arch/x86/kernel/kvm.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * KVM paravirt_ops implementation
   4  *
   5  * Copyright (C) 2007, Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   6  * Copyright IBM Corporation, 2007
   7  *   Authors: Anthony Liguori <aliguori@us.ibm.com>
   8  */
   9
  10 #define pr_fmt(fmt) "kvm-guest: " fmt
  11
  12 #include <linux/context_tracking.h>
  13 #include <linux/init.h>
  14 #include <linux/irq.h>
  15 #include <linux/kernel.h>
  16 #include <linux/kvm_para.h>
  17 #include <linux/cpu.h>
  18 #include <linux/mm.h>
  19 #include <linux/highmem.h>
  20 #include <linux/hardirq.h>
  21 #include <linux/notifier.h>
  22 #include <linux/reboot.h>
  23 #include <linux/hash.h>
  24 #include <linux/sched.h>
  25 #include <linux/slab.h>
  26 #include <linux/kprobes.h>
  27 #include <linux/nmi.h>
  28 #include <linux/swait.h>
  29 #include <linux/syscore_ops.h>
  30 #include <asm/timer.h>
  31 #include <asm/cpu.h>
  32 #include <asm/traps.h>
  33 #include <asm/desc.h>
  34 #include <asm/tlbflush.h>
  35 #include <asm/apic.h>
  36 #include <asm/apicdef.h>
  37 #include <asm/hypervisor.h>
  38 #include <asm/tlb.h>
  39 #include <asm/cpuidle_haltpoll.h>
  40 #include <asm/ptrace.h>
  41 #include <asm/reboot.h>
  42 #include <asm/svm.h>
  43
  44 DEFINE_STATIC_KEY_FALSE(kvm_async_pf_enabled);
  45
  46 static int kvmapf = 1;
  47
  48 static int __init parse_no_kvmapf(char *arg)
  49 {
  50         kvmapf = 0;
  51         return 0;
  52 }
  53
  54 early_param("no-kvmapf", parse_no_kvmapf);
  55
  56 static int steal_acc = 1;
  57 static int __init parse_no_stealacc(char *arg)
  58 {
  59         steal_acc = 0;
  60         return 0;
  61 }
  62
  63 early_param("no-steal-acc", parse_no_stealacc);
  64
  65 static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
  66 DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64) __visible;
  67 static int has_steal_clock = 0;
  68
  69 static int has_guest_poll = 0;
  70 /*
  71  * No need for any "IO delay" on KVM
  72  */
  73 static void kvm_io_delay(void)
  74 {
  75 }
  76
  77 #define KVM_TASK_SLEEP_HASHBITS 8
  78 #define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
  79
  80 struct kvm_task_sleep_node {
  81         struct hlist_node link;
  82         struct swait_queue_head wq;
  83         u32 token;
  84         int cpu;
  85 };
  86
  87 static struct kvm_task_sleep_head {
  88         raw_spinlock_t lock;
  89         struct hlist_head list;
  90 } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
  91
  92 static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
  93                                                   u32 token)
  94 {
  95         struct hlist_node *p;
  96
  97         hlist_for_each(p, &b->list) {
  98                 struct kvm_task_sleep_node *n =
  99                         hlist_entry(p, typeof(*n), link);
 100                 if (n->token == token)
 101                         return n;
 102         }
 103
 104         return NULL;
 105 }
 106
 107 static bool kvm_async_pf_queue_task(u32 token, struct kvm_task_sleep_node *n)
 108 {
 109         u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
 110         struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
 111         struct kvm_task_sleep_node *e;
 112
 113         raw_spin_lock(&b->lock);
 114         e = _find_apf_task(b, token);
 115         if (e) {
 116                 /* dummy entry exist -> wake up was delivered ahead of PF */
 117                 hlist_del(&e->link);
 118                 raw_spin_unlock(&b->lock);
 119                 kfree(e);
 120                 return false;
 121         }
 122
 123         n->token = token;
 124         n->cpu = smp_processor_id();
 125         init_swait_queue_head(&n->wq);
 126         hlist_add_head(&n->link, &b->list);
 127         raw_spin_unlock(&b->lock);
 128         return true;
 129 }
 130
 131 /*
 132  * kvm_async_pf_task_wait_schedule - Wait for pagefault to be handled
 133  * @token:      Token to identify the sleep node entry
 134  *
 135  * Invoked from the async pagefault handling code or from the VM exit page
 136  * fault handler. In both cases RCU is watching.
 137  */
 138 void kvm_async_pf_task_wait_schedule(u32 token)
 139 {
 140         struct kvm_task_sleep_node n;
 141         DECLARE_SWAITQUEUE(wait);
 142
 143         lockdep_assert_irqs_disabled();
 144
 145         if (!kvm_async_pf_queue_task(token, &n))
 146                 return;
 147
 148         for (;;) {
 149                 prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
 150                 if (hlist_unhashed(&n.link))
 151                         break;
 152
 153                 local_irq_enable();
 154                 schedule();
 155                 local_irq_disable();
 156         }
 157         finish_swait(&n.wq, &wait);
 158 }
 159 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait_schedule);
 160
 161 static void apf_task_wake_one(struct kvm_task_sleep_node *n)
 162 {
 163         hlist_del_init(&n->link);
 164         if (swq_has_sleeper(&n->wq))
 165                 swake_up_one(&n->wq);
 166 }
 167
 168 static void apf_task_wake_all(void)
 169 {
 170         int i;
 171
 172         for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
 173                 struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
 174                 struct kvm_task_sleep_node *n;
 175                 struct hlist_node *p, *next;
 176
 177                 raw_spin_lock(&b->lock);
 178                 hlist_for_each_safe(p, next, &b->list) {
 179                         n = hlist_entry(p, typeof(*n), link);
 180                         if (n->cpu == smp_processor_id())
 181                                 apf_task_wake_one(n);
 182                 }
 183                 raw_spin_unlock(&b->lock);
 184         }
 185 }
 186
 187 void kvm_async_pf_task_wake(u32 token)
 188 {
 189         u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
 190         struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
 191         struct kvm_task_sleep_node *n, *dummy = NULL;
 192
 193         if (token == ~0) {
 194                 apf_task_wake_all();
 195                 return;
 196         }
 197
 198 again:
 199         raw_spin_lock(&b->lock);
 200         n = _find_apf_task(b, token);
 201         if (!n) {
 202                 /*
 203                  * Async #PF not yet handled, add a dummy entry for the token.
 204                  * Allocating the token must be down outside of the raw lock
 205                  * as the allocator is preemptible on PREEMPT_RT kernels.
 206                  */
 207                 if (!dummy) {
 208                         raw_spin_unlock(&b->lock);
 209                         dummy = kzalloc(sizeof(*dummy), GFP_ATOMIC);
 210
 211                         /*
 212                          * Continue looping on allocation failure, eventually
 213                          * the async #PF will be handled and allocating a new
 214                          * node will be unnecessary.
 215                          */
 216                         if (!dummy)
 217                                 cpu_relax();
 218
 219                         /*
 220                          * Recheck for async #PF completion before enqueueing
 221                          * the dummy token to avoid duplicate list entries.
 222                          */
 223                         goto again;
 224                 }
 225                 dummy->token = token;
 226                 dummy->cpu = smp_processor_id();
 227                 init_swait_queue_head(&dummy->wq);
 228                 hlist_add_head(&dummy->link, &b->list);
 229                 dummy = NULL;
 230         } else {
 231                 apf_task_wake_one(n);
 232         }
 233         raw_spin_unlock(&b->lock);
 234
 235         /* A dummy token might be allocated and ultimately not used.  */
 236         if (dummy)
 237                 kfree(dummy);
 238 }
 239 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
 240
 241 noinstr u32 kvm_read_and_reset_apf_flags(void)
 242 {
 243         u32 flags = 0;
 244
 245         if (__this_cpu_read(apf_reason.enabled)) {
 246                 flags = __this_cpu_read(apf_reason.flags);
 247                 __this_cpu_write(apf_reason.flags, 0);
 248         }
 249
 250         return flags;
 251 }
 252 EXPORT_SYMBOL_GPL(kvm_read_and_reset_apf_flags);
 253
 254 noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token)
 255 {
 256         u32 flags = kvm_read_and_reset_apf_flags();
 257         irqentry_state_t state;
 258
 259         if (!flags)
 260                 return false;
 261
 262         state = irqentry_enter(regs);
 263         instrumentation_begin();
 264
 265         /*
 266          * If the host managed to inject an async #PF into an interrupt
 267          * disabled region, then die hard as this is not going to end well
 268          * and the host side is seriously broken.
 269          */
 270         if (unlikely(!(regs->flags & X86_EFLAGS_IF)))
 271                 panic("Host injected async #PF in interrupt disabled region\n");
 272
 273         if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) {
 274                 if (unlikely(!(user_mode(regs))))
 275                         panic("Host injected async #PF in kernel mode\n");
 276                 /* Page is swapped out by the host. */
 277                 kvm_async_pf_task_wait_schedule(token);
 278         } else {
 279                 WARN_ONCE(1, "Unexpected async PF flags: %x\n", flags);
 280         }
 281
 282         instrumentation_end();
 283         irqentry_exit(regs, state);
 284         return true;
 285 }
 286
 287 DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)
 288 {
 289         struct pt_regs *old_regs = set_irq_regs(regs);
 290         u32 token;
 291
 292         ack_APIC_irq();
 293
 294         inc_irq_stat(irq_hv_callback_count);
 295
 296         if (__this_cpu_read(apf_reason.enabled)) {
 297                 token = __this_cpu_read(apf_reason.token);
 298                 kvm_async_pf_task_wake(token);
 299                 __this_cpu_write(apf_reason.token, 0);
 300                 wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1);
 301         }
 302
 303         set_irq_regs(old_regs);
 304 }
 305
 306 static void __init paravirt_ops_setup(void)
 307 {
 308         pv_info.name = "KVM";
 309
 310         if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
 311                 pv_ops.cpu.io_delay = kvm_io_delay;
 312
 313 #ifdef CONFIG_X86_IO_APIC
 314         no_timer_check = 1;
 315 #endif
 316 }
 317
 318 static void kvm_register_steal_time(void)
 319 {
 320         int cpu = smp_processor_id();
 321         struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
 322
 323         if (!has_steal_clock)
 324                 return;
 325
 326         wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
 327         pr_info("stealtime: cpu %d, msr %llx\n", cpu,
 328                 (unsigned long long) slow_virt_to_phys(st));
 329 }
 330
 331 static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
 332
 333 static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val)
 334 {
 335         /**
 336          * This relies on __test_and_clear_bit to modify the memory
 337          * in a way that is atomic with respect to the local CPU.
 338          * The hypervisor only accesses this memory from the local CPU so
 339          * there's no need for lock or memory barriers.
 340          * An optimization barrier is implied in apic write.
 341          */
 342         if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi)))
 343                 return;
 344         apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK);
 345 }
 346
 347 static void kvm_guest_cpu_init(void)
 348 {
 349         if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
 350                 u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
 351
 352                 WARN_ON_ONCE(!static_branch_likely(&kvm_async_pf_enabled));
 353
 354                 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
 355                 pa |= KVM_ASYNC_PF_ENABLED | KVM_ASYNC_PF_DELIVERY_AS_INT;
 356
 357                 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
 358                         pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
 359
 360                 wrmsrl(MSR_KVM_ASYNC_PF_INT, HYPERVISOR_CALLBACK_VECTOR);
 361
 362                 wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
 363                 __this_cpu_write(apf_reason.enabled, 1);
 364                 pr_info("setup async PF for cpu %d\n", smp_processor_id());
 365         }
 366
 367         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
 368                 unsigned long pa;
 369
 370                 /* Size alignment is implied but just to make it explicit. */
 371                 BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
 372                 __this_cpu_write(kvm_apic_eoi, 0);
 373                 pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
 374                         | KVM_MSR_ENABLED;
 375                 wrmsrl(MSR_KVM_PV_EOI_EN, pa);
 376         }
 377
 378         if (has_steal_clock)
 379                 kvm_register_steal_time();
 380 }
 381
 382 static void kvm_pv_disable_apf(void)
 383 {
 384         if (!__this_cpu_read(apf_reason.enabled))
 385                 return;
 386
 387         wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
 388         __this_cpu_write(apf_reason.enabled, 0);
 389
 390         pr_info("disable async PF for cpu %d\n", smp_processor_id());
 391 }
 392
 393 static void kvm_disable_steal_time(void)
 394 {
 395         if (!has_steal_clock)
 396                 return;
 397
 398         wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
 399 }
 400
 401 static u64 kvm_steal_clock(int cpu)
 402 {
 403         u64 steal;
 404         struct kvm_steal_time *src;
 405         int version;
 406
 407         src = &per_cpu(steal_time, cpu);
 408         do {
 409                 version = src->version;
 410                 virt_rmb();
 411                 steal = src->steal;
 412                 virt_rmb();
 413         } while ((version & 1) || (version != src->version));
 414
 415         return steal;
 416 }
 417
 418 static inline void __set_percpu_decrypted(void *ptr, unsigned long size)
 419 {
 420         early_set_memory_decrypted((unsigned long) ptr, size);
 421 }
 422
 423 /*
 424  * Iterate through all possible CPUs and map the memory region pointed
 425  * by apf_reason, steal_time and kvm_apic_eoi as decrypted at once.
 426  *
 427  * Note: we iterate through all possible CPUs to ensure that CPUs
 428  * hotplugged will have their per-cpu variable already mapped as
 429  * decrypted.
 430  */
 431 static void __init sev_map_percpu_data(void)
 432 {
 433         int cpu;
 434
 435         if (!sev_active())
 436                 return;
 437
 438         for_each_possible_cpu(cpu) {
 439                 __set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason));
 440                 __set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time));
 441                 __set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi));
 442         }
 443 }
 444
 445 static void kvm_guest_cpu_offline(bool shutdown)
 446 {
 447         kvm_disable_steal_time();
 448         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
 449                 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
 450         kvm_pv_disable_apf();
 451         if (!shutdown)
 452                 apf_task_wake_all();
 453         kvmclock_disable();
 454 }
 455
 456 static int kvm_cpu_online(unsigned int cpu)
 457 {
 458         unsigned long flags;
 459
 460         local_irq_save(flags);
 461         kvm_guest_cpu_init();
 462         local_irq_restore(flags);
 463         return 0;
 464 }
 465
 466 #ifdef CONFIG_SMP
 467
 468 static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask);
 469
 470 static bool pv_tlb_flush_supported(void)
 471 {
 472         return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
 473                 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
 474                 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&
 475                 (num_possible_cpus() != 1));
 476 }
 477
 478 static bool pv_ipi_supported(void)
 479 {
 480         return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) &&
 481                (num_possible_cpus() != 1));
 482 }
 483
 484 static bool pv_sched_yield_supported(void)
 485 {
 486         return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&
 487                 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
 488             kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&
 489             (num_possible_cpus() != 1));
 490 }
 491
 492 #define KVM_IPI_CLUSTER_SIZE    (2 * BITS_PER_LONG)
 493
 494 static void __send_ipi_mask(const struct cpumask *mask, int vector)
 495 {
 496         unsigned long flags;
 497         int cpu, apic_id, icr;
 498         int min = 0, max = 0;
 499 #ifdef CONFIG_X86_64
 500         __uint128_t ipi_bitmap = 0;
 501 #else
 502         u64 ipi_bitmap = 0;
 503 #endif
 504         long ret;
 505
 506         if (cpumask_empty(mask))
 507                 return;
 508
 509         local_irq_save(flags);
 510
 511         switch (vector) {
 512         default:
 513                 icr = APIC_DM_FIXED | vector;
 514                 break;
 515         case NMI_VECTOR:
 516                 icr = APIC_DM_NMI;
 517                 break;
 518         }
 519
 520         for_each_cpu(cpu, mask) {
 521                 apic_id = per_cpu(x86_cpu_to_apicid, cpu);
 522                 if (!ipi_bitmap) {
 523                         min = max = apic_id;
 524                 } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) {
 525                         ipi_bitmap <<= min - apic_id;
 526                         min = apic_id;
 527                 } else if (apic_id > min && apic_id < min + KVM_IPI_CLUSTER_SIZE) {
 528                         max = apic_id < max ? max : apic_id;
 529                 } else {
 530                         ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
 531                                 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
 532                         WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
 533                                   ret);
 534                         min = max = apic_id;
 535                         ipi_bitmap = 0;
 536                 }
 537                 __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap);
 538         }
 539
 540         if (ipi_bitmap) {
 541                 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
 542                         (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
 543                 WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
 544                           ret);
 545         }
 546
 547         local_irq_restore(flags);
 548 }
 549
 550 static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
 551 {
 552         __send_ipi_mask(mask, vector);
 553 }
 554
 555 static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
 556 {
 557         unsigned int this_cpu = smp_processor_id();
 558         struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
 559         const struct cpumask *local_mask;
 560
 561         cpumask_copy(new_mask, mask);
 562         cpumask_clear_cpu(this_cpu, new_mask);
 563         local_mask = new_mask;
 564         __send_ipi_mask(local_mask, vector);
 565 }
 566
 567 /*
 568  * Set the IPI entry points
 569  */
 570 static void kvm_setup_pv_ipi(void)
 571 {
 572         apic->send_IPI_mask = kvm_send_ipi_mask;
 573         apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
 574         pr_info("setup PV IPIs\n");
 575 }
 576
 577 static void kvm_smp_send_call_func_ipi(const struct cpumask *mask)
 578 {
 579         int cpu;
 580
 581         native_send_call_func_ipi(mask);
 582
 583         /* Make sure other vCPUs get a chance to run if they need to. */
 584         for_each_cpu(cpu, mask) {
 585                 if (vcpu_is_preempted(cpu)) {
 586                         kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu));
 587                         break;
 588                 }
 589         }
 590 }
 591
 592 static void kvm_flush_tlb_multi(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_cpu_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                 /*
 607                  * The local vCPU is never preempted, so we do not explicitly
 608                  * skip check for local vCPU - it will never be cleared from
 609                  * flushmask.
 610                  */
 611                 src = &per_cpu(steal_time, cpu);
 612                 state = READ_ONCE(src->preempted);
 613                 if ((state & KVM_VCPU_PREEMPTED)) {
 614                         if (try_cmpxchg(&src->preempted, &state,
 615                                         state | KVM_VCPU_FLUSH_TLB))
 616                                 __cpumask_clear_cpu(cpu, flushmask);
 617                 }
 618         }
 619
 620         native_flush_tlb_multi(flushmask, info);
 621 }
 622
 623 static __init int kvm_alloc_cpumask(void)
 624 {
 625         int cpu;
 626
 627         if (!kvm_para_available() || nopv)
 628                 return 0;
 629
 630         if (pv_tlb_flush_supported() || pv_ipi_supported())
 631                 for_each_possible_cpu(cpu) {
 632                         zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu),
 633                                 GFP_KERNEL, cpu_to_node(cpu));
 634                 }
 635
 636         return 0;
 637 }
 638 arch_initcall(kvm_alloc_cpumask);
 639
 640 static void __init kvm_smp_prepare_boot_cpu(void)
 641 {
 642         /*
 643          * Map the per-cpu variables as decrypted before kvm_guest_cpu_init()
 644          * shares the guest physical address with the hypervisor.
 645          */
 646         sev_map_percpu_data();
 647
 648         kvm_guest_cpu_init();
 649         native_smp_prepare_boot_cpu();
 650         kvm_spinlock_init();
 651 }
 652
 653 static int kvm_cpu_down_prepare(unsigned int cpu)
 654 {
 655         unsigned long flags;
 656
 657         local_irq_save(flags);
 658         kvm_guest_cpu_offline(false);
 659         local_irq_restore(flags);
 660         return 0;
 661 }
 662
 663 #endif
 664
 665 static int kvm_suspend(void)
 666 {
 667         u64 val = 0;
 668
 669         kvm_guest_cpu_offline(false);
 670
 671 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
 672         if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
 673                 rdmsrl(MSR_KVM_POLL_CONTROL, val);
 674         has_guest_poll = !(val & 1);
 675 #endif
 676         return 0;
 677 }
 678
 679 static void kvm_resume(void)
 680 {
 681         kvm_cpu_online(raw_smp_processor_id());
 682
 683 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
 684         if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL) && has_guest_poll)
 685                 wrmsrl(MSR_KVM_POLL_CONTROL, 0);
 686 #endif
 687 }
 688
 689 static struct syscore_ops kvm_syscore_ops = {
 690         .suspend        = kvm_suspend,
 691         .resume         = kvm_resume,
 692 };
 693
 694 static void kvm_pv_guest_cpu_reboot(void *unused)
 695 {
 696         kvm_guest_cpu_offline(true);
 697 }
 698
 699 static int kvm_pv_reboot_notify(struct notifier_block *nb,
 700                                 unsigned long code, void *unused)
 701 {
 702         if (code == SYS_RESTART)
 703                 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
 704         return NOTIFY_DONE;
 705 }
 706
 707 static struct notifier_block kvm_pv_reboot_nb = {
 708         .notifier_call = kvm_pv_reboot_notify,
 709 };
 710
 711 /*
 712  * After a PV feature is registered, the host will keep writing to the
 713  * registered memory location. If the guest happens to shutdown, this memory
 714  * won't be valid. In cases like kexec, in which you install a new kernel, this
 715  * means a random memory location will be kept being written.
 716  */
 717 #ifdef CONFIG_KEXEC_CORE
 718 static void kvm_crash_shutdown(struct pt_regs *regs)
 719 {
 720         kvm_guest_cpu_offline(true);
 721         native_machine_crash_shutdown(regs);
 722 }
 723 #endif
 724
 725 static void __init kvm_guest_init(void)
 726 {
 727         int i;
 728
 729         paravirt_ops_setup();
 730         register_reboot_notifier(&kvm_pv_reboot_nb);
 731         for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
 732                 raw_spin_lock_init(&async_pf_sleepers[i].lock);
 733
 734         if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
 735                 has_steal_clock = 1;
 736                 static_call_update(pv_steal_clock, kvm_steal_clock);
 737         }
 738
 739         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
 740                 apic_set_eoi_write(kvm_guest_apic_eoi_write);
 741
 742         if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
 743                 static_branch_enable(&kvm_async_pf_enabled);
 744                 alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_kvm_asyncpf_interrupt);
 745         }
 746
 747 #ifdef CONFIG_SMP
 748         if (pv_tlb_flush_supported()) {
 749                 pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi;
 750                 pv_ops.mmu.tlb_remove_table = tlb_remove_table;
 751                 pr_info("KVM setup pv remote TLB flush\n");
 752         }
 753
 754         smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
 755         if (pv_sched_yield_supported()) {
 756                 smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi;
 757                 pr_info("setup PV sched yield\n");
 758         }
 759         if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
 760                                       kvm_cpu_online, kvm_cpu_down_prepare) < 0)
 761                 pr_err("failed to install cpu hotplug callbacks\n");
 762 #else
 763         sev_map_percpu_data();
 764         kvm_guest_cpu_init();
 765 #endif
 766
 767 #ifdef CONFIG_KEXEC_CORE
 768         machine_ops.crash_shutdown = kvm_crash_shutdown;
 769 #endif
 770
 771         register_syscore_ops(&kvm_syscore_ops);
 772
 773         /*
 774          * Hard lockup detection is enabled by default. Disable it, as guests
 775          * can get false positives too easily, for example if the host is
 776          * overcommitted.
 777          */
 778         hardlockup_detector_disable();
 779 }
 780
 781 static noinline uint32_t __kvm_cpuid_base(void)
 782 {
 783         if (boot_cpu_data.cpuid_level < 0)
 784                 return 0;       /* So we don't blow up on old processors */
 785
 786         if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
 787                 return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0);
 788
 789         return 0;
 790 }
 791
 792 static inline uint32_t kvm_cpuid_base(void)
 793 {
 794         static int kvm_cpuid_base = -1;
 795
 796         if (kvm_cpuid_base == -1)
 797                 kvm_cpuid_base = __kvm_cpuid_base();
 798
 799         return kvm_cpuid_base;
 800 }
 801
 802 bool kvm_para_available(void)
 803 {
 804         return kvm_cpuid_base() != 0;
 805 }
 806 EXPORT_SYMBOL_GPL(kvm_para_available);
 807
 808 unsigned int kvm_arch_para_features(void)
 809 {
 810         return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
 811 }
 812
 813 unsigned int kvm_arch_para_hints(void)
 814 {
 815         return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
 816 }
 817 EXPORT_SYMBOL_GPL(kvm_arch_para_hints);
 818
 819 static uint32_t __init kvm_detect(void)
 820 {
 821         return kvm_cpuid_base();
 822 }
 823
 824 static void __init kvm_apic_init(void)
 825 {
 826 #ifdef CONFIG_SMP
 827         if (pv_ipi_supported())
 828                 kvm_setup_pv_ipi();
 829 #endif
 830 }
 831
 832 static bool __init kvm_msi_ext_dest_id(void)
 833 {
 834         return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID);
 835 }
 836
 837 static void __init kvm_init_platform(void)
 838 {
 839         kvmclock_init();
 840         x86_platform.apic_post_init = kvm_apic_init;
 841 }
 842
 843 #if defined(CONFIG_AMD_MEM_ENCRYPT)
 844 static void kvm_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs)
 845 {
 846         /* RAX and CPL are already in the GHCB */
 847         ghcb_set_rbx(ghcb, regs->bx);
 848         ghcb_set_rcx(ghcb, regs->cx);
 849         ghcb_set_rdx(ghcb, regs->dx);
 850         ghcb_set_rsi(ghcb, regs->si);
 851 }
 852
 853 static bool kvm_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs)
 854 {
 855         /* No checking of the return state needed */
 856         return true;
 857 }
 858 #endif
 859
 860 const __initconst struct hypervisor_x86 x86_hyper_kvm = {
 861         .name                           = "KVM",
 862         .detect                         = kvm_detect,
 863         .type                           = X86_HYPER_KVM,
 864         .init.guest_late_init           = kvm_guest_init,
 865         .init.x2apic_available          = kvm_para_available,
 866         .init.msi_ext_dest_id           = kvm_msi_ext_dest_id,
 867         .init.init_platform             = kvm_init_platform,
 868 #if defined(CONFIG_AMD_MEM_ENCRYPT)
 869         .runtime.sev_es_hcall_prepare   = kvm_sev_es_hcall_prepare,
 870         .runtime.sev_es_hcall_finish    = kvm_sev_es_hcall_finish,
 871 #endif
 872 };
 873
 874 static __init int activate_jump_labels(void)
 875 {
 876         if (has_steal_clock) {
 877                 static_key_slow_inc(&paravirt_steal_enabled);
 878                 if (steal_acc)
 879                         static_key_slow_inc(&paravirt_steal_rq_enabled);
 880         }
 881
 882         return 0;
 883 }
 884 arch_initcall(activate_jump_labels);
 885
 886 #ifdef CONFIG_PARAVIRT_SPINLOCKS
 887
 888 /* Kick a cpu by its apicid. Used to wake up a halted vcpu */
 889 static void kvm_kick_cpu(int cpu)
 890 {
 891         int apicid;
 892         unsigned long flags = 0;
 893
 894         apicid = per_cpu(x86_cpu_to_apicid, cpu);
 895         kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
 896 }
 897
 898 #include <asm/qspinlock.h>
 899
 900 static void kvm_wait(u8 *ptr, u8 val)
 901 {
 902         if (in_nmi())
 903                 return;
 904
 905         /*
 906          * halt until it's our turn and kicked. Note that we do safe halt
 907          * for irq enabled case to avoid hang when lock info is overwritten
 908          * in irq spinlock slowpath and no spurious interrupt occur to save us.
 909          */
 910         if (irqs_disabled()) {
 911                 if (READ_ONCE(*ptr) == val)
 912                         halt();
 913         } else {
 914                 local_irq_disable();
 915
 916                 /* safe_halt() will enable IRQ */
 917                 if (READ_ONCE(*ptr) == val)
 918                         safe_halt();
 919                 else
 920                         local_irq_enable();
 921         }
 922 }
 923
 924 #ifdef CONFIG_X86_32
 925 __visible bool __kvm_vcpu_is_preempted(long cpu)
 926 {
 927         struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
 928
 929         return !!(src->preempted & KVM_VCPU_PREEMPTED);
 930 }
 931 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
 932
 933 #else
 934
 935 #include <asm/asm-offsets.h>
 936
 937 extern bool __raw_callee_save___kvm_vcpu_is_preempted(long);
 938
 939 /*
 940  * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and
 941  * restoring to/from the stack.
 942  */
 943 asm(
 944 ".pushsection .text;"
 945 ".global __raw_callee_save___kvm_vcpu_is_preempted;"
 946 ".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"
 947 "__raw_callee_save___kvm_vcpu_is_preempted:"
 948 "movq   __per_cpu_offset(,%rdi,8), %rax;"
 949 "cmpb   $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);"
 950 "setne  %al;"
 951 ASM_RET
 952 ".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;"
 953 ".popsection");
 954
 955 #endif
 956
 957 /*
 958  * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
 959  */
 960 void __init kvm_spinlock_init(void)
 961 {
 962         /*
 963          * In case host doesn't support KVM_FEATURE_PV_UNHALT there is still an
 964          * advantage of keeping virt_spin_lock_key enabled: virt_spin_lock() is
 965          * preferred over native qspinlock when vCPU is preempted.
 966          */
 967         if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) {
 968                 pr_info("PV spinlocks disabled, no host support\n");
 969                 return;
 970         }
 971
 972         /*
 973          * Disable PV spinlocks and use native qspinlock when dedicated pCPUs
 974          * are available.
 975          */
 976         if (kvm_para_has_hint(KVM_HINTS_REALTIME)) {
 977                 pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n");
 978                 goto out;
 979         }
 980
 981         if (num_possible_cpus() == 1) {
 982                 pr_info("PV spinlocks disabled, single CPU\n");
 983                 goto out;
 984         }
 985
 986         if (nopvspin) {
 987                 pr_info("PV spinlocks disabled, forced by \"nopvspin\" parameter\n");
 988                 goto out;
 989         }
 990
 991         pr_info("PV spinlocks enabled\n");
 992
 993         __pv_init_lock_hash();
 994         pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
 995         pv_ops.lock.queued_spin_unlock =
 996                 PV_CALLEE_SAVE(__pv_queued_spin_unlock);
 997         pv_ops.lock.wait = kvm_wait;
 998         pv_ops.lock.kick = kvm_kick_cpu;
 999
1000         if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
1001                 pv_ops.lock.vcpu_is_preempted =
1002                         PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
1003         }
1004         /*
1005          * When PV spinlock is enabled which is preferred over
1006          * virt_spin_lock(), virt_spin_lock_key's value is meaningless.
1007          * Just disable it anyway.
1008          */
1009 out:
1010         static_branch_disable(&virt_spin_lock_key);
1011 }
1012
1013 #endif  /* CONFIG_PARAVIRT_SPINLOCKS */
1014
1015 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
1016
1017 static void kvm_disable_host_haltpoll(void *i)
1018 {
1019         wrmsrl(MSR_KVM_POLL_CONTROL, 0);
1020 }
1021
1022 static void kvm_enable_host_haltpoll(void *i)
1023 {
1024         wrmsrl(MSR_KVM_POLL_CONTROL, 1);
1025 }
1026
1027 void arch_haltpoll_enable(unsigned int cpu)
1028 {
1029         if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {
1030                 pr_err_once("host does not support poll control\n");
1031                 pr_err_once("host upgrade recommended\n");
1032                 return;
1033         }
1034
1035         /* Enable guest halt poll disables host halt poll */
1036         smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1);
1037 }
1038 EXPORT_SYMBOL_GPL(arch_haltpoll_enable);
1039
1040 void arch_haltpoll_disable(unsigned int cpu)
1041 {
1042         if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
1043                 return;
1044
1045         /* Disable guest halt poll enables host halt poll */
1046         smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1);
1047 }
1048 EXPORT_SYMBOL_GPL(arch_haltpoll_disable);
1049 #endif