arch/x86/kernel/kvm.c

   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
  49 static int kvmapf = 1;
  50
  51 static int __init parse_no_kvmapf(char *arg)
  52 {
  53         kvmapf = 0;
  54         return 0;
  55 }
  56
  57 early_param("no-kvmapf", parse_no_kvmapf);
  58
  59 static int steal_acc = 1;
  60 static int __init parse_no_stealacc(char *arg)
  61 {
  62         steal_acc = 0;
  63         return 0;
  64 }
  65
  66 early_param("no-steal-acc", parse_no_stealacc);
  67
  68 static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
  69 static DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64);
  70 static int has_steal_clock = 0;
  71
  72 /*
  73  * No need for any "IO delay" on KVM
  74  */
  75 static void kvm_io_delay(void)
  76 {
  77 }
  78
  79 #define KVM_TASK_SLEEP_HASHBITS 8
  80 #define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
  81
  82 struct kvm_task_sleep_node {
  83         struct hlist_node link;
  84         struct swait_queue_head wq;
  85         u32 token;
  86         int cpu;
  87         bool halted;
  88 };
  89
  90 static struct kvm_task_sleep_head {
  91         raw_spinlock_t lock;
  92         struct hlist_head list;
  93 } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
  94
  95 static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
  96                                                   u32 token)
  97 {
  98         struct hlist_node *p;
  99
 100         hlist_for_each(p, &b->list) {
 101                 struct kvm_task_sleep_node *n =
 102                         hlist_entry(p, typeof(*n), link);
 103                 if (n->token == token)
 104                         return n;
 105         }
 106
 107         return NULL;
 108 }
 109
 110 /*
 111  * @interrupt_kernel: Is this called from a routine which interrupts the kernel
 112  *                    (other than user space)?
 113  */
 114 void kvm_async_pf_task_wait(u32 token, int interrupt_kernel)
 115 {
 116         u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
 117         struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
 118         struct kvm_task_sleep_node n, *e;
 119         DECLARE_SWAITQUEUE(wait);
 120
 121         rcu_irq_enter();
 122
 123         raw_spin_lock(&b->lock);
 124         e = _find_apf_task(b, token);
 125         if (e) {
 126                 /* dummy entry exist -> wake up was delivered ahead of PF */
 127                 hlist_del(&e->link);
 128                 kfree(e);
 129                 raw_spin_unlock(&b->lock);
 130
 131                 rcu_irq_exit();
 132                 return;
 133         }
 134
 135         n.token = token;
 136         n.cpu = smp_processor_id();
 137         n.halted = is_idle_task(current) ||
 138                    (IS_ENABLED(CONFIG_PREEMPT_COUNT)
 139                     ? preempt_count() > 1 || rcu_preempt_depth()
 140                     : interrupt_kernel);
 141         init_swait_queue_head(&n.wq);
 142         hlist_add_head(&n.link, &b->list);
 143         raw_spin_unlock(&b->lock);
 144
 145         for (;;) {
 146                 if (!n.halted)
 147                         prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
 148                 if (hlist_unhashed(&n.link))
 149                         break;
 150
 151                 rcu_irq_exit();
 152
 153                 if (!n.halted) {
 154                         local_irq_enable();
 155                         schedule();
 156                         local_irq_disable();
 157                 } else {
 158                         /*
 159                          * We cannot reschedule. So halt.
 160                          */
 161                         native_safe_halt();
 162                         local_irq_disable();
 163                 }
 164
 165                 rcu_irq_enter();
 166         }
 167         if (!n.halted)
 168                 finish_swait(&n.wq, &wait);
 169
 170         rcu_irq_exit();
 171         return;
 172 }
 173 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait);
 174
 175 static void apf_task_wake_one(struct kvm_task_sleep_node *n)
 176 {
 177         hlist_del_init(&n->link);
 178         if (n->halted)
 179                 smp_send_reschedule(n->cpu);
 180         else if (swq_has_sleeper(&n->wq))
 181                 swake_up_one(&n->wq);
 182 }
 183
 184 static void apf_task_wake_all(void)
 185 {
 186         int i;
 187
 188         for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
 189                 struct hlist_node *p, *next;
 190                 struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
 191                 raw_spin_lock(&b->lock);
 192                 hlist_for_each_safe(p, next, &b->list) {
 193                         struct kvm_task_sleep_node *n =
 194                                 hlist_entry(p, typeof(*n), link);
 195                         if (n->cpu == smp_processor_id())
 196                                 apf_task_wake_one(n);
 197                 }
 198                 raw_spin_unlock(&b->lock);
 199         }
 200 }
 201
 202 void kvm_async_pf_task_wake(u32 token)
 203 {
 204         u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
 205         struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
 206         struct kvm_task_sleep_node *n;
 207
 208         if (token == ~0) {
 209                 apf_task_wake_all();
 210                 return;
 211         }
 212
 213 again:
 214         raw_spin_lock(&b->lock);
 215         n = _find_apf_task(b, token);
 216         if (!n) {
 217                 /*
 218                  * async PF was not yet handled.
 219                  * Add dummy entry for the token.
 220                  */
 221                 n = kzalloc(sizeof(*n), GFP_ATOMIC);
 222                 if (!n) {
 223                         /*
 224                          * Allocation failed! Busy wait while other cpu
 225                          * handles async PF.
 226                          */
 227                         raw_spin_unlock(&b->lock);
 228                         cpu_relax();
 229                         goto again;
 230                 }
 231                 n->token = token;
 232                 n->cpu = smp_processor_id();
 233                 init_swait_queue_head(&n->wq);
 234                 hlist_add_head(&n->link, &b->list);
 235         } else
 236                 apf_task_wake_one(n);
 237         raw_spin_unlock(&b->lock);
 238         return;
 239 }
 240 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
 241
 242 u32 kvm_read_and_reset_pf_reason(void)
 243 {
 244         u32 reason = 0;
 245
 246         if (__this_cpu_read(apf_reason.enabled)) {
 247                 reason = __this_cpu_read(apf_reason.reason);
 248                 __this_cpu_write(apf_reason.reason, 0);
 249         }
 250
 251         return reason;
 252 }
 253 EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason);
 254 NOKPROBE_SYMBOL(kvm_read_and_reset_pf_reason);
 255
 256 dotraplinkage void
 257 do_async_page_fault(struct pt_regs *regs, unsigned long error_code)
 258 {
 259         enum ctx_state prev_state;
 260
 261         switch (kvm_read_and_reset_pf_reason()) {
 262         default:
 263                 do_page_fault(regs, error_code);
 264                 break;
 265         case KVM_PV_REASON_PAGE_NOT_PRESENT:
 266                 /* page is swapped out by the host. */
 267                 prev_state = exception_enter();
 268                 kvm_async_pf_task_wait((u32)read_cr2(), !user_mode(regs));
 269                 exception_exit(prev_state);
 270                 break;
 271         case KVM_PV_REASON_PAGE_READY:
 272                 rcu_irq_enter();
 273                 kvm_async_pf_task_wake((u32)read_cr2());
 274                 rcu_irq_exit();
 275                 break;
 276         }
 277 }
 278 NOKPROBE_SYMBOL(do_async_page_fault);
 279
 280 static void __init paravirt_ops_setup(void)
 281 {
 282         pv_info.name = "KVM";
 283
 284         if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
 285                 pv_cpu_ops.io_delay = kvm_io_delay;
 286
 287 #ifdef CONFIG_X86_IO_APIC
 288         no_timer_check = 1;
 289 #endif
 290 }
 291
 292 static void kvm_register_steal_time(void)
 293 {
 294         int cpu = smp_processor_id();
 295         struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
 296
 297         if (!has_steal_clock)
 298                 return;
 299
 300         wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
 301         pr_info("kvm-stealtime: cpu %d, msr %llx\n",
 302                 cpu, (unsigned long long) slow_virt_to_phys(st));
 303 }
 304
 305 static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
 306
 307 static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val)
 308 {
 309         /**
 310          * This relies on __test_and_clear_bit to modify the memory
 311          * in a way that is atomic with respect to the local CPU.
 312          * The hypervisor only accesses this memory from the local CPU so
 313          * there's no need for lock or memory barriers.
 314          * An optimization barrier is implied in apic write.
 315          */
 316         if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi)))
 317                 return;
 318         apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK);
 319 }
 320
 321 static void kvm_guest_cpu_init(void)
 322 {
 323         if (!kvm_para_available())
 324                 return;
 325
 326         if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) {
 327                 u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
 328
 329 #ifdef CONFIG_PREEMPT
 330                 pa |= KVM_ASYNC_PF_SEND_ALWAYS;
 331 #endif
 332                 pa |= KVM_ASYNC_PF_ENABLED;
 333
 334                 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
 335                         pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
 336
 337                 wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
 338                 __this_cpu_write(apf_reason.enabled, 1);
 339                 printk(KERN_INFO"KVM setup async PF for cpu %d\n",
 340                        smp_processor_id());
 341         }
 342
 343         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
 344                 unsigned long pa;
 345                 /* Size alignment is implied but just to make it explicit. */
 346                 BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
 347                 __this_cpu_write(kvm_apic_eoi, 0);
 348                 pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
 349                         | KVM_MSR_ENABLED;
 350                 wrmsrl(MSR_KVM_PV_EOI_EN, pa);
 351         }
 352
 353         if (has_steal_clock)
 354                 kvm_register_steal_time();
 355 }
 356
 357 static void kvm_pv_disable_apf(void)
 358 {
 359         if (!__this_cpu_read(apf_reason.enabled))
 360                 return;
 361
 362         wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
 363         __this_cpu_write(apf_reason.enabled, 0);
 364
 365         printk(KERN_INFO"Unregister pv shared memory for cpu %d\n",
 366                smp_processor_id());
 367 }
 368
 369 static void kvm_pv_guest_cpu_reboot(void *unused)
 370 {
 371         /*
 372          * We disable PV EOI before we load a new kernel by kexec,
 373          * since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory.
 374          * New kernel can re-enable when it boots.
 375          */
 376         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
 377                 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
 378         kvm_pv_disable_apf();
 379         kvm_disable_steal_time();
 380 }
 381
 382 static int kvm_pv_reboot_notify(struct notifier_block *nb,
 383                                 unsigned long code, void *unused)
 384 {
 385         if (code == SYS_RESTART)
 386                 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
 387         return NOTIFY_DONE;
 388 }
 389
 390 static struct notifier_block kvm_pv_reboot_nb = {
 391         .notifier_call = kvm_pv_reboot_notify,
 392 };
 393
 394 static u64 kvm_steal_clock(int cpu)
 395 {
 396         u64 steal;
 397         struct kvm_steal_time *src;
 398         int version;
 399
 400         src = &per_cpu(steal_time, cpu);
 401         do {
 402                 version = src->version;
 403                 virt_rmb();
 404                 steal = src->steal;
 405                 virt_rmb();
 406         } while ((version & 1) || (version != src->version));
 407
 408         return steal;
 409 }
 410
 411 void kvm_disable_steal_time(void)
 412 {
 413         if (!has_steal_clock)
 414                 return;
 415
 416         wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
 417 }
 418
 419 static inline void __set_percpu_decrypted(void *ptr, unsigned long size)
 420 {
 421         early_set_memory_decrypted((unsigned long) ptr, size);
 422 }
 423
 424 /*
 425  * Iterate through all possible CPUs and map the memory region pointed
 426  * by apf_reason, steal_time and kvm_apic_eoi as decrypted at once.
 427  *
 428  * Note: we iterate through all possible CPUs to ensure that CPUs
 429  * hotplugged will have their per-cpu variable already mapped as
 430  * decrypted.
 431  */
 432 static void __init sev_map_percpu_data(void)
 433 {
 434         int cpu;
 435
 436         if (!sev_active())
 437                 return;
 438
 439         for_each_possible_cpu(cpu) {
 440                 __set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason));
 441                 __set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time));
 442                 __set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi));
 443         }
 444 }
 445
 446 #ifdef CONFIG_SMP
 447 #define KVM_IPI_CLUSTER_SIZE    (2 * BITS_PER_LONG)
 448
 449 static void __send_ipi_mask(const struct cpumask *mask, int vector)
 450 {
 451         unsigned long flags;
 452         int cpu, apic_id, icr;
 453         int min = 0, max = 0;
 454 #ifdef CONFIG_X86_64
 455         __uint128_t ipi_bitmap = 0;
 456 #else
 457         u64 ipi_bitmap = 0;
 458 #endif
 459
 460         if (cpumask_empty(mask))
 461                 return;
 462
 463         local_irq_save(flags);
 464
 465         switch (vector) {
 466         default:
 467                 icr = APIC_DM_FIXED | vector;
 468                 break;
 469         case NMI_VECTOR:
 470                 icr = APIC_DM_NMI;
 471                 break;
 472         }
 473
 474         for_each_cpu(cpu, mask) {
 475                 apic_id = per_cpu(x86_cpu_to_apicid, cpu);
 476                 if (!ipi_bitmap) {
 477                         min = max = apic_id;
 478                 } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) {
 479                         ipi_bitmap <<= min - apic_id;
 480                         min = apic_id;
 481                 } else if (apic_id < min + KVM_IPI_CLUSTER_SIZE) {
 482                         max = apic_id < max ? max : apic_id;
 483                 } else {
 484                         kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
 485                                 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
 486                         min = max = apic_id;
 487                         ipi_bitmap = 0;
 488                 }
 489                 __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap);
 490         }
 491
 492         if (ipi_bitmap) {
 493                 kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
 494                         (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
 495         }
 496
 497         local_irq_restore(flags);
 498 }
 499
 500 static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
 501 {
 502         __send_ipi_mask(mask, vector);
 503 }
 504
 505 static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
 506 {
 507         unsigned int this_cpu = smp_processor_id();
 508         struct cpumask new_mask;
 509         const struct cpumask *local_mask;
 510
 511         cpumask_copy(&new_mask, mask);
 512         cpumask_clear_cpu(this_cpu, &new_mask);
 513         local_mask = &new_mask;
 514         __send_ipi_mask(local_mask, vector);
 515 }
 516
 517 static void kvm_send_ipi_allbutself(int vector)
 518 {
 519         kvm_send_ipi_mask_allbutself(cpu_online_mask, vector);
 520 }
 521
 522 static void kvm_send_ipi_all(int vector)
 523 {
 524         __send_ipi_mask(cpu_online_mask, vector);
 525 }
 526
 527 /*
 528  * Set the IPI entry points
 529  */
 530 static void kvm_setup_pv_ipi(void)
 531 {
 532         apic->send_IPI_mask = kvm_send_ipi_mask;
 533         apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
 534         apic->send_IPI_allbutself = kvm_send_ipi_allbutself;
 535         apic->send_IPI_all = kvm_send_ipi_all;
 536         pr_info("KVM setup pv IPIs\n");
 537 }
 538
 539 static void __init kvm_smp_prepare_cpus(unsigned int max_cpus)
 540 {
 541         native_smp_prepare_cpus(max_cpus);
 542         if (kvm_para_has_hint(KVM_HINTS_REALTIME))
 543                 static_branch_disable(&virt_spin_lock_key);
 544 }
 545
 546 static void __init kvm_smp_prepare_boot_cpu(void)
 547 {
 548         /*
 549          * Map the per-cpu variables as decrypted before kvm_guest_cpu_init()
 550          * shares the guest physical address with the hypervisor.
 551          */
 552         sev_map_percpu_data();
 553
 554         kvm_guest_cpu_init();
 555         native_smp_prepare_boot_cpu();
 556         kvm_spinlock_init();
 557 }
 558
 559 static void kvm_guest_cpu_offline(void)
 560 {
 561         kvm_disable_steal_time();
 562         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
 563                 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
 564         kvm_pv_disable_apf();
 565         apf_task_wake_all();
 566 }
 567
 568 static int kvm_cpu_online(unsigned int cpu)
 569 {
 570         local_irq_disable();
 571         kvm_guest_cpu_init();
 572         local_irq_enable();
 573         return 0;
 574 }
 575
 576 static int kvm_cpu_down_prepare(unsigned int cpu)
 577 {
 578         local_irq_disable();
 579         kvm_guest_cpu_offline();
 580         local_irq_enable();
 581         return 0;
 582 }
 583 #endif
 584
 585 static void __init kvm_apf_trap_init(void)
 586 {
 587         update_intr_gate(X86_TRAP_PF, async_page_fault);
 588 }
 589
 590 static DEFINE_PER_CPU(cpumask_var_t, __pv_tlb_mask);
 591
 592 static void kvm_flush_tlb_others(const struct cpumask *cpumask,
 593                         const struct flush_tlb_info *info)
 594 {
 595         u8 state;
 596         int cpu;
 597         struct kvm_steal_time *src;
 598         struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_tlb_mask);
 599
 600         cpumask_copy(flushmask, cpumask);
 601         /*
 602          * We have to call flush only on online vCPUs. And
 603          * queue flush_on_enter for pre-empted vCPUs
 604          */
 605         for_each_cpu(cpu, flushmask) {
 606                 src = &per_cpu(steal_time, cpu);
 607                 state = READ_ONCE(src->preempted);
 608                 if ((state & KVM_VCPU_PREEMPTED)) {
 609                         if (try_cmpxchg(&src->preempted, &state,
 610                                         state | KVM_VCPU_FLUSH_TLB))
 611                                 __cpumask_clear_cpu(cpu, flushmask);
 612                 }
 613         }
 614
 615         native_flush_tlb_others(flushmask, info);
 616 }
 617
 618 static void __init kvm_guest_init(void)
 619 {
 620         int i;
 621
 622         if (!kvm_para_available())
 623                 return;
 624
 625         paravirt_ops_setup();
 626         register_reboot_notifier(&kvm_pv_reboot_nb);
 627         for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
 628                 raw_spin_lock_init(&async_pf_sleepers[i].lock);
 629         if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
 630                 x86_init.irqs.trap_init = kvm_apf_trap_init;
 631
 632         if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
 633                 has_steal_clock = 1;
 634                 pv_time_ops.steal_clock = kvm_steal_clock;
 635         }
 636
 637         if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
 638             !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
 639             kvm_para_has_feature(KVM_FEATURE_STEAL_TIME))
 640                 pv_mmu_ops.flush_tlb_others = kvm_flush_tlb_others;
 641
 642         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
 643                 apic_set_eoi_write(kvm_guest_apic_eoi_write);
 644
 645 #ifdef CONFIG_SMP
 646         smp_ops.smp_prepare_cpus = kvm_smp_prepare_cpus;
 647         smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
 648         if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
 649                                       kvm_cpu_online, kvm_cpu_down_prepare) < 0)
 650                 pr_err("kvm_guest: Failed to install cpu hotplug callbacks\n");
 651 #else
 652         sev_map_percpu_data();
 653         kvm_guest_cpu_init();
 654 #endif
 655
 656         /*
 657          * Hard lockup detection is enabled by default. Disable it, as guests
 658          * can get false positives too easily, for example if the host is
 659          * overcommitted.
 660          */
 661         hardlockup_detector_disable();
 662 }
 663
 664 static noinline uint32_t __kvm_cpuid_base(void)
 665 {
 666         if (boot_cpu_data.cpuid_level < 0)
 667                 return 0;       /* So we don't blow up on old processors */
 668
 669         if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
 670                 return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0);
 671
 672         return 0;
 673 }
 674
 675 static inline uint32_t kvm_cpuid_base(void)
 676 {
 677         static int kvm_cpuid_base = -1;
 678
 679         if (kvm_cpuid_base == -1)
 680                 kvm_cpuid_base = __kvm_cpuid_base();
 681
 682         return kvm_cpuid_base;
 683 }
 684
 685 bool kvm_para_available(void)
 686 {
 687         return kvm_cpuid_base() != 0;
 688 }
 689 EXPORT_SYMBOL_GPL(kvm_para_available);
 690
 691 unsigned int kvm_arch_para_features(void)
 692 {
 693         return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
 694 }
 695
 696 unsigned int kvm_arch_para_hints(void)
 697 {
 698         return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
 699 }
 700
 701 static uint32_t __init kvm_detect(void)
 702 {
 703         return kvm_cpuid_base();
 704 }
 705
 706 static void __init kvm_apic_init(void)
 707 {
 708 #if defined(CONFIG_SMP)
 709         if (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI))
 710                 kvm_setup_pv_ipi();
 711 #endif
 712 }
 713
 714 static void __init kvm_init_platform(void)
 715 {
 716         kvmclock_init();
 717         x86_platform.apic_post_init = kvm_apic_init;
 718 }
 719
 720 const __initconst struct hypervisor_x86 x86_hyper_kvm = {
 721         .name                   = "KVM",
 722         .detect                 = kvm_detect,
 723         .type                   = X86_HYPER_KVM,
 724         .init.guest_late_init   = kvm_guest_init,
 725         .init.x2apic_available  = kvm_para_available,
 726         .init.init_platform     = kvm_init_platform,
 727 };
 728
 729 static __init int activate_jump_labels(void)
 730 {
 731         if (has_steal_clock) {
 732                 static_key_slow_inc(&paravirt_steal_enabled);
 733                 if (steal_acc)
 734                         static_key_slow_inc(&paravirt_steal_rq_enabled);
 735         }
 736
 737         return 0;
 738 }
 739 arch_initcall(activate_jump_labels);
 740
 741 static __init int kvm_setup_pv_tlb_flush(void)
 742 {
 743         int cpu;
 744
 745         if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
 746             !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
 747             kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
 748                 for_each_possible_cpu(cpu) {
 749                         zalloc_cpumask_var_node(per_cpu_ptr(&__pv_tlb_mask, cpu),
 750                                 GFP_KERNEL, cpu_to_node(cpu));
 751                 }
 752                 pr_info("KVM setup pv remote TLB flush\n");
 753         }
 754
 755         return 0;
 756 }
 757 arch_initcall(kvm_setup_pv_tlb_flush);
 758
 759 #ifdef CONFIG_PARAVIRT_SPINLOCKS
 760
 761 /* Kick a cpu by its apicid. Used to wake up a halted vcpu */
 762 static void kvm_kick_cpu(int cpu)
 763 {
 764         int apicid;
 765         unsigned long flags = 0;
 766
 767         apicid = per_cpu(x86_cpu_to_apicid, cpu);
 768         kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
 769 }
 770
 771 #include <asm/qspinlock.h>
 772
 773 static void kvm_wait(u8 *ptr, u8 val)
 774 {
 775         unsigned long flags;
 776
 777         if (in_nmi())
 778                 return;
 779
 780         local_irq_save(flags);
 781
 782         if (READ_ONCE(*ptr) != val)
 783                 goto out;
 784
 785         /*
 786          * halt until it's our turn and kicked. Note that we do safe halt
 787          * for irq enabled case to avoid hang when lock info is overwritten
 788          * in irq spinlock slowpath and no spurious interrupt occur to save us.
 789          */
 790         if (arch_irqs_disabled_flags(flags))
 791                 halt();
 792         else
 793                 safe_halt();
 794
 795 out:
 796         local_irq_restore(flags);
 797 }
 798
 799 #ifdef CONFIG_X86_32
 800 __visible bool __kvm_vcpu_is_preempted(long cpu)
 801 {
 802         struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
 803
 804         return !!(src->preempted & KVM_VCPU_PREEMPTED);
 805 }
 806 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
 807
 808 #else
 809
 810 #include <asm/asm-offsets.h>
 811
 812 extern bool __raw_callee_save___kvm_vcpu_is_preempted(long);
 813
 814 /*
 815  * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and
 816  * restoring to/from the stack.
 817  */
 818 asm(
 819 ".pushsection .text;"
 820 ".global __raw_callee_save___kvm_vcpu_is_preempted;"
 821 ".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"
 822 "__raw_callee_save___kvm_vcpu_is_preempted:"
 823 "movq   __per_cpu_offset(,%rdi,8), %rax;"
 824 "cmpb   $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);"
 825 "setne  %al;"
 826 "ret;"
 827 ".popsection");
 828
 829 #endif
 830
 831 /*
 832  * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
 833  */
 834 void __init kvm_spinlock_init(void)
 835 {
 836         if (!kvm_para_available())
 837                 return;
 838         /* Does host kernel support KVM_FEATURE_PV_UNHALT? */
 839         if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
 840                 return;
 841
 842         if (kvm_para_has_hint(KVM_HINTS_REALTIME))
 843                 return;
 844
 845         /* Don't use the pvqspinlock code if there is only 1 vCPU. */
 846         if (num_possible_cpus() == 1)
 847                 return;
 848
 849         __pv_init_lock_hash();
 850         pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
 851         pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock);
 852         pv_lock_ops.wait = kvm_wait;
 853         pv_lock_ops.kick = kvm_kick_cpu;
 854
 855         if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
 856                 pv_lock_ops.vcpu_is_preempted =
 857                         PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
 858         }
 859 }
 860
 861 #endif  /* CONFIG_PARAVIRT_SPINLOCKS */