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 static void __init kvm_guest_init(void) 756 { 757 int i; 758 759 paravirt_ops_setup(); 760 register_reboot_notifier(&kvm_pv_reboot_nb); 761 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) 762 raw_spin_lock_init(&async_pf_sleepers[i].lock); 763 764 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) { 765 has_steal_clock = 1; 766 static_call_update(pv_steal_clock, kvm_steal_clock); 767 } 768 769 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) 770 apic_set_eoi_write(kvm_guest_apic_eoi_write); 771 772 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) { 773 static_branch_enable(&kvm_async_pf_enabled); 774 alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_kvm_asyncpf_interrupt); 775 } 776 777 #ifdef CONFIG_SMP 778 if (pv_tlb_flush_supported()) { 779 pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi; 780 pv_ops.mmu.tlb_remove_table = tlb_remove_table; 781 pr_info("KVM setup pv remote TLB flush\n"); 782 } 783 784 smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; 785 if (pv_sched_yield_supported()) { 786 smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi; 787 pr_info("setup PV sched yield\n"); 788 } 789 if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online", 790 kvm_cpu_online, kvm_cpu_down_prepare) < 0) 791 pr_err("failed to install cpu hotplug callbacks\n"); 792 #else 793 sev_map_percpu_data(); 794 kvm_guest_cpu_init(); 795 #endif 796 797 #ifdef CONFIG_KEXEC_CORE 798 machine_ops.crash_shutdown = kvm_crash_shutdown; 799 #endif 800 801 register_syscore_ops(&kvm_syscore_ops); 802 803 /* 804 * Hard lockup detection is enabled by default. Disable it, as guests 805 * can get false positives too easily, for example if the host is 806 * overcommitted. 807 */ 808 hardlockup_detector_disable(); 809 } 810 811 static noinline uint32_t __kvm_cpuid_base(void) 812 { 813 if (boot_cpu_data.cpuid_level < 0) 814 return 0; /* So we don't blow up on old processors */ 815 816 if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) 817 return hypervisor_cpuid_base(KVM_SIGNATURE, 0); 818 819 return 0; 820 } 821 822 static inline uint32_t kvm_cpuid_base(void) 823 { 824 static int kvm_cpuid_base = -1; 825 826 if (kvm_cpuid_base == -1) 827 kvm_cpuid_base = __kvm_cpuid_base(); 828 829 return kvm_cpuid_base; 830 } 831 832 bool kvm_para_available(void) 833 { 834 return kvm_cpuid_base() != 0; 835 } 836 EXPORT_SYMBOL_GPL(kvm_para_available); 837 838 unsigned int kvm_arch_para_features(void) 839 { 840 return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES); 841 } 842 843 unsigned int kvm_arch_para_hints(void) 844 { 845 return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES); 846 } 847 EXPORT_SYMBOL_GPL(kvm_arch_para_hints); 848 849 static uint32_t __init kvm_detect(void) 850 { 851 return kvm_cpuid_base(); 852 } 853 854 static void __init kvm_apic_init(void) 855 { 856 #ifdef CONFIG_SMP 857 if (pv_ipi_supported()) 858 kvm_setup_pv_ipi(); 859 #endif 860 } 861 862 static bool __init kvm_msi_ext_dest_id(void) 863 { 864 return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID); 865 } 866 867 static void kvm_sev_hc_page_enc_status(unsigned long pfn, int npages, bool enc) 868 { 869 kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, pfn << PAGE_SHIFT, npages, 870 KVM_MAP_GPA_RANGE_ENC_STAT(enc) | KVM_MAP_GPA_RANGE_PAGE_SZ_4K); 871 } 872 873 static void __init kvm_init_platform(void) 874 { 875 if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) && 876 kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) { 877 unsigned long nr_pages; 878 int i; 879 880 pv_ops.mmu.notify_page_enc_status_changed = 881 kvm_sev_hc_page_enc_status; 882 883 /* 884 * Reset the host's shared pages list related to kernel 885 * specific page encryption status settings before we load a 886 * new kernel by kexec. Reset the page encryption status 887 * during early boot intead of just before kexec to avoid SMP 888 * races during kvm_pv_guest_cpu_reboot(). 889 * NOTE: We cannot reset the complete shared pages list 890 * here as we need to retain the UEFI/OVMF firmware 891 * specific settings. 892 */ 893 894 for (i = 0; i < e820_table->nr_entries; i++) { 895 struct e820_entry *entry = &e820_table->entries[i]; 896 897 if (entry->type != E820_TYPE_RAM) 898 continue; 899 900 nr_pages = DIV_ROUND_UP(entry->size, PAGE_SIZE); 901 902 kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, entry->addr, 903 nr_pages, 904 KVM_MAP_GPA_RANGE_ENCRYPTED | KVM_MAP_GPA_RANGE_PAGE_SZ_4K); 905 } 906 907 /* 908 * Ensure that _bss_decrypted section is marked as decrypted in the 909 * shared pages list. 910 */ 911 nr_pages = DIV_ROUND_UP(__end_bss_decrypted - __start_bss_decrypted, 912 PAGE_SIZE); 913 early_set_mem_enc_dec_hypercall((unsigned long)__start_bss_decrypted, 914 nr_pages, 0); 915 916 /* 917 * If not booted using EFI, enable Live migration support. 918 */ 919 if (!efi_enabled(EFI_BOOT)) 920 wrmsrl(MSR_KVM_MIGRATION_CONTROL, 921 KVM_MIGRATION_READY); 922 } 923 kvmclock_init(); 924 x86_platform.apic_post_init = kvm_apic_init; 925 } 926 927 #if defined(CONFIG_AMD_MEM_ENCRYPT) 928 static void kvm_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs) 929 { 930 /* RAX and CPL are already in the GHCB */ 931 ghcb_set_rbx(ghcb, regs->bx); 932 ghcb_set_rcx(ghcb, regs->cx); 933 ghcb_set_rdx(ghcb, regs->dx); 934 ghcb_set_rsi(ghcb, regs->si); 935 } 936 937 static bool kvm_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs) 938 { 939 /* No checking of the return state needed */ 940 return true; 941 } 942 #endif 943 944 const __initconst struct hypervisor_x86 x86_hyper_kvm = { 945 .name = "KVM", 946 .detect = kvm_detect, 947 .type = X86_HYPER_KVM, 948 .init.guest_late_init = kvm_guest_init, 949 .init.x2apic_available = kvm_para_available, 950 .init.msi_ext_dest_id = kvm_msi_ext_dest_id, 951 .init.init_platform = kvm_init_platform, 952 #if defined(CONFIG_AMD_MEM_ENCRYPT) 953 .runtime.sev_es_hcall_prepare = kvm_sev_es_hcall_prepare, 954 .runtime.sev_es_hcall_finish = kvm_sev_es_hcall_finish, 955 #endif 956 }; 957 958 static __init int activate_jump_labels(void) 959 { 960 if (has_steal_clock) { 961 static_key_slow_inc(¶virt_steal_enabled); 962 if (steal_acc) 963 static_key_slow_inc(¶virt_steal_rq_enabled); 964 } 965 966 return 0; 967 } 968 arch_initcall(activate_jump_labels); 969 970 #ifdef CONFIG_PARAVIRT_SPINLOCKS 971 972 /* Kick a cpu by its apicid. Used to wake up a halted vcpu */ 973 static void kvm_kick_cpu(int cpu) 974 { 975 int apicid; 976 unsigned long flags = 0; 977 978 apicid = per_cpu(x86_cpu_to_apicid, cpu); 979 kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid); 980 } 981 982 #include <asm/qspinlock.h> 983 984 static void kvm_wait(u8 *ptr, u8 val) 985 { 986 if (in_nmi()) 987 return; 988 989 /* 990 * halt until it's our turn and kicked. Note that we do safe halt 991 * for irq enabled case to avoid hang when lock info is overwritten 992 * in irq spinlock slowpath and no spurious interrupt occur to save us. 993 */ 994 if (irqs_disabled()) { 995 if (READ_ONCE(*ptr) == val) 996 halt(); 997 } else { 998 local_irq_disable(); 999 1000 /* safe_halt() will enable IRQ */ 1001 if (READ_ONCE(*ptr) == val) 1002 safe_halt(); 1003 else 1004 local_irq_enable(); 1005 } 1006 } 1007 1008 #ifdef CONFIG_X86_32 1009 __visible bool __kvm_vcpu_is_preempted(long cpu) 1010 { 1011 struct kvm_steal_time *src = &per_cpu(steal_time, cpu); 1012 1013 return !!(src->preempted & KVM_VCPU_PREEMPTED); 1014 } 1015 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted); 1016 1017 #else 1018 1019 #include <asm/asm-offsets.h> 1020 1021 extern bool __raw_callee_save___kvm_vcpu_is_preempted(long); 1022 1023 /* 1024 * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and 1025 * restoring to/from the stack. 1026 */ 1027 asm( 1028 ".pushsection .text;" 1029 ".global __raw_callee_save___kvm_vcpu_is_preempted;" 1030 ".type __raw_callee_save___kvm_vcpu_is_preempted, @function;" 1031 "__raw_callee_save___kvm_vcpu_is_preempted:" 1032 ASM_ENDBR 1033 "movq __per_cpu_offset(,%rdi,8), %rax;" 1034 "cmpb $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);" 1035 "setne %al;" 1036 ASM_RET 1037 ".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;" 1038 ".popsection"); 1039 1040 #endif 1041 1042 /* 1043 * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present. 1044 */ 1045 void __init kvm_spinlock_init(void) 1046 { 1047 /* 1048 * In case host doesn't support KVM_FEATURE_PV_UNHALT there is still an 1049 * advantage of keeping virt_spin_lock_key enabled: virt_spin_lock() is 1050 * preferred over native qspinlock when vCPU is preempted. 1051 */ 1052 if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) { 1053 pr_info("PV spinlocks disabled, no host support\n"); 1054 return; 1055 } 1056 1057 /* 1058 * Disable PV spinlocks and use native qspinlock when dedicated pCPUs 1059 * are available. 1060 */ 1061 if (kvm_para_has_hint(KVM_HINTS_REALTIME)) { 1062 pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n"); 1063 goto out; 1064 } 1065 1066 if (num_possible_cpus() == 1) { 1067 pr_info("PV spinlocks disabled, single CPU\n"); 1068 goto out; 1069 } 1070 1071 if (nopvspin) { 1072 pr_info("PV spinlocks disabled, forced by \"nopvspin\" parameter\n"); 1073 goto out; 1074 } 1075 1076 pr_info("PV spinlocks enabled\n"); 1077 1078 __pv_init_lock_hash(); 1079 pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath; 1080 pv_ops.lock.queued_spin_unlock = 1081 PV_CALLEE_SAVE(__pv_queued_spin_unlock); 1082 pv_ops.lock.wait = kvm_wait; 1083 pv_ops.lock.kick = kvm_kick_cpu; 1084 1085 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) { 1086 pv_ops.lock.vcpu_is_preempted = 1087 PV_CALLEE_SAVE(__kvm_vcpu_is_preempted); 1088 } 1089 /* 1090 * When PV spinlock is enabled which is preferred over 1091 * virt_spin_lock(), virt_spin_lock_key's value is meaningless. 1092 * Just disable it anyway. 1093 */ 1094 out: 1095 static_branch_disable(&virt_spin_lock_key); 1096 } 1097 1098 #endif /* CONFIG_PARAVIRT_SPINLOCKS */ 1099 1100 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL 1101 1102 static void kvm_disable_host_haltpoll(void *i) 1103 { 1104 wrmsrl(MSR_KVM_POLL_CONTROL, 0); 1105 } 1106 1107 static void kvm_enable_host_haltpoll(void *i) 1108 { 1109 wrmsrl(MSR_KVM_POLL_CONTROL, 1); 1110 } 1111 1112 void arch_haltpoll_enable(unsigned int cpu) 1113 { 1114 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) { 1115 pr_err_once("host does not support poll control\n"); 1116 pr_err_once("host upgrade recommended\n"); 1117 return; 1118 } 1119 1120 /* Enable guest halt poll disables host halt poll */ 1121 smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1); 1122 } 1123 EXPORT_SYMBOL_GPL(arch_haltpoll_enable); 1124 1125 void arch_haltpoll_disable(unsigned int cpu) 1126 { 1127 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) 1128 return; 1129 1130 /* Disable guest halt poll enables host halt poll */ 1131 smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1); 1132 } 1133 EXPORT_SYMBOL_GPL(arch_haltpoll_disable); 1134 #endif 1135