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_READ_MOSTLY(bool, async_pf_enabled);
  69 static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
  70 DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64) __visible;
  71 static int has_steal_clock = 0;
  72
  73 static int has_guest_poll = 0;
  74 /*
  75  * No need for any "IO delay" on KVM
  76  */
  77 static void kvm_io_delay(void)
  78 {
  79 }
  80
  81 #define KVM_TASK_SLEEP_HASHBITS 8
  82 #define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
  83
  84 struct kvm_task_sleep_node {
  85         struct hlist_node link;
  86         struct swait_queue_head wq;
  87         u32 token;
  88         int cpu;
  89 };
  90
  91 static struct kvm_task_sleep_head {
  92         raw_spinlock_t lock;
  93         struct hlist_head list;
  94 } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
  95
  96 static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
  97                                                   u32 token)
  98 {
  99         struct hlist_node *p;
 100
 101         hlist_for_each(p, &b->list) {
 102                 struct kvm_task_sleep_node *n =
 103                         hlist_entry(p, typeof(*n), link);
 104                 if (n->token == token)
 105                         return n;
 106         }
 107
 108         return NULL;
 109 }
 110
 111 static bool kvm_async_pf_queue_task(u32 token, struct kvm_task_sleep_node *n)
 112 {
 113         u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
 114         struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
 115         struct kvm_task_sleep_node *e;
 116
 117         raw_spin_lock(&b->lock);
 118         e = _find_apf_task(b, token);
 119         if (e) {
 120                 /* dummy entry exist -> wake up was delivered ahead of PF */
 121                 hlist_del(&e->link);
 122                 raw_spin_unlock(&b->lock);
 123                 kfree(e);
 124                 return false;
 125         }
 126
 127         n->token = token;
 128         n->cpu = smp_processor_id();
 129         init_swait_queue_head(&n->wq);
 130         hlist_add_head(&n->link, &b->list);
 131         raw_spin_unlock(&b->lock);
 132         return true;
 133 }
 134
 135 /*
 136  * kvm_async_pf_task_wait_schedule - Wait for pagefault to be handled
 137  * @token:      Token to identify the sleep node entry
 138  *
 139  * Invoked from the async pagefault handling code or from the VM exit page
 140  * fault handler. In both cases RCU is watching.
 141  */
 142 void kvm_async_pf_task_wait_schedule(u32 token)
 143 {
 144         struct kvm_task_sleep_node n;
 145         DECLARE_SWAITQUEUE(wait);
 146
 147         lockdep_assert_irqs_disabled();
 148
 149         if (!kvm_async_pf_queue_task(token, &n))
 150                 return;
 151
 152         for (;;) {
 153                 prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
 154                 if (hlist_unhashed(&n.link))
 155                         break;
 156
 157                 local_irq_enable();
 158                 schedule();
 159                 local_irq_disable();
 160         }
 161         finish_swait(&n.wq, &wait);
 162 }
 163 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait_schedule);
 164
 165 static void apf_task_wake_one(struct kvm_task_sleep_node *n)
 166 {
 167         hlist_del_init(&n->link);
 168         if (swq_has_sleeper(&n->wq))
 169                 swake_up_one(&n->wq);
 170 }
 171
 172 static void apf_task_wake_all(void)
 173 {
 174         int i;
 175
 176         for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
 177                 struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
 178                 struct kvm_task_sleep_node *n;
 179                 struct hlist_node *p, *next;
 180
 181                 raw_spin_lock(&b->lock);
 182                 hlist_for_each_safe(p, next, &b->list) {
 183                         n = hlist_entry(p, typeof(*n), link);
 184                         if (n->cpu == smp_processor_id())
 185                                 apf_task_wake_one(n);
 186                 }
 187                 raw_spin_unlock(&b->lock);
 188         }
 189 }
 190
 191 void kvm_async_pf_task_wake(u32 token)
 192 {
 193         u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
 194         struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
 195         struct kvm_task_sleep_node *n, *dummy = NULL;
 196
 197         if (token == ~0) {
 198                 apf_task_wake_all();
 199                 return;
 200         }
 201
 202 again:
 203         raw_spin_lock(&b->lock);
 204         n = _find_apf_task(b, token);
 205         if (!n) {
 206                 /*
 207                  * Async #PF not yet handled, add a dummy entry for the token.
 208                  * Allocating the token must be down outside of the raw lock
 209                  * as the allocator is preemptible on PREEMPT_RT kernels.
 210                  */
 211                 if (!dummy) {
 212                         raw_spin_unlock(&b->lock);
 213                         dummy = kzalloc(sizeof(*dummy), GFP_ATOMIC);
 214
 215                         /*
 216                          * Continue looping on allocation failure, eventually
 217                          * the async #PF will be handled and allocating a new
 218                          * node will be unnecessary.
 219                          */
 220                         if (!dummy)
 221                                 cpu_relax();
 222
 223                         /*
 224                          * Recheck for async #PF completion before enqueueing
 225                          * the dummy token to avoid duplicate list entries.
 226                          */
 227                         goto again;
 228                 }
 229                 dummy->token = token;
 230                 dummy->cpu = smp_processor_id();
 231                 init_swait_queue_head(&dummy->wq);
 232                 hlist_add_head(&dummy->link, &b->list);
 233                 dummy = NULL;
 234         } else {
 235                 apf_task_wake_one(n);
 236         }
 237         raw_spin_unlock(&b->lock);
 238
 239         /* A dummy token might be allocated and ultimately not used.  */
 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(async_pf_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         apic_eoi();
 296
 297         inc_irq_stat(irq_hv_callback_count);
 298
 299         if (__this_cpu_read(async_pf_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 __maybe_unused void kvm_guest_apic_eoi_write(void)
 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();
 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;
 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(async_pf_enabled, true);
 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(async_pf_enabled))
 388                 return;
 389
 390         wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
 391         __this_cpu_write(async_pf_enabled, false);
 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_vendor != CC_VENDOR_AMD ||
 439             !cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
 440                 return;
 441
 442         for_each_possible_cpu(cpu) {
 443                 __set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason));
 444                 __set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time));
 445                 __set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi));
 446         }
 447 }
 448
 449 static void kvm_guest_cpu_offline(bool shutdown)
 450 {
 451         kvm_disable_steal_time();
 452         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
 453                 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
 454         if (kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL))
 455                 wrmsrl(MSR_KVM_MIGRATION_CONTROL, 0);
 456         kvm_pv_disable_apf();
 457         if (!shutdown)
 458                 apf_task_wake_all();
 459         kvmclock_disable();
 460 }
 461
 462 static int kvm_cpu_online(unsigned int cpu)
 463 {
 464         unsigned long flags;
 465
 466         local_irq_save(flags);
 467         kvm_guest_cpu_init();
 468         local_irq_restore(flags);
 469         return 0;
 470 }
 471
 472 #ifdef CONFIG_SMP
 473
 474 static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask);
 475
 476 static bool pv_tlb_flush_supported(void)
 477 {
 478         return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
 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 static bool pv_ipi_supported(void)
 486 {
 487         return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) &&
 488                (num_possible_cpus() != 1));
 489 }
 490
 491 static bool pv_sched_yield_supported(void)
 492 {
 493         return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&
 494                 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
 495             kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&
 496             !boot_cpu_has(X86_FEATURE_MWAIT) &&
 497             (num_possible_cpus() != 1));
 498 }
 499
 500 #define KVM_IPI_CLUSTER_SIZE    (2 * BITS_PER_LONG)
 501
 502 static void __send_ipi_mask(const struct cpumask *mask, int vector)
 503 {
 504         unsigned long flags;
 505         int cpu, 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         u32 apic_id, icr;
 512         long ret;
 513
 514         if (cpumask_empty(mask))
 515                 return;
 516
 517         local_irq_save(flags);
 518
 519         switch (vector) {
 520         default:
 521                 icr = APIC_DM_FIXED | vector;
 522                 break;
 523         case NMI_VECTOR:
 524                 icr = APIC_DM_NMI;
 525                 break;
 526         }
 527
 528         for_each_cpu(cpu, mask) {
 529                 apic_id = per_cpu(x86_cpu_to_apicid, cpu);
 530                 if (!ipi_bitmap) {
 531                         min = max = apic_id;
 532                 } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) {
 533                         ipi_bitmap <<= min - apic_id;
 534                         min = apic_id;
 535                 } else if (apic_id > min && apic_id < min + KVM_IPI_CLUSTER_SIZE) {
 536                         max = apic_id < max ? max : apic_id;
 537                 } else {
 538                         ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
 539                                 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
 540                         WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
 541                                   ret);
 542                         min = max = apic_id;
 543                         ipi_bitmap = 0;
 544                 }
 545                 __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap);
 546         }
 547
 548         if (ipi_bitmap) {
 549                 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
 550                         (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
 551                 WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
 552                           ret);
 553         }
 554
 555         local_irq_restore(flags);
 556 }
 557
 558 static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
 559 {
 560         __send_ipi_mask(mask, vector);
 561 }
 562
 563 static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
 564 {
 565         unsigned int this_cpu = smp_processor_id();
 566         struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
 567         const struct cpumask *local_mask;
 568
 569         cpumask_copy(new_mask, mask);
 570         cpumask_clear_cpu(this_cpu, new_mask);
 571         local_mask = new_mask;
 572         __send_ipi_mask(local_mask, vector);
 573 }
 574
 575 static int __init setup_efi_kvm_sev_migration(void)
 576 {
 577         efi_char16_t efi_sev_live_migration_enabled[] = L"SevLiveMigrationEnabled";
 578         efi_guid_t efi_variable_guid = AMD_SEV_MEM_ENCRYPT_GUID;
 579         efi_status_t status;
 580         unsigned long size;
 581         bool enabled;
 582
 583         if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) ||
 584             !kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL))
 585                 return 0;
 586
 587         if (!efi_enabled(EFI_BOOT))
 588                 return 0;
 589
 590         if (!efi_enabled(EFI_RUNTIME_SERVICES)) {
 591                 pr_info("%s : EFI runtime services are not enabled\n", __func__);
 592                 return 0;
 593         }
 594
 595         size = sizeof(enabled);
 596
 597         /* Get variable contents into buffer */
 598         status = efi.get_variable(efi_sev_live_migration_enabled,
 599                                   &efi_variable_guid, NULL, &size, &enabled);
 600
 601         if (status == EFI_NOT_FOUND) {
 602                 pr_info("%s : EFI live migration variable not found\n", __func__);
 603                 return 0;
 604         }
 605
 606         if (status != EFI_SUCCESS) {
 607                 pr_info("%s : EFI variable retrieval failed\n", __func__);
 608                 return 0;
 609         }
 610
 611         if (enabled == 0) {
 612                 pr_info("%s: live migration disabled in EFI\n", __func__);
 613                 return 0;
 614         }
 615
 616         pr_info("%s : live migration enabled in EFI\n", __func__);
 617         wrmsrl(MSR_KVM_MIGRATION_CONTROL, KVM_MIGRATION_READY);
 618
 619         return 1;
 620 }
 621
 622 late_initcall(setup_efi_kvm_sev_migration);
 623
 624 /*
 625  * Set the IPI entry points
 626  */
 627 static __init void kvm_setup_pv_ipi(void)
 628 {
 629         apic_update_callback(send_IPI_mask, kvm_send_ipi_mask);
 630         apic_update_callback(send_IPI_mask_allbutself, kvm_send_ipi_mask_allbutself);
 631         pr_info("setup PV IPIs\n");
 632 }
 633
 634 static void kvm_smp_send_call_func_ipi(const struct cpumask *mask)
 635 {
 636         int cpu;
 637
 638         native_send_call_func_ipi(mask);
 639
 640         /* Make sure other vCPUs get a chance to run if they need to. */
 641         for_each_cpu(cpu, mask) {
 642                 if (!idle_cpu(cpu) && vcpu_is_preempted(cpu)) {
 643                         kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu));
 644                         break;
 645                 }
 646         }
 647 }
 648
 649 static void kvm_flush_tlb_multi(const struct cpumask *cpumask,
 650                         const struct flush_tlb_info *info)
 651 {
 652         u8 state;
 653         int cpu;
 654         struct kvm_steal_time *src;
 655         struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
 656
 657         cpumask_copy(flushmask, cpumask);
 658         /*
 659          * We have to call flush only on online vCPUs. And
 660          * queue flush_on_enter for pre-empted vCPUs
 661          */
 662         for_each_cpu(cpu, flushmask) {
 663                 /*
 664                  * The local vCPU is never preempted, so we do not explicitly
 665                  * skip check for local vCPU - it will never be cleared from
 666                  * flushmask.
 667                  */
 668                 src = &per_cpu(steal_time, cpu);
 669                 state = READ_ONCE(src->preempted);
 670                 if ((state & KVM_VCPU_PREEMPTED)) {
 671                         if (try_cmpxchg(&src->preempted, &state,
 672                                         state | KVM_VCPU_FLUSH_TLB))
 673                                 __cpumask_clear_cpu(cpu, flushmask);
 674                 }
 675         }
 676
 677         native_flush_tlb_multi(flushmask, info);
 678 }
 679
 680 static __init int kvm_alloc_cpumask(void)
 681 {
 682         int cpu;
 683
 684         if (!kvm_para_available() || nopv)
 685                 return 0;
 686
 687         if (pv_tlb_flush_supported() || pv_ipi_supported())
 688                 for_each_possible_cpu(cpu) {
 689                         zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu),
 690                                 GFP_KERNEL, cpu_to_node(cpu));
 691                 }
 692
 693         return 0;
 694 }
 695 arch_initcall(kvm_alloc_cpumask);
 696
 697 static void __init kvm_smp_prepare_boot_cpu(void)
 698 {
 699         /*
 700          * Map the per-cpu variables as decrypted before kvm_guest_cpu_init()
 701          * shares the guest physical address with the hypervisor.
 702          */
 703         sev_map_percpu_data();
 704
 705         kvm_guest_cpu_init();
 706         native_smp_prepare_boot_cpu();
 707         kvm_spinlock_init();
 708 }
 709
 710 static int kvm_cpu_down_prepare(unsigned int cpu)
 711 {
 712         unsigned long flags;
 713
 714         local_irq_save(flags);
 715         kvm_guest_cpu_offline(false);
 716         local_irq_restore(flags);
 717         return 0;
 718 }
 719
 720 #endif
 721
 722 static int kvm_suspend(void)
 723 {
 724         u64 val = 0;
 725
 726         kvm_guest_cpu_offline(false);
 727
 728 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
 729         if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
 730                 rdmsrl(MSR_KVM_POLL_CONTROL, val);
 731         has_guest_poll = !(val & 1);
 732 #endif
 733         return 0;
 734 }
 735
 736 static void kvm_resume(void)
 737 {
 738         kvm_cpu_online(raw_smp_processor_id());
 739
 740 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
 741         if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL) && has_guest_poll)
 742                 wrmsrl(MSR_KVM_POLL_CONTROL, 0);
 743 #endif
 744 }
 745
 746 static struct syscore_ops kvm_syscore_ops = {
 747         .suspend        = kvm_suspend,
 748         .resume         = kvm_resume,
 749 };
 750
 751 static void kvm_pv_guest_cpu_reboot(void *unused)
 752 {
 753         kvm_guest_cpu_offline(true);
 754 }
 755
 756 static int kvm_pv_reboot_notify(struct notifier_block *nb,
 757                                 unsigned long code, void *unused)
 758 {
 759         if (code == SYS_RESTART)
 760                 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
 761         return NOTIFY_DONE;
 762 }
 763
 764 static struct notifier_block kvm_pv_reboot_nb = {
 765         .notifier_call = kvm_pv_reboot_notify,
 766 };
 767
 768 /*
 769  * After a PV feature is registered, the host will keep writing to the
 770  * registered memory location. If the guest happens to shutdown, this memory
 771  * won't be valid. In cases like kexec, in which you install a new kernel, this
 772  * means a random memory location will be kept being written.
 773  */
 774 #ifdef CONFIG_CRASH_DUMP
 775 static void kvm_crash_shutdown(struct pt_regs *regs)
 776 {
 777         kvm_guest_cpu_offline(true);
 778         native_machine_crash_shutdown(regs);
 779 }
 780 #endif
 781
 782 #if defined(CONFIG_X86_32) || !defined(CONFIG_SMP)
 783 bool __kvm_vcpu_is_preempted(long cpu);
 784
 785 __visible bool __kvm_vcpu_is_preempted(long cpu)
 786 {
 787         struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
 788
 789         return !!(src->preempted & KVM_VCPU_PREEMPTED);
 790 }
 791 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
 792
 793 #else
 794
 795 #include <asm/asm-offsets.h>
 796
 797 extern bool __raw_callee_save___kvm_vcpu_is_preempted(long);
 798
 799 /*
 800  * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and
 801  * restoring to/from the stack.
 802  */
 803 #define PV_VCPU_PREEMPTED_ASM                                                \
 804  "movq   __per_cpu_offset(,%rdi,8), %rax\n\t"                                \
 805  "cmpb   $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax)\n\t" \
 806  "setne  %al\n\t"
 807
 808 DEFINE_ASM_FUNC(__raw_callee_save___kvm_vcpu_is_preempted,
 809                 PV_VCPU_PREEMPTED_ASM, .text);
 810 #endif
 811
 812 static void __init kvm_guest_init(void)
 813 {
 814         int i;
 815
 816         paravirt_ops_setup();
 817         register_reboot_notifier(&kvm_pv_reboot_nb);
 818         for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
 819                 raw_spin_lock_init(&async_pf_sleepers[i].lock);
 820
 821         if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
 822                 has_steal_clock = 1;
 823                 static_call_update(pv_steal_clock, kvm_steal_clock);
 824
 825                 pv_ops.lock.vcpu_is_preempted =
 826                         PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
 827         }
 828
 829         if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
 830                 apic_update_callback(eoi, kvm_guest_apic_eoi_write);
 831
 832         if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
 833                 static_branch_enable(&kvm_async_pf_enabled);
 834                 sysvec_install(HYPERVISOR_CALLBACK_VECTOR, sysvec_kvm_asyncpf_interrupt);
 835         }
 836
 837 #ifdef CONFIG_SMP
 838         if (pv_tlb_flush_supported()) {
 839                 pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi;
 840                 pv_ops.mmu.tlb_remove_table = tlb_remove_table;
 841                 pr_info("KVM setup pv remote TLB flush\n");
 842         }
 843
 844         smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
 845         if (pv_sched_yield_supported()) {
 846                 smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi;
 847                 pr_info("setup PV sched yield\n");
 848         }
 849         if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
 850                                       kvm_cpu_online, kvm_cpu_down_prepare) < 0)
 851                 pr_err("failed to install cpu hotplug callbacks\n");
 852 #else
 853         sev_map_percpu_data();
 854         kvm_guest_cpu_init();
 855 #endif
 856
 857 #ifdef CONFIG_CRASH_DUMP
 858         machine_ops.crash_shutdown = kvm_crash_shutdown;
 859 #endif
 860
 861         register_syscore_ops(&kvm_syscore_ops);
 862
 863         /*
 864          * Hard lockup detection is enabled by default. Disable it, as guests
 865          * can get false positives too easily, for example if the host is
 866          * overcommitted.
 867          */
 868         hardlockup_detector_disable();
 869 }
 870
 871 static noinline uint32_t __kvm_cpuid_base(void)
 872 {
 873         if (boot_cpu_data.cpuid_level < 0)
 874                 return 0;       /* So we don't blow up on old processors */
 875
 876         if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
 877                 return hypervisor_cpuid_base(KVM_SIGNATURE, 0);
 878
 879         return 0;
 880 }
 881
 882 static inline uint32_t kvm_cpuid_base(void)
 883 {
 884         static int kvm_cpuid_base = -1;
 885
 886         if (kvm_cpuid_base == -1)
 887                 kvm_cpuid_base = __kvm_cpuid_base();
 888
 889         return kvm_cpuid_base;
 890 }
 891
 892 bool kvm_para_available(void)
 893 {
 894         return kvm_cpuid_base() != 0;
 895 }
 896 EXPORT_SYMBOL_GPL(kvm_para_available);
 897
 898 unsigned int kvm_arch_para_features(void)
 899 {
 900         return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
 901 }
 902
 903 unsigned int kvm_arch_para_hints(void)
 904 {
 905         return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
 906 }
 907 EXPORT_SYMBOL_GPL(kvm_arch_para_hints);
 908
 909 static uint32_t __init kvm_detect(void)
 910 {
 911         return kvm_cpuid_base();
 912 }
 913
 914 static void __init kvm_apic_init(void)
 915 {
 916 #ifdef CONFIG_SMP
 917         if (pv_ipi_supported())
 918                 kvm_setup_pv_ipi();
 919 #endif
 920 }
 921
 922 static bool __init kvm_msi_ext_dest_id(void)
 923 {
 924         return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID);
 925 }
 926
 927 static void kvm_sev_hc_page_enc_status(unsigned long pfn, int npages, bool enc)
 928 {
 929         kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, pfn << PAGE_SHIFT, npages,
 930                            KVM_MAP_GPA_RANGE_ENC_STAT(enc) | KVM_MAP_GPA_RANGE_PAGE_SZ_4K);
 931 }
 932
 933 static void __init kvm_init_platform(void)
 934 {
 935         if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) &&
 936             kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) {
 937                 unsigned long nr_pages;
 938                 int i;
 939
 940                 pv_ops.mmu.notify_page_enc_status_changed =
 941                         kvm_sev_hc_page_enc_status;
 942
 943                 /*
 944                  * Reset the host's shared pages list related to kernel
 945                  * specific page encryption status settings before we load a
 946                  * new kernel by kexec. Reset the page encryption status
 947                  * during early boot instead of just before kexec to avoid SMP
 948                  * races during kvm_pv_guest_cpu_reboot().
 949                  * NOTE: We cannot reset the complete shared pages list
 950                  * here as we need to retain the UEFI/OVMF firmware
 951                  * specific settings.
 952                  */
 953
 954                 for (i = 0; i < e820_table->nr_entries; i++) {
 955                         struct e820_entry *entry = &e820_table->entries[i];
 956
 957                         if (entry->type != E820_TYPE_RAM)
 958                                 continue;
 959
 960                         nr_pages = DIV_ROUND_UP(entry->size, PAGE_SIZE);
 961
 962                         kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, entry->addr,
 963                                        nr_pages,
 964                                        KVM_MAP_GPA_RANGE_ENCRYPTED | KVM_MAP_GPA_RANGE_PAGE_SZ_4K);
 965                 }
 966
 967                 /*
 968                  * Ensure that _bss_decrypted section is marked as decrypted in the
 969                  * shared pages list.
 970                  */
 971                 early_set_mem_enc_dec_hypercall((unsigned long)__start_bss_decrypted,
 972                                                 __end_bss_decrypted - __start_bss_decrypted, 0);
 973
 974                 /*
 975                  * If not booted using EFI, enable Live migration support.
 976                  */
 977                 if (!efi_enabled(EFI_BOOT))
 978                         wrmsrl(MSR_KVM_MIGRATION_CONTROL,
 979                                KVM_MIGRATION_READY);
 980         }
 981         kvmclock_init();
 982         x86_platform.apic_post_init = kvm_apic_init;
 983 }
 984
 985 #if defined(CONFIG_AMD_MEM_ENCRYPT)
 986 static void kvm_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs)
 987 {
 988         /* RAX and CPL are already in the GHCB */
 989         ghcb_set_rbx(ghcb, regs->bx);
 990         ghcb_set_rcx(ghcb, regs->cx);
 991         ghcb_set_rdx(ghcb, regs->dx);
 992         ghcb_set_rsi(ghcb, regs->si);
 993 }
 994
 995 static bool kvm_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs)
 996 {
 997         /* No checking of the return state needed */
 998         return true;
 999 }
1000 #endif
1001
1002 const __initconst struct hypervisor_x86 x86_hyper_kvm = {
1003         .name                           = "KVM",
1004         .detect                         = kvm_detect,
1005         .type                           = X86_HYPER_KVM,
1006         .init.guest_late_init           = kvm_guest_init,
1007         .init.x2apic_available          = kvm_para_available,
1008         .init.msi_ext_dest_id           = kvm_msi_ext_dest_id,
1009         .init.init_platform             = kvm_init_platform,
1010 #if defined(CONFIG_AMD_MEM_ENCRYPT)
1011         .runtime.sev_es_hcall_prepare   = kvm_sev_es_hcall_prepare,
1012         .runtime.sev_es_hcall_finish    = kvm_sev_es_hcall_finish,
1013 #endif
1014 };
1015
1016 static __init int activate_jump_labels(void)
1017 {
1018         if (has_steal_clock) {
1019                 static_key_slow_inc(&paravirt_steal_enabled);
1020                 if (steal_acc)
1021                         static_key_slow_inc(&paravirt_steal_rq_enabled);
1022         }
1023
1024         return 0;
1025 }
1026 arch_initcall(activate_jump_labels);
1027
1028 #ifdef CONFIG_PARAVIRT_SPINLOCKS
1029
1030 /* Kick a cpu by its apicid. Used to wake up a halted vcpu */
1031 static void kvm_kick_cpu(int cpu)
1032 {
1033         unsigned long flags = 0;
1034         u32 apicid;
1035
1036         apicid = per_cpu(x86_cpu_to_apicid, cpu);
1037         kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
1038 }
1039
1040 #include <asm/qspinlock.h>
1041
1042 static void kvm_wait(u8 *ptr, u8 val)
1043 {
1044         if (in_nmi())
1045                 return;
1046
1047         /*
1048          * halt until it's our turn and kicked. Note that we do safe halt
1049          * for irq enabled case to avoid hang when lock info is overwritten
1050          * in irq spinlock slowpath and no spurious interrupt occur to save us.
1051          */
1052         if (irqs_disabled()) {
1053                 if (READ_ONCE(*ptr) == val)
1054                         halt();
1055         } else {
1056                 local_irq_disable();
1057
1058                 /* safe_halt() will enable IRQ */
1059                 if (READ_ONCE(*ptr) == val)
1060                         safe_halt();
1061                 else
1062                         local_irq_enable();
1063         }
1064 }
1065
1066 /*
1067  * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
1068  */
1069 void __init kvm_spinlock_init(void)
1070 {
1071         /*
1072          * In case host doesn't support KVM_FEATURE_PV_UNHALT there is still an
1073          * advantage of keeping virt_spin_lock_key enabled: virt_spin_lock() is
1074          * preferred over native qspinlock when vCPU is preempted.
1075          */
1076         if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) {
1077                 pr_info("PV spinlocks disabled, no host support\n");
1078                 return;
1079         }
1080
1081         /*
1082          * Disable PV spinlocks and use native qspinlock when dedicated pCPUs
1083          * are available.
1084          */
1085         if (kvm_para_has_hint(KVM_HINTS_REALTIME)) {
1086                 pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n");
1087                 goto out;
1088         }
1089
1090         if (num_possible_cpus() == 1) {
1091                 pr_info("PV spinlocks disabled, single CPU\n");
1092                 goto out;
1093         }
1094
1095         if (nopvspin) {
1096                 pr_info("PV spinlocks disabled, forced by \"nopvspin\" parameter\n");
1097                 goto out;
1098         }
1099
1100         pr_info("PV spinlocks enabled\n");
1101
1102         __pv_init_lock_hash();
1103         pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
1104         pv_ops.lock.queued_spin_unlock =
1105                 PV_CALLEE_SAVE(__pv_queued_spin_unlock);
1106         pv_ops.lock.wait = kvm_wait;
1107         pv_ops.lock.kick = kvm_kick_cpu;
1108
1109         /*
1110          * When PV spinlock is enabled which is preferred over
1111          * virt_spin_lock(), virt_spin_lock_key's value is meaningless.
1112          * Just disable it anyway.
1113          */
1114 out:
1115         static_branch_disable(&virt_spin_lock_key);
1116 }
1117
1118 #endif  /* CONFIG_PARAVIRT_SPINLOCKS */
1119
1120 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
1121
1122 static void kvm_disable_host_haltpoll(void *i)
1123 {
1124         wrmsrl(MSR_KVM_POLL_CONTROL, 0);
1125 }
1126
1127 static void kvm_enable_host_haltpoll(void *i)
1128 {
1129         wrmsrl(MSR_KVM_POLL_CONTROL, 1);
1130 }
1131
1132 void arch_haltpoll_enable(unsigned int cpu)
1133 {
1134         if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {
1135                 pr_err_once("host does not support poll control\n");
1136                 pr_err_once("host upgrade recommended\n");
1137                 return;
1138         }
1139
1140         /* Enable guest halt poll disables host halt poll */
1141         smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1);
1142 }
1143 EXPORT_SYMBOL_GPL(arch_haltpoll_enable);
1144
1145 void arch_haltpoll_disable(unsigned int cpu)
1146 {
1147         if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
1148                 return;
1149
1150         /* Disable guest halt poll enables host halt poll */
1151         smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1);
1152 }
1153 EXPORT_SYMBOL_GPL(arch_haltpoll_disable);
1154 #endif