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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/module.h>
24#include <linux/kernel.h>
25#include <linux/kvm_para.h>
26#include <linux/cpu.h>
27#include <linux/mm.h>
28#include <linux/highmem.h>
29#include <linux/hardirq.h>
30#include <linux/notifier.h>
31#include <linux/reboot.h>
32#include <linux/hash.h>
33#include <linux/sched.h>
34#include <linux/slab.h>
35#include <linux/kprobes.h>
36#include <asm/timer.h>
37#include <asm/cpu.h>
38#include <asm/traps.h>
39#include <asm/desc.h>
40#include <asm/tlbflush.h>
41
42#define MMU_QUEUE_SIZE 1024
43
44static int kvmapf = 1;
45
46static int parse_no_kvmapf(char *arg)
47{
48 kvmapf = 0;
49 return 0;
50}
51
52early_param("no-kvmapf", parse_no_kvmapf);
53
54static int steal_acc = 1;
55static int parse_no_stealacc(char *arg)
56{
57 steal_acc = 0;
58 return 0;
59}
60
61early_param("no-steal-acc", parse_no_stealacc);
62
63struct kvm_para_state {
64 u8 mmu_queue[MMU_QUEUE_SIZE];
65 int mmu_queue_len;
66};
67
68static DEFINE_PER_CPU(struct kvm_para_state, para_state);
69static DEFINE_PER_CPU(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
70static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64);
71static int has_steal_clock = 0;
72
73static struct kvm_para_state *kvm_para_state(void)
74{
75 return &per_cpu(para_state, raw_smp_processor_id());
76}
77
78/*
79 * No need for any "IO delay" on KVM
80 */
81static void kvm_io_delay(void)
82{
83}
84
85#define KVM_TASK_SLEEP_HASHBITS 8
86#define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
87
88struct kvm_task_sleep_node {
89 struct hlist_node link;
90 wait_queue_head_t wq;
91 u32 token;
92 int cpu;
93 bool halted;
94 struct mm_struct *mm;
95};
96
97static struct kvm_task_sleep_head {
98 spinlock_t lock;
99 struct hlist_head list;
100} async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
101
102static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
103 u32 token)
104{
105 struct hlist_node *p;
106
107 hlist_for_each(p, &b->list) {
108 struct kvm_task_sleep_node *n =
109 hlist_entry(p, typeof(*n), link);
110 if (n->token == token)
111 return n;
112 }
113
114 return NULL;
115}
116
117void kvm_async_pf_task_wait(u32 token)
118{
119 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
120 struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
121 struct kvm_task_sleep_node n, *e;
122 DEFINE_WAIT(wait);
123 int cpu, idle;
124
125 cpu = get_cpu();
126 idle = idle_cpu(cpu);
127 put_cpu();
128
129 spin_lock(&b->lock);
130 e = _find_apf_task(b, token);
131 if (e) {
132 /* dummy entry exist -> wake up was delivered ahead of PF */
133 hlist_del(&e->link);
134 kfree(e);
135 spin_unlock(&b->lock);
136 return;
137 }
138
139 n.token = token;
140 n.cpu = smp_processor_id();
141 n.mm = current->active_mm;
142 n.halted = idle || preempt_count() > 1;
143 atomic_inc(&n.mm->mm_count);
144 init_waitqueue_head(&n.wq);
145 hlist_add_head(&n.link, &b->list);
146 spin_unlock(&b->lock);
147
148 for (;;) {
149 if (!n.halted)
150 prepare_to_wait(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
151 if (hlist_unhashed(&n.link))
152 break;
153
154 if (!n.halted) {
155 local_irq_enable();
156 schedule();
157 local_irq_disable();
158 } else {
159 /*
160 * We cannot reschedule. So halt.
161 */
162 native_safe_halt();
163 local_irq_disable();
164 }
165 }
166 if (!n.halted)
167 finish_wait(&n.wq, &wait);
168
169 return;
170}
171EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait);
172
173static void apf_task_wake_one(struct kvm_task_sleep_node *n)
174{
175 hlist_del_init(&n->link);
176 if (!n->mm)
177 return;
178 mmdrop(n->mm);
179 if (n->halted)
180 smp_send_reschedule(n->cpu);
181 else if (waitqueue_active(&n->wq))
182 wake_up(&n->wq);
183}
184
185static void apf_task_wake_all(void)
186{
187 int i;
188
189 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
190 struct hlist_node *p, *next;
191 struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
192 spin_lock(&b->lock);
193 hlist_for_each_safe(p, next, &b->list) {
194 struct kvm_task_sleep_node *n =
195 hlist_entry(p, typeof(*n), link);
196 if (n->cpu == smp_processor_id())
197 apf_task_wake_one(n);
198 }
199 spin_unlock(&b->lock);
200 }
201}
202
203void kvm_async_pf_task_wake(u32 token)
204{
205 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
206 struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
207 struct kvm_task_sleep_node *n;
208
209 if (token == ~0) {
210 apf_task_wake_all();
211 return;
212 }
213
214again:
215 spin_lock(&b->lock);
216 n = _find_apf_task(b, token);
217 if (!n) {
218 /*
219 * async PF was not yet handled.
220 * Add dummy entry for the token.
221 */
222 n = kmalloc(sizeof(*n), GFP_ATOMIC);
223 if (!n) {
224 /*
225 * Allocation failed! Busy wait while other cpu
226 * handles async PF.
227 */
228 spin_unlock(&b->lock);
229 cpu_relax();
230 goto again;
231 }
232 n->token = token;
233 n->cpu = smp_processor_id();
234 n->mm = NULL;
235 init_waitqueue_head(&n->wq);
236 hlist_add_head(&n->link, &b->list);
237 } else
238 apf_task_wake_one(n);
239 spin_unlock(&b->lock);
240 return;
241}
242EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
243
244u32 kvm_read_and_reset_pf_reason(void)
245{
246 u32 reason = 0;
247
248 if (__get_cpu_var(apf_reason).enabled) {
249 reason = __get_cpu_var(apf_reason).reason;
250 __get_cpu_var(apf_reason).reason = 0;
251 }
252
253 return reason;
254}
255EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason);
256
257dotraplinkage void __kprobes
258do_async_page_fault(struct pt_regs *regs, unsigned long error_code)
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 kvm_async_pf_task_wait((u32)read_cr2());
267 break;
268 case KVM_PV_REASON_PAGE_READY:
269 kvm_async_pf_task_wake((u32)read_cr2());
270 break;
271 }
272}
273
274static void kvm_mmu_op(void *buffer, unsigned len)
275{
276 int r;
277 unsigned long a1, a2;
278
279 do {
280 a1 = __pa(buffer);
281 a2 = 0; /* on i386 __pa() always returns <4G */
282 r = kvm_hypercall3(KVM_HC_MMU_OP, len, a1, a2);
283 buffer += r;
284 len -= r;
285 } while (len);
286}
287
288static void mmu_queue_flush(struct kvm_para_state *state)
289{
290 if (state->mmu_queue_len) {
291 kvm_mmu_op(state->mmu_queue, state->mmu_queue_len);
292 state->mmu_queue_len = 0;
293 }
294}
295
296static void kvm_deferred_mmu_op(void *buffer, int len)
297{
298 struct kvm_para_state *state = kvm_para_state();
299
300 if (paravirt_get_lazy_mode() != PARAVIRT_LAZY_MMU) {
301 kvm_mmu_op(buffer, len);
302 return;
303 }
304 if (state->mmu_queue_len + len > sizeof state->mmu_queue)
305 mmu_queue_flush(state);
306 memcpy(state->mmu_queue + state->mmu_queue_len, buffer, len);
307 state->mmu_queue_len += len;
308}
309
310static void kvm_mmu_write(void *dest, u64 val)
311{
312 __u64 pte_phys;
313 struct kvm_mmu_op_write_pte wpte;
314
315#ifdef CONFIG_HIGHPTE
316 struct page *page;
317 unsigned long dst = (unsigned long) dest;
318
319 page = kmap_atomic_to_page(dest);
320 pte_phys = page_to_pfn(page);
321 pte_phys <<= PAGE_SHIFT;
322 pte_phys += (dst & ~(PAGE_MASK));
323#else
324 pte_phys = (unsigned long)__pa(dest);
325#endif
326 wpte.header.op = KVM_MMU_OP_WRITE_PTE;
327 wpte.pte_val = val;
328 wpte.pte_phys = pte_phys;
329
330 kvm_deferred_mmu_op(&wpte, sizeof wpte);
331}
332
333/*
334 * We only need to hook operations that are MMU writes. We hook these so that
335 * we can use lazy MMU mode to batch these operations. We could probably
336 * improve the performance of the host code if we used some of the information
337 * here to simplify processing of batched writes.
338 */
339static void kvm_set_pte(pte_t *ptep, pte_t pte)
340{
341 kvm_mmu_write(ptep, pte_val(pte));
342}
343
344static void kvm_set_pte_at(struct mm_struct *mm, unsigned long addr,
345 pte_t *ptep, pte_t pte)
346{
347 kvm_mmu_write(ptep, pte_val(pte));
348}
349
350static void kvm_set_pmd(pmd_t *pmdp, pmd_t pmd)
351{
352 kvm_mmu_write(pmdp, pmd_val(pmd));
353}
354
355#if PAGETABLE_LEVELS >= 3
356#ifdef CONFIG_X86_PAE
357static void kvm_set_pte_atomic(pte_t *ptep, pte_t pte)
358{
359 kvm_mmu_write(ptep, pte_val(pte));
360}
361
362static void kvm_pte_clear(struct mm_struct *mm,
363 unsigned long addr, pte_t *ptep)
364{
365 kvm_mmu_write(ptep, 0);
366}
367
368static void kvm_pmd_clear(pmd_t *pmdp)
369{
370 kvm_mmu_write(pmdp, 0);
371}
372#endif
373
374static void kvm_set_pud(pud_t *pudp, pud_t pud)
375{
376 kvm_mmu_write(pudp, pud_val(pud));
377}
378
379#if PAGETABLE_LEVELS == 4
380static void kvm_set_pgd(pgd_t *pgdp, pgd_t pgd)
381{
382 kvm_mmu_write(pgdp, pgd_val(pgd));
383}
384#endif
385#endif /* PAGETABLE_LEVELS >= 3 */
386
387static void kvm_flush_tlb(void)
388{
389 struct kvm_mmu_op_flush_tlb ftlb = {
390 .header.op = KVM_MMU_OP_FLUSH_TLB,
391 };
392
393 kvm_deferred_mmu_op(&ftlb, sizeof ftlb);
394}
395
396static void kvm_release_pt(unsigned long pfn)
397{
398 struct kvm_mmu_op_release_pt rpt = {
399 .header.op = KVM_MMU_OP_RELEASE_PT,
400 .pt_phys = (u64)pfn << PAGE_SHIFT,
401 };
402
403 kvm_mmu_op(&rpt, sizeof rpt);
404}
405
406static void kvm_enter_lazy_mmu(void)
407{
408 paravirt_enter_lazy_mmu();
409}
410
411static void kvm_leave_lazy_mmu(void)
412{
413 struct kvm_para_state *state = kvm_para_state();
414
415 mmu_queue_flush(state);
416 paravirt_leave_lazy_mmu();
417}
418
419static void __init paravirt_ops_setup(void)
420{
421 pv_info.name = "KVM";
422 pv_info.paravirt_enabled = 1;
423
424 if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
425 pv_cpu_ops.io_delay = kvm_io_delay;
426
427 if (kvm_para_has_feature(KVM_FEATURE_MMU_OP)) {
428 pv_mmu_ops.set_pte = kvm_set_pte;
429 pv_mmu_ops.set_pte_at = kvm_set_pte_at;
430 pv_mmu_ops.set_pmd = kvm_set_pmd;
431#if PAGETABLE_LEVELS >= 3
432#ifdef CONFIG_X86_PAE
433 pv_mmu_ops.set_pte_atomic = kvm_set_pte_atomic;
434 pv_mmu_ops.pte_clear = kvm_pte_clear;
435 pv_mmu_ops.pmd_clear = kvm_pmd_clear;
436#endif
437 pv_mmu_ops.set_pud = kvm_set_pud;
438#if PAGETABLE_LEVELS == 4
439 pv_mmu_ops.set_pgd = kvm_set_pgd;
440#endif
441#endif
442 pv_mmu_ops.flush_tlb_user = kvm_flush_tlb;
443 pv_mmu_ops.release_pte = kvm_release_pt;
444 pv_mmu_ops.release_pmd = kvm_release_pt;
445 pv_mmu_ops.release_pud = kvm_release_pt;
446
447 pv_mmu_ops.lazy_mode.enter = kvm_enter_lazy_mmu;
448 pv_mmu_ops.lazy_mode.leave = kvm_leave_lazy_mmu;
449 }
450#ifdef CONFIG_X86_IO_APIC
451 no_timer_check = 1;
452#endif
453}
454
455static void kvm_register_steal_time(void)
456{
457 int cpu = smp_processor_id();
458 struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
459
460 if (!has_steal_clock)
461 return;
462
463 memset(st, 0, sizeof(*st));
464
465 wrmsrl(MSR_KVM_STEAL_TIME, (__pa(st) | KVM_MSR_ENABLED));
466 printk(KERN_INFO "kvm-stealtime: cpu %d, msr %lx\n",
467 cpu, __pa(st));
468}
469
470void __cpuinit kvm_guest_cpu_init(void)
471{
472 if (!kvm_para_available())
473 return;
474
475 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) {
476 u64 pa = __pa(&__get_cpu_var(apf_reason));
477
478#ifdef CONFIG_PREEMPT
479 pa |= KVM_ASYNC_PF_SEND_ALWAYS;
480#endif
481 wrmsrl(MSR_KVM_ASYNC_PF_EN, pa | KVM_ASYNC_PF_ENABLED);
482 __get_cpu_var(apf_reason).enabled = 1;
483 printk(KERN_INFO"KVM setup async PF for cpu %d\n",
484 smp_processor_id());
485 }
486
487 if (has_steal_clock)
488 kvm_register_steal_time();
489}
490
491static void kvm_pv_disable_apf(void *unused)
492{
493 if (!__get_cpu_var(apf_reason).enabled)
494 return;
495
496 wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
497 __get_cpu_var(apf_reason).enabled = 0;
498
499 printk(KERN_INFO"Unregister pv shared memory for cpu %d\n",
500 smp_processor_id());
501}
502
503static int kvm_pv_reboot_notify(struct notifier_block *nb,
504 unsigned long code, void *unused)
505{
506 if (code == SYS_RESTART)
507 on_each_cpu(kvm_pv_disable_apf, NULL, 1);
508 return NOTIFY_DONE;
509}
510
511static struct notifier_block kvm_pv_reboot_nb = {
512 .notifier_call = kvm_pv_reboot_notify,
513};
514
515static u64 kvm_steal_clock(int cpu)
516{
517 u64 steal;
518 struct kvm_steal_time *src;
519 int version;
520
521 src = &per_cpu(steal_time, cpu);
522 do {
523 version = src->version;
524 rmb();
525 steal = src->steal;
526 rmb();
527 } while ((version & 1) || (version != src->version));
528
529 return steal;
530}
531
532void kvm_disable_steal_time(void)
533{
534 if (!has_steal_clock)
535 return;
536
537 wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
538}
539
540#ifdef CONFIG_SMP
541static void __init kvm_smp_prepare_boot_cpu(void)
542{
543#ifdef CONFIG_KVM_CLOCK
544 WARN_ON(kvm_register_clock("primary cpu clock"));
545#endif
546 kvm_guest_cpu_init();
547 native_smp_prepare_boot_cpu();
548}
549
550static void __cpuinit kvm_guest_cpu_online(void *dummy)
551{
552 kvm_guest_cpu_init();
553}
554
555static void kvm_guest_cpu_offline(void *dummy)
556{
557 kvm_disable_steal_time();
558 kvm_pv_disable_apf(NULL);
559 apf_task_wake_all();
560}
561
562static int __cpuinit kvm_cpu_notify(struct notifier_block *self,
563 unsigned long action, void *hcpu)
564{
565 int cpu = (unsigned long)hcpu;
566 switch (action) {
567 case CPU_ONLINE:
568 case CPU_DOWN_FAILED:
569 case CPU_ONLINE_FROZEN:
570 smp_call_function_single(cpu, kvm_guest_cpu_online, NULL, 0);
571 break;
572 case CPU_DOWN_PREPARE:
573 case CPU_DOWN_PREPARE_FROZEN:
574 smp_call_function_single(cpu, kvm_guest_cpu_offline, NULL, 1);
575 break;
576 default:
577 break;
578 }
579 return NOTIFY_OK;
580}
581
582static struct notifier_block __cpuinitdata kvm_cpu_notifier = {
583 .notifier_call = kvm_cpu_notify,
584};
585#endif
586
587static void __init kvm_apf_trap_init(void)
588{
589 set_intr_gate(14, &async_page_fault);
590}
591
592void __init kvm_guest_init(void)
593{
594 int i;
595
596 if (!kvm_para_available())
597 return;
598
599 paravirt_ops_setup();
600 register_reboot_notifier(&kvm_pv_reboot_nb);
601 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
602 spin_lock_init(&async_pf_sleepers[i].lock);
603 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
604 x86_init.irqs.trap_init = kvm_apf_trap_init;
605
606 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
607 has_steal_clock = 1;
608 pv_time_ops.steal_clock = kvm_steal_clock;
609 }
610
611#ifdef CONFIG_SMP
612 smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
613 register_cpu_notifier(&kvm_cpu_notifier);
614#else
615 kvm_guest_cpu_init();
616#endif
617}
618
619static __init int activate_jump_labels(void)
620{
621 if (has_steal_clock) {
622 jump_label_inc(¶virt_steal_enabled);
623 if (steal_acc)
624 jump_label_inc(¶virt_steal_rq_enabled);
625 }
626
627 return 0;
628}
629arch_initcall(activate_jump_labels);
1/*
2 * KVM paravirt_ops implementation
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
17 *
18 * Copyright (C) 2007, Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
19 * Copyright IBM Corporation, 2007
20 * Authors: Anthony Liguori <aliguori@us.ibm.com>
21 */
22
23#include <linux/context_tracking.h>
24#include <linux/init.h>
25#include <linux/kernel.h>
26#include <linux/kvm_para.h>
27#include <linux/cpu.h>
28#include <linux/mm.h>
29#include <linux/highmem.h>
30#include <linux/hardirq.h>
31#include <linux/notifier.h>
32#include <linux/reboot.h>
33#include <linux/hash.h>
34#include <linux/sched.h>
35#include <linux/slab.h>
36#include <linux/kprobes.h>
37#include <linux/debugfs.h>
38#include <linux/nmi.h>
39#include <linux/swait.h>
40#include <asm/timer.h>
41#include <asm/cpu.h>
42#include <asm/traps.h>
43#include <asm/desc.h>
44#include <asm/tlbflush.h>
45#include <asm/apic.h>
46#include <asm/apicdef.h>
47#include <asm/hypervisor.h>
48#include <asm/kvm_guest.h>
49
50static int kvmapf = 1;
51
52static int parse_no_kvmapf(char *arg)
53{
54 kvmapf = 0;
55 return 0;
56}
57
58early_param("no-kvmapf", parse_no_kvmapf);
59
60static int steal_acc = 1;
61static int parse_no_stealacc(char *arg)
62{
63 steal_acc = 0;
64 return 0;
65}
66
67early_param("no-steal-acc", parse_no_stealacc);
68
69static int kvmclock_vsyscall = 1;
70static int parse_no_kvmclock_vsyscall(char *arg)
71{
72 kvmclock_vsyscall = 0;
73 return 0;
74}
75
76early_param("no-kvmclock-vsyscall", parse_no_kvmclock_vsyscall);
77
78static DEFINE_PER_CPU(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
79static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64);
80static int has_steal_clock = 0;
81
82/*
83 * No need for any "IO delay" on KVM
84 */
85static void kvm_io_delay(void)
86{
87}
88
89#define KVM_TASK_SLEEP_HASHBITS 8
90#define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
91
92struct kvm_task_sleep_node {
93 struct hlist_node link;
94 struct swait_queue_head wq;
95 u32 token;
96 int cpu;
97 bool halted;
98};
99
100static struct kvm_task_sleep_head {
101 raw_spinlock_t lock;
102 struct hlist_head list;
103} async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
104
105static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
106 u32 token)
107{
108 struct hlist_node *p;
109
110 hlist_for_each(p, &b->list) {
111 struct kvm_task_sleep_node *n =
112 hlist_entry(p, typeof(*n), link);
113 if (n->token == token)
114 return n;
115 }
116
117 return NULL;
118}
119
120void kvm_async_pf_task_wait(u32 token)
121{
122 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
123 struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
124 struct kvm_task_sleep_node n, *e;
125 DECLARE_SWAITQUEUE(wait);
126
127 rcu_irq_enter();
128
129 raw_spin_lock(&b->lock);
130 e = _find_apf_task(b, token);
131 if (e) {
132 /* dummy entry exist -> wake up was delivered ahead of PF */
133 hlist_del(&e->link);
134 kfree(e);
135 raw_spin_unlock(&b->lock);
136
137 rcu_irq_exit();
138 return;
139 }
140
141 n.token = token;
142 n.cpu = smp_processor_id();
143 n.halted = is_idle_task(current) || preempt_count() > 1;
144 init_swait_queue_head(&n.wq);
145 hlist_add_head(&n.link, &b->list);
146 raw_spin_unlock(&b->lock);
147
148 for (;;) {
149 if (!n.halted)
150 prepare_to_swait(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
151 if (hlist_unhashed(&n.link))
152 break;
153
154 if (!n.halted) {
155 local_irq_enable();
156 schedule();
157 local_irq_disable();
158 } else {
159 /*
160 * We cannot reschedule. So halt.
161 */
162 rcu_irq_exit();
163 native_safe_halt();
164 rcu_irq_enter();
165 local_irq_disable();
166 }
167 }
168 if (!n.halted)
169 finish_swait(&n.wq, &wait);
170
171 rcu_irq_exit();
172 return;
173}
174EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait);
175
176static void apf_task_wake_one(struct kvm_task_sleep_node *n)
177{
178 hlist_del_init(&n->link);
179 if (n->halted)
180 smp_send_reschedule(n->cpu);
181 else if (swait_active(&n->wq))
182 swake_up(&n->wq);
183}
184
185static void apf_task_wake_all(void)
186{
187 int i;
188
189 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
190 struct hlist_node *p, *next;
191 struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
192 raw_spin_lock(&b->lock);
193 hlist_for_each_safe(p, next, &b->list) {
194 struct kvm_task_sleep_node *n =
195 hlist_entry(p, typeof(*n), link);
196 if (n->cpu == smp_processor_id())
197 apf_task_wake_one(n);
198 }
199 raw_spin_unlock(&b->lock);
200 }
201}
202
203void kvm_async_pf_task_wake(u32 token)
204{
205 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
206 struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
207 struct kvm_task_sleep_node *n;
208
209 if (token == ~0) {
210 apf_task_wake_all();
211 return;
212 }
213
214again:
215 raw_spin_lock(&b->lock);
216 n = _find_apf_task(b, token);
217 if (!n) {
218 /*
219 * async PF was not yet handled.
220 * Add dummy entry for the token.
221 */
222 n = kzalloc(sizeof(*n), GFP_ATOMIC);
223 if (!n) {
224 /*
225 * Allocation failed! Busy wait while other cpu
226 * handles async PF.
227 */
228 raw_spin_unlock(&b->lock);
229 cpu_relax();
230 goto again;
231 }
232 n->token = token;
233 n->cpu = smp_processor_id();
234 init_swait_queue_head(&n->wq);
235 hlist_add_head(&n->link, &b->list);
236 } else
237 apf_task_wake_one(n);
238 raw_spin_unlock(&b->lock);
239 return;
240}
241EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
242
243u32 kvm_read_and_reset_pf_reason(void)
244{
245 u32 reason = 0;
246
247 if (__this_cpu_read(apf_reason.enabled)) {
248 reason = __this_cpu_read(apf_reason.reason);
249 __this_cpu_write(apf_reason.reason, 0);
250 }
251
252 return reason;
253}
254EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason);
255NOKPROBE_SYMBOL(kvm_read_and_reset_pf_reason);
256
257dotraplinkage void
258do_async_page_fault(struct pt_regs *regs, unsigned long error_code)
259{
260 enum ctx_state prev_state;
261
262 switch (kvm_read_and_reset_pf_reason()) {
263 default:
264 trace_do_page_fault(regs, error_code);
265 break;
266 case KVM_PV_REASON_PAGE_NOT_PRESENT:
267 /* page is swapped out by the host. */
268 prev_state = exception_enter();
269 kvm_async_pf_task_wait((u32)read_cr2());
270 exception_exit(prev_state);
271 break;
272 case KVM_PV_REASON_PAGE_READY:
273 rcu_irq_enter();
274 kvm_async_pf_task_wake((u32)read_cr2());
275 rcu_irq_exit();
276 break;
277 }
278}
279NOKPROBE_SYMBOL(do_async_page_fault);
280
281static void __init paravirt_ops_setup(void)
282{
283 pv_info.name = "KVM";
284
285 if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
286 pv_cpu_ops.io_delay = kvm_io_delay;
287
288#ifdef CONFIG_X86_IO_APIC
289 no_timer_check = 1;
290#endif
291}
292
293static void kvm_register_steal_time(void)
294{
295 int cpu = smp_processor_id();
296 struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
297
298 if (!has_steal_clock)
299 return;
300
301 wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
302 pr_info("kvm-stealtime: cpu %d, msr %llx\n",
303 cpu, (unsigned long long) slow_virt_to_phys(st));
304}
305
306static DEFINE_PER_CPU(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
307
308static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val)
309{
310 /**
311 * This relies on __test_and_clear_bit to modify the memory
312 * in a way that is atomic with respect to the local CPU.
313 * The hypervisor only accesses this memory from the local CPU so
314 * there's no need for lock or memory barriers.
315 * An optimization barrier is implied in apic write.
316 */
317 if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi)))
318 return;
319 apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK);
320}
321
322static void kvm_guest_cpu_init(void)
323{
324 if (!kvm_para_available())
325 return;
326
327 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) {
328 u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
329
330#ifdef CONFIG_PREEMPT
331 pa |= KVM_ASYNC_PF_SEND_ALWAYS;
332#endif
333 wrmsrl(MSR_KVM_ASYNC_PF_EN, pa | KVM_ASYNC_PF_ENABLED);
334 __this_cpu_write(apf_reason.enabled, 1);
335 printk(KERN_INFO"KVM setup async PF for cpu %d\n",
336 smp_processor_id());
337 }
338
339 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
340 unsigned long pa;
341 /* Size alignment is implied but just to make it explicit. */
342 BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
343 __this_cpu_write(kvm_apic_eoi, 0);
344 pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
345 | KVM_MSR_ENABLED;
346 wrmsrl(MSR_KVM_PV_EOI_EN, pa);
347 }
348
349 if (has_steal_clock)
350 kvm_register_steal_time();
351}
352
353static void kvm_pv_disable_apf(void)
354{
355 if (!__this_cpu_read(apf_reason.enabled))
356 return;
357
358 wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
359 __this_cpu_write(apf_reason.enabled, 0);
360
361 printk(KERN_INFO"Unregister pv shared memory for cpu %d\n",
362 smp_processor_id());
363}
364
365static void kvm_pv_guest_cpu_reboot(void *unused)
366{
367 /*
368 * We disable PV EOI before we load a new kernel by kexec,
369 * since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory.
370 * New kernel can re-enable when it boots.
371 */
372 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
373 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
374 kvm_pv_disable_apf();
375 kvm_disable_steal_time();
376}
377
378static int kvm_pv_reboot_notify(struct notifier_block *nb,
379 unsigned long code, void *unused)
380{
381 if (code == SYS_RESTART)
382 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
383 return NOTIFY_DONE;
384}
385
386static struct notifier_block kvm_pv_reboot_nb = {
387 .notifier_call = kvm_pv_reboot_notify,
388};
389
390static u64 kvm_steal_clock(int cpu)
391{
392 u64 steal;
393 struct kvm_steal_time *src;
394 int version;
395
396 src = &per_cpu(steal_time, cpu);
397 do {
398 version = src->version;
399 rmb();
400 steal = src->steal;
401 rmb();
402 } while ((version & 1) || (version != src->version));
403
404 return steal;
405}
406
407void kvm_disable_steal_time(void)
408{
409 if (!has_steal_clock)
410 return;
411
412 wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
413}
414
415#ifdef CONFIG_SMP
416static void __init kvm_smp_prepare_boot_cpu(void)
417{
418 kvm_guest_cpu_init();
419 native_smp_prepare_boot_cpu();
420 kvm_spinlock_init();
421}
422
423static void kvm_guest_cpu_offline(void)
424{
425 kvm_disable_steal_time();
426 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
427 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
428 kvm_pv_disable_apf();
429 apf_task_wake_all();
430}
431
432static int kvm_cpu_online(unsigned int cpu)
433{
434 local_irq_disable();
435 kvm_guest_cpu_init();
436 local_irq_enable();
437 return 0;
438}
439
440static int kvm_cpu_down_prepare(unsigned int cpu)
441{
442 local_irq_disable();
443 kvm_guest_cpu_offline();
444 local_irq_enable();
445 return 0;
446}
447#endif
448
449static void __init kvm_apf_trap_init(void)
450{
451 set_intr_gate(14, async_page_fault);
452}
453
454void __init kvm_guest_init(void)
455{
456 int i;
457
458 if (!kvm_para_available())
459 return;
460
461 paravirt_ops_setup();
462 register_reboot_notifier(&kvm_pv_reboot_nb);
463 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
464 raw_spin_lock_init(&async_pf_sleepers[i].lock);
465 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
466 x86_init.irqs.trap_init = kvm_apf_trap_init;
467
468 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
469 has_steal_clock = 1;
470 pv_time_ops.steal_clock = kvm_steal_clock;
471 }
472
473 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
474 apic_set_eoi_write(kvm_guest_apic_eoi_write);
475
476 if (kvmclock_vsyscall)
477 kvm_setup_vsyscall_timeinfo();
478
479#ifdef CONFIG_SMP
480 smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
481 if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
482 kvm_cpu_online, kvm_cpu_down_prepare) < 0)
483 pr_err("kvm_guest: Failed to install cpu hotplug callbacks\n");
484#else
485 kvm_guest_cpu_init();
486#endif
487
488 /*
489 * Hard lockup detection is enabled by default. Disable it, as guests
490 * can get false positives too easily, for example if the host is
491 * overcommitted.
492 */
493 hardlockup_detector_disable();
494}
495
496static noinline uint32_t __kvm_cpuid_base(void)
497{
498 if (boot_cpu_data.cpuid_level < 0)
499 return 0; /* So we don't blow up on old processors */
500
501 if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
502 return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0);
503
504 return 0;
505}
506
507static inline uint32_t kvm_cpuid_base(void)
508{
509 static int kvm_cpuid_base = -1;
510
511 if (kvm_cpuid_base == -1)
512 kvm_cpuid_base = __kvm_cpuid_base();
513
514 return kvm_cpuid_base;
515}
516
517bool kvm_para_available(void)
518{
519 return kvm_cpuid_base() != 0;
520}
521EXPORT_SYMBOL_GPL(kvm_para_available);
522
523unsigned int kvm_arch_para_features(void)
524{
525 return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
526}
527
528static uint32_t __init kvm_detect(void)
529{
530 return kvm_cpuid_base();
531}
532
533const struct hypervisor_x86 x86_hyper_kvm __refconst = {
534 .name = "KVM",
535 .detect = kvm_detect,
536 .x2apic_available = kvm_para_available,
537};
538EXPORT_SYMBOL_GPL(x86_hyper_kvm);
539
540static __init int activate_jump_labels(void)
541{
542 if (has_steal_clock) {
543 static_key_slow_inc(¶virt_steal_enabled);
544 if (steal_acc)
545 static_key_slow_inc(¶virt_steal_rq_enabled);
546 }
547
548 return 0;
549}
550arch_initcall(activate_jump_labels);
551
552#ifdef CONFIG_PARAVIRT_SPINLOCKS
553
554/* Kick a cpu by its apicid. Used to wake up a halted vcpu */
555static void kvm_kick_cpu(int cpu)
556{
557 int apicid;
558 unsigned long flags = 0;
559
560 apicid = per_cpu(x86_cpu_to_apicid, cpu);
561 kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
562}
563
564#include <asm/qspinlock.h>
565
566static void kvm_wait(u8 *ptr, u8 val)
567{
568 unsigned long flags;
569
570 if (in_nmi())
571 return;
572
573 local_irq_save(flags);
574
575 if (READ_ONCE(*ptr) != val)
576 goto out;
577
578 /*
579 * halt until it's our turn and kicked. Note that we do safe halt
580 * for irq enabled case to avoid hang when lock info is overwritten
581 * in irq spinlock slowpath and no spurious interrupt occur to save us.
582 */
583 if (arch_irqs_disabled_flags(flags))
584 halt();
585 else
586 safe_halt();
587
588out:
589 local_irq_restore(flags);
590}
591
592__visible bool __kvm_vcpu_is_preempted(int cpu)
593{
594 struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
595
596 return !!src->preempted;
597}
598PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
599
600/*
601 * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
602 */
603void __init kvm_spinlock_init(void)
604{
605 if (!kvm_para_available())
606 return;
607 /* Does host kernel support KVM_FEATURE_PV_UNHALT? */
608 if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
609 return;
610
611 __pv_init_lock_hash();
612 pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
613 pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock);
614 pv_lock_ops.wait = kvm_wait;
615 pv_lock_ops.kick = kvm_kick_cpu;
616
617 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
618 pv_lock_ops.vcpu_is_preempted =
619 PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
620 }
621}
622
623static __init int kvm_spinlock_init_jump(void)
624{
625 if (!kvm_para_available())
626 return 0;
627 if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
628 return 0;
629
630 static_key_slow_inc(¶virt_ticketlocks_enabled);
631 printk(KERN_INFO "KVM setup paravirtual spinlock\n");
632
633 return 0;
634}
635early_initcall(kvm_spinlock_init_jump);
636
637#endif /* CONFIG_PARAVIRT_SPINLOCKS */