~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/arch/x86/kernel/kvm.c

Version: ~ [ linux-5.12-rc7 ] ~ [ linux-5.11.13 ] ~ [ linux-5.10.29 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.111 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.186 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.230 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.266 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.266 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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 
 50 static int kvmapf = 1;
 51 
 52 static int __init parse_no_kvmapf(char *arg)
 53 {
 54         kvmapf = 0;
 55         return 0;
 56 }
 57 
 58 early_param("no-kvmapf", parse_no_kvmapf);
 59 
 60 static int steal_acc = 1;
 61 static int __init parse_no_stealacc(char *arg)
 62 {
 63         steal_acc = 0;
 64         return 0;
 65 }
 66 
 67 early_param("no-steal-acc", parse_no_stealacc);
 68 
 69 static int kvmclock_vsyscall = 1;
 70 static int __init parse_no_kvmclock_vsyscall(char *arg)
 71 {
 72         kvmclock_vsyscall = 0;
 73         return 0;
 74 }
 75 
 76 early_param("no-kvmclock-vsyscall", parse_no_kvmclock_vsyscall);
 77 
 78 static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
 79 static DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64);
 80 static int has_steal_clock = 0;
 81 
 82 /*
 83  * No need for any "IO delay" on KVM
 84  */
 85 static 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 
 92 struct 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 
100 static struct kvm_task_sleep_head {
101         raw_spinlock_t lock;
102         struct hlist_head list;
103 } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
104 
105 static 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 
120 /*
121  * @interrupt_kernel: Is this called from a routine which interrupts the kernel
122  *                    (other than user space)?
123  */
124 void kvm_async_pf_task_wait(u32 token, int interrupt_kernel)
125 {
126         u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
127         struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
128         struct kvm_task_sleep_node n, *e;
129         DECLARE_SWAITQUEUE(wait);
130 
131         rcu_irq_enter();
132 
133         raw_spin_lock(&b->lock);
134         e = _find_apf_task(b, token);
135         if (e) {
136                 /* dummy entry exist -> wake up was delivered ahead of PF */
137                 hlist_del(&e->link);
138                 kfree(e);
139                 raw_spin_unlock(&b->lock);
140 
141                 rcu_irq_exit();
142                 return;
143         }
144 
145         n.token = token;
146         n.cpu = smp_processor_id();
147         n.halted = is_idle_task(current) ||
148                    (IS_ENABLED(CONFIG_PREEMPT_COUNT)
149                     ? preempt_count() > 1 || rcu_preempt_depth()
150                     : interrupt_kernel);
151         init_swait_queue_head(&n.wq);
152         hlist_add_head(&n.link, &b->list);
153         raw_spin_unlock(&b->lock);
154 
155         for (;;) {
156                 if (!n.halted)
157                         prepare_to_swait(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
158                 if (hlist_unhashed(&n.link))
159                         break;
160 
161                 rcu_irq_exit();
162 
163                 if (!n.halted) {
164                         local_irq_enable();
165                         schedule();
166                         local_irq_disable();
167                 } else {
168                         /*
169                          * We cannot reschedule. So halt.
170                          */
171                         native_safe_halt();
172                         local_irq_disable();
173                 }
174 
175                 rcu_irq_enter();
176         }
177         if (!n.halted)
178                 finish_swait(&n.wq, &wait);
179 
180         rcu_irq_exit();
181         return;
182 }
183 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait);
184 
185 static void apf_task_wake_one(struct kvm_task_sleep_node *n)
186 {
187         hlist_del_init(&n->link);
188         if (n->halted)
189                 smp_send_reschedule(n->cpu);
190         else if (swq_has_sleeper(&n->wq))
191                 swake_up(&n->wq);
192 }
193 
194 static void apf_task_wake_all(void)
195 {
196         int i;
197 
198         for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
199                 struct hlist_node *p, *next;
200                 struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
201                 raw_spin_lock(&b->lock);
202                 hlist_for_each_safe(p, next, &b->list) {
203                         struct kvm_task_sleep_node *n =
204                                 hlist_entry(p, typeof(*n), link);
205                         if (n->cpu == smp_processor_id())
206                                 apf_task_wake_one(n);
207                 }
208                 raw_spin_unlock(&b->lock);
209         }
210 }
211 
212 void kvm_async_pf_task_wake(u32 token)
213 {
214         u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
215         struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
216         struct kvm_task_sleep_node *n;
217 
218         if (token == ~0) {
219                 apf_task_wake_all();
220                 return;
221         }
222 
223 again:
224         raw_spin_lock(&b->lock);
225         n = _find_apf_task(b, token);
226         if (!n) {
227                 /*
228                  * async PF was not yet handled.
229                  * Add dummy entry for the token.
230                  */
231                 n = kzalloc(sizeof(*n), GFP_ATOMIC);
232                 if (!n) {
233                         /*
234                          * Allocation failed! Busy wait while other cpu
235                          * handles async PF.
236                          */
237                         raw_spin_unlock(&b->lock);
238                         cpu_relax();
239                         goto again;
240                 }
241                 n->token = token;
242                 n->cpu = smp_processor_id();
243                 init_swait_queue_head(&n->wq);
244                 hlist_add_head(&n->link, &b->list);
245         } else
246                 apf_task_wake_one(n);
247         raw_spin_unlock(&b->lock);
248         return;
249 }
250 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
251 
252 u32 kvm_read_and_reset_pf_reason(void)
253 {
254         u32 reason = 0;
255 
256         if (__this_cpu_read(apf_reason.enabled)) {
257                 reason = __this_cpu_read(apf_reason.reason);
258                 __this_cpu_write(apf_reason.reason, 0);
259         }
260 
261         return reason;
262 }
263 EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason);
264 NOKPROBE_SYMBOL(kvm_read_and_reset_pf_reason);
265 
266 dotraplinkage void
267 do_async_page_fault(struct pt_regs *regs, unsigned long error_code)
268 {
269         enum ctx_state prev_state;
270 
271         switch (kvm_read_and_reset_pf_reason()) {
272         default:
273                 do_page_fault(regs, error_code);
274                 break;
275         case KVM_PV_REASON_PAGE_NOT_PRESENT:
276                 /* page is swapped out by the host. */
277                 prev_state = exception_enter();
278                 kvm_async_pf_task_wait((u32)read_cr2(), !user_mode(regs));
279                 exception_exit(prev_state);
280                 break;
281         case KVM_PV_REASON_PAGE_READY:
282                 rcu_irq_enter();
283                 kvm_async_pf_task_wake((u32)read_cr2());
284                 rcu_irq_exit();
285                 break;
286         }
287 }
288 NOKPROBE_SYMBOL(do_async_page_fault);
289 
290 static void __init paravirt_ops_setup(void)
291 {
292         pv_info.name = "KVM";
293 
294         if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
295                 pv_cpu_ops.io_delay = kvm_io_delay;
296 
297 #ifdef CONFIG_X86_IO_APIC
298         no_timer_check = 1;
299 #endif
300 }
301 
302 static void kvm_register_steal_time(void)
303 {
304         int cpu = smp_processor_id();
305         struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
306 
307         if (!has_steal_clock)
308                 return;
309 
310         wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
311         pr_info("kvm-stealtime: cpu %d, msr %llx\n",
312                 cpu, (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 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         if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi)))
327                 return;
328         apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK);
329 }
330 
331 static void kvm_guest_cpu_init(void)
332 {
333         if (!kvm_para_available())
334                 return;
335 
336         if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) {
337                 u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
338 
339 #ifdef CONFIG_PREEMPT
340                 pa |= KVM_ASYNC_PF_SEND_ALWAYS;
341 #endif
342                 pa |= KVM_ASYNC_PF_ENABLED;
343 
344                 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
345                         pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
346 
347                 wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
348                 __this_cpu_write(apf_reason.enabled, 1);
349                 printk(KERN_INFO"KVM setup async PF for cpu %d\n",
350                        smp_processor_id());
351         }
352 
353         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
354                 unsigned long pa;
355                 /* Size alignment is implied but just to make it explicit. */
356                 BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
357                 __this_cpu_write(kvm_apic_eoi, 0);
358                 pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
359                         | KVM_MSR_ENABLED;
360                 wrmsrl(MSR_KVM_PV_EOI_EN, pa);
361         }
362 
363         if (has_steal_clock)
364                 kvm_register_steal_time();
365 }
366 
367 static void kvm_pv_disable_apf(void)
368 {
369         if (!__this_cpu_read(apf_reason.enabled))
370                 return;
371 
372         wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
373         __this_cpu_write(apf_reason.enabled, 0);
374 
375         printk(KERN_INFO"Unregister pv shared memory for cpu %d\n",
376                smp_processor_id());
377 }
378 
379 static void kvm_pv_guest_cpu_reboot(void *unused)
380 {
381         /*
382          * We disable PV EOI before we load a new kernel by kexec,
383          * since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory.
384          * New kernel can re-enable when it boots.
385          */
386         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
387                 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
388         kvm_pv_disable_apf();
389         kvm_disable_steal_time();
390 }
391 
392 static int kvm_pv_reboot_notify(struct notifier_block *nb,
393                                 unsigned long code, void *unused)
394 {
395         if (code == SYS_RESTART)
396                 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
397         return NOTIFY_DONE;
398 }
399 
400 static struct notifier_block kvm_pv_reboot_nb = {
401         .notifier_call = kvm_pv_reboot_notify,
402 };
403 
404 static u64 kvm_steal_clock(int cpu)
405 {
406         u64 steal;
407         struct kvm_steal_time *src;
408         int version;
409 
410         src = &per_cpu(steal_time, cpu);
411         do {
412                 version = src->version;
413                 virt_rmb();
414                 steal = src->steal;
415                 virt_rmb();
416         } while ((version & 1) || (version != src->version));
417 
418         return steal;
419 }
420 
421 void kvm_disable_steal_time(void)
422 {
423         if (!has_steal_clock)
424                 return;
425 
426         wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
427 }
428 
429 static inline void __set_percpu_decrypted(void *ptr, unsigned long size)
430 {
431         early_set_memory_decrypted((unsigned long) ptr, size);
432 }
433 
434 /*
435  * Iterate through all possible CPUs and map the memory region pointed
436  * by apf_reason, steal_time and kvm_apic_eoi as decrypted at once.
437  *
438  * Note: we iterate through all possible CPUs to ensure that CPUs
439  * hotplugged will have their per-cpu variable already mapped as
440  * decrypted.
441  */
442 static void __init sev_map_percpu_data(void)
443 {
444         int cpu;
445 
446         if (!sev_active())
447                 return;
448 
449         for_each_possible_cpu(cpu) {
450                 __set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason));
451                 __set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time));
452                 __set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi));
453         }
454 }
455 
456 #ifdef CONFIG_SMP
457 static void __init kvm_smp_prepare_cpus(unsigned int max_cpus)
458 {
459         native_smp_prepare_cpus(max_cpus);
460         if (kvm_para_has_hint(KVM_HINTS_REALTIME))
461                 static_branch_disable(&virt_spin_lock_key);
462 }
463 
464 static void __init kvm_smp_prepare_boot_cpu(void)
465 {
466         /*
467          * Map the per-cpu variables as decrypted before kvm_guest_cpu_init()
468          * shares the guest physical address with the hypervisor.
469          */
470         sev_map_percpu_data();
471 
472         kvm_guest_cpu_init();
473         native_smp_prepare_boot_cpu();
474         kvm_spinlock_init();
475 }
476 
477 static void kvm_guest_cpu_offline(void)
478 {
479         kvm_disable_steal_time();
480         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
481                 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
482         kvm_pv_disable_apf();
483         apf_task_wake_all();
484 }
485 
486 static int kvm_cpu_online(unsigned int cpu)
487 {
488         local_irq_disable();
489         kvm_guest_cpu_init();
490         local_irq_enable();
491         return 0;
492 }
493 
494 static int kvm_cpu_down_prepare(unsigned int cpu)
495 {
496         local_irq_disable();
497         kvm_guest_cpu_offline();
498         local_irq_enable();
499         return 0;
500 }
501 #endif
502 
503 static void __init kvm_apf_trap_init(void)
504 {
505         update_intr_gate(X86_TRAP_PF, async_page_fault);
506 }
507 
508 static DEFINE_PER_CPU(cpumask_var_t, __pv_tlb_mask);
509 
510 static void kvm_flush_tlb_others(const struct cpumask *cpumask,
511                         const struct flush_tlb_info *info)
512 {
513         u8 state;
514         int cpu;
515         struct kvm_steal_time *src;
516         struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_tlb_mask);
517 
518         cpumask_copy(flushmask, cpumask);
519         /*
520          * We have to call flush only on online vCPUs. And
521          * queue flush_on_enter for pre-empted vCPUs
522          */
523         for_each_cpu(cpu, flushmask) {
524                 src = &per_cpu(steal_time, cpu);
525                 state = READ_ONCE(src->preempted);
526                 if ((state & KVM_VCPU_PREEMPTED)) {
527                         if (try_cmpxchg(&src->preempted, &state,
528                                         state | KVM_VCPU_FLUSH_TLB))
529                                 __cpumask_clear_cpu(cpu, flushmask);
530                 }
531         }
532 
533         native_flush_tlb_others(flushmask, info);
534 }
535 
536 static void __init kvm_guest_init(void)
537 {
538         int i;
539 
540         if (!kvm_para_available())
541                 return;
542 
543         paravirt_ops_setup();
544         register_reboot_notifier(&kvm_pv_reboot_nb);
545         for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
546                 raw_spin_lock_init(&async_pf_sleepers[i].lock);
547         if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
548                 x86_init.irqs.trap_init = kvm_apf_trap_init;
549 
550         if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
551                 has_steal_clock = 1;
552                 pv_time_ops.steal_clock = kvm_steal_clock;
553         }
554 
555         if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
556             !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
557             kvm_para_has_feature(KVM_FEATURE_STEAL_TIME))
558                 pv_mmu_ops.flush_tlb_others = kvm_flush_tlb_others;
559 
560         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
561                 apic_set_eoi_write(kvm_guest_apic_eoi_write);
562 
563         if (kvmclock_vsyscall)
564                 kvm_setup_vsyscall_timeinfo();
565 
566 #ifdef CONFIG_SMP
567         smp_ops.smp_prepare_cpus = kvm_smp_prepare_cpus;
568         smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
569         if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
570                                       kvm_cpu_online, kvm_cpu_down_prepare) < 0)
571                 pr_err("kvm_guest: Failed to install cpu hotplug callbacks\n");
572 #else
573         sev_map_percpu_data();
574         kvm_guest_cpu_init();
575 #endif
576 
577         /*
578          * Hard lockup detection is enabled by default. Disable it, as guests
579          * can get false positives too easily, for example if the host is
580          * overcommitted.
581          */
582         hardlockup_detector_disable();
583 }
584 
585 static noinline uint32_t __kvm_cpuid_base(void)
586 {
587         if (boot_cpu_data.cpuid_level < 0)
588                 return 0;       /* So we don't blow up on old processors */
589 
590         if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
591                 return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0);
592 
593         return 0;
594 }
595 
596 static inline uint32_t kvm_cpuid_base(void)
597 {
598         static int kvm_cpuid_base = -1;
599 
600         if (kvm_cpuid_base == -1)
601                 kvm_cpuid_base = __kvm_cpuid_base();
602 
603         return kvm_cpuid_base;
604 }
605 
606 bool kvm_para_available(void)
607 {
608         return kvm_cpuid_base() != 0;
609 }
610 EXPORT_SYMBOL_GPL(kvm_para_available);
611 
612 unsigned int kvm_arch_para_features(void)
613 {
614         return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
615 }
616 
617 unsigned int kvm_arch_para_hints(void)
618 {
619         return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
620 }
621 
622 static uint32_t __init kvm_detect(void)
623 {
624         return kvm_cpuid_base();
625 }
626 
627 const __initconst struct hypervisor_x86 x86_hyper_kvm = {
628         .name                   = "KVM",
629         .detect                 = kvm_detect,
630         .type                   = X86_HYPER_KVM,
631         .init.guest_late_init   = kvm_guest_init,
632         .init.x2apic_available  = kvm_para_available,
633 };
634 
635 static __init int activate_jump_labels(void)
636 {
637         if (has_steal_clock) {
638                 static_key_slow_inc(&paravirt_steal_enabled);
639                 if (steal_acc)
640                         static_key_slow_inc(&paravirt_steal_rq_enabled);
641         }
642 
643         return 0;
644 }
645 arch_initcall(activate_jump_labels);
646 
647 static __init int kvm_setup_pv_tlb_flush(void)
648 {
649         int cpu;
650 
651         if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
652             !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
653             kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
654                 for_each_possible_cpu(cpu) {
655                         zalloc_cpumask_var_node(per_cpu_ptr(&__pv_tlb_mask, cpu),
656                                 GFP_KERNEL, cpu_to_node(cpu));
657                 }
658                 pr_info("KVM setup pv remote TLB flush\n");
659         }
660 
661         return 0;
662 }
663 arch_initcall(kvm_setup_pv_tlb_flush);
664 
665 #ifdef CONFIG_PARAVIRT_SPINLOCKS
666 
667 /* Kick a cpu by its apicid. Used to wake up a halted vcpu */
668 static void kvm_kick_cpu(int cpu)
669 {
670         int apicid;
671         unsigned long flags = 0;
672 
673         apicid = per_cpu(x86_cpu_to_apicid, cpu);
674         kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
675 }
676 
677 #include <asm/qspinlock.h>
678 
679 static void kvm_wait(u8 *ptr, u8 val)
680 {
681         unsigned long flags;
682 
683         if (in_nmi())
684                 return;
685 
686         local_irq_save(flags);
687 
688         if (READ_ONCE(*ptr) != val)
689                 goto out;
690 
691         /*
692          * halt until it's our turn and kicked. Note that we do safe halt
693          * for irq enabled case to avoid hang when lock info is overwritten
694          * in irq spinlock slowpath and no spurious interrupt occur to save us.
695          */
696         if (arch_irqs_disabled_flags(flags))
697                 halt();
698         else
699                 safe_halt();
700 
701 out:
702         local_irq_restore(flags);
703 }
704 
705 #ifdef CONFIG_X86_32
706 __visible bool __kvm_vcpu_is_preempted(long cpu)
707 {
708         struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
709 
710         return !!(src->preempted & KVM_VCPU_PREEMPTED);
711 }
712 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
713 
714 #else
715 
716 #include <asm/asm-offsets.h>
717 
718 extern bool __raw_callee_save___kvm_vcpu_is_preempted(long);
719 
720 /*
721  * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and
722  * restoring to/from the stack.
723  */
724 asm(
725 ".pushsection .text;"
726 ".global __raw_callee_save___kvm_vcpu_is_preempted;"
727 ".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"
728 "__raw_callee_save___kvm_vcpu_is_preempted:"
729 "movq   __per_cpu_offset(,%rdi,8), %rax;"
730 "cmpb   $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);"
731 "setne  %al;"
732 "ret;"
733 ".popsection");
734 
735 #endif
736 
737 /*
738  * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
739  */
740 void __init kvm_spinlock_init(void)
741 {
742         if (!kvm_para_available())
743                 return;
744         /* Does host kernel support KVM_FEATURE_PV_UNHALT? */
745         if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
746                 return;
747 
748         if (kvm_para_has_hint(KVM_HINTS_REALTIME))
749                 return;
750 
751         __pv_init_lock_hash();
752         pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
753         pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock);
754         pv_lock_ops.wait = kvm_wait;
755         pv_lock_ops.kick = kvm_kick_cpu;
756 
757         if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
758                 pv_lock_ops.vcpu_is_preempted =
759                         PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
760         }
761 }
762 
763 #endif  /* CONFIG_PARAVIRT_SPINLOCKS */
764 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp