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 47DEFINE_STATIC_KEY_FALSE(kvm_async_pf_enabled); 48 49static int kvmapf = 1; 50 51static int __init parse_no_kvmapf(char *arg) 52{ 53 kvmapf = 0; 54 return 0; 55} 56 57early_param("no-kvmapf", parse_no_kvmapf); 58 59static int steal_acc = 1; 60static int __init parse_no_stealacc(char *arg) 61{ 62 steal_acc = 0; 63 return 0; 64} 65 66early_param("no-steal-acc", parse_no_stealacc); 67 68static DEFINE_PER_CPU_READ_MOSTLY(bool, async_pf_enabled); 69static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64); 70DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64) __visible; 71static int has_steal_clock = 0; 72 73static int has_guest_poll = 0; 74/* 75 * No need for any "IO delay" on KVM 76 */ 77static 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 84struct kvm_task_sleep_node { 85 struct hlist_node link; 86 struct swait_queue_head wq; 87 u32 token; 88 int cpu; 89}; 90 91static struct kvm_task_sleep_head { 92 raw_spinlock_t lock; 93 struct hlist_head list; 94} async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE]; 95 96static 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 111static 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 */ 142void 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} 163EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait_schedule); 164 165static 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 172static 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 191void 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 202again: 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} 242EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake); 243 244noinstr 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} 255EXPORT_SYMBOL_GPL(kvm_read_and_reset_apf_flags); 256 257noinstr 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 290DEFINE_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 309static 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 321static 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 334static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED; 335 336static 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 350static 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 385static 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 396static 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 404static 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 421static 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 */ 434static 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 449static 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 462static 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 474static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask); 475 476static 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 485static bool pv_ipi_supported(void) 486{ 487 return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) && 488 (num_possible_cpus() != 1)); 489} 490 491static 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 502static 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 558static void kvm_send_ipi_mask(const struct cpumask *mask, int vector) 559{ 560 __send_ipi_mask(mask, vector); 561} 562 563static 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 575static 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 622late_initcall(setup_efi_kvm_sev_migration); 623 624/* 625 * Set the IPI entry points 626 */ 627static __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 634static 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 649static 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 680static __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} 695arch_initcall(kvm_alloc_cpumask); 696 697static 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 710static 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 722static 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 736static 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 746static struct syscore_ops kvm_syscore_ops = { 747 .suspend = kvm_suspend, 748 .resume = kvm_resume, 749}; 750 751static void kvm_pv_guest_cpu_reboot(void *unused) 752{ 753 kvm_guest_cpu_offline(true); 754} 755 756static 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 764static 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 775static 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) 783bool __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} 791PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted); 792 793#else 794 795#include <asm/asm-offsets.h> 796 797extern 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 808DEFINE_ASM_FUNC(__raw_callee_save___kvm_vcpu_is_preempted, 809 PV_VCPU_PREEMPTED_ASM, .text); 810#endif 811 812static 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 871static 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 882static 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 892bool kvm_para_available(void) 893{ 894 return kvm_cpuid_base() != 0; 895} 896EXPORT_SYMBOL_GPL(kvm_para_available); 897 898unsigned int kvm_arch_para_features(void) 899{ 900 return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES); 901} 902 903unsigned int kvm_arch_para_hints(void) 904{ 905 return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES); 906} 907EXPORT_SYMBOL_GPL(kvm_arch_para_hints); 908 909static uint32_t __init kvm_detect(void) 910{ 911 return kvm_cpuid_base(); 912} 913 914static 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 922static bool __init kvm_msi_ext_dest_id(void) 923{ 924 return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID); 925} 926 927static 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 933static 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) 986static 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 995static 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 1002const __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 1016static __init int activate_jump_labels(void) 1017{ 1018 if (has_steal_clock) { 1019 static_key_slow_inc(¶virt_steal_enabled); 1020 if (steal_acc) 1021 static_key_slow_inc(¶virt_steal_rq_enabled); 1022 } 1023 1024 return 0; 1025} 1026arch_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 */ 1031static 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 1042static 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 */ 1069void __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 */ 1114out: 1115 static_branch_disable(&virt_spin_lock_key); 1116} 1117 1118#endif /* CONFIG_PARAVIRT_SPINLOCKS */ 1119 1120#ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL 1121 1122static void kvm_disable_host_haltpoll(void *i) 1123{ 1124 wrmsrl(MSR_KVM_POLL_CONTROL, 0); 1125} 1126 1127static void kvm_enable_host_haltpoll(void *i) 1128{ 1129 wrmsrl(MSR_KVM_POLL_CONTROL, 1); 1130} 1131 1132void 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} 1143EXPORT_SYMBOL_GPL(arch_haltpoll_enable); 1144 1145void 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} 1153EXPORT_SYMBOL_GPL(arch_haltpoll_disable); 1154#endif 1155