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 /*
  73  * No need for any "IO delay" on KVM
  74  */
  75 static void kvm_io_delay(void)
  76 {
  77 }
  78
  79 #define KVM_TASK_SLEEP_HASHBITS 8
  80 #define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
  81
  82 struct kvm_task_sleep_node {
  83         struct hlist_node link;
  84         struct swait_queue_head wq;
  85         u32 token;
  86         int cpu;
  87 };
  88
  89 static struct kvm_task_sleep_head {
  90         raw_spinlock_t lock;
  91         struct hlist_head list;
  92 } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
  93
  94 static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
  95                                                   u32 token)
  96 {
  97         struct hlist_node *p;
  98
  99         hlist_for_each(p, &b->list) {
 100                 struct kvm_task_sleep_node *n =
 101                         hlist_entry(p, typeof(*n), link);
 102                 if (n->token == token)
 103                         return n;
 104         }
 105
 106         return NULL;
 107 }
 108
 109 static bool kvm_async_pf_queue_task(u32 token, struct kvm_task_sleep_node *n)
 110 {
 111         u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
 112         struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
 113         struct kvm_task_sleep_node *e;
 114
 115         raw_spin_lock(&b->lock);
 116         e = _find_apf_task(b, token);
 117         if (e) {
 118                 /* dummy entry exist -> wake up was delivered ahead of PF */
 119                 hlist_del(&e->link);
 120                 raw_spin_unlock(&b->lock);
 121                 kfree(e);
 122                 return false;
 123         }
 124
 125         n->token = token;
 126         n->cpu = smp_processor_id();
 127         init_swait_queue_head(&n->wq);
 128         hlist_add_head(&n->link, &b->list);
 129         raw_spin_unlock(&b->lock);
 130         return true;
 131 }
 132
 133 /*
 134  * kvm_async_pf_task_wait_schedule - Wait for pagefault to be handled
 135  * @token:      Token to identify the sleep node entry
 136  *
 137  * Invoked from the async pagefault handling code or from the VM exit page
 138  * fault handler. In both cases RCU is watching.
 139  */
 140 void kvm_async_pf_task_wait_schedule(u32 token)
 141 {
 142         struct kvm_task_sleep_node n;
 143         DECLARE_SWAITQUEUE(wait);
 144
 145         lockdep_assert_irqs_disabled();
 146
 147         if (!kvm_async_pf_queue_task(token, &n))
 148                 return;
 149
 150         for (;;) {
 151                 prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
 152                 if (hlist_unhashed(&n.link))
 153                         break;
 154
 155                 local_irq_enable();
 156                 schedule();
 157                 local_irq_disable();
 158         }
 159         finish_swait(&n.wq, &wait);
 160 }
 161 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait_schedule);
 162
 163 static void apf_task_wake_one(struct kvm_task_sleep_node *n)
 164 {
 165         hlist_del_init(&n->link);
 166         if (swq_has_sleeper(&n->wq))
 167                 swake_up_one(&n->wq);
 168 }
 169
 170 static void apf_task_wake_all(void)
 171 {
 172         int i;
 173
 174         for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
 175                 struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
 176                 struct kvm_task_sleep_node *n;
 177                 struct hlist_node *p, *next;
 178
 179                 raw_spin_lock(&b->lock);
 180                 hlist_for_each_safe(p, next, &b->list) {
 181                         n = hlist_entry(p, typeof(*n), link);
 182                         if (n->cpu == smp_processor_id())
 183                                 apf_task_wake_one(n);
 184                 }
 185                 raw_spin_unlock(&b->lock);
 186         }
 187 }
 188
 189 void kvm_async_pf_task_wake(u32 token)
 190 {
 191         u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
 192         struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
 193         struct kvm_task_sleep_node *n;
 194
 195         if (token == ~0) {
 196                 apf_task_wake_all();
 197                 return;
 198         }
 199
 200 again:
 201         raw_spin_lock(&b->lock);
 202         n = _find_apf_task(b, token);
 203         if (!n) {
 204                 /*
 205                  * async PF was not yet handled.
 206                  * Add dummy entry for the token.
 207                  */
 208                 n = kzalloc(sizeof(*n), GFP_ATOMIC);
 209                 if (!n) {
 210                         /*
 211                          * Allocation failed! Busy wait while other cpu
 212                          * handles async PF.
 213                          */
 214                         raw_spin_unlock(&b->lock);
 215                         cpu_relax();
 216                         goto again;
 217                 }
 218                 n->token = token;
 219                 n->cpu = smp_processor_id();
 220                 init_swait_queue_head(&n->wq);
 221                 hlist_add_head(&n->link, &b->list);
 222         } else {
 223                 apf_task_wake_one(n);
 224         }
 225         raw_spin_unlock(&b->lock);
 226         return;
 227 }
 228 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
 229
 230 noinstr u32 kvm_read_and_reset_apf_flags(void)
 231 {
 232         u32 flags = 0;
 233
 234         if (__this_cpu_read(apf_reason.enabled)) {
 235                 flags = __this_cpu_read(apf_reason.flags);
 236                 __this_cpu_write(apf_reason.flags, 0);
 237         }
 238
 239         return flags;
 240 }
 241 EXPORT_SYMBOL_GPL(kvm_read_and_reset_apf_flags);
 242
 243 noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token)
 244 {
 245         u32 flags = kvm_read_and_reset_apf_flags();
 246         irqentry_state_t state;
 247
 248         if (!flags)
 249                 return false;
 250
 251         state = irqentry_enter(regs);
 252         instrumentation_begin();
 253
 254         /*
 255          * If the host managed to inject an async #PF into an interrupt
 256          * disabled region, then die hard as this is not going to end well
 257          * and the host side is seriously broken.
 258          */
 259         if (unlikely(!(regs->flags & X86_EFLAGS_IF)))
 260                 panic("Host injected async #PF in interrupt disabled region\n");
 261
 262         if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) {
 263                 if (unlikely(!(user_mode(regs))))
 264                         panic("Host injected async #PF in kernel mode\n");
 265                 /* Page is swapped out by the host. */
 266                 kvm_async_pf_task_wait_schedule(token);
 267         } else {
 268                 WARN_ONCE(1, "Unexpected async PF flags: %x\n", flags);
 269         }
 270
 271         instrumentation_end();
 272         irqentry_exit(regs, state);
 273         return true;
 274 }
 275
 276 DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)
 277 {
 278         struct pt_regs *old_regs = set_irq_regs(regs);
 279         u32 token;
 280
 281         ack_APIC_irq();
 282
 283         inc_irq_stat(irq_hv_callback_count);
 284
 285         if (__this_cpu_read(apf_reason.enabled)) {
 286                 token = __this_cpu_read(apf_reason.token);
 287                 kvm_async_pf_task_wake(token);
 288                 __this_cpu_write(apf_reason.token, 0);
 289                 wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1);
 290         }
 291
 292         set_irq_regs(old_regs);
 293 }
 294
 295 static void __init paravirt_ops_setup(void)
 296 {
 297         pv_info.name = "KVM";
 298
 299         if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
 300                 pv_ops.cpu.io_delay = kvm_io_delay;
 301
 302 #ifdef CONFIG_X86_IO_APIC
 303         no_timer_check = 1;
 304 #endif
 305 }
 306
 307 static void kvm_register_steal_time(void)
 308 {
 309         int cpu = smp_processor_id();
 310         struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
 311
 312         if (!has_steal_clock)
 313                 return;
 314
 315         wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
 316         pr_debug("stealtime: cpu %d, msr %llx\n", cpu,
 317                 (unsigned long long) slow_virt_to_phys(st));
 318 }
 319
 320 static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
 321
 322 static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val)
 323 {
 324         /**
 325          * This relies on __test_and_clear_bit to modify the memory
 326          * in a way that is atomic with respect to the local CPU.
 327          * The hypervisor only accesses this memory from the local CPU so
 328          * there's no need for lock or memory barriers.
 329          * An optimization barrier is implied in apic write.
 330          */
 331         if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi)))
 332                 return;
 333         apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK);
 334 }
 335
 336 static void kvm_guest_cpu_init(void)
 337 {
 338         if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
 339                 u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
 340
 341                 WARN_ON_ONCE(!static_branch_likely(&kvm_async_pf_enabled));
 342
 343                 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
 344                 pa |= KVM_ASYNC_PF_ENABLED | KVM_ASYNC_PF_DELIVERY_AS_INT;
 345
 346                 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
 347                         pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
 348
 349                 wrmsrl(MSR_KVM_ASYNC_PF_INT, HYPERVISOR_CALLBACK_VECTOR);
 350
 351                 wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
 352                 __this_cpu_write(apf_reason.enabled, 1);
 353                 pr_debug("setup async PF for cpu %d\n", smp_processor_id());
 354         }
 355
 356         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
 357                 unsigned long pa;
 358
 359                 /* Size alignment is implied but just to make it explicit. */
 360                 BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
 361                 __this_cpu_write(kvm_apic_eoi, 0);
 362                 pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
 363                         | KVM_MSR_ENABLED;
 364                 wrmsrl(MSR_KVM_PV_EOI_EN, pa);
 365         }
 366
 367         if (has_steal_clock)
 368                 kvm_register_steal_time();
 369 }
 370
 371 static void kvm_pv_disable_apf(void)
 372 {
 373         if (!__this_cpu_read(apf_reason.enabled))
 374                 return;
 375
 376         wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
 377         __this_cpu_write(apf_reason.enabled, 0);
 378
 379         pr_debug("disable async PF for cpu %d\n", smp_processor_id());
 380 }
 381
 382 static void kvm_disable_steal_time(void)
 383 {
 384         if (!has_steal_clock)
 385                 return;
 386
 387         wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
 388 }
 389
 390 static u64 kvm_steal_clock(int cpu)
 391 {
 392         u64 steal;
 393         struct kvm_steal_time *src;
 394         int version;
 395
 396         src = &per_cpu(steal_time, cpu);
 397         do {
 398                 version = src->version;
 399                 virt_rmb();
 400                 steal = src->steal;
 401                 virt_rmb();
 402         } while ((version & 1) || (version != src->version));
 403
 404         return steal;
 405 }
 406
 407 static inline void __set_percpu_decrypted(void *ptr, unsigned long size)
 408 {
 409         early_set_memory_decrypted((unsigned long) ptr, size);
 410 }
 411
 412 /*
 413  * Iterate through all possible CPUs and map the memory region pointed
 414  * by apf_reason, steal_time and kvm_apic_eoi as decrypted at once.
 415  *
 416  * Note: we iterate through all possible CPUs to ensure that CPUs
 417  * hotplugged will have their per-cpu variable already mapped as
 418  * decrypted.
 419  */
 420 static void __init sev_map_percpu_data(void)
 421 {
 422         int cpu;
 423
 424         if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
 425                 return;
 426
 427         for_each_possible_cpu(cpu) {
 428                 __set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason));
 429                 __set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time));
 430                 __set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi));
 431         }
 432 }
 433
 434 static void kvm_guest_cpu_offline(bool shutdown)
 435 {
 436         kvm_disable_steal_time();
 437         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
 438                 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
 439         if (kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL))
 440                 wrmsrl(MSR_KVM_MIGRATION_CONTROL, 0);
 441         kvm_pv_disable_apf();
 442         if (!shutdown)
 443                 apf_task_wake_all();
 444         kvmclock_disable();
 445 }
 446
 447 static int kvm_cpu_online(unsigned int cpu)
 448 {
 449         unsigned long flags;
 450
 451         local_irq_save(flags);
 452         kvm_guest_cpu_init();
 453         local_irq_restore(flags);
 454         return 0;
 455 }
 456
 457 #ifdef CONFIG_SMP
 458
 459 static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask);
 460
 461 static bool pv_tlb_flush_supported(void)
 462 {
 463         return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
 464                 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
 465                 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&
 466                 !boot_cpu_has(X86_FEATURE_MWAIT) &&
 467                 (num_possible_cpus() != 1));
 468 }
 469
 470 static bool pv_ipi_supported(void)
 471 {
 472         return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) &&
 473                (num_possible_cpus() != 1));
 474 }
 475
 476 static bool pv_sched_yield_supported(void)
 477 {
 478         return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&
 479                 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
 480             kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&
 481             !boot_cpu_has(X86_FEATURE_MWAIT) &&
 482             (num_possible_cpus() != 1));
 483 }
 484
 485 #define KVM_IPI_CLUSTER_SIZE    (2 * BITS_PER_LONG)
 486
 487 static void __send_ipi_mask(const struct cpumask *mask, int vector)
 488 {
 489         unsigned long flags;
 490         int cpu, apic_id, icr;
 491         int min = 0, max = 0;
 492 #ifdef CONFIG_X86_64
 493         __uint128_t ipi_bitmap = 0;
 494 #else
 495         u64 ipi_bitmap = 0;
 496 #endif
 497         long ret;
 498
 499         if (cpumask_empty(mask))
 500                 return;
 501
 502         local_irq_save(flags);
 503
 504         switch (vector) {
 505         default:
 506                 icr = APIC_DM_FIXED | vector;
 507                 break;
 508         case NMI_VECTOR:
 509                 icr = APIC_DM_NMI;
 510                 break;
 511         }
 512
 513         for_each_cpu(cpu, mask) {
 514                 apic_id = per_cpu(x86_cpu_to_apicid, cpu);
 515                 if (!ipi_bitmap) {
 516                         min = max = apic_id;
 517                 } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) {
 518                         ipi_bitmap <<= min - apic_id;
 519                         min = apic_id;
 520                 } else if (apic_id > min && apic_id < min + KVM_IPI_CLUSTER_SIZE) {
 521                         max = apic_id < max ? max : apic_id;
 522                 } else {
 523                         ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
 524                                 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
 525                         WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
 526                                   ret);
 527                         min = max = apic_id;
 528                         ipi_bitmap = 0;
 529                 }
 530                 __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap);
 531         }
 532
 533         if (ipi_bitmap) {
 534                 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
 535                         (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
 536                 WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
 537                           ret);
 538         }
 539
 540         local_irq_restore(flags);
 541 }
 542
 543 static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
 544 {
 545         __send_ipi_mask(mask, vector);
 546 }
 547
 548 static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
 549 {
 550         unsigned int this_cpu = smp_processor_id();
 551         struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
 552         const struct cpumask *local_mask;
 553
 554         cpumask_copy(new_mask, mask);
 555         cpumask_clear_cpu(this_cpu, new_mask);
 556         local_mask = new_mask;
 557         __send_ipi_mask(local_mask, vector);
 558 }
 559
 560 static int __init setup_efi_kvm_sev_migration(void)
 561 {
 562         efi_char16_t efi_sev_live_migration_enabled[] = L"SevLiveMigrationEnabled";
 563         efi_guid_t efi_variable_guid = AMD_SEV_MEM_ENCRYPT_GUID;
 564         efi_status_t status;
 565         unsigned long size;
 566         bool enabled;
 567
 568         if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) ||
 569             !kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL))
 570                 return 0;
 571
 572         if (!efi_enabled(EFI_BOOT))
 573                 return 0;
 574
 575         if (!efi_enabled(EFI_RUNTIME_SERVICES)) {
 576                 pr_info("%s : EFI runtime services are not enabled\n", __func__);
 577                 return 0;
 578         }
 579
 580         size = sizeof(enabled);
 581
 582         /* Get variable contents into buffer */
 583         status = efi.get_variable(efi_sev_live_migration_enabled,
 584                                   &efi_variable_guid, NULL, &size, &enabled);
 585
 586         if (status == EFI_NOT_FOUND) {
 587                 pr_info("%s : EFI live migration variable not found\n", __func__);
 588                 return 0;
 589         }
 590
 591         if (status != EFI_SUCCESS) {
 592                 pr_info("%s : EFI variable retrieval failed\n", __func__);
 593                 return 0;
 594         }
 595
 596         if (enabled == 0) {
 597                 pr_info("%s: live migration disabled in EFI\n", __func__);
 598                 return 0;
 599         }
 600
 601         pr_info("%s : live migration enabled in EFI\n", __func__);
 602         wrmsrl(MSR_KVM_MIGRATION_CONTROL, KVM_MIGRATION_READY);
 603
 604         return 1;
 605 }
 606
 607 late_initcall(setup_efi_kvm_sev_migration);
 608
 609 /*
 610  * Set the IPI entry points
 611  */
 612 static void kvm_setup_pv_ipi(void)
 613 {
 614         apic->send_IPI_mask = kvm_send_ipi_mask;
 615         apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
 616         pr_info("setup PV IPIs\n");
 617 }
 618
 619 static void kvm_smp_send_call_func_ipi(const struct cpumask *mask)
 620 {
 621         int cpu;
 622
 623         native_send_call_func_ipi(mask);
 624
 625         /* Make sure other vCPUs get a chance to run if they need to. */
 626         for_each_cpu(cpu, mask) {
 627                 if (!idle_cpu(cpu) && vcpu_is_preempted(cpu)) {
 628                         kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu));
 629                         break;
 630                 }
 631         }
 632 }
 633
 634 static void kvm_flush_tlb_multi(const struct cpumask *cpumask,
 635                         const struct flush_tlb_info *info)
 636 {
 637         u8 state;
 638         int cpu;
 639         struct kvm_steal_time *src;
 640         struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
 641
 642         cpumask_copy(flushmask, cpumask);
 643         /*
 644          * We have to call flush only on online vCPUs. And
 645          * queue flush_on_enter for pre-empted vCPUs
 646          */
 647         for_each_cpu(cpu, flushmask) {
 648                 /*
 649                  * The local vCPU is never preempted, so we do not explicitly
 650                  * skip check for local vCPU - it will never be cleared from
 651                  * flushmask.
 652                  */
 653                 src = &per_cpu(steal_time, cpu);
 654                 state = READ_ONCE(src->preempted);
 655                 if ((state & KVM_VCPU_PREEMPTED)) {
 656                         if (try_cmpxchg(&src->preempted, &state,
 657                                         state | KVM_VCPU_FLUSH_TLB))
 658                                 __cpumask_clear_cpu(cpu, flushmask);
 659                 }
 660         }
 661
 662         native_flush_tlb_multi(flushmask, info);
 663 }
 664
 665 static __init int kvm_alloc_cpumask(void)
 666 {
 667         int cpu;
 668
 669         if (!kvm_para_available() || nopv)
 670                 return 0;
 671
 672         if (pv_tlb_flush_supported() || pv_ipi_supported())
 673                 for_each_possible_cpu(cpu) {
 674                         zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu),
 675                                 GFP_KERNEL, cpu_to_node(cpu));
 676                 }
 677
 678         return 0;
 679 }
 680 arch_initcall(kvm_alloc_cpumask);
 681
 682 static void __init kvm_smp_prepare_boot_cpu(void)
 683 {
 684         /*
 685          * Map the per-cpu variables as decrypted before kvm_guest_cpu_init()
 686          * shares the guest physical address with the hypervisor.
 687          */
 688         sev_map_percpu_data();
 689
 690         kvm_guest_cpu_init();
 691         native_smp_prepare_boot_cpu();
 692         kvm_spinlock_init();
 693 }
 694
 695 static int kvm_cpu_down_prepare(unsigned int cpu)
 696 {
 697         unsigned long flags;
 698
 699         local_irq_save(flags);
 700         kvm_guest_cpu_offline(false);
 701         local_irq_restore(flags);
 702         return 0;
 703 }
 704
 705 #endif
 706
 707 static int kvm_suspend(void)
 708 {
 709         kvm_guest_cpu_offline(false);
 710
 711         return 0;
 712 }
 713
 714 static void kvm_resume(void)
 715 {
 716         kvm_cpu_online(raw_smp_processor_id());
 717 }
 718
 719 static struct syscore_ops kvm_syscore_ops = {
 720         .suspend        = kvm_suspend,
 721         .resume         = kvm_resume,
 722 };
 723
 724 static void kvm_pv_guest_cpu_reboot(void *unused)
 725 {
 726         kvm_guest_cpu_offline(true);
 727 }
 728
 729 static int kvm_pv_reboot_notify(struct notifier_block *nb,
 730                                 unsigned long code, void *unused)
 731 {
 732         if (code == SYS_RESTART)
 733                 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
 734         return NOTIFY_DONE;
 735 }
 736
 737 static struct notifier_block kvm_pv_reboot_nb = {
 738         .notifier_call = kvm_pv_reboot_notify,
 739 };
 740
 741 /*
 742  * After a PV feature is registered, the host will keep writing to the
 743  * registered memory location. If the guest happens to shutdown, this memory
 744  * won't be valid. In cases like kexec, in which you install a new kernel, this
 745  * means a random memory location will be kept being written.
 746  */
 747 #ifdef CONFIG_KEXEC_CORE
 748 static void kvm_crash_shutdown(struct pt_regs *regs)
 749 {
 750         kvm_guest_cpu_offline(true);
 751         native_machine_crash_shutdown(regs);
 752 }
 753 #endif
 754
 755 #if defined(CONFIG_X86_32) || !defined(CONFIG_SMP)
 756 bool __kvm_vcpu_is_preempted(long cpu);
 757
 758 __visible bool __kvm_vcpu_is_preempted(long cpu)
 759 {
 760         struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
 761
 762         return !!(src->preempted & KVM_VCPU_PREEMPTED);
 763 }
 764 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
 765
 766 #else
 767
 768 #include <asm/asm-offsets.h>
 769
 770 extern bool __raw_callee_save___kvm_vcpu_is_preempted(long);
 771
 772 /*
 773  * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and
 774  * restoring to/from the stack.
 775  */
 776 asm(
 777 ".pushsection .text;"
 778 ".global __raw_callee_save___kvm_vcpu_is_preempted;"
 779 ".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"
 780 "__raw_callee_save___kvm_vcpu_is_preempted:"
 781 ASM_ENDBR
 782 "movq   __per_cpu_offset(,%rdi,8), %rax;"
 783 "cmpb   $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);"
 784 "setne  %al;"
 785 ASM_RET
 786 ".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;"
 787 ".popsection");
 788
 789 #endif
 790
 791 static void __init kvm_guest_init(void)
 792 {
 793         int i;
 794
 795         paravirt_ops_setup();
 796         register_reboot_notifier(&kvm_pv_reboot_nb);
 797         for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
 798                 raw_spin_lock_init(&async_pf_sleepers[i].lock);
 799
 800         if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
 801                 has_steal_clock = 1;
 802                 static_call_update(pv_steal_clock, kvm_steal_clock);
 803
 804                 pv_ops.lock.vcpu_is_preempted =
 805                         PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
 806         }
 807
 808         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
 809                 apic_set_eoi_write(kvm_guest_apic_eoi_write);
 810
 811         if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
 812                 static_branch_enable(&kvm_async_pf_enabled);
 813                 alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_kvm_asyncpf_interrupt);
 814         }
 815
 816 #ifdef CONFIG_SMP
 817         if (pv_tlb_flush_supported()) {
 818                 pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi;
 819                 pv_ops.mmu.tlb_remove_table = tlb_remove_table;
 820                 pr_info("KVM setup pv remote TLB flush\n");
 821         }
 822
 823         smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
 824         if (pv_sched_yield_supported()) {
 825                 smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi;
 826                 pr_info("setup PV sched yield\n");
 827         }
 828         if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
 829                                       kvm_cpu_online, kvm_cpu_down_prepare) < 0)
 830                 pr_err("failed to install cpu hotplug callbacks\n");
 831 #else
 832         sev_map_percpu_data();
 833         kvm_guest_cpu_init();
 834 #endif
 835
 836 #ifdef CONFIG_KEXEC_CORE
 837         machine_ops.crash_shutdown = kvm_crash_shutdown;
 838 #endif
 839
 840         register_syscore_ops(&kvm_syscore_ops);
 841
 842         /*
 843          * Hard lockup detection is enabled by default. Disable it, as guests
 844          * can get false positives too easily, for example if the host is
 845          * overcommitted.
 846          */
 847         hardlockup_detector_disable();
 848 }
 849
 850 static noinline uint32_t __kvm_cpuid_base(void)
 851 {
 852         if (boot_cpu_data.cpuid_level < 0)
 853                 return 0;       /* So we don't blow up on old processors */
 854
 855         if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
 856                 return hypervisor_cpuid_base(KVM_SIGNATURE, 0);
 857
 858         return 0;
 859 }
 860
 861 static inline uint32_t kvm_cpuid_base(void)
 862 {
 863         static int kvm_cpuid_base = -1;
 864
 865         if (kvm_cpuid_base == -1)
 866                 kvm_cpuid_base = __kvm_cpuid_base();
 867
 868         return kvm_cpuid_base;
 869 }
 870
 871 bool kvm_para_available(void)
 872 {
 873         return kvm_cpuid_base() != 0;
 874 }
 875 EXPORT_SYMBOL_GPL(kvm_para_available);
 876
 877 unsigned int kvm_arch_para_features(void)
 878 {
 879         return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
 880 }
 881
 882 unsigned int kvm_arch_para_hints(void)
 883 {
 884         return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
 885 }
 886 EXPORT_SYMBOL_GPL(kvm_arch_para_hints);
 887
 888 static uint32_t __init kvm_detect(void)
 889 {
 890         return kvm_cpuid_base();
 891 }
 892
 893 static void __init kvm_apic_init(void)
 894 {
 895 #ifdef CONFIG_SMP
 896         if (pv_ipi_supported())
 897                 kvm_setup_pv_ipi();
 898 #endif
 899 }
 900
 901 static bool __init kvm_msi_ext_dest_id(void)
 902 {
 903         return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID);
 904 }
 905
 906 static void kvm_sev_hc_page_enc_status(unsigned long pfn, int npages, bool enc)
 907 {
 908         kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, pfn << PAGE_SHIFT, npages,
 909                            KVM_MAP_GPA_RANGE_ENC_STAT(enc) | KVM_MAP_GPA_RANGE_PAGE_SZ_4K);
 910 }
 911
 912 static void __init kvm_init_platform(void)
 913 {
 914         if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) &&
 915             kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) {
 916                 unsigned long nr_pages;
 917                 int i;
 918
 919                 pv_ops.mmu.notify_page_enc_status_changed =
 920                         kvm_sev_hc_page_enc_status;
 921
 922                 /*
 923                  * Reset the host's shared pages list related to kernel
 924                  * specific page encryption status settings before we load a
 925                  * new kernel by kexec. Reset the page encryption status
 926                  * during early boot intead of just before kexec to avoid SMP
 927                  * races during kvm_pv_guest_cpu_reboot().
 928                  * NOTE: We cannot reset the complete shared pages list
 929                  * here as we need to retain the UEFI/OVMF firmware
 930                  * specific settings.
 931                  */
 932
 933                 for (i = 0; i < e820_table->nr_entries; i++) {
 934                         struct e820_entry *entry = &e820_table->entries[i];
 935
 936                         if (entry->type != E820_TYPE_RAM)
 937                                 continue;
 938
 939                         nr_pages = DIV_ROUND_UP(entry->size, PAGE_SIZE);
 940
 941                         kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, entry->addr,
 942                                        nr_pages,
 943                                        KVM_MAP_GPA_RANGE_ENCRYPTED | KVM_MAP_GPA_RANGE_PAGE_SZ_4K);
 944                 }
 945
 946                 /*
 947                  * Ensure that _bss_decrypted section is marked as decrypted in the
 948                  * shared pages list.
 949                  */
 950                 nr_pages = DIV_ROUND_UP(__end_bss_decrypted - __start_bss_decrypted,
 951                                         PAGE_SIZE);
 952                 early_set_mem_enc_dec_hypercall((unsigned long)__start_bss_decrypted,
 953                                                 nr_pages, 0);
 954
 955                 /*
 956                  * If not booted using EFI, enable Live migration support.
 957                  */
 958                 if (!efi_enabled(EFI_BOOT))
 959                         wrmsrl(MSR_KVM_MIGRATION_CONTROL,
 960                                KVM_MIGRATION_READY);
 961         }
 962         kvmclock_init();
 963         x86_platform.apic_post_init = kvm_apic_init;
 964 }
 965
 966 #if defined(CONFIG_AMD_MEM_ENCRYPT)
 967 static void kvm_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs)
 968 {
 969         /* RAX and CPL are already in the GHCB */
 970         ghcb_set_rbx(ghcb, regs->bx);
 971         ghcb_set_rcx(ghcb, regs->cx);
 972         ghcb_set_rdx(ghcb, regs->dx);
 973         ghcb_set_rsi(ghcb, regs->si);
 974 }
 975
 976 static bool kvm_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs)
 977 {
 978         /* No checking of the return state needed */
 979         return true;
 980 }
 981 #endif
 982
 983 const __initconst struct hypervisor_x86 x86_hyper_kvm = {
 984         .name                           = "KVM",
 985         .detect                         = kvm_detect,
 986         .type                           = X86_HYPER_KVM,
 987         .init.guest_late_init           = kvm_guest_init,
 988         .init.x2apic_available          = kvm_para_available,
 989         .init.msi_ext_dest_id           = kvm_msi_ext_dest_id,
 990         .init.init_platform             = kvm_init_platform,
 991 #if defined(CONFIG_AMD_MEM_ENCRYPT)
 992         .runtime.sev_es_hcall_prepare   = kvm_sev_es_hcall_prepare,
 993         .runtime.sev_es_hcall_finish    = kvm_sev_es_hcall_finish,
 994 #endif
 995 };
 996
 997 static __init int activate_jump_labels(void)
 998 {
 999         if (has_steal_clock) {
1000                 static_key_slow_inc(&paravirt_steal_enabled);
1001                 if (steal_acc)
1002                         static_key_slow_inc(&paravirt_steal_rq_enabled);
1003         }
1004
1005         return 0;
1006 }
1007 arch_initcall(activate_jump_labels);
1008
1009 #ifdef CONFIG_PARAVIRT_SPINLOCKS
1010
1011 /* Kick a cpu by its apicid. Used to wake up a halted vcpu */
1012 static void kvm_kick_cpu(int cpu)
1013 {
1014         int apicid;
1015         unsigned long flags = 0;
1016
1017         apicid = per_cpu(x86_cpu_to_apicid, cpu);
1018         kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
1019 }
1020
1021 #include <asm/qspinlock.h>
1022
1023 static void kvm_wait(u8 *ptr, u8 val)
1024 {
1025         if (in_nmi())
1026                 return;
1027
1028         /*
1029          * halt until it's our turn and kicked. Note that we do safe halt
1030          * for irq enabled case to avoid hang when lock info is overwritten
1031          * in irq spinlock slowpath and no spurious interrupt occur to save us.
1032          */
1033         if (irqs_disabled()) {
1034                 if (READ_ONCE(*ptr) == val)
1035                         halt();
1036         } else {
1037                 local_irq_disable();
1038
1039                 /* safe_halt() will enable IRQ */
1040                 if (READ_ONCE(*ptr) == val)
1041                         safe_halt();
1042                 else
1043                         local_irq_enable();
1044         }
1045 }
1046
1047 /*
1048  * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
1049  */
1050 void __init kvm_spinlock_init(void)
1051 {
1052         /*
1053          * In case host doesn't support KVM_FEATURE_PV_UNHALT there is still an
1054          * advantage of keeping virt_spin_lock_key enabled: virt_spin_lock() is
1055          * preferred over native qspinlock when vCPU is preempted.
1056          */
1057         if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) {
1058                 pr_info("PV spinlocks disabled, no host support\n");
1059                 return;
1060         }
1061
1062         /*
1063          * Disable PV spinlocks and use native qspinlock when dedicated pCPUs
1064          * are available.
1065          */
1066         if (kvm_para_has_hint(KVM_HINTS_REALTIME)) {
1067                 pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n");
1068                 goto out;
1069         }
1070
1071         if (num_possible_cpus() == 1) {
1072                 pr_info("PV spinlocks disabled, single CPU\n");
1073                 goto out;
1074         }
1075
1076         if (nopvspin) {
1077                 pr_info("PV spinlocks disabled, forced by \"nopvspin\" parameter\n");
1078                 goto out;
1079         }
1080
1081         pr_info("PV spinlocks enabled\n");
1082
1083         __pv_init_lock_hash();
1084         pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
1085         pv_ops.lock.queued_spin_unlock =
1086                 PV_CALLEE_SAVE(__pv_queued_spin_unlock);
1087         pv_ops.lock.wait = kvm_wait;
1088         pv_ops.lock.kick = kvm_kick_cpu;
1089
1090         /*
1091          * When PV spinlock is enabled which is preferred over
1092          * virt_spin_lock(), virt_spin_lock_key's value is meaningless.
1093          * Just disable it anyway.
1094          */
1095 out:
1096         static_branch_disable(&virt_spin_lock_key);
1097 }
1098
1099 #endif  /* CONFIG_PARAVIRT_SPINLOCKS */
1100
1101 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
1102
1103 static void kvm_disable_host_haltpoll(void *i)
1104 {
1105         wrmsrl(MSR_KVM_POLL_CONTROL, 0);
1106 }
1107
1108 static void kvm_enable_host_haltpoll(void *i)
1109 {
1110         wrmsrl(MSR_KVM_POLL_CONTROL, 1);
1111 }
1112
1113 void arch_haltpoll_enable(unsigned int cpu)
1114 {
1115         if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {
1116                 pr_err_once("host does not support poll control\n");
1117                 pr_err_once("host upgrade recommended\n");
1118                 return;
1119         }
1120
1121         /* Enable guest halt poll disables host halt poll */
1122         smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1);
1123 }
1124 EXPORT_SYMBOL_GPL(arch_haltpoll_enable);
1125
1126 void arch_haltpoll_disable(unsigned int cpu)
1127 {
1128         if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
1129                 return;
1130
1131         /* Disable guest halt poll enables host halt poll */
1132         smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1);
1133 }
1134 EXPORT_SYMBOL_GPL(arch_haltpoll_disable);
1135 #endif