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 (num_possible_cpus() != 1)); 467 } 468 469 static bool pv_ipi_supported(void) 470 { 471 return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) && 472 (num_possible_cpus() != 1)); 473 } 474 475 static bool pv_sched_yield_supported(void) 476 { 477 return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) && 478 !kvm_para_has_hint(KVM_HINTS_REALTIME) && 479 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) && 480 (num_possible_cpus() != 1)); 481 } 482 483 #define KVM_IPI_CLUSTER_SIZE (2 * BITS_PER_LONG) 484 485 static void __send_ipi_mask(const struct cpumask *mask, int vector) 486 { 487 unsigned long flags; 488 int cpu, apic_id, icr; 489 int min = 0, max = 0; 490 #ifdef CONFIG_X86_64 491 __uint128_t ipi_bitmap = 0; 492 #else 493 u64 ipi_bitmap = 0; 494 #endif 495 long ret; 496 497 if (cpumask_empty(mask)) 498 return; 499 500 local_irq_save(flags); 501 502 switch (vector) { 503 default: 504 icr = APIC_DM_FIXED | vector; 505 break; 506 case NMI_VECTOR: 507 icr = APIC_DM_NMI; 508 break; 509 } 510 511 for_each_cpu(cpu, mask) { 512 apic_id = per_cpu(x86_cpu_to_apicid, cpu); 513 if (!ipi_bitmap) { 514 min = max = apic_id; 515 } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) { 516 ipi_bitmap <<= min - apic_id; 517 min = apic_id; 518 } else if (apic_id < min + KVM_IPI_CLUSTER_SIZE) { 519 max = apic_id < max ? max : apic_id; 520 } else { 521 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap, 522 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr); 523 WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld", 524 ret); 525 min = max = apic_id; 526 ipi_bitmap = 0; 527 } 528 __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap); 529 } 530 531 if (ipi_bitmap) { 532 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap, 533 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr); 534 WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld", 535 ret); 536 } 537 538 local_irq_restore(flags); 539 } 540 541 static void kvm_send_ipi_mask(const struct cpumask *mask, int vector) 542 { 543 __send_ipi_mask(mask, vector); 544 } 545 546 static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector) 547 { 548 unsigned int this_cpu = smp_processor_id(); 549 struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); 550 const struct cpumask *local_mask; 551 552 cpumask_copy(new_mask, mask); 553 cpumask_clear_cpu(this_cpu, new_mask); 554 local_mask = new_mask; 555 __send_ipi_mask(local_mask, vector); 556 } 557 558 static int __init setup_efi_kvm_sev_migration(void) 559 { 560 efi_char16_t efi_sev_live_migration_enabled[] = L"SevLiveMigrationEnabled"; 561 efi_guid_t efi_variable_guid = AMD_SEV_MEM_ENCRYPT_GUID; 562 efi_status_t status; 563 unsigned long size; 564 bool enabled; 565 566 if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) || 567 !kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) 568 return 0; 569 570 if (!efi_enabled(EFI_BOOT)) 571 return 0; 572 573 if (!efi_enabled(EFI_RUNTIME_SERVICES)) { 574 pr_info("%s : EFI runtime services are not enabled\n", __func__); 575 return 0; 576 } 577 578 size = sizeof(enabled); 579 580 /* Get variable contents into buffer */ 581 status = efi.get_variable(efi_sev_live_migration_enabled, 582 &efi_variable_guid, NULL, &size, &enabled); 583 584 if (status == EFI_NOT_FOUND) { 585 pr_info("%s : EFI live migration variable not found\n", __func__); 586 return 0; 587 } 588 589 if (status != EFI_SUCCESS) { 590 pr_info("%s : EFI variable retrieval failed\n", __func__); 591 return 0; 592 } 593 594 if (enabled == 0) { 595 pr_info("%s: live migration disabled in EFI\n", __func__); 596 return 0; 597 } 598 599 pr_info("%s : live migration enabled in EFI\n", __func__); 600 wrmsrl(MSR_KVM_MIGRATION_CONTROL, KVM_MIGRATION_READY); 601 602 return 1; 603 } 604 605 late_initcall(setup_efi_kvm_sev_migration); 606 607 /* 608 * Set the IPI entry points 609 */ 610 static void kvm_setup_pv_ipi(void) 611 { 612 apic->send_IPI_mask = kvm_send_ipi_mask; 613 apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself; 614 pr_info("setup PV IPIs\n"); 615 } 616 617 static void kvm_smp_send_call_func_ipi(const struct cpumask *mask) 618 { 619 int cpu; 620 621 native_send_call_func_ipi(mask); 622 623 /* Make sure other vCPUs get a chance to run if they need to. */ 624 for_each_cpu(cpu, mask) { 625 if (vcpu_is_preempted(cpu)) { 626 kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu)); 627 break; 628 } 629 } 630 } 631 632 static void kvm_flush_tlb_multi(const struct cpumask *cpumask, 633 const struct flush_tlb_info *info) 634 { 635 u8 state; 636 int cpu; 637 struct kvm_steal_time *src; 638 struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); 639 640 cpumask_copy(flushmask, cpumask); 641 /* 642 * We have to call flush only on online vCPUs. And 643 * queue flush_on_enter for pre-empted vCPUs 644 */ 645 for_each_cpu(cpu, flushmask) { 646 /* 647 * The local vCPU is never preempted, so we do not explicitly 648 * skip check for local vCPU - it will never be cleared from 649 * flushmask. 650 */ 651 src = &per_cpu(steal_time, cpu); 652 state = READ_ONCE(src->preempted); 653 if ((state & KVM_VCPU_PREEMPTED)) { 654 if (try_cmpxchg(&src->preempted, &state, 655 state | KVM_VCPU_FLUSH_TLB)) 656 __cpumask_clear_cpu(cpu, flushmask); 657 } 658 } 659 660 native_flush_tlb_multi(flushmask, info); 661 } 662 663 static __init int kvm_alloc_cpumask(void) 664 { 665 int cpu; 666 667 if (!kvm_para_available() || nopv) 668 return 0; 669 670 if (pv_tlb_flush_supported() || pv_ipi_supported()) 671 for_each_possible_cpu(cpu) { 672 zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu), 673 GFP_KERNEL, cpu_to_node(cpu)); 674 } 675 676 return 0; 677 } 678 arch_initcall(kvm_alloc_cpumask); 679 680 static void __init kvm_smp_prepare_boot_cpu(void) 681 { 682 /* 683 * Map the per-cpu variables as decrypted before kvm_guest_cpu_init() 684 * shares the guest physical address with the hypervisor. 685 */ 686 sev_map_percpu_data(); 687 688 kvm_guest_cpu_init(); 689 native_smp_prepare_boot_cpu(); 690 kvm_spinlock_init(); 691 } 692 693 static int kvm_cpu_down_prepare(unsigned int cpu) 694 { 695 unsigned long flags; 696 697 local_irq_save(flags); 698 kvm_guest_cpu_offline(false); 699 local_irq_restore(flags); 700 return 0; 701 } 702 703 #endif 704 705 static int kvm_suspend(void) 706 { 707 kvm_guest_cpu_offline(false); 708 709 return 0; 710 } 711 712 static void kvm_resume(void) 713 { 714 kvm_cpu_online(raw_smp_processor_id()); 715 } 716 717 static struct syscore_ops kvm_syscore_ops = { 718 .suspend = kvm_suspend, 719 .resume = kvm_resume, 720 }; 721 722 static void kvm_pv_guest_cpu_reboot(void *unused) 723 { 724 kvm_guest_cpu_offline(true); 725 } 726 727 static int kvm_pv_reboot_notify(struct notifier_block *nb, 728 unsigned long code, void *unused) 729 { 730 if (code == SYS_RESTART) 731 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1); 732 return NOTIFY_DONE; 733 } 734 735 static struct notifier_block kvm_pv_reboot_nb = { 736 .notifier_call = kvm_pv_reboot_notify, 737 }; 738 739 /* 740 * After a PV feature is registered, the host will keep writing to the 741 * registered memory location. If the guest happens to shutdown, this memory 742 * won't be valid. In cases like kexec, in which you install a new kernel, this 743 * means a random memory location will be kept being written. 744 */ 745 #ifdef CONFIG_KEXEC_CORE 746 static void kvm_crash_shutdown(struct pt_regs *regs) 747 { 748 kvm_guest_cpu_offline(true); 749 native_machine_crash_shutdown(regs); 750 } 751 #endif 752 753 static void __init kvm_guest_init(void) 754 { 755 int i; 756 757 paravirt_ops_setup(); 758 register_reboot_notifier(&kvm_pv_reboot_nb); 759 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) 760 raw_spin_lock_init(&async_pf_sleepers[i].lock); 761 762 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) { 763 has_steal_clock = 1; 764 static_call_update(pv_steal_clock, kvm_steal_clock); 765 } 766 767 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) 768 apic_set_eoi_write(kvm_guest_apic_eoi_write); 769 770 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) { 771 static_branch_enable(&kvm_async_pf_enabled); 772 alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_kvm_asyncpf_interrupt); 773 } 774 775 #ifdef CONFIG_SMP 776 if (pv_tlb_flush_supported()) { 777 pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi; 778 pv_ops.mmu.tlb_remove_table = tlb_remove_table; 779 pr_info("KVM setup pv remote TLB flush\n"); 780 } 781 782 smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; 783 if (pv_sched_yield_supported()) { 784 smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi; 785 pr_info("setup PV sched yield\n"); 786 } 787 if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online", 788 kvm_cpu_online, kvm_cpu_down_prepare) < 0) 789 pr_err("failed to install cpu hotplug callbacks\n"); 790 #else 791 sev_map_percpu_data(); 792 kvm_guest_cpu_init(); 793 #endif 794 795 #ifdef CONFIG_KEXEC_CORE 796 machine_ops.crash_shutdown = kvm_crash_shutdown; 797 #endif 798 799 register_syscore_ops(&kvm_syscore_ops); 800 801 /* 802 * Hard lockup detection is enabled by default. Disable it, as guests 803 * can get false positives too easily, for example if the host is 804 * overcommitted. 805 */ 806 hardlockup_detector_disable(); 807 } 808 809 static noinline uint32_t __kvm_cpuid_base(void) 810 { 811 if (boot_cpu_data.cpuid_level < 0) 812 return 0; /* So we don't blow up on old processors */ 813 814 if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) 815 return hypervisor_cpuid_base(KVM_SIGNATURE, 0); 816 817 return 0; 818 } 819 820 static inline uint32_t kvm_cpuid_base(void) 821 { 822 static int kvm_cpuid_base = -1; 823 824 if (kvm_cpuid_base == -1) 825 kvm_cpuid_base = __kvm_cpuid_base(); 826 827 return kvm_cpuid_base; 828 } 829 830 bool kvm_para_available(void) 831 { 832 return kvm_cpuid_base() != 0; 833 } 834 EXPORT_SYMBOL_GPL(kvm_para_available); 835 836 unsigned int kvm_arch_para_features(void) 837 { 838 return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES); 839 } 840 841 unsigned int kvm_arch_para_hints(void) 842 { 843 return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES); 844 } 845 EXPORT_SYMBOL_GPL(kvm_arch_para_hints); 846 847 static uint32_t __init kvm_detect(void) 848 { 849 return kvm_cpuid_base(); 850 } 851 852 static void __init kvm_apic_init(void) 853 { 854 #ifdef CONFIG_SMP 855 if (pv_ipi_supported()) 856 kvm_setup_pv_ipi(); 857 #endif 858 } 859 860 static bool __init kvm_msi_ext_dest_id(void) 861 { 862 return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID); 863 } 864 865 static void kvm_sev_hc_page_enc_status(unsigned long pfn, int npages, bool enc) 866 { 867 kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, pfn << PAGE_SHIFT, npages, 868 KVM_MAP_GPA_RANGE_ENC_STAT(enc) | KVM_MAP_GPA_RANGE_PAGE_SZ_4K); 869 } 870 871 static void __init kvm_init_platform(void) 872 { 873 if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) && 874 kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) { 875 unsigned long nr_pages; 876 int i; 877 878 pv_ops.mmu.notify_page_enc_status_changed = 879 kvm_sev_hc_page_enc_status; 880 881 /* 882 * Reset the host's shared pages list related to kernel 883 * specific page encryption status settings before we load a 884 * new kernel by kexec. Reset the page encryption status 885 * during early boot intead of just before kexec to avoid SMP 886 * races during kvm_pv_guest_cpu_reboot(). 887 * NOTE: We cannot reset the complete shared pages list 888 * here as we need to retain the UEFI/OVMF firmware 889 * specific settings. 890 */ 891 892 for (i = 0; i < e820_table->nr_entries; i++) { 893 struct e820_entry *entry = &e820_table->entries[i]; 894 895 if (entry->type != E820_TYPE_RAM) 896 continue; 897 898 nr_pages = DIV_ROUND_UP(entry->size, PAGE_SIZE); 899 900 kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, entry->addr, 901 nr_pages, 902 KVM_MAP_GPA_RANGE_ENCRYPTED | KVM_MAP_GPA_RANGE_PAGE_SZ_4K); 903 } 904 905 /* 906 * Ensure that _bss_decrypted section is marked as decrypted in the 907 * shared pages list. 908 */ 909 nr_pages = DIV_ROUND_UP(__end_bss_decrypted - __start_bss_decrypted, 910 PAGE_SIZE); 911 early_set_mem_enc_dec_hypercall((unsigned long)__start_bss_decrypted, 912 nr_pages, 0); 913 914 /* 915 * If not booted using EFI, enable Live migration support. 916 */ 917 if (!efi_enabled(EFI_BOOT)) 918 wrmsrl(MSR_KVM_MIGRATION_CONTROL, 919 KVM_MIGRATION_READY); 920 } 921 kvmclock_init(); 922 x86_platform.apic_post_init = kvm_apic_init; 923 } 924 925 #if defined(CONFIG_AMD_MEM_ENCRYPT) 926 static void kvm_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs) 927 { 928 /* RAX and CPL are already in the GHCB */ 929 ghcb_set_rbx(ghcb, regs->bx); 930 ghcb_set_rcx(ghcb, regs->cx); 931 ghcb_set_rdx(ghcb, regs->dx); 932 ghcb_set_rsi(ghcb, regs->si); 933 } 934 935 static bool kvm_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs) 936 { 937 /* No checking of the return state needed */ 938 return true; 939 } 940 #endif 941 942 const __initconst struct hypervisor_x86 x86_hyper_kvm = { 943 .name = "KVM", 944 .detect = kvm_detect, 945 .type = X86_HYPER_KVM, 946 .init.guest_late_init = kvm_guest_init, 947 .init.x2apic_available = kvm_para_available, 948 .init.msi_ext_dest_id = kvm_msi_ext_dest_id, 949 .init.init_platform = kvm_init_platform, 950 #if defined(CONFIG_AMD_MEM_ENCRYPT) 951 .runtime.sev_es_hcall_prepare = kvm_sev_es_hcall_prepare, 952 .runtime.sev_es_hcall_finish = kvm_sev_es_hcall_finish, 953 #endif 954 }; 955 956 static __init int activate_jump_labels(void) 957 { 958 if (has_steal_clock) { 959 static_key_slow_inc(¶virt_steal_enabled); 960 if (steal_acc) 961 static_key_slow_inc(¶virt_steal_rq_enabled); 962 } 963 964 return 0; 965 } 966 arch_initcall(activate_jump_labels); 967 968 #ifdef CONFIG_PARAVIRT_SPINLOCKS 969 970 /* Kick a cpu by its apicid. Used to wake up a halted vcpu */ 971 static void kvm_kick_cpu(int cpu) 972 { 973 int apicid; 974 unsigned long flags = 0; 975 976 apicid = per_cpu(x86_cpu_to_apicid, cpu); 977 kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid); 978 } 979 980 #include <asm/qspinlock.h> 981 982 static void kvm_wait(u8 *ptr, u8 val) 983 { 984 if (in_nmi()) 985 return; 986 987 /* 988 * halt until it's our turn and kicked. Note that we do safe halt 989 * for irq enabled case to avoid hang when lock info is overwritten 990 * in irq spinlock slowpath and no spurious interrupt occur to save us. 991 */ 992 if (irqs_disabled()) { 993 if (READ_ONCE(*ptr) == val) 994 halt(); 995 } else { 996 local_irq_disable(); 997 998 /* safe_halt() will enable IRQ */ 999 if (READ_ONCE(*ptr) == val) 1000 safe_halt(); 1001 else 1002 local_irq_enable(); 1003 } 1004 } 1005 1006 #ifdef CONFIG_X86_32 1007 __visible bool __kvm_vcpu_is_preempted(long cpu) 1008 { 1009 struct kvm_steal_time *src = &per_cpu(steal_time, cpu); 1010 1011 return !!(src->preempted & KVM_VCPU_PREEMPTED); 1012 } 1013 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted); 1014 1015 #else 1016 1017 #include <asm/asm-offsets.h> 1018 1019 extern bool __raw_callee_save___kvm_vcpu_is_preempted(long); 1020 1021 /* 1022 * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and 1023 * restoring to/from the stack. 1024 */ 1025 asm( 1026 ".pushsection .text;" 1027 ".global __raw_callee_save___kvm_vcpu_is_preempted;" 1028 ".type __raw_callee_save___kvm_vcpu_is_preempted, @function;" 1029 "__raw_callee_save___kvm_vcpu_is_preempted:" 1030 "movq __per_cpu_offset(,%rdi,8), %rax;" 1031 "cmpb $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);" 1032 "setne %al;" 1033 "ret;" 1034 ".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;" 1035 ".popsection"); 1036 1037 #endif 1038 1039 /* 1040 * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present. 1041 */ 1042 void __init kvm_spinlock_init(void) 1043 { 1044 /* 1045 * In case host doesn't support KVM_FEATURE_PV_UNHALT there is still an 1046 * advantage of keeping virt_spin_lock_key enabled: virt_spin_lock() is 1047 * preferred over native qspinlock when vCPU is preempted. 1048 */ 1049 if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) { 1050 pr_info("PV spinlocks disabled, no host support\n"); 1051 return; 1052 } 1053 1054 /* 1055 * Disable PV spinlocks and use native qspinlock when dedicated pCPUs 1056 * are available. 1057 */ 1058 if (kvm_para_has_hint(KVM_HINTS_REALTIME)) { 1059 pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n"); 1060 goto out; 1061 } 1062 1063 if (num_possible_cpus() == 1) { 1064 pr_info("PV spinlocks disabled, single CPU\n"); 1065 goto out; 1066 } 1067 1068 if (nopvspin) { 1069 pr_info("PV spinlocks disabled, forced by \"nopvspin\" parameter\n"); 1070 goto out; 1071 } 1072 1073 pr_info("PV spinlocks enabled\n"); 1074 1075 __pv_init_lock_hash(); 1076 pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath; 1077 pv_ops.lock.queued_spin_unlock = 1078 PV_CALLEE_SAVE(__pv_queued_spin_unlock); 1079 pv_ops.lock.wait = kvm_wait; 1080 pv_ops.lock.kick = kvm_kick_cpu; 1081 1082 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) { 1083 pv_ops.lock.vcpu_is_preempted = 1084 PV_CALLEE_SAVE(__kvm_vcpu_is_preempted); 1085 } 1086 /* 1087 * When PV spinlock is enabled which is preferred over 1088 * virt_spin_lock(), virt_spin_lock_key's value is meaningless. 1089 * Just disable it anyway. 1090 */ 1091 out: 1092 static_branch_disable(&virt_spin_lock_key); 1093 } 1094 1095 #endif /* CONFIG_PARAVIRT_SPINLOCKS */ 1096 1097 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL 1098 1099 static void kvm_disable_host_haltpoll(void *i) 1100 { 1101 wrmsrl(MSR_KVM_POLL_CONTROL, 0); 1102 } 1103 1104 static void kvm_enable_host_haltpoll(void *i) 1105 { 1106 wrmsrl(MSR_KVM_POLL_CONTROL, 1); 1107 } 1108 1109 void arch_haltpoll_enable(unsigned int cpu) 1110 { 1111 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) { 1112 pr_err_once("host does not support poll control\n"); 1113 pr_err_once("host upgrade recommended\n"); 1114 return; 1115 } 1116 1117 /* Enable guest halt poll disables host halt poll */ 1118 smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1); 1119 } 1120 EXPORT_SYMBOL_GPL(arch_haltpoll_enable); 1121 1122 void arch_haltpoll_disable(unsigned int cpu) 1123 { 1124 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) 1125 return; 1126 1127 /* Disable guest halt poll enables host halt poll */ 1128 smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1); 1129 } 1130 EXPORT_SYMBOL_GPL(arch_haltpoll_disable); 1131 #endif 1132