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 #include <asm/tlb.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 DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
  70 static DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64);
  71 static int has_steal_clock = 0;
  72
  73 /*
  74  * No need for any "IO delay" on KVM
  75  */
  76 static void kvm_io_delay(void)
  77 {
  78 }
  79
  80 #define KVM_TASK_SLEEP_HASHBITS 8
  81 #define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
  82
  83 struct kvm_task_sleep_node {
  84         struct hlist_node link;
  85         struct swait_queue_head wq;
  86         u32 token;
  87         int cpu;
  88         bool halted;
  89 };
  90
  91 static struct kvm_task_sleep_head {
  92         raw_spinlock_t lock;
  93         struct hlist_head list;
  94 } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
  95
  96 static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
  97                                                   u32 token)
  98 {
  99         struct hlist_node *p;
 100
 101         hlist_for_each(p, &b->list) {
 102                 struct kvm_task_sleep_node *n =
 103                         hlist_entry(p, typeof(*n), link);
 104                 if (n->token == token)
 105                         return n;
 106         }
 107
 108         return NULL;
 109 }
 110
 111 /*
 112  * @interrupt_kernel: Is this called from a routine which interrupts the kernel
 113  *                    (other than user space)?
 114  */
 115 void kvm_async_pf_task_wait(u32 token, int interrupt_kernel)
 116 {
 117         u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
 118         struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
 119         struct kvm_task_sleep_node n, *e;
 120         DECLARE_SWAITQUEUE(wait);
 121
 122         rcu_irq_enter();
 123
 124         raw_spin_lock(&b->lock);
 125         e = _find_apf_task(b, token);
 126         if (e) {
 127                 /* dummy entry exist -> wake up was delivered ahead of PF */
 128                 hlist_del(&e->link);
 129                 kfree(e);
 130                 raw_spin_unlock(&b->lock);
 131
 132                 rcu_irq_exit();
 133                 return;
 134         }
 135
 136         n.token = token;
 137         n.cpu = smp_processor_id();
 138         n.halted = is_idle_task(current) ||
 139                    (IS_ENABLED(CONFIG_PREEMPT_COUNT)
 140                     ? preempt_count() > 1 || rcu_preempt_depth()
 141                     : interrupt_kernel);
 142         init_swait_queue_head(&n.wq);
 143         hlist_add_head(&n.link, &b->list);
 144         raw_spin_unlock(&b->lock);
 145
 146         for (;;) {
 147                 if (!n.halted)
 148                         prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
 149                 if (hlist_unhashed(&n.link))
 150                         break;
 151
 152                 rcu_irq_exit();
 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                 rcu_irq_enter();
 167         }
 168         if (!n.halted)
 169                 finish_swait(&n.wq, &wait);
 170
 171         rcu_irq_exit();
 172         return;
 173 }
 174 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait);
 175
 176 static 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 (swq_has_sleeper(&n->wq))
 182                 swake_up_one(&n->wq);
 183 }
 184
 185 static 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
 203 void 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
 214 again:
 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 }
 241 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
 242
 243 u32 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 }
 254 EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason);
 255 NOKPROBE_SYMBOL(kvm_read_and_reset_pf_reason);
 256
 257 dotraplinkage void
 258 do_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                 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(), !user_mode(regs));
 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 }
 279 NOKPROBE_SYMBOL(do_async_page_fault);
 280
 281 static 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_ops.cpu.io_delay = kvm_io_delay;
 287
 288 #ifdef CONFIG_X86_IO_APIC
 289         no_timer_check = 1;
 290 #endif
 291 }
 292
 293 static 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
 306 static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
 307
 308 static 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
 322 static 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                 pa |= KVM_ASYNC_PF_ENABLED;
 334
 335                 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
 336                         pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
 337
 338                 wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
 339                 __this_cpu_write(apf_reason.enabled, 1);
 340                 printk(KERN_INFO"KVM setup async PF for cpu %d\n",
 341                        smp_processor_id());
 342         }
 343
 344         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
 345                 unsigned long pa;
 346                 /* Size alignment is implied but just to make it explicit. */
 347                 BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
 348                 __this_cpu_write(kvm_apic_eoi, 0);
 349                 pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
 350                         | KVM_MSR_ENABLED;
 351                 wrmsrl(MSR_KVM_PV_EOI_EN, pa);
 352         }
 353
 354         if (has_steal_clock)
 355                 kvm_register_steal_time();
 356 }
 357
 358 static void kvm_pv_disable_apf(void)
 359 {
 360         if (!__this_cpu_read(apf_reason.enabled))
 361                 return;
 362
 363         wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
 364         __this_cpu_write(apf_reason.enabled, 0);
 365
 366         printk(KERN_INFO"Unregister pv shared memory for cpu %d\n",
 367                smp_processor_id());
 368 }
 369
 370 static void kvm_pv_guest_cpu_reboot(void *unused)
 371 {
 372         /*
 373          * We disable PV EOI before we load a new kernel by kexec,
 374          * since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory.
 375          * New kernel can re-enable when it boots.
 376          */
 377         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
 378                 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
 379         kvm_pv_disable_apf();
 380         kvm_disable_steal_time();
 381 }
 382
 383 static int kvm_pv_reboot_notify(struct notifier_block *nb,
 384                                 unsigned long code, void *unused)
 385 {
 386         if (code == SYS_RESTART)
 387                 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
 388         return NOTIFY_DONE;
 389 }
 390
 391 static struct notifier_block kvm_pv_reboot_nb = {
 392         .notifier_call = kvm_pv_reboot_notify,
 393 };
 394
 395 static u64 kvm_steal_clock(int cpu)
 396 {
 397         u64 steal;
 398         struct kvm_steal_time *src;
 399         int version;
 400
 401         src = &per_cpu(steal_time, cpu);
 402         do {
 403                 version = src->version;
 404                 virt_rmb();
 405                 steal = src->steal;
 406                 virt_rmb();
 407         } while ((version & 1) || (version != src->version));
 408
 409         return steal;
 410 }
 411
 412 void kvm_disable_steal_time(void)
 413 {
 414         if (!has_steal_clock)
 415                 return;
 416
 417         wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
 418 }
 419
 420 static inline void __set_percpu_decrypted(void *ptr, unsigned long size)
 421 {
 422         early_set_memory_decrypted((unsigned long) ptr, size);
 423 }
 424
 425 /*
 426  * Iterate through all possible CPUs and map the memory region pointed
 427  * by apf_reason, steal_time and kvm_apic_eoi as decrypted at once.
 428  *
 429  * Note: we iterate through all possible CPUs to ensure that CPUs
 430  * hotplugged will have their per-cpu variable already mapped as
 431  * decrypted.
 432  */
 433 static void __init sev_map_percpu_data(void)
 434 {
 435         int cpu;
 436
 437         if (!sev_active())
 438                 return;
 439
 440         for_each_possible_cpu(cpu) {
 441                 __set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason));
 442                 __set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time));
 443                 __set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi));
 444         }
 445 }
 446
 447 #ifdef CONFIG_SMP
 448 #define KVM_IPI_CLUSTER_SIZE    (2 * BITS_PER_LONG)
 449
 450 static void __send_ipi_mask(const struct cpumask *mask, int vector)
 451 {
 452         unsigned long flags;
 453         int cpu, apic_id, icr;
 454         int min = 0, max = 0;
 455 #ifdef CONFIG_X86_64
 456         __uint128_t ipi_bitmap = 0;
 457 #else
 458         u64 ipi_bitmap = 0;
 459 #endif
 460
 461         if (cpumask_empty(mask))
 462                 return;
 463
 464         local_irq_save(flags);
 465
 466         switch (vector) {
 467         default:
 468                 icr = APIC_DM_FIXED | vector;
 469                 break;
 470         case NMI_VECTOR:
 471                 icr = APIC_DM_NMI;
 472                 break;
 473         }
 474
 475         for_each_cpu(cpu, mask) {
 476                 apic_id = per_cpu(x86_cpu_to_apicid, cpu);
 477                 if (!ipi_bitmap) {
 478                         min = max = apic_id;
 479                 } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) {
 480                         ipi_bitmap <<= min - apic_id;
 481                         min = apic_id;
 482                 } else if (apic_id < min + KVM_IPI_CLUSTER_SIZE) {
 483                         max = apic_id < max ? max : apic_id;
 484                 } else {
 485                         kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
 486                                 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
 487                         min = max = apic_id;
 488                         ipi_bitmap = 0;
 489                 }
 490                 __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap);
 491         }
 492
 493         if (ipi_bitmap) {
 494                 kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
 495                         (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
 496         }
 497
 498         local_irq_restore(flags);
 499 }
 500
 501 static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
 502 {
 503         __send_ipi_mask(mask, vector);
 504 }
 505
 506 static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
 507 {
 508         unsigned int this_cpu = smp_processor_id();
 509         struct cpumask new_mask;
 510         const struct cpumask *local_mask;
 511
 512         cpumask_copy(&new_mask, mask);
 513         cpumask_clear_cpu(this_cpu, &new_mask);
 514         local_mask = &new_mask;
 515         __send_ipi_mask(local_mask, vector);
 516 }
 517
 518 static void kvm_send_ipi_allbutself(int vector)
 519 {
 520         kvm_send_ipi_mask_allbutself(cpu_online_mask, vector);
 521 }
 522
 523 static void kvm_send_ipi_all(int vector)
 524 {
 525         __send_ipi_mask(cpu_online_mask, vector);
 526 }
 527
 528 /*
 529  * Set the IPI entry points
 530  */
 531 static void kvm_setup_pv_ipi(void)
 532 {
 533         apic->send_IPI_mask = kvm_send_ipi_mask;
 534         apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
 535         apic->send_IPI_allbutself = kvm_send_ipi_allbutself;
 536         apic->send_IPI_all = kvm_send_ipi_all;
 537         pr_info("KVM setup pv IPIs\n");
 538 }
 539
 540 static void __init kvm_smp_prepare_cpus(unsigned int max_cpus)
 541 {
 542         native_smp_prepare_cpus(max_cpus);
 543         if (kvm_para_has_hint(KVM_HINTS_REALTIME))
 544                 static_branch_disable(&virt_spin_lock_key);
 545 }
 546
 547 static void __init kvm_smp_prepare_boot_cpu(void)
 548 {
 549         /*
 550          * Map the per-cpu variables as decrypted before kvm_guest_cpu_init()
 551          * shares the guest physical address with the hypervisor.
 552          */
 553         sev_map_percpu_data();
 554
 555         kvm_guest_cpu_init();
 556         native_smp_prepare_boot_cpu();
 557         kvm_spinlock_init();
 558 }
 559
 560 static void kvm_guest_cpu_offline(void)
 561 {
 562         kvm_disable_steal_time();
 563         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
 564                 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
 565         kvm_pv_disable_apf();
 566         apf_task_wake_all();
 567 }
 568
 569 static int kvm_cpu_online(unsigned int cpu)
 570 {
 571         local_irq_disable();
 572         kvm_guest_cpu_init();
 573         local_irq_enable();
 574         return 0;
 575 }
 576
 577 static int kvm_cpu_down_prepare(unsigned int cpu)
 578 {
 579         local_irq_disable();
 580         kvm_guest_cpu_offline();
 581         local_irq_enable();
 582         return 0;
 583 }
 584 #endif
 585
 586 static void __init kvm_apf_trap_init(void)
 587 {
 588         update_intr_gate(X86_TRAP_PF, async_page_fault);
 589 }
 590
 591 static DEFINE_PER_CPU(cpumask_var_t, __pv_tlb_mask);
 592
 593 static void kvm_flush_tlb_others(const struct cpumask *cpumask,
 594                         const struct flush_tlb_info *info)
 595 {
 596         u8 state;
 597         int cpu;
 598         struct kvm_steal_time *src;
 599         struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_tlb_mask);
 600
 601         cpumask_copy(flushmask, cpumask);
 602         /*
 603          * We have to call flush only on online vCPUs. And
 604          * queue flush_on_enter for pre-empted vCPUs
 605          */
 606         for_each_cpu(cpu, flushmask) {
 607                 src = &per_cpu(steal_time, cpu);
 608                 state = READ_ONCE(src->preempted);
 609                 if ((state & KVM_VCPU_PREEMPTED)) {
 610                         if (try_cmpxchg(&src->preempted, &state,
 611                                         state | KVM_VCPU_FLUSH_TLB))
 612                                 __cpumask_clear_cpu(cpu, flushmask);
 613                 }
 614         }
 615
 616         native_flush_tlb_others(flushmask, info);
 617 }
 618
 619 static void __init kvm_guest_init(void)
 620 {
 621         int i;
 622
 623         if (!kvm_para_available())
 624                 return;
 625
 626         paravirt_ops_setup();
 627         register_reboot_notifier(&kvm_pv_reboot_nb);
 628         for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
 629                 raw_spin_lock_init(&async_pf_sleepers[i].lock);
 630         if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
 631                 x86_init.irqs.trap_init = kvm_apf_trap_init;
 632
 633         if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
 634                 has_steal_clock = 1;
 635                 pv_ops.time.steal_clock = kvm_steal_clock;
 636         }
 637
 638         if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
 639             !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
 640             kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
 641                 pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;
 642                 pv_ops.mmu.tlb_remove_table = tlb_remove_table;
 643         }
 644
 645         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
 646                 apic_set_eoi_write(kvm_guest_apic_eoi_write);
 647
 648 #ifdef CONFIG_SMP
 649         smp_ops.smp_prepare_cpus = kvm_smp_prepare_cpus;
 650         smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
 651         if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
 652                                       kvm_cpu_online, kvm_cpu_down_prepare) < 0)
 653                 pr_err("kvm_guest: Failed to install cpu hotplug callbacks\n");
 654 #else
 655         sev_map_percpu_data();
 656         kvm_guest_cpu_init();
 657 #endif
 658
 659         /*
 660          * Hard lockup detection is enabled by default. Disable it, as guests
 661          * can get false positives too easily, for example if the host is
 662          * overcommitted.
 663          */
 664         hardlockup_detector_disable();
 665 }
 666
 667 static noinline uint32_t __kvm_cpuid_base(void)
 668 {
 669         if (boot_cpu_data.cpuid_level < 0)
 670                 return 0;       /* So we don't blow up on old processors */
 671
 672         if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
 673                 return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0);
 674
 675         return 0;
 676 }
 677
 678 static inline uint32_t kvm_cpuid_base(void)
 679 {
 680         static int kvm_cpuid_base = -1;
 681
 682         if (kvm_cpuid_base == -1)
 683                 kvm_cpuid_base = __kvm_cpuid_base();
 684
 685         return kvm_cpuid_base;
 686 }
 687
 688 bool kvm_para_available(void)
 689 {
 690         return kvm_cpuid_base() != 0;
 691 }
 692 EXPORT_SYMBOL_GPL(kvm_para_available);
 693
 694 unsigned int kvm_arch_para_features(void)
 695 {
 696         return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
 697 }
 698
 699 unsigned int kvm_arch_para_hints(void)
 700 {
 701         return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
 702 }
 703
 704 static uint32_t __init kvm_detect(void)
 705 {
 706         return kvm_cpuid_base();
 707 }
 708
 709 static void __init kvm_apic_init(void)
 710 {
 711 #if defined(CONFIG_SMP)
 712         if (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI))
 713                 kvm_setup_pv_ipi();
 714 #endif
 715 }
 716
 717 static void __init kvm_init_platform(void)
 718 {
 719         kvmclock_init();
 720         x86_platform.apic_post_init = kvm_apic_init;
 721 }
 722
 723 const __initconst struct hypervisor_x86 x86_hyper_kvm = {
 724         .name                   = "KVM",
 725         .detect                 = kvm_detect,
 726         .type                   = X86_HYPER_KVM,
 727         .init.guest_late_init   = kvm_guest_init,
 728         .init.x2apic_available  = kvm_para_available,
 729         .init.init_platform     = kvm_init_platform,
 730 };
 731
 732 static __init int activate_jump_labels(void)
 733 {
 734         if (has_steal_clock) {
 735                 static_key_slow_inc(&paravirt_steal_enabled);
 736                 if (steal_acc)
 737                         static_key_slow_inc(&paravirt_steal_rq_enabled);
 738         }
 739
 740         return 0;
 741 }
 742 arch_initcall(activate_jump_labels);
 743
 744 static __init int kvm_setup_pv_tlb_flush(void)
 745 {
 746         int cpu;
 747
 748         if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
 749             !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
 750             kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
 751                 for_each_possible_cpu(cpu) {
 752                         zalloc_cpumask_var_node(per_cpu_ptr(&__pv_tlb_mask, cpu),
 753                                 GFP_KERNEL, cpu_to_node(cpu));
 754                 }
 755                 pr_info("KVM setup pv remote TLB flush\n");
 756         }
 757
 758         return 0;
 759 }
 760 arch_initcall(kvm_setup_pv_tlb_flush);
 761
 762 #ifdef CONFIG_PARAVIRT_SPINLOCKS
 763
 764 /* Kick a cpu by its apicid. Used to wake up a halted vcpu */
 765 static void kvm_kick_cpu(int cpu)
 766 {
 767         int apicid;
 768         unsigned long flags = 0;
 769
 770         apicid = per_cpu(x86_cpu_to_apicid, cpu);
 771         kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
 772 }
 773
 774 #include <asm/qspinlock.h>
 775
 776 static void kvm_wait(u8 *ptr, u8 val)
 777 {
 778         unsigned long flags;
 779
 780         if (in_nmi())
 781                 return;
 782
 783         local_irq_save(flags);
 784
 785         if (READ_ONCE(*ptr) != val)
 786                 goto out;
 787
 788         /*
 789          * halt until it's our turn and kicked. Note that we do safe halt
 790          * for irq enabled case to avoid hang when lock info is overwritten
 791          * in irq spinlock slowpath and no spurious interrupt occur to save us.
 792          */
 793         if (arch_irqs_disabled_flags(flags))
 794                 halt();
 795         else
 796                 safe_halt();
 797
 798 out:
 799         local_irq_restore(flags);
 800 }
 801
 802 #ifdef CONFIG_X86_32
 803 __visible bool __kvm_vcpu_is_preempted(long cpu)
 804 {
 805         struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
 806
 807         return !!(src->preempted & KVM_VCPU_PREEMPTED);
 808 }
 809 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
 810
 811 #else
 812
 813 #include <asm/asm-offsets.h>
 814
 815 extern bool __raw_callee_save___kvm_vcpu_is_preempted(long);
 816
 817 /*
 818  * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and
 819  * restoring to/from the stack.
 820  */
 821 asm(
 822 ".pushsection .text;"
 823 ".global __raw_callee_save___kvm_vcpu_is_preempted;"
 824 ".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"
 825 "__raw_callee_save___kvm_vcpu_is_preempted:"
 826 "movq   __per_cpu_offset(,%rdi,8), %rax;"
 827 "cmpb   $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);"
 828 "setne  %al;"
 829 "ret;"
 830 ".popsection");
 831
 832 #endif
 833
 834 /*
 835  * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
 836  */
 837 void __init kvm_spinlock_init(void)
 838 {
 839         if (!kvm_para_available())
 840                 return;
 841         /* Does host kernel support KVM_FEATURE_PV_UNHALT? */
 842         if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
 843                 return;
 844
 845         if (kvm_para_has_hint(KVM_HINTS_REALTIME))
 846                 return;
 847
 848         /* Don't use the pvqspinlock code if there is only 1 vCPU. */
 849         if (num_possible_cpus() == 1)
 850                 return;
 851
 852         __pv_init_lock_hash();
 853         pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
 854         pv_ops.lock.queued_spin_unlock =
 855                 PV_CALLEE_SAVE(__pv_queued_spin_unlock);
 856         pv_ops.lock.wait = kvm_wait;
 857         pv_ops.lock.kick = kvm_kick_cpu;
 858
 859         if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
 860                 pv_ops.lock.vcpu_is_preempted =
 861                         PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
 862         }
 863 }
 864
 865 #endif  /* CONFIG_PARAVIRT_SPINLOCKS */