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 <linux/cc_platform.h>
  31 #include <linux/efi.h>
  32 #include <asm/timer.h>
  33 #include <asm/cpu.h>
  34 #include <asm/traps.h>
  35 #include <asm/desc.h>
  36 #include <asm/tlbflush.h>
  37 #include <asm/apic.h>
  38 #include <asm/apicdef.h>
  39 #include <asm/hypervisor.h>
  40 #include <asm/tlb.h>
  41 #include <asm/cpuidle_haltpoll.h>
  42 #include <asm/ptrace.h>
  43 #include <asm/reboot.h>
  44 #include <asm/svm.h>
  45 #include <asm/e820/api.h>
  46
  47 DEFINE_STATIC_KEY_FALSE(kvm_async_pf_enabled);
  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 DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64) __visible;
  70 static int has_steal_clock = 0;
  71
  72 static int has_guest_poll = 0;
  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 };
  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 static bool kvm_async_pf_queue_task(u32 token, struct kvm_task_sleep_node *n)
 111 {
 112         u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
 113         struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
 114         struct kvm_task_sleep_node *e;
 115
 116         raw_spin_lock(&b->lock);
 117         e = _find_apf_task(b, token);
 118         if (e) {
 119                 /* dummy entry exist -> wake up was delivered ahead of PF */
 120                 hlist_del(&e->link);
 121                 raw_spin_unlock(&b->lock);
 122                 kfree(e);
 123                 return false;
 124         }
 125
 126         n->token = token;
 127         n->cpu = smp_processor_id();
 128         init_swait_queue_head(&n->wq);
 129         hlist_add_head(&n->link, &b->list);
 130         raw_spin_unlock(&b->lock);
 131         return true;
 132 }
 133
 134 /*
 135  * kvm_async_pf_task_wait_schedule - Wait for pagefault to be handled
 136  * @token:      Token to identify the sleep node entry
 137  *
 138  * Invoked from the async pagefault handling code or from the VM exit page
 139  * fault handler. In both cases RCU is watching.
 140  */
 141 void kvm_async_pf_task_wait_schedule(u32 token)
 142 {
 143         struct kvm_task_sleep_node n;
 144         DECLARE_SWAITQUEUE(wait);
 145
 146         lockdep_assert_irqs_disabled();
 147
 148         if (!kvm_async_pf_queue_task(token, &n))
 149                 return;
 150
 151         for (;;) {
 152                 prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
 153                 if (hlist_unhashed(&n.link))
 154                         break;
 155
 156                 local_irq_enable();
 157                 schedule();
 158                 local_irq_disable();
 159         }
 160         finish_swait(&n.wq, &wait);
 161 }
 162 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait_schedule);
 163
 164 static void apf_task_wake_one(struct kvm_task_sleep_node *n)
 165 {
 166         hlist_del_init(&n->link);
 167         if (swq_has_sleeper(&n->wq))
 168                 swake_up_one(&n->wq);
 169 }
 170
 171 static void apf_task_wake_all(void)
 172 {
 173         int i;
 174
 175         for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
 176                 struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
 177                 struct kvm_task_sleep_node *n;
 178                 struct hlist_node *p, *next;
 179
 180                 raw_spin_lock(&b->lock);
 181                 hlist_for_each_safe(p, next, &b->list) {
 182                         n = hlist_entry(p, typeof(*n), link);
 183                         if (n->cpu == smp_processor_id())
 184                                 apf_task_wake_one(n);
 185                 }
 186                 raw_spin_unlock(&b->lock);
 187         }
 188 }
 189
 190 void kvm_async_pf_task_wake(u32 token)
 191 {
 192         u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
 193         struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
 194         struct kvm_task_sleep_node *n, *dummy = NULL;
 195
 196         if (token == ~0) {
 197                 apf_task_wake_all();
 198                 return;
 199         }
 200
 201 again:
 202         raw_spin_lock(&b->lock);
 203         n = _find_apf_task(b, token);
 204         if (!n) {
 205                 /*
 206                  * Async #PF not yet handled, add a dummy entry for the token.
 207                  * Allocating the token must be down outside of the raw lock
 208                  * as the allocator is preemptible on PREEMPT_RT kernels.
 209                  */
 210                 if (!dummy) {
 211                         raw_spin_unlock(&b->lock);
 212                         dummy = kzalloc(sizeof(*dummy), GFP_ATOMIC);
 213
 214                         /*
 215                          * Continue looping on allocation failure, eventually
 216                          * the async #PF will be handled and allocating a new
 217                          * node will be unnecessary.
 218                          */
 219                         if (!dummy)
 220                                 cpu_relax();
 221
 222                         /*
 223                          * Recheck for async #PF completion before enqueueing
 224                          * the dummy token to avoid duplicate list entries.
 225                          */
 226                         goto again;
 227                 }
 228                 dummy->token = token;
 229                 dummy->cpu = smp_processor_id();
 230                 init_swait_queue_head(&dummy->wq);
 231                 hlist_add_head(&dummy->link, &b->list);
 232                 dummy = NULL;
 233         } else {
 234                 apf_task_wake_one(n);
 235         }
 236         raw_spin_unlock(&b->lock);
 237
 238         /* A dummy token might be allocated and ultimately not used.  */
 239         kfree(dummy);
 240 }
 241 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
 242
 243 noinstr u32 kvm_read_and_reset_apf_flags(void)
 244 {
 245         u32 flags = 0;
 246
 247         if (__this_cpu_read(apf_reason.enabled)) {
 248                 flags = __this_cpu_read(apf_reason.flags);
 249                 __this_cpu_write(apf_reason.flags, 0);
 250         }
 251
 252         return flags;
 253 }
 254 EXPORT_SYMBOL_GPL(kvm_read_and_reset_apf_flags);
 255
 256 noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token)
 257 {
 258         u32 flags = kvm_read_and_reset_apf_flags();
 259         irqentry_state_t state;
 260
 261         if (!flags)
 262                 return false;
 263
 264         state = irqentry_enter(regs);
 265         instrumentation_begin();
 266
 267         /*
 268          * If the host managed to inject an async #PF into an interrupt
 269          * disabled region, then die hard as this is not going to end well
 270          * and the host side is seriously broken.
 271          */
 272         if (unlikely(!(regs->flags & X86_EFLAGS_IF)))
 273                 panic("Host injected async #PF in interrupt disabled region\n");
 274
 275         if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) {
 276                 if (unlikely(!(user_mode(regs))))
 277                         panic("Host injected async #PF in kernel mode\n");
 278                 /* Page is swapped out by the host. */
 279                 kvm_async_pf_task_wait_schedule(token);
 280         } else {
 281                 WARN_ONCE(1, "Unexpected async PF flags: %x\n", flags);
 282         }
 283
 284         instrumentation_end();
 285         irqentry_exit(regs, state);
 286         return true;
 287 }
 288
 289 DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)
 290 {
 291         struct pt_regs *old_regs = set_irq_regs(regs);
 292         u32 token;
 293
 294         ack_APIC_irq();
 295
 296         inc_irq_stat(irq_hv_callback_count);
 297
 298         if (__this_cpu_read(apf_reason.enabled)) {
 299                 token = __this_cpu_read(apf_reason.token);
 300                 kvm_async_pf_task_wake(token);
 301                 __this_cpu_write(apf_reason.token, 0);
 302                 wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1);
 303         }
 304
 305         set_irq_regs(old_regs);
 306 }
 307
 308 static void __init paravirt_ops_setup(void)
 309 {
 310         pv_info.name = "KVM";
 311
 312         if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
 313                 pv_ops.cpu.io_delay = kvm_io_delay;
 314
 315 #ifdef CONFIG_X86_IO_APIC
 316         no_timer_check = 1;
 317 #endif
 318 }
 319
 320 static void kvm_register_steal_time(void)
 321 {
 322         int cpu = smp_processor_id();
 323         struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
 324
 325         if (!has_steal_clock)
 326                 return;
 327
 328         wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
 329         pr_debug("stealtime: cpu %d, msr %llx\n", cpu,
 330                 (unsigned long long) slow_virt_to_phys(st));
 331 }
 332
 333 static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
 334
 335 static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val)
 336 {
 337         /**
 338          * This relies on __test_and_clear_bit to modify the memory
 339          * in a way that is atomic with respect to the local CPU.
 340          * The hypervisor only accesses this memory from the local CPU so
 341          * there's no need for lock or memory barriers.
 342          * An optimization barrier is implied in apic write.
 343          */
 344         if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi)))
 345                 return;
 346         apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK);
 347 }
 348
 349 static void kvm_guest_cpu_init(void)
 350 {
 351         if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
 352                 u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
 353
 354                 WARN_ON_ONCE(!static_branch_likely(&kvm_async_pf_enabled));
 355
 356                 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
 357                 pa |= KVM_ASYNC_PF_ENABLED | KVM_ASYNC_PF_DELIVERY_AS_INT;
 358
 359                 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
 360                         pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
 361
 362                 wrmsrl(MSR_KVM_ASYNC_PF_INT, HYPERVISOR_CALLBACK_VECTOR);
 363
 364                 wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
 365                 __this_cpu_write(apf_reason.enabled, 1);
 366                 pr_debug("setup async PF for cpu %d\n", smp_processor_id());
 367         }
 368
 369         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
 370                 unsigned long pa;
 371
 372                 /* Size alignment is implied but just to make it explicit. */
 373                 BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
 374                 __this_cpu_write(kvm_apic_eoi, 0);
 375                 pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
 376                         | KVM_MSR_ENABLED;
 377                 wrmsrl(MSR_KVM_PV_EOI_EN, pa);
 378         }
 379
 380         if (has_steal_clock)
 381                 kvm_register_steal_time();
 382 }
 383
 384 static void kvm_pv_disable_apf(void)
 385 {
 386         if (!__this_cpu_read(apf_reason.enabled))
 387                 return;
 388
 389         wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
 390         __this_cpu_write(apf_reason.enabled, 0);
 391
 392         pr_debug("disable async PF for cpu %d\n", smp_processor_id());
 393 }
 394
 395 static void kvm_disable_steal_time(void)
 396 {
 397         if (!has_steal_clock)
 398                 return;
 399
 400         wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
 401 }
 402
 403 static u64 kvm_steal_clock(int cpu)
 404 {
 405         u64 steal;
 406         struct kvm_steal_time *src;
 407         int version;
 408
 409         src = &per_cpu(steal_time, cpu);
 410         do {
 411                 version = src->version;
 412                 virt_rmb();
 413                 steal = src->steal;
 414                 virt_rmb();
 415         } while ((version & 1) || (version != src->version));
 416
 417         return steal;
 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 (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
 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 static void kvm_guest_cpu_offline(bool shutdown)
 448 {
 449         kvm_disable_steal_time();
 450         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
 451                 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
 452         if (kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL))
 453                 wrmsrl(MSR_KVM_MIGRATION_CONTROL, 0);
 454         kvm_pv_disable_apf();
 455         if (!shutdown)
 456                 apf_task_wake_all();
 457         kvmclock_disable();
 458 }
 459
 460 static int kvm_cpu_online(unsigned int cpu)
 461 {
 462         unsigned long flags;
 463
 464         local_irq_save(flags);
 465         kvm_guest_cpu_init();
 466         local_irq_restore(flags);
 467         return 0;
 468 }
 469
 470 #ifdef CONFIG_SMP
 471
 472 static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask);
 473
 474 static bool pv_tlb_flush_supported(void)
 475 {
 476         return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
 477                 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
 478                 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&
 479                 !boot_cpu_has(X86_FEATURE_MWAIT) &&
 480                 (num_possible_cpus() != 1));
 481 }
 482
 483 static bool pv_ipi_supported(void)
 484 {
 485         return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) &&
 486                (num_possible_cpus() != 1));
 487 }
 488
 489 static bool pv_sched_yield_supported(void)
 490 {
 491         return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&
 492                 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
 493             kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&
 494             !boot_cpu_has(X86_FEATURE_MWAIT) &&
 495             (num_possible_cpus() != 1));
 496 }
 497
 498 #define KVM_IPI_CLUSTER_SIZE    (2 * BITS_PER_LONG)
 499
 500 static void __send_ipi_mask(const struct cpumask *mask, int vector)
 501 {
 502         unsigned long flags;
 503         int cpu, apic_id, icr;
 504         int min = 0, max = 0;
 505 #ifdef CONFIG_X86_64
 506         __uint128_t ipi_bitmap = 0;
 507 #else
 508         u64 ipi_bitmap = 0;
 509 #endif
 510         long ret;
 511
 512         if (cpumask_empty(mask))
 513                 return;
 514
 515         local_irq_save(flags);
 516
 517         switch (vector) {
 518         default:
 519                 icr = APIC_DM_FIXED | vector;
 520                 break;
 521         case NMI_VECTOR:
 522                 icr = APIC_DM_NMI;
 523                 break;
 524         }
 525
 526         for_each_cpu(cpu, mask) {
 527                 apic_id = per_cpu(x86_cpu_to_apicid, cpu);
 528                 if (!ipi_bitmap) {
 529                         min = max = apic_id;
 530                 } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) {
 531                         ipi_bitmap <<= min - apic_id;
 532                         min = apic_id;
 533                 } else if (apic_id > min && apic_id < min + KVM_IPI_CLUSTER_SIZE) {
 534                         max = apic_id < max ? max : apic_id;
 535                 } else {
 536                         ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
 537                                 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
 538                         WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
 539                                   ret);
 540                         min = max = apic_id;
 541                         ipi_bitmap = 0;
 542                 }
 543                 __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap);
 544         }
 545
 546         if (ipi_bitmap) {
 547                 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
 548                         (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
 549                 WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
 550                           ret);
 551         }
 552
 553         local_irq_restore(flags);
 554 }
 555
 556 static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
 557 {
 558         __send_ipi_mask(mask, vector);
 559 }
 560
 561 static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
 562 {
 563         unsigned int this_cpu = smp_processor_id();
 564         struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
 565         const struct cpumask *local_mask;
 566
 567         cpumask_copy(new_mask, mask);
 568         cpumask_clear_cpu(this_cpu, new_mask);
 569         local_mask = new_mask;
 570         __send_ipi_mask(local_mask, vector);
 571 }
 572
 573 static int __init setup_efi_kvm_sev_migration(void)
 574 {
 575         efi_char16_t efi_sev_live_migration_enabled[] = L"SevLiveMigrationEnabled";
 576         efi_guid_t efi_variable_guid = AMD_SEV_MEM_ENCRYPT_GUID;
 577         efi_status_t status;
 578         unsigned long size;
 579         bool enabled;
 580
 581         if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) ||
 582             !kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL))
 583                 return 0;
 584
 585         if (!efi_enabled(EFI_BOOT))
 586                 return 0;
 587
 588         if (!efi_enabled(EFI_RUNTIME_SERVICES)) {
 589                 pr_info("%s : EFI runtime services are not enabled\n", __func__);
 590                 return 0;
 591         }
 592
 593         size = sizeof(enabled);
 594
 595         /* Get variable contents into buffer */
 596         status = efi.get_variable(efi_sev_live_migration_enabled,
 597                                   &efi_variable_guid, NULL, &size, &enabled);
 598
 599         if (status == EFI_NOT_FOUND) {
 600                 pr_info("%s : EFI live migration variable not found\n", __func__);
 601                 return 0;
 602         }
 603
 604         if (status != EFI_SUCCESS) {
 605                 pr_info("%s : EFI variable retrieval failed\n", __func__);
 606                 return 0;
 607         }
 608
 609         if (enabled == 0) {
 610                 pr_info("%s: live migration disabled in EFI\n", __func__);
 611                 return 0;
 612         }
 613
 614         pr_info("%s : live migration enabled in EFI\n", __func__);
 615         wrmsrl(MSR_KVM_MIGRATION_CONTROL, KVM_MIGRATION_READY);
 616
 617         return 1;
 618 }
 619
 620 late_initcall(setup_efi_kvm_sev_migration);
 621
 622 /*
 623  * Set the IPI entry points
 624  */
 625 static void kvm_setup_pv_ipi(void)
 626 {
 627         apic->send_IPI_mask = kvm_send_ipi_mask;
 628         apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
 629         pr_info("setup PV IPIs\n");
 630 }
 631
 632 static void kvm_smp_send_call_func_ipi(const struct cpumask *mask)
 633 {
 634         int cpu;
 635
 636         native_send_call_func_ipi(mask);
 637
 638         /* Make sure other vCPUs get a chance to run if they need to. */
 639         for_each_cpu(cpu, mask) {
 640                 if (!idle_cpu(cpu) && vcpu_is_preempted(cpu)) {
 641                         kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu));
 642                         break;
 643                 }
 644         }
 645 }
 646
 647 static void kvm_flush_tlb_multi(const struct cpumask *cpumask,
 648                         const struct flush_tlb_info *info)
 649 {
 650         u8 state;
 651         int cpu;
 652         struct kvm_steal_time *src;
 653         struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
 654
 655         cpumask_copy(flushmask, cpumask);
 656         /*
 657          * We have to call flush only on online vCPUs. And
 658          * queue flush_on_enter for pre-empted vCPUs
 659          */
 660         for_each_cpu(cpu, flushmask) {
 661                 /*
 662                  * The local vCPU is never preempted, so we do not explicitly
 663                  * skip check for local vCPU - it will never be cleared from
 664                  * flushmask.
 665                  */
 666                 src = &per_cpu(steal_time, cpu);
 667                 state = READ_ONCE(src->preempted);
 668                 if ((state & KVM_VCPU_PREEMPTED)) {
 669                         if (try_cmpxchg(&src->preempted, &state,
 670                                         state | KVM_VCPU_FLUSH_TLB))
 671                                 __cpumask_clear_cpu(cpu, flushmask);
 672                 }
 673         }
 674
 675         native_flush_tlb_multi(flushmask, info);
 676 }
 677
 678 static __init int kvm_alloc_cpumask(void)
 679 {
 680         int cpu;
 681
 682         if (!kvm_para_available() || nopv)
 683                 return 0;
 684
 685         if (pv_tlb_flush_supported() || pv_ipi_supported())
 686                 for_each_possible_cpu(cpu) {
 687                         zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu),
 688                                 GFP_KERNEL, cpu_to_node(cpu));
 689                 }
 690
 691         return 0;
 692 }
 693 arch_initcall(kvm_alloc_cpumask);
 694
 695 static void __init kvm_smp_prepare_boot_cpu(void)
 696 {
 697         /*
 698          * Map the per-cpu variables as decrypted before kvm_guest_cpu_init()
 699          * shares the guest physical address with the hypervisor.
 700          */
 701         sev_map_percpu_data();
 702
 703         kvm_guest_cpu_init();
 704         native_smp_prepare_boot_cpu();
 705         kvm_spinlock_init();
 706 }
 707
 708 static int kvm_cpu_down_prepare(unsigned int cpu)
 709 {
 710         unsigned long flags;
 711
 712         local_irq_save(flags);
 713         kvm_guest_cpu_offline(false);
 714         local_irq_restore(flags);
 715         return 0;
 716 }
 717
 718 #endif
 719
 720 static int kvm_suspend(void)
 721 {
 722         u64 val = 0;
 723
 724         kvm_guest_cpu_offline(false);
 725
 726 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
 727         if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
 728                 rdmsrl(MSR_KVM_POLL_CONTROL, val);
 729         has_guest_poll = !(val & 1);
 730 #endif
 731         return 0;
 732 }
 733
 734 static void kvm_resume(void)
 735 {
 736         kvm_cpu_online(raw_smp_processor_id());
 737
 738 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
 739         if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL) && has_guest_poll)
 740                 wrmsrl(MSR_KVM_POLL_CONTROL, 0);
 741 #endif
 742 }
 743
 744 static struct syscore_ops kvm_syscore_ops = {
 745         .suspend        = kvm_suspend,
 746         .resume         = kvm_resume,
 747 };
 748
 749 static void kvm_pv_guest_cpu_reboot(void *unused)
 750 {
 751         kvm_guest_cpu_offline(true);
 752 }
 753
 754 static int kvm_pv_reboot_notify(struct notifier_block *nb,
 755                                 unsigned long code, void *unused)
 756 {
 757         if (code == SYS_RESTART)
 758                 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
 759         return NOTIFY_DONE;
 760 }
 761
 762 static struct notifier_block kvm_pv_reboot_nb = {
 763         .notifier_call = kvm_pv_reboot_notify,
 764 };
 765
 766 /*
 767  * After a PV feature is registered, the host will keep writing to the
 768  * registered memory location. If the guest happens to shutdown, this memory
 769  * won't be valid. In cases like kexec, in which you install a new kernel, this
 770  * means a random memory location will be kept being written.
 771  */
 772 #ifdef CONFIG_KEXEC_CORE
 773 static void kvm_crash_shutdown(struct pt_regs *regs)
 774 {
 775         kvm_guest_cpu_offline(true);
 776         native_machine_crash_shutdown(regs);
 777 }
 778 #endif
 779
 780 #if defined(CONFIG_X86_32) || !defined(CONFIG_SMP)
 781 bool __kvm_vcpu_is_preempted(long cpu);
 782
 783 __visible bool __kvm_vcpu_is_preempted(long cpu)
 784 {
 785         struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
 786
 787         return !!(src->preempted & KVM_VCPU_PREEMPTED);
 788 }
 789 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
 790
 791 #else
 792
 793 #include <asm/asm-offsets.h>
 794
 795 extern bool __raw_callee_save___kvm_vcpu_is_preempted(long);
 796
 797 /*
 798  * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and
 799  * restoring to/from the stack.
 800  */
 801 asm(
 802 ".pushsection .text;"
 803 ".global __raw_callee_save___kvm_vcpu_is_preempted;"
 804 ".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"
 805 "__raw_callee_save___kvm_vcpu_is_preempted:"
 806 ASM_ENDBR
 807 "movq   __per_cpu_offset(,%rdi,8), %rax;"
 808 "cmpb   $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);"
 809 "setne  %al;"
 810 ASM_RET
 811 ".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;"
 812 ".popsection");
 813
 814 #endif
 815
 816 static void __init kvm_guest_init(void)
 817 {
 818         int i;
 819
 820         paravirt_ops_setup();
 821         register_reboot_notifier(&kvm_pv_reboot_nb);
 822         for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
 823                 raw_spin_lock_init(&async_pf_sleepers[i].lock);
 824
 825         if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
 826                 has_steal_clock = 1;
 827                 static_call_update(pv_steal_clock, kvm_steal_clock);
 828
 829                 pv_ops.lock.vcpu_is_preempted =
 830                         PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
 831         }
 832
 833         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
 834                 apic_set_eoi_write(kvm_guest_apic_eoi_write);
 835
 836         if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
 837                 static_branch_enable(&kvm_async_pf_enabled);
 838                 alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_kvm_asyncpf_interrupt);
 839         }
 840
 841 #ifdef CONFIG_SMP
 842         if (pv_tlb_flush_supported()) {
 843                 pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi;
 844                 pv_ops.mmu.tlb_remove_table = tlb_remove_table;
 845                 pr_info("KVM setup pv remote TLB flush\n");
 846         }
 847
 848         smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
 849         if (pv_sched_yield_supported()) {
 850                 smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi;
 851                 pr_info("setup PV sched yield\n");
 852         }
 853         if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
 854                                       kvm_cpu_online, kvm_cpu_down_prepare) < 0)
 855                 pr_err("failed to install cpu hotplug callbacks\n");
 856 #else
 857         sev_map_percpu_data();
 858         kvm_guest_cpu_init();
 859 #endif
 860
 861 #ifdef CONFIG_KEXEC_CORE
 862         machine_ops.crash_shutdown = kvm_crash_shutdown;
 863 #endif
 864
 865         register_syscore_ops(&kvm_syscore_ops);
 866
 867         /*
 868          * Hard lockup detection is enabled by default. Disable it, as guests
 869          * can get false positives too easily, for example if the host is
 870          * overcommitted.
 871          */
 872         hardlockup_detector_disable();
 873 }
 874
 875 static noinline uint32_t __kvm_cpuid_base(void)
 876 {
 877         if (boot_cpu_data.cpuid_level < 0)
 878                 return 0;       /* So we don't blow up on old processors */
 879
 880         if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
 881                 return hypervisor_cpuid_base(KVM_SIGNATURE, 0);
 882
 883         return 0;
 884 }
 885
 886 static inline uint32_t kvm_cpuid_base(void)
 887 {
 888         static int kvm_cpuid_base = -1;
 889
 890         if (kvm_cpuid_base == -1)
 891                 kvm_cpuid_base = __kvm_cpuid_base();
 892
 893         return kvm_cpuid_base;
 894 }
 895
 896 bool kvm_para_available(void)
 897 {
 898         return kvm_cpuid_base() != 0;
 899 }
 900 EXPORT_SYMBOL_GPL(kvm_para_available);
 901
 902 unsigned int kvm_arch_para_features(void)
 903 {
 904         return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
 905 }
 906
 907 unsigned int kvm_arch_para_hints(void)
 908 {
 909         return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
 910 }
 911 EXPORT_SYMBOL_GPL(kvm_arch_para_hints);
 912
 913 static uint32_t __init kvm_detect(void)
 914 {
 915         return kvm_cpuid_base();
 916 }
 917
 918 static void __init kvm_apic_init(void)
 919 {
 920 #ifdef CONFIG_SMP
 921         if (pv_ipi_supported())
 922                 kvm_setup_pv_ipi();
 923 #endif
 924 }
 925
 926 static bool __init kvm_msi_ext_dest_id(void)
 927 {
 928         return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID);
 929 }
 930
 931 static void kvm_sev_hc_page_enc_status(unsigned long pfn, int npages, bool enc)
 932 {
 933         kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, pfn << PAGE_SHIFT, npages,
 934                            KVM_MAP_GPA_RANGE_ENC_STAT(enc) | KVM_MAP_GPA_RANGE_PAGE_SZ_4K);
 935 }
 936
 937 static void __init kvm_init_platform(void)
 938 {
 939         if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) &&
 940             kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) {
 941                 unsigned long nr_pages;
 942                 int i;
 943
 944                 pv_ops.mmu.notify_page_enc_status_changed =
 945                         kvm_sev_hc_page_enc_status;
 946
 947                 /*
 948                  * Reset the host's shared pages list related to kernel
 949                  * specific page encryption status settings before we load a
 950                  * new kernel by kexec. Reset the page encryption status
 951                  * during early boot intead of just before kexec to avoid SMP
 952                  * races during kvm_pv_guest_cpu_reboot().
 953                  * NOTE: We cannot reset the complete shared pages list
 954                  * here as we need to retain the UEFI/OVMF firmware
 955                  * specific settings.
 956                  */
 957
 958                 for (i = 0; i < e820_table->nr_entries; i++) {
 959                         struct e820_entry *entry = &e820_table->entries[i];
 960
 961                         if (entry->type != E820_TYPE_RAM)
 962                                 continue;
 963
 964                         nr_pages = DIV_ROUND_UP(entry->size, PAGE_SIZE);
 965
 966                         kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, entry->addr,
 967                                        nr_pages,
 968                                        KVM_MAP_GPA_RANGE_ENCRYPTED | KVM_MAP_GPA_RANGE_PAGE_SZ_4K);
 969                 }
 970
 971                 /*
 972                  * Ensure that _bss_decrypted section is marked as decrypted in the
 973                  * shared pages list.
 974                  */
 975                 nr_pages = DIV_ROUND_UP(__end_bss_decrypted - __start_bss_decrypted,
 976                                         PAGE_SIZE);
 977                 early_set_mem_enc_dec_hypercall((unsigned long)__start_bss_decrypted,
 978                                                 nr_pages, 0);
 979
 980                 /*
 981                  * If not booted using EFI, enable Live migration support.
 982                  */
 983                 if (!efi_enabled(EFI_BOOT))
 984                         wrmsrl(MSR_KVM_MIGRATION_CONTROL,
 985                                KVM_MIGRATION_READY);
 986         }
 987         kvmclock_init();
 988         x86_platform.apic_post_init = kvm_apic_init;
 989 }
 990
 991 #if defined(CONFIG_AMD_MEM_ENCRYPT)
 992 static void kvm_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs)
 993 {
 994         /* RAX and CPL are already in the GHCB */
 995         ghcb_set_rbx(ghcb, regs->bx);
 996         ghcb_set_rcx(ghcb, regs->cx);
 997         ghcb_set_rdx(ghcb, regs->dx);
 998         ghcb_set_rsi(ghcb, regs->si);
 999 }
1000
1001 static bool kvm_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs)
1002 {
1003         /* No checking of the return state needed */
1004         return true;
1005 }
1006 #endif
1007
1008 const __initconst struct hypervisor_x86 x86_hyper_kvm = {
1009         .name                           = "KVM",
1010         .detect                         = kvm_detect,
1011         .type                           = X86_HYPER_KVM,
1012         .init.guest_late_init           = kvm_guest_init,
1013         .init.x2apic_available          = kvm_para_available,
1014         .init.msi_ext_dest_id           = kvm_msi_ext_dest_id,
1015         .init.init_platform             = kvm_init_platform,
1016 #if defined(CONFIG_AMD_MEM_ENCRYPT)
1017         .runtime.sev_es_hcall_prepare   = kvm_sev_es_hcall_prepare,
1018         .runtime.sev_es_hcall_finish    = kvm_sev_es_hcall_finish,
1019 #endif
1020 };
1021
1022 static __init int activate_jump_labels(void)
1023 {
1024         if (has_steal_clock) {
1025                 static_key_slow_inc(&paravirt_steal_enabled);
1026                 if (steal_acc)
1027                         static_key_slow_inc(&paravirt_steal_rq_enabled);
1028         }
1029
1030         return 0;
1031 }
1032 arch_initcall(activate_jump_labels);
1033
1034 #ifdef CONFIG_PARAVIRT_SPINLOCKS
1035
1036 /* Kick a cpu by its apicid. Used to wake up a halted vcpu */
1037 static void kvm_kick_cpu(int cpu)
1038 {
1039         int apicid;
1040         unsigned long flags = 0;
1041
1042         apicid = per_cpu(x86_cpu_to_apicid, cpu);
1043         kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
1044 }
1045
1046 #include <asm/qspinlock.h>
1047
1048 static void kvm_wait(u8 *ptr, u8 val)
1049 {
1050         if (in_nmi())
1051                 return;
1052
1053         /*
1054          * halt until it's our turn and kicked. Note that we do safe halt
1055          * for irq enabled case to avoid hang when lock info is overwritten
1056          * in irq spinlock slowpath and no spurious interrupt occur to save us.
1057          */
1058         if (irqs_disabled()) {
1059                 if (READ_ONCE(*ptr) == val)
1060                         halt();
1061         } else {
1062                 local_irq_disable();
1063
1064                 /* safe_halt() will enable IRQ */
1065                 if (READ_ONCE(*ptr) == val)
1066                         safe_halt();
1067                 else
1068                         local_irq_enable();
1069         }
1070 }
1071
1072 /*
1073  * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
1074  */
1075 void __init kvm_spinlock_init(void)
1076 {
1077         /*
1078          * In case host doesn't support KVM_FEATURE_PV_UNHALT there is still an
1079          * advantage of keeping virt_spin_lock_key enabled: virt_spin_lock() is
1080          * preferred over native qspinlock when vCPU is preempted.
1081          */
1082         if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) {
1083                 pr_info("PV spinlocks disabled, no host support\n");
1084                 return;
1085         }
1086
1087         /*
1088          * Disable PV spinlocks and use native qspinlock when dedicated pCPUs
1089          * are available.
1090          */
1091         if (kvm_para_has_hint(KVM_HINTS_REALTIME)) {
1092                 pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n");
1093                 goto out;
1094         }
1095
1096         if (num_possible_cpus() == 1) {
1097                 pr_info("PV spinlocks disabled, single CPU\n");
1098                 goto out;
1099         }
1100
1101         if (nopvspin) {
1102                 pr_info("PV spinlocks disabled, forced by \"nopvspin\" parameter\n");
1103                 goto out;
1104         }
1105
1106         pr_info("PV spinlocks enabled\n");
1107
1108         __pv_init_lock_hash();
1109         pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
1110         pv_ops.lock.queued_spin_unlock =
1111                 PV_CALLEE_SAVE(__pv_queued_spin_unlock);
1112         pv_ops.lock.wait = kvm_wait;
1113         pv_ops.lock.kick = kvm_kick_cpu;
1114
1115         /*
1116          * When PV spinlock is enabled which is preferred over
1117          * virt_spin_lock(), virt_spin_lock_key's value is meaningless.
1118          * Just disable it anyway.
1119          */
1120 out:
1121         static_branch_disable(&virt_spin_lock_key);
1122 }
1123
1124 #endif  /* CONFIG_PARAVIRT_SPINLOCKS */
1125
1126 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
1127
1128 static void kvm_disable_host_haltpoll(void *i)
1129 {
1130         wrmsrl(MSR_KVM_POLL_CONTROL, 0);
1131 }
1132
1133 static void kvm_enable_host_haltpoll(void *i)
1134 {
1135         wrmsrl(MSR_KVM_POLL_CONTROL, 1);
1136 }
1137
1138 void arch_haltpoll_enable(unsigned int cpu)
1139 {
1140         if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {
1141                 pr_err_once("host does not support poll control\n");
1142                 pr_err_once("host upgrade recommended\n");
1143                 return;
1144         }
1145
1146         /* Enable guest halt poll disables host halt poll */
1147         smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1);
1148 }
1149 EXPORT_SYMBOL_GPL(arch_haltpoll_enable);
1150
1151 void arch_haltpoll_disable(unsigned int cpu)
1152 {
1153         if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
1154                 return;
1155
1156         /* Disable guest halt poll enables host halt poll */
1157         smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1);
1158 }
1159 EXPORT_SYMBOL_GPL(arch_haltpoll_disable);
1160 #endif