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         if (dummy)
 240                 kfree(dummy);
 241 }
 242 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
 243
 244 noinstr u32 kvm_read_and_reset_apf_flags(void)
 245 {
 246         u32 flags = 0;
 247
 248         if (__this_cpu_read(apf_reason.enabled)) {
 249                 flags = __this_cpu_read(apf_reason.flags);
 250                 __this_cpu_write(apf_reason.flags, 0);
 251         }
 252
 253         return flags;
 254 }
 255 EXPORT_SYMBOL_GPL(kvm_read_and_reset_apf_flags);
 256
 257 noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token)
 258 {
 259         u32 flags = kvm_read_and_reset_apf_flags();
 260         irqentry_state_t state;
 261
 262         if (!flags)
 263                 return false;
 264
 265         state = irqentry_enter(regs);
 266         instrumentation_begin();
 267
 268         /*
 269          * If the host managed to inject an async #PF into an interrupt
 270          * disabled region, then die hard as this is not going to end well
 271          * and the host side is seriously broken.
 272          */
 273         if (unlikely(!(regs->flags & X86_EFLAGS_IF)))
 274                 panic("Host injected async #PF in interrupt disabled region\n");
 275
 276         if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) {
 277                 if (unlikely(!(user_mode(regs))))
 278                         panic("Host injected async #PF in kernel mode\n");
 279                 /* Page is swapped out by the host. */
 280                 kvm_async_pf_task_wait_schedule(token);
 281         } else {
 282                 WARN_ONCE(1, "Unexpected async PF flags: %x\n", flags);
 283         }
 284
 285         instrumentation_end();
 286         irqentry_exit(regs, state);
 287         return true;
 288 }
 289
 290 DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)
 291 {
 292         struct pt_regs *old_regs = set_irq_regs(regs);
 293         u32 token;
 294
 295         ack_APIC_irq();
 296
 297         inc_irq_stat(irq_hv_callback_count);
 298
 299         if (__this_cpu_read(apf_reason.enabled)) {
 300                 token = __this_cpu_read(apf_reason.token);
 301                 kvm_async_pf_task_wake(token);
 302                 __this_cpu_write(apf_reason.token, 0);
 303                 wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1);
 304         }
 305
 306         set_irq_regs(old_regs);
 307 }
 308
 309 static void __init paravirt_ops_setup(void)
 310 {
 311         pv_info.name = "KVM";
 312
 313         if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
 314                 pv_ops.cpu.io_delay = kvm_io_delay;
 315
 316 #ifdef CONFIG_X86_IO_APIC
 317         no_timer_check = 1;
 318 #endif
 319 }
 320
 321 static void kvm_register_steal_time(void)
 322 {
 323         int cpu = smp_processor_id();
 324         struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
 325
 326         if (!has_steal_clock)
 327                 return;
 328
 329         wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
 330         pr_debug("stealtime: cpu %d, msr %llx\n", cpu,
 331                 (unsigned long long) slow_virt_to_phys(st));
 332 }
 333
 334 static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
 335
 336 static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val)
 337 {
 338         /**
 339          * This relies on __test_and_clear_bit to modify the memory
 340          * in a way that is atomic with respect to the local CPU.
 341          * The hypervisor only accesses this memory from the local CPU so
 342          * there's no need for lock or memory barriers.
 343          * An optimization barrier is implied in apic write.
 344          */
 345         if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi)))
 346                 return;
 347         apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK);
 348 }
 349
 350 static void kvm_guest_cpu_init(void)
 351 {
 352         if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
 353                 u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
 354
 355                 WARN_ON_ONCE(!static_branch_likely(&kvm_async_pf_enabled));
 356
 357                 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
 358                 pa |= KVM_ASYNC_PF_ENABLED | KVM_ASYNC_PF_DELIVERY_AS_INT;
 359
 360                 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
 361                         pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
 362
 363                 wrmsrl(MSR_KVM_ASYNC_PF_INT, HYPERVISOR_CALLBACK_VECTOR);
 364
 365                 wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
 366                 __this_cpu_write(apf_reason.enabled, 1);
 367                 pr_debug("setup async PF for cpu %d\n", smp_processor_id());
 368         }
 369
 370         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
 371                 unsigned long pa;
 372
 373                 /* Size alignment is implied but just to make it explicit. */
 374                 BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
 375                 __this_cpu_write(kvm_apic_eoi, 0);
 376                 pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
 377                         | KVM_MSR_ENABLED;
 378                 wrmsrl(MSR_KVM_PV_EOI_EN, pa);
 379         }
 380
 381         if (has_steal_clock)
 382                 kvm_register_steal_time();
 383 }
 384
 385 static void kvm_pv_disable_apf(void)
 386 {
 387         if (!__this_cpu_read(apf_reason.enabled))
 388                 return;
 389
 390         wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
 391         __this_cpu_write(apf_reason.enabled, 0);
 392
 393         pr_debug("disable async PF for cpu %d\n", smp_processor_id());
 394 }
 395
 396 static void kvm_disable_steal_time(void)
 397 {
 398         if (!has_steal_clock)
 399                 return;
 400
 401         wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
 402 }
 403
 404 static u64 kvm_steal_clock(int cpu)
 405 {
 406         u64 steal;
 407         struct kvm_steal_time *src;
 408         int version;
 409
 410         src = &per_cpu(steal_time, cpu);
 411         do {
 412                 version = src->version;
 413                 virt_rmb();
 414                 steal = src->steal;
 415                 virt_rmb();
 416         } while ((version & 1) || (version != src->version));
 417
 418         return steal;
 419 }
 420
 421 static inline void __set_percpu_decrypted(void *ptr, unsigned long size)
 422 {
 423         early_set_memory_decrypted((unsigned long) ptr, size);
 424 }
 425
 426 /*
 427  * Iterate through all possible CPUs and map the memory region pointed
 428  * by apf_reason, steal_time and kvm_apic_eoi as decrypted at once.
 429  *
 430  * Note: we iterate through all possible CPUs to ensure that CPUs
 431  * hotplugged will have their per-cpu variable already mapped as
 432  * decrypted.
 433  */
 434 static void __init sev_map_percpu_data(void)
 435 {
 436         int cpu;
 437
 438         if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
 439                 return;
 440
 441         for_each_possible_cpu(cpu) {
 442                 __set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason));
 443                 __set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time));
 444                 __set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi));
 445         }
 446 }
 447
 448 static void kvm_guest_cpu_offline(bool shutdown)
 449 {
 450         kvm_disable_steal_time();
 451         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
 452                 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
 453         if (kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL))
 454                 wrmsrl(MSR_KVM_MIGRATION_CONTROL, 0);
 455         kvm_pv_disable_apf();
 456         if (!shutdown)
 457                 apf_task_wake_all();
 458         kvmclock_disable();
 459 }
 460
 461 static int kvm_cpu_online(unsigned int cpu)
 462 {
 463         unsigned long flags;
 464
 465         local_irq_save(flags);
 466         kvm_guest_cpu_init();
 467         local_irq_restore(flags);
 468         return 0;
 469 }
 470
 471 #ifdef CONFIG_SMP
 472
 473 static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask);
 474
 475 static bool pv_tlb_flush_supported(void)
 476 {
 477         return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
 478                 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
 479                 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&
 480                 !boot_cpu_has(X86_FEATURE_MWAIT) &&
 481                 (num_possible_cpus() != 1));
 482 }
 483
 484 static bool pv_ipi_supported(void)
 485 {
 486         return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) &&
 487                (num_possible_cpus() != 1));
 488 }
 489
 490 static bool pv_sched_yield_supported(void)
 491 {
 492         return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&
 493                 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
 494             kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&
 495             !boot_cpu_has(X86_FEATURE_MWAIT) &&
 496             (num_possible_cpus() != 1));
 497 }
 498
 499 #define KVM_IPI_CLUSTER_SIZE    (2 * BITS_PER_LONG)
 500
 501 static void __send_ipi_mask(const struct cpumask *mask, int vector)
 502 {
 503         unsigned long flags;
 504         int cpu, apic_id, icr;
 505         int min = 0, max = 0;
 506 #ifdef CONFIG_X86_64
 507         __uint128_t ipi_bitmap = 0;
 508 #else
 509         u64 ipi_bitmap = 0;
 510 #endif
 511         long ret;
 512
 513         if (cpumask_empty(mask))
 514                 return;
 515
 516         local_irq_save(flags);
 517
 518         switch (vector) {
 519         default:
 520                 icr = APIC_DM_FIXED | vector;
 521                 break;
 522         case NMI_VECTOR:
 523                 icr = APIC_DM_NMI;
 524                 break;
 525         }
 526
 527         for_each_cpu(cpu, mask) {
 528                 apic_id = per_cpu(x86_cpu_to_apicid, cpu);
 529                 if (!ipi_bitmap) {
 530                         min = max = apic_id;
 531                 } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) {
 532                         ipi_bitmap <<= min - apic_id;
 533                         min = apic_id;
 534                 } else if (apic_id > min && apic_id < min + KVM_IPI_CLUSTER_SIZE) {
 535                         max = apic_id < max ? max : apic_id;
 536                 } else {
 537                         ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
 538                                 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
 539                         WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
 540                                   ret);
 541                         min = max = apic_id;
 542                         ipi_bitmap = 0;
 543                 }
 544                 __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap);
 545         }
 546
 547         if (ipi_bitmap) {
 548                 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
 549                         (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
 550                 WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
 551                           ret);
 552         }
 553
 554         local_irq_restore(flags);
 555 }
 556
 557 static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
 558 {
 559         __send_ipi_mask(mask, vector);
 560 }
 561
 562 static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
 563 {
 564         unsigned int this_cpu = smp_processor_id();
 565         struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
 566         const struct cpumask *local_mask;
 567
 568         cpumask_copy(new_mask, mask);
 569         cpumask_clear_cpu(this_cpu, new_mask);
 570         local_mask = new_mask;
 571         __send_ipi_mask(local_mask, vector);
 572 }
 573
 574 static int __init setup_efi_kvm_sev_migration(void)
 575 {
 576         efi_char16_t efi_sev_live_migration_enabled[] = L"SevLiveMigrationEnabled";
 577         efi_guid_t efi_variable_guid = AMD_SEV_MEM_ENCRYPT_GUID;
 578         efi_status_t status;
 579         unsigned long size;
 580         bool enabled;
 581
 582         if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) ||
 583             !kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL))
 584                 return 0;
 585
 586         if (!efi_enabled(EFI_BOOT))
 587                 return 0;
 588
 589         if (!efi_enabled(EFI_RUNTIME_SERVICES)) {
 590                 pr_info("%s : EFI runtime services are not enabled\n", __func__);
 591                 return 0;
 592         }
 593
 594         size = sizeof(enabled);
 595
 596         /* Get variable contents into buffer */
 597         status = efi.get_variable(efi_sev_live_migration_enabled,
 598                                   &efi_variable_guid, NULL, &size, &enabled);
 599
 600         if (status == EFI_NOT_FOUND) {
 601                 pr_info("%s : EFI live migration variable not found\n", __func__);
 602                 return 0;
 603         }
 604
 605         if (status != EFI_SUCCESS) {
 606                 pr_info("%s : EFI variable retrieval failed\n", __func__);
 607                 return 0;
 608         }
 609
 610         if (enabled == 0) {
 611                 pr_info("%s: live migration disabled in EFI\n", __func__);
 612                 return 0;
 613         }
 614
 615         pr_info("%s : live migration enabled in EFI\n", __func__);
 616         wrmsrl(MSR_KVM_MIGRATION_CONTROL, KVM_MIGRATION_READY);
 617
 618         return 1;
 619 }
 620
 621 late_initcall(setup_efi_kvm_sev_migration);
 622
 623 /*
 624  * Set the IPI entry points
 625  */
 626 static void kvm_setup_pv_ipi(void)
 627 {
 628         apic->send_IPI_mask = kvm_send_ipi_mask;
 629         apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
 630         pr_info("setup PV IPIs\n");
 631 }
 632
 633 static void kvm_smp_send_call_func_ipi(const struct cpumask *mask)
 634 {
 635         int cpu;
 636
 637         native_send_call_func_ipi(mask);
 638
 639         /* Make sure other vCPUs get a chance to run if they need to. */
 640         for_each_cpu(cpu, mask) {
 641                 if (!idle_cpu(cpu) && vcpu_is_preempted(cpu)) {
 642                         kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu));
 643                         break;
 644                 }
 645         }
 646 }
 647
 648 static void kvm_flush_tlb_multi(const struct cpumask *cpumask,
 649                         const struct flush_tlb_info *info)
 650 {
 651         u8 state;
 652         int cpu;
 653         struct kvm_steal_time *src;
 654         struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
 655
 656         cpumask_copy(flushmask, cpumask);
 657         /*
 658          * We have to call flush only on online vCPUs. And
 659          * queue flush_on_enter for pre-empted vCPUs
 660          */
 661         for_each_cpu(cpu, flushmask) {
 662                 /*
 663                  * The local vCPU is never preempted, so we do not explicitly
 664                  * skip check for local vCPU - it will never be cleared from
 665                  * flushmask.
 666                  */
 667                 src = &per_cpu(steal_time, cpu);
 668                 state = READ_ONCE(src->preempted);
 669                 if ((state & KVM_VCPU_PREEMPTED)) {
 670                         if (try_cmpxchg(&src->preempted, &state,
 671                                         state | KVM_VCPU_FLUSH_TLB))
 672                                 __cpumask_clear_cpu(cpu, flushmask);
 673                 }
 674         }
 675
 676         native_flush_tlb_multi(flushmask, info);
 677 }
 678
 679 static __init int kvm_alloc_cpumask(void)
 680 {
 681         int cpu;
 682
 683         if (!kvm_para_available() || nopv)
 684                 return 0;
 685
 686         if (pv_tlb_flush_supported() || pv_ipi_supported())
 687                 for_each_possible_cpu(cpu) {
 688                         zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu),
 689                                 GFP_KERNEL, cpu_to_node(cpu));
 690                 }
 691
 692         return 0;
 693 }
 694 arch_initcall(kvm_alloc_cpumask);
 695
 696 static void __init kvm_smp_prepare_boot_cpu(void)
 697 {
 698         /*
 699          * Map the per-cpu variables as decrypted before kvm_guest_cpu_init()
 700          * shares the guest physical address with the hypervisor.
 701          */
 702         sev_map_percpu_data();
 703
 704         kvm_guest_cpu_init();
 705         native_smp_prepare_boot_cpu();
 706         kvm_spinlock_init();
 707 }
 708
 709 static int kvm_cpu_down_prepare(unsigned int cpu)
 710 {
 711         unsigned long flags;
 712
 713         local_irq_save(flags);
 714         kvm_guest_cpu_offline(false);
 715         local_irq_restore(flags);
 716         return 0;
 717 }
 718
 719 #endif
 720
 721 static int kvm_suspend(void)
 722 {
 723         u64 val = 0;
 724
 725         kvm_guest_cpu_offline(false);
 726
 727 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
 728         if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
 729                 rdmsrl(MSR_KVM_POLL_CONTROL, val);
 730         has_guest_poll = !(val & 1);
 731 #endif
 732         return 0;
 733 }
 734
 735 static void kvm_resume(void)
 736 {
 737         kvm_cpu_online(raw_smp_processor_id());
 738
 739 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
 740         if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL) && has_guest_poll)
 741                 wrmsrl(MSR_KVM_POLL_CONTROL, 0);
 742 #endif
 743 }
 744
 745 static struct syscore_ops kvm_syscore_ops = {
 746         .suspend        = kvm_suspend,
 747         .resume         = kvm_resume,
 748 };
 749
 750 static void kvm_pv_guest_cpu_reboot(void *unused)
 751 {
 752         kvm_guest_cpu_offline(true);
 753 }
 754
 755 static int kvm_pv_reboot_notify(struct notifier_block *nb,
 756                                 unsigned long code, void *unused)
 757 {
 758         if (code == SYS_RESTART)
 759                 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
 760         return NOTIFY_DONE;
 761 }
 762
 763 static struct notifier_block kvm_pv_reboot_nb = {
 764         .notifier_call = kvm_pv_reboot_notify,
 765 };
 766
 767 /*
 768  * After a PV feature is registered, the host will keep writing to the
 769  * registered memory location. If the guest happens to shutdown, this memory
 770  * won't be valid. In cases like kexec, in which you install a new kernel, this
 771  * means a random memory location will be kept being written.
 772  */
 773 #ifdef CONFIG_KEXEC_CORE
 774 static void kvm_crash_shutdown(struct pt_regs *regs)
 775 {
 776         kvm_guest_cpu_offline(true);
 777         native_machine_crash_shutdown(regs);
 778 }
 779 #endif
 780
 781 #if defined(CONFIG_X86_32) || !defined(CONFIG_SMP)
 782 bool __kvm_vcpu_is_preempted(long cpu);
 783
 784 __visible bool __kvm_vcpu_is_preempted(long cpu)
 785 {
 786         struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
 787
 788         return !!(src->preempted & KVM_VCPU_PREEMPTED);
 789 }
 790 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
 791
 792 #else
 793
 794 #include <asm/asm-offsets.h>
 795
 796 extern bool __raw_callee_save___kvm_vcpu_is_preempted(long);
 797
 798 /*
 799  * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and
 800  * restoring to/from the stack.
 801  */
 802 asm(
 803 ".pushsection .text;"
 804 ".global __raw_callee_save___kvm_vcpu_is_preempted;"
 805 ".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"
 806 "__raw_callee_save___kvm_vcpu_is_preempted:"
 807 ASM_ENDBR
 808 "movq   __per_cpu_offset(,%rdi,8), %rax;"
 809 "cmpb   $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);"
 810 "setne  %al;"
 811 ASM_RET
 812 ".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;"
 813 ".popsection");
 814
 815 #endif
 816
 817 static void __init kvm_guest_init(void)
 818 {
 819         int i;
 820
 821         paravirt_ops_setup();
 822         register_reboot_notifier(&kvm_pv_reboot_nb);
 823         for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
 824                 raw_spin_lock_init(&async_pf_sleepers[i].lock);
 825
 826         if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
 827                 has_steal_clock = 1;
 828                 static_call_update(pv_steal_clock, kvm_steal_clock);
 829
 830                 pv_ops.lock.vcpu_is_preempted =
 831                         PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
 832         }
 833
 834         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
 835                 apic_set_eoi_write(kvm_guest_apic_eoi_write);
 836
 837         if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
 838                 static_branch_enable(&kvm_async_pf_enabled);
 839                 alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_kvm_asyncpf_interrupt);
 840         }
 841
 842 #ifdef CONFIG_SMP
 843         if (pv_tlb_flush_supported()) {
 844                 pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi;
 845                 pv_ops.mmu.tlb_remove_table = tlb_remove_table;
 846                 pr_info("KVM setup pv remote TLB flush\n");
 847         }
 848
 849         smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
 850         if (pv_sched_yield_supported()) {
 851                 smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi;
 852                 pr_info("setup PV sched yield\n");
 853         }
 854         if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
 855                                       kvm_cpu_online, kvm_cpu_down_prepare) < 0)
 856                 pr_err("failed to install cpu hotplug callbacks\n");
 857 #else
 858         sev_map_percpu_data();
 859         kvm_guest_cpu_init();
 860 #endif
 861
 862 #ifdef CONFIG_KEXEC_CORE
 863         machine_ops.crash_shutdown = kvm_crash_shutdown;
 864 #endif
 865
 866         register_syscore_ops(&kvm_syscore_ops);
 867
 868         /*
 869          * Hard lockup detection is enabled by default. Disable it, as guests
 870          * can get false positives too easily, for example if the host is
 871          * overcommitted.
 872          */
 873         hardlockup_detector_disable();
 874 }
 875
 876 static noinline uint32_t __kvm_cpuid_base(void)
 877 {
 878         if (boot_cpu_data.cpuid_level < 0)
 879                 return 0;       /* So we don't blow up on old processors */
 880
 881         if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
 882                 return hypervisor_cpuid_base(KVM_SIGNATURE, 0);
 883
 884         return 0;
 885 }
 886
 887 static inline uint32_t kvm_cpuid_base(void)
 888 {
 889         static int kvm_cpuid_base = -1;
 890
 891         if (kvm_cpuid_base == -1)
 892                 kvm_cpuid_base = __kvm_cpuid_base();
 893
 894         return kvm_cpuid_base;
 895 }
 896
 897 bool kvm_para_available(void)
 898 {
 899         return kvm_cpuid_base() != 0;
 900 }
 901 EXPORT_SYMBOL_GPL(kvm_para_available);
 902
 903 unsigned int kvm_arch_para_features(void)
 904 {
 905         return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
 906 }
 907
 908 unsigned int kvm_arch_para_hints(void)
 909 {
 910         return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
 911 }
 912 EXPORT_SYMBOL_GPL(kvm_arch_para_hints);
 913
 914 static uint32_t __init kvm_detect(void)
 915 {
 916         return kvm_cpuid_base();
 917 }
 918
 919 static void __init kvm_apic_init(void)
 920 {
 921 #ifdef CONFIG_SMP
 922         if (pv_ipi_supported())
 923                 kvm_setup_pv_ipi();
 924 #endif
 925 }
 926
 927 static bool __init kvm_msi_ext_dest_id(void)
 928 {
 929         return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID);
 930 }
 931
 932 static void kvm_sev_hc_page_enc_status(unsigned long pfn, int npages, bool enc)
 933 {
 934         kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, pfn << PAGE_SHIFT, npages,
 935                            KVM_MAP_GPA_RANGE_ENC_STAT(enc) | KVM_MAP_GPA_RANGE_PAGE_SZ_4K);
 936 }
 937
 938 static void __init kvm_init_platform(void)
 939 {
 940         if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) &&
 941             kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) {
 942                 unsigned long nr_pages;
 943                 int i;
 944
 945                 pv_ops.mmu.notify_page_enc_status_changed =
 946                         kvm_sev_hc_page_enc_status;
 947
 948                 /*
 949                  * Reset the host's shared pages list related to kernel
 950                  * specific page encryption status settings before we load a
 951                  * new kernel by kexec. Reset the page encryption status
 952                  * during early boot intead of just before kexec to avoid SMP
 953                  * races during kvm_pv_guest_cpu_reboot().
 954                  * NOTE: We cannot reset the complete shared pages list
 955                  * here as we need to retain the UEFI/OVMF firmware
 956                  * specific settings.
 957                  */
 958
 959                 for (i = 0; i < e820_table->nr_entries; i++) {
 960                         struct e820_entry *entry = &e820_table->entries[i];
 961
 962                         if (entry->type != E820_TYPE_RAM)
 963                                 continue;
 964
 965                         nr_pages = DIV_ROUND_UP(entry->size, PAGE_SIZE);
 966
 967                         kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, entry->addr,
 968                                        nr_pages,
 969                                        KVM_MAP_GPA_RANGE_ENCRYPTED | KVM_MAP_GPA_RANGE_PAGE_SZ_4K);
 970                 }
 971
 972                 /*
 973                  * Ensure that _bss_decrypted section is marked as decrypted in the
 974                  * shared pages list.
 975                  */
 976                 nr_pages = DIV_ROUND_UP(__end_bss_decrypted - __start_bss_decrypted,
 977                                         PAGE_SIZE);
 978                 early_set_mem_enc_dec_hypercall((unsigned long)__start_bss_decrypted,
 979                                                 nr_pages, 0);
 980
 981                 /*
 982                  * If not booted using EFI, enable Live migration support.
 983                  */
 984                 if (!efi_enabled(EFI_BOOT))
 985                         wrmsrl(MSR_KVM_MIGRATION_CONTROL,
 986                                KVM_MIGRATION_READY);
 987         }
 988         kvmclock_init();
 989         x86_platform.apic_post_init = kvm_apic_init;
 990 }
 991
 992 #if defined(CONFIG_AMD_MEM_ENCRYPT)
 993 static void kvm_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs)
 994 {
 995         /* RAX and CPL are already in the GHCB */
 996         ghcb_set_rbx(ghcb, regs->bx);
 997         ghcb_set_rcx(ghcb, regs->cx);
 998         ghcb_set_rdx(ghcb, regs->dx);
 999         ghcb_set_rsi(ghcb, regs->si);
1000 }
1001
1002 static bool kvm_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs)
1003 {
1004         /* No checking of the return state needed */
1005         return true;
1006 }
1007 #endif
1008
1009 const __initconst struct hypervisor_x86 x86_hyper_kvm = {
1010         .name                           = "KVM",
1011         .detect                         = kvm_detect,
1012         .type                           = X86_HYPER_KVM,
1013         .init.guest_late_init           = kvm_guest_init,
1014         .init.x2apic_available          = kvm_para_available,
1015         .init.msi_ext_dest_id           = kvm_msi_ext_dest_id,
1016         .init.init_platform             = kvm_init_platform,
1017 #if defined(CONFIG_AMD_MEM_ENCRYPT)
1018         .runtime.sev_es_hcall_prepare   = kvm_sev_es_hcall_prepare,
1019         .runtime.sev_es_hcall_finish    = kvm_sev_es_hcall_finish,
1020 #endif
1021 };
1022
1023 static __init int activate_jump_labels(void)
1024 {
1025         if (has_steal_clock) {
1026                 static_key_slow_inc(&paravirt_steal_enabled);
1027                 if (steal_acc)
1028                         static_key_slow_inc(&paravirt_steal_rq_enabled);
1029         }
1030
1031         return 0;
1032 }
1033 arch_initcall(activate_jump_labels);
1034
1035 #ifdef CONFIG_PARAVIRT_SPINLOCKS
1036
1037 /* Kick a cpu by its apicid. Used to wake up a halted vcpu */
1038 static void kvm_kick_cpu(int cpu)
1039 {
1040         int apicid;
1041         unsigned long flags = 0;
1042
1043         apicid = per_cpu(x86_cpu_to_apicid, cpu);
1044         kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
1045 }
1046
1047 #include <asm/qspinlock.h>
1048
1049 static void kvm_wait(u8 *ptr, u8 val)
1050 {
1051         if (in_nmi())
1052                 return;
1053
1054         /*
1055          * halt until it's our turn and kicked. Note that we do safe halt
1056          * for irq enabled case to avoid hang when lock info is overwritten
1057          * in irq spinlock slowpath and no spurious interrupt occur to save us.
1058          */
1059         if (irqs_disabled()) {
1060                 if (READ_ONCE(*ptr) == val)
1061                         halt();
1062         } else {
1063                 local_irq_disable();
1064
1065                 /* safe_halt() will enable IRQ */
1066                 if (READ_ONCE(*ptr) == val)
1067                         safe_halt();
1068                 else
1069                         local_irq_enable();
1070         }
1071 }
1072
1073 /*
1074  * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
1075  */
1076 void __init kvm_spinlock_init(void)
1077 {
1078         /*
1079          * In case host doesn't support KVM_FEATURE_PV_UNHALT there is still an
1080          * advantage of keeping virt_spin_lock_key enabled: virt_spin_lock() is
1081          * preferred over native qspinlock when vCPU is preempted.
1082          */
1083         if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) {
1084                 pr_info("PV spinlocks disabled, no host support\n");
1085                 return;
1086         }
1087
1088         /*
1089          * Disable PV spinlocks and use native qspinlock when dedicated pCPUs
1090          * are available.
1091          */
1092         if (kvm_para_has_hint(KVM_HINTS_REALTIME)) {
1093                 pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n");
1094                 goto out;
1095         }
1096
1097         if (num_possible_cpus() == 1) {
1098                 pr_info("PV spinlocks disabled, single CPU\n");
1099                 goto out;
1100         }
1101
1102         if (nopvspin) {
1103                 pr_info("PV spinlocks disabled, forced by \"nopvspin\" parameter\n");
1104                 goto out;
1105         }
1106
1107         pr_info("PV spinlocks enabled\n");
1108
1109         __pv_init_lock_hash();
1110         pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
1111         pv_ops.lock.queued_spin_unlock =
1112                 PV_CALLEE_SAVE(__pv_queued_spin_unlock);
1113         pv_ops.lock.wait = kvm_wait;
1114         pv_ops.lock.kick = kvm_kick_cpu;
1115
1116         /*
1117          * When PV spinlock is enabled which is preferred over
1118          * virt_spin_lock(), virt_spin_lock_key's value is meaningless.
1119          * Just disable it anyway.
1120          */
1121 out:
1122         static_branch_disable(&virt_spin_lock_key);
1123 }
1124
1125 #endif  /* CONFIG_PARAVIRT_SPINLOCKS */
1126
1127 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
1128
1129 static void kvm_disable_host_haltpoll(void *i)
1130 {
1131         wrmsrl(MSR_KVM_POLL_CONTROL, 0);
1132 }
1133
1134 static void kvm_enable_host_haltpoll(void *i)
1135 {
1136         wrmsrl(MSR_KVM_POLL_CONTROL, 1);
1137 }
1138
1139 void arch_haltpoll_enable(unsigned int cpu)
1140 {
1141         if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {
1142                 pr_err_once("host does not support poll control\n");
1143                 pr_err_once("host upgrade recommended\n");
1144                 return;
1145         }
1146
1147         /* Enable guest halt poll disables host halt poll */
1148         smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1);
1149 }
1150 EXPORT_SYMBOL_GPL(arch_haltpoll_enable);
1151
1152 void arch_haltpoll_disable(unsigned int cpu)
1153 {
1154         if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
1155                 return;
1156
1157         /* Disable guest halt poll enables host halt poll */
1158         smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1);
1159 }
1160 EXPORT_SYMBOL_GPL(arch_haltpoll_disable);
1161 #endif