops.lock.wait = kvm_wait;
937 1 : pv_ops.lock.kick = kvm_kick_cpu;
938 :
939 2 : if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
940 1 : pv_ops.lock.vcpu_is_preempted =
941 : PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
942 : }
943 : /*
944 : * When PV spinlock is enabled which is preferred over
945 : * virt_spin_lock(), virt_spin_lock_key's value is meaningless.
946 : * Just disable it anyway.
947 : */
948 0 : out:
949 1 : static_branch_disable(&virt_spin_lock_key);
950 : }
951 :
952 : #endif /* CONFIG_PARAVIRT_SPINLOCKS */
953 :
954 : #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
955 :
956 0 : static void kvm_disable_host_haltpoll(void *i)
957 : {
958 0 : wrmsrl(MSR_KVM_POLL_CONTROL, 0);
959 0 : }
960 :
961 0 : static void kvm_enable_host_haltpoll(void *i)
962 : {
963 0 : wrmsrl(MSR_KVM_POLL_CONTROL, 1);
964 0 : }
965 :
966 0 : void arch_haltpoll_enable(unsigned int cpu)
967 : {
968 0 : if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {
969 0 : pr_err_once("host does not support poll control\n");
970 0 : pr_err_once("host upgrade recommended\n");
971 0 : return;
972 : }
973 :
974 : /* Enable guest halt poll disables host halt poll */
975 0 : smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1);
976 : }
977 : EXPORT_SYMBOL_GPL(arch_haltpoll_enable);
978 :
979 0 : void arch_haltpoll_disable(unsigned int cpu)
980 : {
981 0 : if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
982 : return;
983 :
984 : /* Disable guest halt poll enables host halt poll */
985 0 : smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1);
986 : }
987 : EXPORT_SYMBOL_GPL(arch_haltpoll_disable);
988 : #endif
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