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 static int has_guest_poll = 0; 73 /* 74 * No need for any "IO delay" on KVM 75 */ 76 static void kvm_io_delay(void) 77 { 78 } 79 80 #define KVM_TASK_SLEEP_HASHBITS 8 81 #define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS) 82 83 struct kvm_task_sleep_node { 84 struct hlist_node link; 85 struct swait_queue_head wq; 86 u32 token; 87 int cpu; 88 }; 89 90 static struct kvm_task_sleep_head { 91 raw_spinlock_t lock; 92 struct hlist_head list; 93 } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE]; 94 95 static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b, 96 u32 token) 97 { 98 struct hlist_node *p; 99 100 hlist_for_each(p, &b->list) { 101 struct kvm_task_sleep_node *n = 102 hlist_entry(p, typeof(*n), link); 103 if (n->token == token) 104 return n; 105 } 106 107 return NULL; 108 } 109 110 static bool kvm_async_pf_queue_task(u32 token, struct kvm_task_sleep_node *n) 111 { 112 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS); 113 struct kvm_task_sleep_head *b = &async_pf_sleepers[key]; 114 struct kvm_task_sleep_node *e; 115 116 raw_spin_lock(&b->lock); 117 e = _find_apf_task(b, token); 118 if (e) { 119 /* dummy entry exist -> wake up was delivered ahead of PF */ 120 hlist_del(&e->link); 121 raw_spin_unlock(&b->lock); 122 kfree(e); 123 return false; 124 } 125 126 n->token = token; 127 n->cpu = smp_processor_id(); 128 init_swait_queue_head(&n->wq); 129 hlist_add_head(&n->link, &b->list); 130 raw_spin_unlock(&b->lock); 131 return true; 132 } 133 134 /* 135 * kvm_async_pf_task_wait_schedule - Wait for pagefault to be handled 136 * @token: Token to identify the sleep node entry 137 * 138 * Invoked from the async pagefault handling code or from the VM exit page 139 * fault handler. In both cases RCU is watching. 140 */ 141 void kvm_async_pf_task_wait_schedule(u32 token) 142 { 143 struct kvm_task_sleep_node n; 144 DECLARE_SWAITQUEUE(wait); 145 146 lockdep_assert_irqs_disabled(); 147 148 if (!kvm_async_pf_queue_task(token, &n)) 149 return; 150 151 for (;;) { 152 prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE); 153 if (hlist_unhashed(&n.link)) 154 break; 155 156 local_irq_enable(); 157 schedule(); 158 local_irq_disable(); 159 } 160 finish_swait(&n.wq, &wait); 161 } 162 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait_schedule); 163 164 static void apf_task_wake_one(struct kvm_task_sleep_node *n) 165 { 166 hlist_del_init(&n->link); 167 if (swq_has_sleeper(&n->wq)) 168 swake_up_one(&n->wq); 169 } 170 171 static void apf_task_wake_all(void) 172 { 173 int i; 174 175 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) { 176 struct kvm_task_sleep_head *b = &async_pf_sleepers[i]; 177 struct kvm_task_sleep_node *n; 178 struct hlist_node *p, *next; 179 180 raw_spin_lock(&b->lock); 181 hlist_for_each_safe(p, next, &b->list) { 182 n = hlist_entry(p, typeof(*n), link); 183 if (n->cpu == smp_processor_id()) 184 apf_task_wake_one(n); 185 } 186 raw_spin_unlock(&b->lock); 187 } 188 } 189 190 void kvm_async_pf_task_wake(u32 token) 191 { 192 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS); 193 struct kvm_task_sleep_head *b = &async_pf_sleepers[key]; 194 struct kvm_task_sleep_node *n, *dummy = NULL; 195 196 if (token == ~0) { 197 apf_task_wake_all(); 198 return; 199 } 200 201 again: 202 raw_spin_lock(&b->lock); 203 n = _find_apf_task(b, token); 204 if (!n) { 205 /* 206 * Async #PF not yet handled, add a dummy entry for the token. 207 * Allocating the token must be down outside of the raw lock 208 * as the allocator is preemptible on PREEMPT_RT kernels. 209 */ 210 if (!dummy) { 211 raw_spin_unlock(&b->lock); 212 dummy = kzalloc(sizeof(*dummy), GFP_ATOMIC); 213 214 /* 215 * Continue looping on allocation failure, eventually 216 * the async #PF will be handled and allocating a new 217 * node will be unnecessary. 218 */ 219 if (!dummy) 220 cpu_relax(); 221 222 /* 223 * Recheck for async #PF completion before enqueueing 224 * the dummy token to avoid duplicate list entries. 225 */ 226 goto again; 227 } 228 dummy->token = token; 229 dummy->cpu = smp_processor_id(); 230 init_swait_queue_head(&dummy->wq); 231 hlist_add_head(&dummy->link, &b->list); 232 dummy = NULL; 233 } else { 234 apf_task_wake_one(n); 235 } 236 raw_spin_unlock(&b->lock); 237 238 /* A dummy token might be allocated and ultimately not used. */ 239 kfree(dummy); 240 } 241 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake); 242 243 noinstr u32 kvm_read_and_reset_apf_flags(void) 244 { 245 u32 flags = 0; 246 247 if (__this_cpu_read(apf_reason.enabled)) { 248 flags = __this_cpu_read(apf_reason.flags); 249 __this_cpu_write(apf_reason.flags, 0); 250 } 251 252 return flags; 253 } 254 EXPORT_SYMBOL_GPL(kvm_read_and_reset_apf_flags); 255 256 noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token) 257 { 258 u32 flags = kvm_read_and_reset_apf_flags(); 259 irqentry_state_t state; 260 261 if (!flags) 262 return false; 263 264 state = irqentry_enter(regs); 265 instrumentation_begin(); 266 267 /* 268 * If the host managed to inject an async #PF into an interrupt 269 * disabled region, then die hard as this is not going to end well 270 * and the host side is seriously broken. 271 */ 272 if (unlikely(!(regs->flags & X86_EFLAGS_IF))) 273 panic("Host injected async #PF in interrupt disabled region\n"); 274 275 if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) { 276 if (unlikely(!(user_mode(regs)))) 277 panic("Host injected async #PF in kernel mode\n"); 278 /* Page is swapped out by the host. */ 279 kvm_async_pf_task_wait_schedule(token); 280 } else { 281 WARN_ONCE(1, "Unexpected async PF flags: %x\n", flags); 282 } 283 284 instrumentation_end(); 285 irqentry_exit(regs, state); 286 return true; 287 } 288 289 DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt) 290 { 291 struct pt_regs *old_regs = set_irq_regs(regs); 292 u32 token; 293 294 ack_APIC_irq(); 295 296 inc_irq_stat(irq_hv_callback_count); 297 298 if (__this_cpu_read(apf_reason.enabled)) { 299 token = __this_cpu_read(apf_reason.token); 300 kvm_async_pf_task_wake(token); 301 __this_cpu_write(apf_reason.token, 0); 302 wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1); 303 } 304 305 set_irq_regs(old_regs); 306 } 307 308 static void __init paravirt_ops_setup(void) 309 { 310 pv_info.name = "KVM"; 311 312 if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY)) 313 pv_ops.cpu.io_delay = kvm_io_delay; 314 315 #ifdef CONFIG_X86_IO_APIC 316 no_timer_check = 1; 317 #endif 318 } 319 320 static void kvm_register_steal_time(void) 321 { 322 int cpu = smp_processor_id(); 323 struct kvm_steal_time *st = &per_cpu(steal_time, cpu); 324 325 if (!has_steal_clock) 326 return; 327 328 wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED)); 329 pr_debug("stealtime: cpu %d, msr %llx\n", cpu, 330 (unsigned long long) slow_virt_to_phys(st)); 331 } 332 333 static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED; 334 335 static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val) 336 { 337 /** 338 * This relies on __test_and_clear_bit to modify the memory 339 * in a way that is atomic with respect to the local CPU. 340 * The hypervisor only accesses this memory from the local CPU so 341 * there's no need for lock or memory barriers. 342 * An optimization barrier is implied in apic write. 343 */ 344 if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi))) 345 return; 346 apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK); 347 } 348 349 static void kvm_guest_cpu_init(void) 350 { 351 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) { 352 u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason)); 353 354 WARN_ON_ONCE(!static_branch_likely(&kvm_async_pf_enabled)); 355 356 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason)); 357 pa |= KVM_ASYNC_PF_ENABLED | KVM_ASYNC_PF_DELIVERY_AS_INT; 358 359 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT)) 360 pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT; 361 362 wrmsrl(MSR_KVM_ASYNC_PF_INT, HYPERVISOR_CALLBACK_VECTOR); 363 364 wrmsrl(MSR_KVM_ASYNC_PF_EN, pa); 365 __this_cpu_write(apf_reason.enabled, 1); 366 pr_debug("setup async PF for cpu %d\n", smp_processor_id()); 367 } 368 369 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) { 370 unsigned long pa; 371 372 /* Size alignment is implied but just to make it explicit. */ 373 BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4); 374 __this_cpu_write(kvm_apic_eoi, 0); 375 pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi)) 376 | KVM_MSR_ENABLED; 377 wrmsrl(MSR_KVM_PV_EOI_EN, pa); 378 } 379 380 if (has_steal_clock) 381 kvm_register_steal_time(); 382 } 383 384 static void kvm_pv_disable_apf(void) 385 { 386 if (!__this_cpu_read(apf_reason.enabled)) 387 return; 388 389 wrmsrl(MSR_KVM_ASYNC_PF_EN, 0); 390 __this_cpu_write(apf_reason.enabled, 0); 391 392 pr_debug("disable async PF for cpu %d\n", smp_processor_id()); 393 } 394 395 static void kvm_disable_steal_time(void) 396 { 397 if (!has_steal_clock) 398 return; 399 400 wrmsr(MSR_KVM_STEAL_TIME, 0, 0); 401 } 402 403 static u64 kvm_steal_clock(int cpu) 404 { 405 u64 steal; 406 struct kvm_steal_time *src; 407 int version; 408 409 src = &per_cpu(steal_time, cpu); 410 do { 411 version = src->version; 412 virt_rmb(); 413 steal = src->steal; 414 virt_rmb(); 415 } while ((version & 1) || (version != src->version)); 416 417 return steal; 418 } 419 420 static inline void __set_percpu_decrypted(void *ptr, unsigned long size) 421 { 422 early_set_memory_decrypted((unsigned long) ptr, size); 423 } 424 425 /* 426 * Iterate through all possible CPUs and map the memory region pointed 427 * by apf_reason, steal_time and kvm_apic_eoi as decrypted at once. 428 * 429 * Note: we iterate through all possible CPUs to ensure that CPUs 430 * hotplugged will have their per-cpu variable already mapped as 431 * decrypted. 432 */ 433 static void __init sev_map_percpu_data(void) 434 { 435 int cpu; 436 437 if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)) 438 return; 439 440 for_each_possible_cpu(cpu) { 441 __set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason)); 442 __set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time)); 443 __set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi)); 444 } 445 } 446 447 static void kvm_guest_cpu_offline(bool shutdown) 448 { 449 kvm_disable_steal_time(); 450 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) 451 wrmsrl(MSR_KVM_PV_EOI_EN, 0); 452 if (kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) 453 wrmsrl(MSR_KVM_MIGRATION_CONTROL, 0); 454 kvm_pv_disable_apf(); 455 if (!shutdown) 456 apf_task_wake_all(); 457 kvmclock_disable(); 458 } 459 460 static int kvm_cpu_online(unsigned int cpu) 461 { 462 unsigned long flags; 463 464 local_irq_save(flags); 465 kvm_guest_cpu_init(); 466 local_irq_restore(flags); 467 return 0; 468 } 469 470 #ifdef CONFIG_SMP 471 472 static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask); 473 474 static bool pv_tlb_flush_supported(void) 475 { 476 return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) && 477 !kvm_para_has_hint(KVM_HINTS_REALTIME) && 478 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) && 479 !boot_cpu_has(X86_FEATURE_MWAIT) && 480 (num_possible_cpus() != 1)); 481 } 482 483 static bool pv_ipi_supported(void) 484 { 485 return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) && 486 (num_possible_cpus() != 1)); 487 } 488 489 static bool pv_sched_yield_supported(void) 490 { 491 return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) && 492 !kvm_para_has_hint(KVM_HINTS_REALTIME) && 493 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) && 494 !boot_cpu_has(X86_FEATURE_MWAIT) && 495 (num_possible_cpus() != 1)); 496 } 497 498 #define KVM_IPI_CLUSTER_SIZE (2 * BITS_PER_LONG) 499 500 static void __send_ipi_mask(const struct cpumask *mask, int vector) 501 { 502 unsigned long flags; 503 int cpu, apic_id, icr; 504 int min = 0, max = 0; 505 #ifdef CONFIG_X86_64 506 __uint128_t ipi_bitmap = 0; 507 #else 508 u64 ipi_bitmap = 0; 509 #endif 510 long ret; 511 512 if (cpumask_empty(mask)) 513 return; 514 515 local_irq_save(flags); 516 517 switch (vector) { 518 default: 519 icr = APIC_DM_FIXED | vector; 520 break; 521 case NMI_VECTOR: 522 icr = APIC_DM_NMI; 523 break; 524 } 525 526 for_each_cpu(cpu, mask) { 527 apic_id = per_cpu(x86_cpu_to_apicid, cpu); 528 if (!ipi_bitmap) { 529 min = max = apic_id; 530 } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) { 531 ipi_bitmap <<= min - apic_id; 532 min = apic_id; 533 } else if (apic_id > min && apic_id < min + KVM_IPI_CLUSTER_SIZE) { 534 max = apic_id < max ? max : apic_id; 535 } else { 536 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap, 537 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr); 538 WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld", 539 ret); 540 min = max = apic_id; 541 ipi_bitmap = 0; 542 } 543 __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap); 544 } 545 546 if (ipi_bitmap) { 547 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap, 548 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr); 549 WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld", 550 ret); 551 } 552 553 local_irq_restore(flags); 554 } 555 556 static void kvm_send_ipi_mask(const struct cpumask *mask, int vector) 557 { 558 __send_ipi_mask(mask, vector); 559 } 560 561 static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector) 562 { 563 unsigned int this_cpu = smp_processor_id(); 564 struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); 565 const struct cpumask *local_mask; 566 567 cpumask_copy(new_mask, mask); 568 cpumask_clear_cpu(this_cpu, new_mask); 569 local_mask = new_mask; 570 __send_ipi_mask(local_mask, vector); 571 } 572 573 static int __init setup_efi_kvm_sev_migration(void) 574 { 575 efi_char16_t efi_sev_live_migration_enabled[] = L"SevLiveMigrationEnabled"; 576 efi_guid_t efi_variable_guid = AMD_SEV_MEM_ENCRYPT_GUID; 577 efi_status_t status; 578 unsigned long size; 579 bool enabled; 580 581 if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) || 582 !kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) 583 return 0; 584 585 if (!efi_enabled(EFI_BOOT)) 586 return 0; 587 588 if (!efi_enabled(EFI_RUNTIME_SERVICES)) { 589 pr_info("%s : EFI runtime services are not enabled\n", __func__); 590 return 0; 591 } 592 593 size = sizeof(enabled); 594 595 /* Get variable contents into buffer */ 596 status = efi.get_variable(efi_sev_live_migration_enabled, 597 &efi_variable_guid, NULL, &size, &enabled); 598 599 if (status == EFI_NOT_FOUND) { 600 pr_info("%s : EFI live migration variable not found\n", __func__); 601 return 0; 602 } 603 604 if (status != EFI_SUCCESS) { 605 pr_info("%s : EFI variable retrieval failed\n", __func__); 606 return 0; 607 } 608 609 if (enabled == 0) { 610 pr_info("%s: live migration disabled in EFI\n", __func__); 611 return 0; 612 } 613 614 pr_info("%s : live migration enabled in EFI\n", __func__); 615 wrmsrl(MSR_KVM_MIGRATION_CONTROL, KVM_MIGRATION_READY); 616 617 return 1; 618 } 619 620 late_initcall(setup_efi_kvm_sev_migration); 621 622 /* 623 * Set the IPI entry points 624 */ 625 static void kvm_setup_pv_ipi(void) 626 { 627 apic->send_IPI_mask = kvm_send_ipi_mask; 628 apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself; 629 pr_info("setup PV IPIs\n"); 630 } 631 632 static void kvm_smp_send_call_func_ipi(const struct cpumask *mask) 633 { 634 int cpu; 635 636 native_send_call_func_ipi(mask); 637 638 /* Make sure other vCPUs get a chance to run if they need to. */ 639 for_each_cpu(cpu, mask) { 640 if (!idle_cpu(cpu) && vcpu_is_preempted(cpu)) { 641 kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu)); 642 break; 643 } 644 } 645 } 646 647 static void kvm_flush_tlb_multi(const struct cpumask *cpumask, 648 const struct flush_tlb_info *info) 649 { 650 u8 state; 651 int cpu; 652 struct kvm_steal_time *src; 653 struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); 654 655 cpumask_copy(flushmask, cpumask); 656 /* 657 * We have to call flush only on online vCPUs. And 658 * queue flush_on_enter for pre-empted vCPUs 659 */ 660 for_each_cpu(cpu, flushmask) { 661 /* 662 * The local vCPU is never preempted, so we do not explicitly 663 * skip check for local vCPU - it will never be cleared from 664 * flushmask. 665 */ 666 src = &per_cpu(steal_time, cpu); 667 state = READ_ONCE(src->preempted); 668 if ((state & KVM_VCPU_PREEMPTED)) { 669 if (try_cmpxchg(&src->preempted, &state, 670 state | KVM_VCPU_FLUSH_TLB)) 671 __cpumask_clear_cpu(cpu, flushmask); 672 } 673 } 674 675 native_flush_tlb_multi(flushmask, info); 676 } 677 678 static __init int kvm_alloc_cpumask(void) 679 { 680 int cpu; 681 682 if (!kvm_para_available() || nopv) 683 return 0; 684 685 if (pv_tlb_flush_supported() || pv_ipi_supported()) 686 for_each_possible_cpu(cpu) { 687 zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu), 688 GFP_KERNEL, cpu_to_node(cpu)); 689 } 690 691 return 0; 692 } 693 arch_initcall(kvm_alloc_cpumask); 694 695 static void __init kvm_smp_prepare_boot_cpu(void) 696 { 697 /* 698 * Map the per-cpu variables as decrypted before kvm_guest_cpu_init() 699 * shares the guest physical address with the hypervisor. 700 */ 701 sev_map_percpu_data(); 702 703 kvm_guest_cpu_init(); 704 native_smp_prepare_boot_cpu(); 705 kvm_spinlock_init(); 706 } 707 708 static int kvm_cpu_down_prepare(unsigned int cpu) 709 { 710 unsigned long flags; 711 712 local_irq_save(flags); 713 kvm_guest_cpu_offline(false); 714 local_irq_restore(flags); 715 return 0; 716 } 717 718 #endif 719 720 static int kvm_suspend(void) 721 { 722 u64 val = 0; 723 724 kvm_guest_cpu_offline(false); 725 726 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL 727 if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) 728 rdmsrl(MSR_KVM_POLL_CONTROL, val); 729 has_guest_poll = !(val & 1); 730 #endif 731 return 0; 732 } 733 734 static void kvm_resume(void) 735 { 736 kvm_cpu_online(raw_smp_processor_id()); 737 738 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL 739 if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL) && has_guest_poll) 740 wrmsrl(MSR_KVM_POLL_CONTROL, 0); 741 #endif 742 } 743 744 static struct syscore_ops kvm_syscore_ops = { 745 .suspend = kvm_suspend, 746 .resume = kvm_resume, 747 }; 748 749 static void kvm_pv_guest_cpu_reboot(void *unused) 750 { 751 kvm_guest_cpu_offline(true); 752 } 753 754 static int kvm_pv_reboot_notify(struct notifier_block *nb, 755 unsigned long code, void *unused) 756 { 757 if (code == SYS_RESTART) 758 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1); 759 return NOTIFY_DONE; 760 } 761 762 static struct notifier_block kvm_pv_reboot_nb = { 763 .notifier_call = kvm_pv_reboot_notify, 764 }; 765 766 /* 767 * After a PV feature is registered, the host will keep writing to the 768 * registered memory location. If the guest happens to shutdown, this memory 769 * won't be valid. In cases like kexec, in which you install a new kernel, this 770 * means a random memory location will be kept being written. 771 */ 772 #ifdef CONFIG_KEXEC_CORE 773 static void kvm_crash_shutdown(struct pt_regs *regs) 774 { 775 kvm_guest_cpu_offline(true); 776 native_machine_crash_shutdown(regs); 777 } 778 #endif 779 780 #if defined(CONFIG_X86_32) || !defined(CONFIG_SMP) 781 bool __kvm_vcpu_is_preempted(long cpu); 782 783 __visible bool __kvm_vcpu_is_preempted(long cpu) 784 { 785 struct kvm_steal_time *src = &per_cpu(steal_time, cpu); 786 787 return !!(src->preempted & KVM_VCPU_PREEMPTED); 788 } 789 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted); 790 791 #else 792 793 #include <asm/asm-offsets.h> 794 795 extern bool __raw_callee_save___kvm_vcpu_is_preempted(long); 796 797 /* 798 * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and 799 * restoring to/from the stack. 800 */ 801 asm( 802 ".pushsection .text;" 803 ".global __raw_callee_save___kvm_vcpu_is_preempted;" 804 ".type __raw_callee_save___kvm_vcpu_is_preempted, @function;" 805 "__raw_callee_save___kvm_vcpu_is_preempted:" 806 ASM_ENDBR 807 "movq __per_cpu_offset(,%rdi,8), %rax;" 808 "cmpb $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);" 809 "setne %al;" 810 ASM_RET 811 ".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;" 812 ".popsection"); 813 814 #endif 815 816 static void __init kvm_guest_init(void) 817 { 818 int i; 819 820 paravirt_ops_setup(); 821 register_reboot_notifier(&kvm_pv_reboot_nb); 822 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) 823 raw_spin_lock_init(&async_pf_sleepers[i].lock); 824 825 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) { 826 has_steal_clock = 1; 827 static_call_update(pv_steal_clock, kvm_steal_clock); 828 829 pv_ops.lock.vcpu_is_preempted = 830 PV_CALLEE_SAVE(__kvm_vcpu_is_preempted); 831 } 832 833 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) 834 apic_set_eoi_write(kvm_guest_apic_eoi_write); 835 836 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) { 837 static_branch_enable(&kvm_async_pf_enabled); 838 alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_kvm_asyncpf_interrupt); 839 } 840 841 #ifdef CONFIG_SMP 842 if (pv_tlb_flush_supported()) { 843 pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi; 844 pv_ops.mmu.tlb_remove_table = tlb_remove_table; 845 pr_info("KVM setup pv remote TLB flush\n"); 846 } 847 848 smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; 849 if (pv_sched_yield_supported()) { 850 smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi; 851 pr_info("setup PV sched yield\n"); 852 } 853 if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online", 854 kvm_cpu_online, kvm_cpu_down_prepare) < 0) 855 pr_err("failed to install cpu hotplug callbacks\n"); 856 #else 857 sev_map_percpu_data(); 858 kvm_guest_cpu_init(); 859 #endif 860 861 #ifdef CONFIG_KEXEC_CORE 862 machine_ops.crash_shutdown = kvm_crash_shutdown; 863 #endif 864 865 register_syscore_ops(&kvm_syscore_ops); 866 867 /* 868 * Hard lockup detection is enabled by default. Disable it, as guests 869 * can get false positives too easily, for example if the host is 870 * overcommitted. 871 */ 872 hardlockup_detector_disable(); 873 } 874 875 static noinline uint32_t __kvm_cpuid_base(void) 876 { 877 if (boot_cpu_data.cpuid_level < 0) 878 return 0; /* So we don't blow up on old processors */ 879 880 if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) 881 return hypervisor_cpuid_base(KVM_SIGNATURE, 0); 882 883 return 0; 884 } 885 886 static inline uint32_t kvm_cpuid_base(void) 887 { 888 static int kvm_cpuid_base = -1; 889 890 if (kvm_cpuid_base == -1) 891 kvm_cpuid_base = __kvm_cpuid_base(); 892 893 return kvm_cpuid_base; 894 } 895 896 bool kvm_para_available(void) 897 { 898 return kvm_cpuid_base() != 0; 899 } 900 EXPORT_SYMBOL_GPL(kvm_para_available); 901 902 unsigned int kvm_arch_para_features(void) 903 { 904 return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES); 905 } 906 907 unsigned int kvm_arch_para_hints(void) 908 { 909 return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES); 910 } 911 EXPORT_SYMBOL_GPL(kvm_arch_para_hints); 912 913 static uint32_t __init kvm_detect(void) 914 { 915 return kvm_cpuid_base(); 916 } 917 918 static void __init kvm_apic_init(void) 919 { 920 #ifdef CONFIG_SMP 921 if (pv_ipi_supported()) 922 kvm_setup_pv_ipi(); 923 #endif 924 } 925 926 static bool __init kvm_msi_ext_dest_id(void) 927 { 928 return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID); 929 } 930 931 static void kvm_sev_hc_page_enc_status(unsigned long pfn, int npages, bool enc) 932 { 933 kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, pfn << PAGE_SHIFT, npages, 934 KVM_MAP_GPA_RANGE_ENC_STAT(enc) | KVM_MAP_GPA_RANGE_PAGE_SZ_4K); 935 } 936 937 static void __init kvm_init_platform(void) 938 { 939 if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) && 940 kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) { 941 unsigned long nr_pages; 942 int i; 943 944 pv_ops.mmu.notify_page_enc_status_changed = 945 kvm_sev_hc_page_enc_status; 946 947 /* 948 * Reset the host's shared pages list related to kernel 949 * specific page encryption status settings before we load a 950 * new kernel by kexec. Reset the page encryption status 951 * during early boot intead of just before kexec to avoid SMP 952 * races during kvm_pv_guest_cpu_reboot(). 953 * NOTE: We cannot reset the complete shared pages list 954 * here as we need to retain the UEFI/OVMF firmware 955 * specific settings. 956 */ 957 958 for (i = 0; i < e820_table->nr_entries; i++) { 959 struct e820_entry *entry = &e820_table->entries[i]; 960 961 if (entry->type != E820_TYPE_RAM) 962 continue; 963 964 nr_pages = DIV_ROUND_UP(entry->size, PAGE_SIZE); 965 966 kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, entry->addr, 967 nr_pages, 968 KVM_MAP_GPA_RANGE_ENCRYPTED | KVM_MAP_GPA_RANGE_PAGE_SZ_4K); 969 } 970 971 /* 972 * Ensure that _bss_decrypted section is marked as decrypted in the 973 * shared pages list. 974 */ 975 nr_pages = DIV_ROUND_UP(__end_bss_decrypted - __start_bss_decrypted, 976 PAGE_SIZE); 977 early_set_mem_enc_dec_hypercall((unsigned long)__start_bss_decrypted, 978 nr_pages, 0); 979 980 /* 981 * If not booted using EFI, enable Live migration support. 982 */ 983 if (!efi_enabled(EFI_BOOT)) 984 wrmsrl(MSR_KVM_MIGRATION_CONTROL, 985 KVM_MIGRATION_READY); 986 } 987 kvmclock_init(); 988 x86_platform.apic_post_init = kvm_apic_init; 989 } 990 991 #if defined(CONFIG_AMD_MEM_ENCRYPT) 992 static void kvm_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs) 993 { 994 /* RAX and CPL are already in the GHCB */ 995 ghcb_set_rbx(ghcb, regs->bx); 996 ghcb_set_rcx(ghcb, regs->cx); 997 ghcb_set_rdx(ghcb, regs->dx); 998 ghcb_set_rsi(ghcb, regs->si); 999 } 1000 1001 static bool kvm_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs) 1002 { 1003 /* No checking of the return state needed */ 1004 return true; 1005 } 1006 #endif 1007 1008 const __initconst struct hypervisor_x86 x86_hyper_kvm = { 1009 .name = "KVM", 1010 .detect = kvm_detect, 1011 .type = X86_HYPER_KVM, 1012 .init.guest_late_init = kvm_guest_init, 1013 .init.x2apic_available = kvm_para_available, 1014 .init.msi_ext_dest_id = kvm_msi_ext_dest_id, 1015 .init.init_platform = kvm_init_platform, 1016 #if defined(CONFIG_AMD_MEM_ENCRYPT) 1017 .runtime.sev_es_hcall_prepare = kvm_sev_es_hcall_prepare, 1018 .runtime.sev_es_hcall_finish = kvm_sev_es_hcall_finish, 1019 #endif 1020 }; 1021 1022 static __init int activate_jump_labels(void) 1023 { 1024 if (has_steal_clock) { 1025 static_key_slow_inc(¶virt_steal_enabled); 1026 if (steal_acc) 1027 static_key_slow_inc(¶virt_steal_rq_enabled); 1028 } 1029 1030 return 0; 1031 } 1032 arch_initcall(activate_jump_labels); 1033 1034 #ifdef CONFIG_PARAVIRT_SPINLOCKS 1035 1036 /* Kick a cpu by its apicid. Used to wake up a halted vcpu */ 1037 static void kvm_kick_cpu(int cpu) 1038 { 1039 int apicid; 1040 unsigned long flags = 0; 1041 1042 apicid = per_cpu(x86_cpu_to_apicid, cpu); 1043 kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid); 1044 } 1045 1046 #include <asm/qspinlock.h> 1047 1048 static void kvm_wait(u8 *ptr, u8 val) 1049 { 1050 if (in_nmi()) 1051 return; 1052 1053 /* 1054 * halt until it's our turn and kicked. Note that we do safe halt 1055 * for irq enabled case to avoid hang when lock info is overwritten 1056 * in irq spinlock slowpath and no spurious interrupt occur to save us. 1057 */ 1058 if (irqs_disabled()) { 1059 if (READ_ONCE(*ptr) == val) 1060 halt(); 1061 } else { 1062 local_irq_disable(); 1063 1064 /* safe_halt() will enable IRQ */ 1065 if (READ_ONCE(*ptr) == val) 1066 safe_halt(); 1067 else 1068 local_irq_enable(); 1069 } 1070 } 1071 1072 /* 1073 * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present. 1074 */ 1075 void __init kvm_spinlock_init(void) 1076 { 1077 /* 1078 * In case host doesn't support KVM_FEATURE_PV_UNHALT there is still an 1079 * advantage of keeping virt_spin_lock_key enabled: virt_spin_lock() is 1080 * preferred over native qspinlock when vCPU is preempted. 1081 */ 1082 if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) { 1083 pr_info("PV spinlocks disabled, no host support\n"); 1084 return; 1085 } 1086 1087 /* 1088 * Disable PV spinlocks and use native qspinlock when dedicated pCPUs 1089 * are available. 1090 */ 1091 if (kvm_para_has_hint(KVM_HINTS_REALTIME)) { 1092 pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n"); 1093 goto out; 1094 } 1095 1096 if (num_possible_cpus() == 1) { 1097 pr_info("PV spinlocks disabled, single CPU\n"); 1098 goto out; 1099 } 1100 1101 if (nopvspin) { 1102 pr_info("PV spinlocks disabled, forced by \"nopvspin\" parameter\n"); 1103 goto out; 1104 } 1105 1106 pr_info("PV spinlocks enabled\n"); 1107 1108 __pv_init_lock_hash(); 1109 pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath; 1110 pv_ops.lock.queued_spin_unlock = 1111 PV_CALLEE_SAVE(__pv_queued_spin_unlock); 1112 pv_ops.lock.wait = kvm_wait; 1113 pv_ops.lock.kick = kvm_kick_cpu; 1114 1115 /* 1116 * When PV spinlock is enabled which is preferred over 1117 * virt_spin_lock(), virt_spin_lock_key's value is meaningless. 1118 * Just disable it anyway. 1119 */ 1120 out: 1121 static_branch_disable(&virt_spin_lock_key); 1122 } 1123 1124 #endif /* CONFIG_PARAVIRT_SPINLOCKS */ 1125 1126 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL 1127 1128 static void kvm_disable_host_haltpoll(void *i) 1129 { 1130 wrmsrl(MSR_KVM_POLL_CONTROL, 0); 1131 } 1132 1133 static void kvm_enable_host_haltpoll(void *i) 1134 { 1135 wrmsrl(MSR_KVM_POLL_CONTROL, 1); 1136 } 1137 1138 void arch_haltpoll_enable(unsigned int cpu) 1139 { 1140 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) { 1141 pr_err_once("host does not support poll control\n"); 1142 pr_err_once("host upgrade recommended\n"); 1143 return; 1144 } 1145 1146 /* Enable guest halt poll disables host halt poll */ 1147 smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1); 1148 } 1149 EXPORT_SYMBOL_GPL(arch_haltpoll_enable); 1150 1151 void arch_haltpoll_disable(unsigned int cpu) 1152 { 1153 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) 1154 return; 1155 1156 /* Disable guest halt poll enables host halt poll */ 1157 smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1); 1158 } 1159 EXPORT_SYMBOL_GPL(arch_haltpoll_disable); 1160 #endif 1161