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 <linux/kvm_types.h> 33 #include <linux/sched/cputime.h> 34 #include <asm/timer.h> 35 #include <asm/cpu.h> 36 #include <asm/traps.h> 37 #include <asm/desc.h> 38 #include <asm/tlbflush.h> 39 #include <asm/apic.h> 40 #include <asm/apicdef.h> 41 #include <asm/hypervisor.h> 42 #include <asm/mtrr.h> 43 #include <asm/tlb.h> 44 #include <asm/cpuidle_haltpoll.h> 45 #include <asm/msr.h> 46 #include <asm/ptrace.h> 47 #include <asm/reboot.h> 48 #include <asm/svm.h> 49 #include <asm/e820/api.h> 50 51 DEFINE_STATIC_KEY_FALSE_RO(kvm_async_pf_enabled); 52 53 static int kvmapf = 1; 54 55 static int __init parse_no_kvmapf(char *arg) 56 { 57 kvmapf = 0; 58 return 0; 59 } 60 61 early_param("no-kvmapf", parse_no_kvmapf); 62 63 static int steal_acc = 1; 64 static int __init parse_no_stealacc(char *arg) 65 { 66 steal_acc = 0; 67 return 0; 68 } 69 70 early_param("no-steal-acc", parse_no_stealacc); 71 72 static DEFINE_PER_CPU_READ_MOSTLY(bool, async_pf_enabled); 73 static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64); 74 DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64) __visible; 75 static int has_steal_clock = 0; 76 77 static int has_guest_poll = 0; 78 /* 79 * No need for any "IO delay" on KVM 80 */ 81 static void kvm_io_delay(void) 82 { 83 } 84 85 #define KVM_TASK_SLEEP_HASHBITS 8 86 #define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS) 87 88 struct kvm_task_sleep_node { 89 struct hlist_node link; 90 struct swait_queue_head wq; 91 u32 token; 92 int cpu; 93 bool dummy; 94 }; 95 96 static struct kvm_task_sleep_head { 97 raw_spinlock_t lock; 98 struct hlist_head list; 99 } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE]; 100 101 static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b, 102 u32 token) 103 { 104 struct hlist_node *p; 105 106 hlist_for_each(p, &b->list) { 107 struct kvm_task_sleep_node *n = 108 hlist_entry(p, typeof(*n), link); 109 if (n->token == token) 110 return n; 111 } 112 113 return NULL; 114 } 115 116 static bool kvm_async_pf_queue_task(u32 token, struct kvm_task_sleep_node *n) 117 { 118 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS); 119 struct kvm_task_sleep_head *b = &async_pf_sleepers[key]; 120 struct kvm_task_sleep_node *e; 121 122 raw_spin_lock(&b->lock); 123 e = _find_apf_task(b, token); 124 if (e) { 125 struct kvm_task_sleep_node *dummy = NULL; 126 127 /* 128 * The entry can either be a 'dummy' entry (which is put on the 129 * list when wake-up happens ahead of APF handling completion) 130 * or a token from another task which should not be touched. 131 */ 132 if (e->dummy) { 133 hlist_del(&e->link); 134 dummy = e; 135 } 136 137 raw_spin_unlock(&b->lock); 138 kfree(dummy); 139 return false; 140 } 141 142 n->token = token; 143 n->cpu = smp_processor_id(); 144 n->dummy = false; 145 init_swait_queue_head(&n->wq); 146 hlist_add_head(&n->link, &b->list); 147 raw_spin_unlock(&b->lock); 148 return true; 149 } 150 151 /* 152 * kvm_async_pf_task_wait_schedule - Wait for pagefault to be handled 153 * @token: Token to identify the sleep node entry 154 * 155 * Invoked from the async pagefault handling code or from the VM exit page 156 * fault handler. In both cases RCU is watching. 157 */ 158 void kvm_async_pf_task_wait_schedule(u32 token) 159 { 160 struct kvm_task_sleep_node n; 161 DECLARE_SWAITQUEUE(wait); 162 163 lockdep_assert_irqs_disabled(); 164 165 if (!kvm_async_pf_queue_task(token, &n)) 166 return; 167 168 for (;;) { 169 prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE); 170 if (hlist_unhashed(&n.link)) 171 break; 172 173 local_irq_enable(); 174 schedule(); 175 local_irq_disable(); 176 } 177 finish_swait(&n.wq, &wait); 178 } 179 EXPORT_SYMBOL_FOR_KVM(kvm_async_pf_task_wait_schedule); 180 181 static void apf_task_wake_one(struct kvm_task_sleep_node *n) 182 { 183 hlist_del_init(&n->link); 184 if (swq_has_sleeper(&n->wq)) 185 swake_up_one(&n->wq); 186 } 187 188 static void apf_task_wake_all(void) 189 { 190 int i; 191 192 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) { 193 struct kvm_task_sleep_head *b = &async_pf_sleepers[i]; 194 struct kvm_task_sleep_node *n; 195 struct hlist_node *p, *next; 196 197 raw_spin_lock(&b->lock); 198 hlist_for_each_safe(p, next, &b->list) { 199 n = hlist_entry(p, typeof(*n), link); 200 if (n->cpu == smp_processor_id()) 201 apf_task_wake_one(n); 202 } 203 raw_spin_unlock(&b->lock); 204 } 205 } 206 207 static void kvm_async_pf_task_wake(u32 token) 208 { 209 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS); 210 struct kvm_task_sleep_head *b = &async_pf_sleepers[key]; 211 struct kvm_task_sleep_node *n, *dummy = NULL; 212 213 if (token == ~0) { 214 apf_task_wake_all(); 215 return; 216 } 217 218 again: 219 raw_spin_lock(&b->lock); 220 n = _find_apf_task(b, token); 221 if (!n) { 222 /* 223 * Async #PF not yet handled, add a dummy entry for the token. 224 * Allocating the token must be down outside of the raw lock 225 * as the allocator is preemptible on PREEMPT_RT kernels. 226 */ 227 if (!dummy) { 228 raw_spin_unlock(&b->lock); 229 dummy = kzalloc(sizeof(*dummy), GFP_ATOMIC); 230 231 /* 232 * Continue looping on allocation failure, eventually 233 * the async #PF will be handled and allocating a new 234 * node will be unnecessary. 235 */ 236 if (!dummy) 237 cpu_relax(); 238 239 /* 240 * Recheck for async #PF completion before enqueueing 241 * the dummy token to avoid duplicate list entries. 242 */ 243 goto again; 244 } 245 dummy->token = token; 246 dummy->cpu = smp_processor_id(); 247 dummy->dummy = true; 248 init_swait_queue_head(&dummy->wq); 249 hlist_add_head(&dummy->link, &b->list); 250 dummy = NULL; 251 } else { 252 apf_task_wake_one(n); 253 } 254 raw_spin_unlock(&b->lock); 255 256 /* A dummy token might be allocated and ultimately not used. */ 257 kfree(dummy); 258 } 259 260 noinstr u32 kvm_read_and_reset_apf_flags(void) 261 { 262 u32 flags = 0; 263 264 if (__this_cpu_read(async_pf_enabled)) { 265 flags = __this_cpu_read(apf_reason.flags); 266 __this_cpu_write(apf_reason.flags, 0); 267 } 268 269 return flags; 270 } 271 EXPORT_SYMBOL_FOR_KVM(kvm_read_and_reset_apf_flags); 272 273 noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token) 274 { 275 u32 flags = kvm_read_and_reset_apf_flags(); 276 irqentry_state_t state; 277 278 if (!flags) 279 return false; 280 281 state = irqentry_enter(regs); 282 instrumentation_begin(); 283 284 /* 285 * If the host managed to inject an async #PF into an interrupt 286 * disabled region, then die hard as this is not going to end well 287 * and the host side is seriously broken. 288 */ 289 if (unlikely(!(regs->flags & X86_EFLAGS_IF))) 290 panic("Host injected async #PF in interrupt disabled region\n"); 291 292 if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) { 293 if (unlikely(!(user_mode(regs)))) 294 panic("Host injected async #PF in kernel mode\n"); 295 /* Page is swapped out by the host. */ 296 kvm_async_pf_task_wait_schedule(token); 297 } else { 298 WARN_ONCE(1, "Unexpected async PF flags: %x\n", flags); 299 } 300 301 instrumentation_end(); 302 irqentry_exit(regs, state); 303 return true; 304 } 305 306 DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt) 307 { 308 struct pt_regs *old_regs = set_irq_regs(regs); 309 u32 token; 310 311 apic_eoi(); 312 313 inc_irq_stat(irq_hv_callback_count); 314 315 if (__this_cpu_read(async_pf_enabled)) { 316 token = __this_cpu_read(apf_reason.token); 317 kvm_async_pf_task_wake(token); 318 __this_cpu_write(apf_reason.token, 0); 319 wrmsrq(MSR_KVM_ASYNC_PF_ACK, 1); 320 } 321 322 set_irq_regs(old_regs); 323 } 324 325 static void __init paravirt_ops_setup(void) 326 { 327 pv_info.name = "KVM"; 328 329 if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY)) 330 pv_ops.cpu.io_delay = kvm_io_delay; 331 332 #ifdef CONFIG_X86_IO_APIC 333 no_timer_check = 1; 334 #endif 335 } 336 337 static void kvm_register_steal_time(void) 338 { 339 int cpu = smp_processor_id(); 340 struct kvm_steal_time *st = &per_cpu(steal_time, cpu); 341 342 if (!has_steal_clock) 343 return; 344 345 wrmsrq(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED)); 346 pr_debug("stealtime: cpu %d, msr %llx\n", cpu, 347 (unsigned long long) slow_virt_to_phys(st)); 348 } 349 350 static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED; 351 352 static notrace __maybe_unused void kvm_guest_apic_eoi_write(void) 353 { 354 /** 355 * This relies on __test_and_clear_bit to modify the memory 356 * in a way that is atomic with respect to the local CPU. 357 * The hypervisor only accesses this memory from the local CPU so 358 * there's no need for lock or memory barriers. 359 * An optimization barrier is implied in apic write. 360 */ 361 if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi))) 362 return; 363 apic_native_eoi(); 364 } 365 366 static void kvm_guest_cpu_init(void) 367 { 368 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) { 369 u64 pa; 370 371 WARN_ON_ONCE(!static_branch_likely(&kvm_async_pf_enabled)); 372 373 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason)); 374 pa |= KVM_ASYNC_PF_ENABLED | KVM_ASYNC_PF_DELIVERY_AS_INT; 375 376 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT)) 377 pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT; 378 379 wrmsrq(MSR_KVM_ASYNC_PF_INT, HYPERVISOR_CALLBACK_VECTOR); 380 381 wrmsrq(MSR_KVM_ASYNC_PF_EN, pa); 382 __this_cpu_write(async_pf_enabled, true); 383 pr_debug("setup async PF for cpu %d\n", smp_processor_id()); 384 } 385 386 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) { 387 unsigned long pa; 388 389 /* Size alignment is implied but just to make it explicit. */ 390 BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4); 391 __this_cpu_write(kvm_apic_eoi, 0); 392 pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi)) 393 | KVM_MSR_ENABLED; 394 wrmsrq(MSR_KVM_PV_EOI_EN, pa); 395 } 396 397 if (has_steal_clock) 398 kvm_register_steal_time(); 399 } 400 401 static void kvm_pv_disable_apf(void) 402 { 403 if (!__this_cpu_read(async_pf_enabled)) 404 return; 405 406 wrmsrq(MSR_KVM_ASYNC_PF_EN, 0); 407 __this_cpu_write(async_pf_enabled, false); 408 409 pr_debug("disable async PF for cpu %d\n", smp_processor_id()); 410 } 411 412 static void kvm_disable_steal_time(void) 413 { 414 if (!has_steal_clock) 415 return; 416 417 wrmsrq(MSR_KVM_STEAL_TIME, 0); 418 } 419 420 static u64 kvm_steal_clock(int cpu) 421 { 422 u64 steal; 423 struct kvm_steal_time *src; 424 int version; 425 426 src = &per_cpu(steal_time, cpu); 427 do { 428 version = src->version; 429 virt_rmb(); 430 steal = src->steal; 431 virt_rmb(); 432 } while ((version & 1) || (version != src->version)); 433 434 return steal; 435 } 436 437 static inline __init void __set_percpu_decrypted(void *ptr, unsigned long size) 438 { 439 early_set_memory_decrypted((unsigned long) ptr, size); 440 } 441 442 /* 443 * Iterate through all possible CPUs and map the memory region pointed 444 * by apf_reason, steal_time and kvm_apic_eoi as decrypted at once. 445 * 446 * Note: we iterate through all possible CPUs to ensure that CPUs 447 * hotplugged will have their per-cpu variable already mapped as 448 * decrypted. 449 */ 450 static void __init sev_map_percpu_data(void) 451 { 452 int cpu; 453 454 if (cc_vendor != CC_VENDOR_AMD || 455 !cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)) 456 return; 457 458 for_each_possible_cpu(cpu) { 459 __set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason)); 460 __set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time)); 461 __set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi)); 462 } 463 } 464 465 static void kvm_guest_cpu_offline(bool shutdown) 466 { 467 kvm_disable_steal_time(); 468 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) 469 wrmsrq(MSR_KVM_PV_EOI_EN, 0); 470 if (kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) 471 wrmsrq(MSR_KVM_MIGRATION_CONTROL, 0); 472 kvm_pv_disable_apf(); 473 if (!shutdown) 474 apf_task_wake_all(); 475 kvmclock_disable(); 476 } 477 478 static int kvm_cpu_online(unsigned int cpu) 479 { 480 unsigned long flags; 481 482 local_irq_save(flags); 483 kvm_guest_cpu_init(); 484 local_irq_restore(flags); 485 return 0; 486 } 487 488 #ifdef CONFIG_SMP 489 490 static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask); 491 492 static bool pv_tlb_flush_supported(void) 493 { 494 return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) && 495 !kvm_para_has_hint(KVM_HINTS_REALTIME) && 496 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) && 497 !boot_cpu_has(X86_FEATURE_MWAIT) && 498 (num_possible_cpus() != 1)); 499 } 500 501 static bool pv_ipi_supported(void) 502 { 503 return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) && 504 (num_possible_cpus() != 1)); 505 } 506 507 static bool pv_sched_yield_supported(void) 508 { 509 return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) && 510 !kvm_para_has_hint(KVM_HINTS_REALTIME) && 511 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) && 512 !boot_cpu_has(X86_FEATURE_MWAIT) && 513 (num_possible_cpus() != 1)); 514 } 515 516 #define KVM_IPI_CLUSTER_SIZE (2 * BITS_PER_LONG) 517 518 static void __send_ipi_mask(const struct cpumask *mask, int vector) 519 { 520 unsigned long flags; 521 int cpu, min = 0, max = 0; 522 #ifdef CONFIG_X86_64 523 __uint128_t ipi_bitmap = 0; 524 #else 525 u64 ipi_bitmap = 0; 526 #endif 527 u32 apic_id, icr; 528 long ret; 529 530 if (cpumask_empty(mask)) 531 return; 532 533 local_irq_save(flags); 534 535 switch (vector) { 536 default: 537 icr = APIC_DM_FIXED | vector; 538 break; 539 case NMI_VECTOR: 540 icr = APIC_DM_NMI; 541 break; 542 } 543 544 for_each_cpu(cpu, mask) { 545 apic_id = per_cpu(x86_cpu_to_apicid, cpu); 546 if (!ipi_bitmap) { 547 min = max = apic_id; 548 } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) { 549 ipi_bitmap <<= min - apic_id; 550 min = apic_id; 551 } else if (apic_id > min && apic_id < min + KVM_IPI_CLUSTER_SIZE) { 552 max = apic_id < max ? max : apic_id; 553 } else { 554 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap, 555 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr); 556 WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld", 557 ret); 558 min = max = apic_id; 559 ipi_bitmap = 0; 560 } 561 __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap); 562 } 563 564 if (ipi_bitmap) { 565 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap, 566 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr); 567 WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld", 568 ret); 569 } 570 571 local_irq_restore(flags); 572 } 573 574 static void kvm_send_ipi_mask(const struct cpumask *mask, int vector) 575 { 576 __send_ipi_mask(mask, vector); 577 } 578 579 static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector) 580 { 581 unsigned int this_cpu = smp_processor_id(); 582 struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); 583 const struct cpumask *local_mask; 584 585 cpumask_copy(new_mask, mask); 586 cpumask_clear_cpu(this_cpu, new_mask); 587 local_mask = new_mask; 588 __send_ipi_mask(local_mask, vector); 589 } 590 591 static int __init setup_efi_kvm_sev_migration(void) 592 { 593 efi_char16_t efi_sev_live_migration_enabled[] = L"SevLiveMigrationEnabled"; 594 efi_guid_t efi_variable_guid = AMD_SEV_MEM_ENCRYPT_GUID; 595 efi_status_t status; 596 unsigned long size; 597 bool enabled; 598 599 if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) || 600 !kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) 601 return 0; 602 603 if (!efi_enabled(EFI_BOOT)) 604 return 0; 605 606 if (!efi_enabled(EFI_RUNTIME_SERVICES)) { 607 pr_info("%s : EFI runtime services are not enabled\n", __func__); 608 return 0; 609 } 610 611 size = sizeof(enabled); 612 613 /* Get variable contents into buffer */ 614 status = efi.get_variable(efi_sev_live_migration_enabled, 615 &efi_variable_guid, NULL, &size, &enabled); 616 617 if (status == EFI_NOT_FOUND) { 618 pr_info("%s : EFI live migration variable not found\n", __func__); 619 return 0; 620 } 621 622 if (status != EFI_SUCCESS) { 623 pr_info("%s : EFI variable retrieval failed\n", __func__); 624 return 0; 625 } 626 627 if (enabled == 0) { 628 pr_info("%s: live migration disabled in EFI\n", __func__); 629 return 0; 630 } 631 632 pr_info("%s : live migration enabled in EFI\n", __func__); 633 wrmsrq(MSR_KVM_MIGRATION_CONTROL, KVM_MIGRATION_READY); 634 635 return 1; 636 } 637 638 late_initcall(setup_efi_kvm_sev_migration); 639 640 /* 641 * Set the IPI entry points 642 */ 643 static __init void kvm_setup_pv_ipi(void) 644 { 645 apic_update_callback(send_IPI_mask, kvm_send_ipi_mask); 646 apic_update_callback(send_IPI_mask_allbutself, kvm_send_ipi_mask_allbutself); 647 pr_info("setup PV IPIs\n"); 648 } 649 650 static void kvm_smp_send_call_func_ipi(const struct cpumask *mask) 651 { 652 int cpu; 653 654 native_send_call_func_ipi(mask); 655 656 /* Make sure other vCPUs get a chance to run if they need to. */ 657 for_each_cpu(cpu, mask) { 658 if (!idle_cpu(cpu) && vcpu_is_preempted(cpu)) { 659 kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu)); 660 break; 661 } 662 } 663 } 664 665 static void kvm_flush_tlb_multi(const struct cpumask *cpumask, 666 const struct flush_tlb_info *info) 667 { 668 u8 state; 669 int cpu; 670 struct kvm_steal_time *src; 671 struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); 672 673 cpumask_copy(flushmask, cpumask); 674 /* 675 * We have to call flush only on online vCPUs. And 676 * queue flush_on_enter for pre-empted vCPUs 677 */ 678 for_each_cpu(cpu, flushmask) { 679 /* 680 * The local vCPU is never preempted, so we do not explicitly 681 * skip check for local vCPU - it will never be cleared from 682 * flushmask. 683 */ 684 src = &per_cpu(steal_time, cpu); 685 state = READ_ONCE(src->preempted); 686 if ((state & KVM_VCPU_PREEMPTED)) { 687 if (try_cmpxchg(&src->preempted, &state, 688 state | KVM_VCPU_FLUSH_TLB)) 689 __cpumask_clear_cpu(cpu, flushmask); 690 } 691 } 692 693 native_flush_tlb_multi(flushmask, info); 694 } 695 696 static __init int kvm_alloc_cpumask(void) 697 { 698 int cpu; 699 700 if (!kvm_para_available() || nopv) 701 return 0; 702 703 if (pv_tlb_flush_supported() || pv_ipi_supported()) 704 for_each_possible_cpu(cpu) { 705 zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu), 706 GFP_KERNEL, cpu_to_node(cpu)); 707 } 708 709 return 0; 710 } 711 arch_initcall(kvm_alloc_cpumask); 712 713 static void __init kvm_smp_prepare_boot_cpu(void) 714 { 715 /* 716 * Map the per-cpu variables as decrypted before kvm_guest_cpu_init() 717 * shares the guest physical address with the hypervisor. 718 */ 719 sev_map_percpu_data(); 720 721 kvm_guest_cpu_init(); 722 native_smp_prepare_boot_cpu(); 723 kvm_spinlock_init(); 724 } 725 726 static int kvm_cpu_down_prepare(unsigned int cpu) 727 { 728 unsigned long flags; 729 730 local_irq_save(flags); 731 kvm_guest_cpu_offline(false); 732 local_irq_restore(flags); 733 return 0; 734 } 735 736 #endif 737 738 static int kvm_suspend(void *data) 739 { 740 u64 val = 0; 741 742 kvm_guest_cpu_offline(false); 743 744 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL 745 if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) 746 rdmsrq(MSR_KVM_POLL_CONTROL, val); 747 has_guest_poll = !(val & 1); 748 #endif 749 return 0; 750 } 751 752 static void kvm_resume(void *data) 753 { 754 kvm_cpu_online(raw_smp_processor_id()); 755 756 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL 757 if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL) && has_guest_poll) 758 wrmsrq(MSR_KVM_POLL_CONTROL, 0); 759 #endif 760 } 761 762 static const struct syscore_ops kvm_syscore_ops = { 763 .suspend = kvm_suspend, 764 .resume = kvm_resume, 765 }; 766 767 static struct syscore kvm_syscore = { 768 .ops = &kvm_syscore_ops, 769 }; 770 771 static void kvm_pv_guest_cpu_reboot(void *unused) 772 { 773 kvm_guest_cpu_offline(true); 774 } 775 776 static int kvm_pv_reboot_notify(struct notifier_block *nb, 777 unsigned long code, void *unused) 778 { 779 if (code == SYS_RESTART) 780 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1); 781 return NOTIFY_DONE; 782 } 783 784 static struct notifier_block kvm_pv_reboot_nb = { 785 .notifier_call = kvm_pv_reboot_notify, 786 }; 787 788 /* 789 * After a PV feature is registered, the host will keep writing to the 790 * registered memory location. If the guest happens to shutdown, this memory 791 * won't be valid. In cases like kexec, in which you install a new kernel, this 792 * means a random memory location will be kept being written. 793 */ 794 #ifdef CONFIG_CRASH_DUMP 795 static void kvm_crash_shutdown(struct pt_regs *regs) 796 { 797 kvm_guest_cpu_offline(true); 798 native_machine_crash_shutdown(regs); 799 } 800 #endif 801 802 #if defined(CONFIG_X86_32) || !defined(CONFIG_SMP) 803 bool __kvm_vcpu_is_preempted(long cpu); 804 805 __visible bool __kvm_vcpu_is_preempted(long cpu) 806 { 807 struct kvm_steal_time *src = &per_cpu(steal_time, cpu); 808 809 return !!(src->preempted & KVM_VCPU_PREEMPTED); 810 } 811 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted); 812 813 #else 814 815 #include <asm/asm-offsets.h> 816 817 extern bool __raw_callee_save___kvm_vcpu_is_preempted(long); 818 819 /* 820 * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and 821 * restoring to/from the stack. 822 */ 823 #define PV_VCPU_PREEMPTED_ASM \ 824 "movq __per_cpu_offset(,%rdi,8), %rax\n\t" \ 825 "cmpb $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax)\n\t" \ 826 "setne %al\n\t" 827 828 DEFINE_ASM_FUNC(__raw_callee_save___kvm_vcpu_is_preempted, 829 PV_VCPU_PREEMPTED_ASM, .text); 830 #endif 831 832 static void __init kvm_guest_init(void) 833 { 834 int i; 835 836 paravirt_ops_setup(); 837 register_reboot_notifier(&kvm_pv_reboot_nb); 838 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) 839 raw_spin_lock_init(&async_pf_sleepers[i].lock); 840 841 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) { 842 has_steal_clock = 1; 843 static_call_update(pv_steal_clock, kvm_steal_clock); 844 845 #ifdef CONFIG_PARAVIRT_SPINLOCKS 846 pv_ops_lock.vcpu_is_preempted = 847 PV_CALLEE_SAVE(__kvm_vcpu_is_preempted); 848 #endif 849 } 850 851 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) 852 apic_update_callback(eoi, kvm_guest_apic_eoi_write); 853 854 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) { 855 static_branch_enable(&kvm_async_pf_enabled); 856 sysvec_install(HYPERVISOR_CALLBACK_VECTOR, sysvec_kvm_asyncpf_interrupt); 857 } 858 859 #ifdef CONFIG_SMP 860 if (pv_tlb_flush_supported()) { 861 pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi; 862 pr_info("KVM setup pv remote TLB flush\n"); 863 } 864 865 smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; 866 if (pv_sched_yield_supported()) { 867 smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi; 868 pr_info("setup PV sched yield\n"); 869 } 870 if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online", 871 kvm_cpu_online, kvm_cpu_down_prepare) < 0) 872 pr_err("failed to install cpu hotplug callbacks\n"); 873 #else 874 sev_map_percpu_data(); 875 kvm_guest_cpu_init(); 876 #endif 877 878 #ifdef CONFIG_CRASH_DUMP 879 machine_ops.crash_shutdown = kvm_crash_shutdown; 880 #endif 881 882 register_syscore(&kvm_syscore); 883 884 /* 885 * Hard lockup detection is enabled by default. Disable it, as guests 886 * can get false positives too easily, for example if the host is 887 * overcommitted. 888 */ 889 hardlockup_detector_disable(); 890 } 891 892 static noinline uint32_t __kvm_cpuid_base(void) 893 { 894 if (boot_cpu_data.cpuid_level < 0) 895 return 0; /* So we don't blow up on old processors */ 896 897 if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) 898 return cpuid_base_hypervisor(KVM_SIGNATURE, 0); 899 900 return 0; 901 } 902 903 static inline uint32_t kvm_cpuid_base(void) 904 { 905 static int kvm_cpuid_base = -1; 906 907 if (kvm_cpuid_base == -1) 908 kvm_cpuid_base = __kvm_cpuid_base(); 909 910 return kvm_cpuid_base; 911 } 912 913 bool kvm_para_available(void) 914 { 915 return kvm_cpuid_base() != 0; 916 } 917 EXPORT_SYMBOL_GPL(kvm_para_available); 918 919 unsigned int kvm_arch_para_features(void) 920 { 921 return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES); 922 } 923 924 unsigned int kvm_arch_para_hints(void) 925 { 926 return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES); 927 } 928 EXPORT_SYMBOL_GPL(kvm_arch_para_hints); 929 930 static uint32_t __init kvm_detect(void) 931 { 932 return kvm_cpuid_base(); 933 } 934 935 static void __init kvm_apic_init(void) 936 { 937 #ifdef CONFIG_SMP 938 if (pv_ipi_supported()) 939 kvm_setup_pv_ipi(); 940 #endif 941 } 942 943 static bool __init kvm_msi_ext_dest_id(void) 944 { 945 return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID); 946 } 947 948 static void kvm_sev_hc_page_enc_status(unsigned long pfn, int npages, bool enc) 949 { 950 kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, pfn << PAGE_SHIFT, npages, 951 KVM_MAP_GPA_RANGE_ENC_STAT(enc) | KVM_MAP_GPA_RANGE_PAGE_SZ_4K); 952 } 953 954 static void __init kvm_init_platform(void) 955 { 956 u64 tolud = PFN_PHYS(e820__end_of_low_ram_pfn()); 957 /* 958 * Note, hardware requires variable MTRR ranges to be power-of-2 sized 959 * and naturally aligned. But when forcing guest MTRR state, Linux 960 * doesn't program the forced ranges into hardware. Don't bother doing 961 * the math to generate a technically-legal range. 962 */ 963 struct mtrr_var_range pci_hole = { 964 .base_lo = tolud | X86_MEMTYPE_UC, 965 .mask_lo = (u32)(~(SZ_4G - tolud - 1)) | MTRR_PHYSMASK_V, 966 .mask_hi = (BIT_ULL(boot_cpu_data.x86_phys_bits) - 1) >> 32, 967 }; 968 969 if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) && 970 kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) { 971 unsigned long nr_pages; 972 int i; 973 974 pv_ops.mmu.notify_page_enc_status_changed = 975 kvm_sev_hc_page_enc_status; 976 977 /* 978 * Reset the host's shared pages list related to kernel 979 * specific page encryption status settings before we load a 980 * new kernel by kexec. Reset the page encryption status 981 * during early boot instead of just before kexec to avoid SMP 982 * races during kvm_pv_guest_cpu_reboot(). 983 * NOTE: We cannot reset the complete shared pages list 984 * here as we need to retain the UEFI/OVMF firmware 985 * specific settings. 986 */ 987 988 for (i = 0; i < e820_table->nr_entries; i++) { 989 struct e820_entry *entry = &e820_table->entries[i]; 990 991 if (entry->type != E820_TYPE_RAM) 992 continue; 993 994 nr_pages = DIV_ROUND_UP(entry->size, PAGE_SIZE); 995 996 kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, entry->addr, 997 nr_pages, 998 KVM_MAP_GPA_RANGE_ENCRYPTED | KVM_MAP_GPA_RANGE_PAGE_SZ_4K); 999 } 1000 1001 /* 1002 * Ensure that _bss_decrypted section is marked as decrypted in the 1003 * shared pages list. 1004 */ 1005 early_set_mem_enc_dec_hypercall((unsigned long)__start_bss_decrypted, 1006 __end_bss_decrypted - __start_bss_decrypted, 0); 1007 1008 /* 1009 * If not booted using EFI, enable Live migration support. 1010 */ 1011 if (!efi_enabled(EFI_BOOT)) 1012 wrmsrq(MSR_KVM_MIGRATION_CONTROL, 1013 KVM_MIGRATION_READY); 1014 } 1015 kvmclock_init(); 1016 x86_platform.apic_post_init = kvm_apic_init; 1017 1018 /* 1019 * Set WB as the default cache mode for SEV-SNP and TDX, with a single 1020 * UC range for the legacy PCI hole, e.g. so that devices that expect 1021 * to get UC/WC mappings don't get surprised with WB. 1022 */ 1023 guest_force_mtrr_state(&pci_hole, 1, MTRR_TYPE_WRBACK); 1024 } 1025 1026 #if defined(CONFIG_AMD_MEM_ENCRYPT) 1027 static void kvm_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs) 1028 { 1029 /* RAX and CPL are already in the GHCB */ 1030 ghcb_set_rbx(ghcb, regs->bx); 1031 ghcb_set_rcx(ghcb, regs->cx); 1032 ghcb_set_rdx(ghcb, regs->dx); 1033 ghcb_set_rsi(ghcb, regs->si); 1034 } 1035 1036 static bool kvm_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs) 1037 { 1038 /* No checking of the return state needed */ 1039 return true; 1040 } 1041 #endif 1042 1043 const __initconst struct hypervisor_x86 x86_hyper_kvm = { 1044 .name = "KVM", 1045 .detect = kvm_detect, 1046 .type = X86_HYPER_KVM, 1047 .init.guest_late_init = kvm_guest_init, 1048 .init.x2apic_available = kvm_para_available, 1049 .init.msi_ext_dest_id = kvm_msi_ext_dest_id, 1050 .init.init_platform = kvm_init_platform, 1051 #if defined(CONFIG_AMD_MEM_ENCRYPT) 1052 .runtime.sev_es_hcall_prepare = kvm_sev_es_hcall_prepare, 1053 .runtime.sev_es_hcall_finish = kvm_sev_es_hcall_finish, 1054 #endif 1055 }; 1056 1057 static __init int activate_jump_labels(void) 1058 { 1059 if (has_steal_clock) { 1060 static_key_slow_inc(¶virt_steal_enabled); 1061 if (steal_acc) 1062 static_key_slow_inc(¶virt_steal_rq_enabled); 1063 } 1064 1065 return 0; 1066 } 1067 arch_initcall(activate_jump_labels); 1068 1069 #ifdef CONFIG_PARAVIRT_SPINLOCKS 1070 1071 /* Kick a cpu by its apicid. Used to wake up a halted vcpu */ 1072 static void kvm_kick_cpu(int cpu) 1073 { 1074 unsigned long flags = 0; 1075 u32 apicid; 1076 1077 apicid = per_cpu(x86_cpu_to_apicid, cpu); 1078 kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid); 1079 } 1080 1081 #include <asm/qspinlock.h> 1082 1083 static void kvm_wait(u8 *ptr, u8 val) 1084 { 1085 if (in_nmi()) 1086 return; 1087 1088 /* 1089 * halt until it's our turn and kicked. Note that we do safe halt 1090 * for irq enabled case to avoid hang when lock info is overwritten 1091 * in irq spinlock slowpath and no spurious interrupt occur to save us. 1092 */ 1093 if (irqs_disabled()) { 1094 if (READ_ONCE(*ptr) == val) 1095 halt(); 1096 } else { 1097 local_irq_disable(); 1098 1099 /* safe_halt() will enable IRQ */ 1100 if (READ_ONCE(*ptr) == val) 1101 safe_halt(); 1102 else 1103 local_irq_enable(); 1104 } 1105 } 1106 1107 /* 1108 * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present. 1109 */ 1110 void __init kvm_spinlock_init(void) 1111 { 1112 /* 1113 * Disable PV spinlocks and use native qspinlock when dedicated pCPUs 1114 * are available. 1115 */ 1116 if (kvm_para_has_hint(KVM_HINTS_REALTIME)) { 1117 pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n"); 1118 goto out; 1119 } 1120 1121 if (num_possible_cpus() == 1) { 1122 pr_info("PV spinlocks disabled, single CPU\n"); 1123 goto out; 1124 } 1125 1126 if (nopvspin) { 1127 pr_info("PV spinlocks disabled, forced by \"nopvspin\" parameter\n"); 1128 goto out; 1129 } 1130 1131 /* 1132 * In case host doesn't support KVM_FEATURE_PV_UNHALT there is still an 1133 * advantage of keeping virt_spin_lock_key enabled: virt_spin_lock() is 1134 * preferred over native qspinlock when vCPU is preempted. 1135 */ 1136 if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) { 1137 pr_info("PV spinlocks disabled, no host support\n"); 1138 return; 1139 } 1140 1141 pr_info("PV spinlocks enabled\n"); 1142 1143 __pv_init_lock_hash(); 1144 pv_ops_lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath; 1145 pv_ops_lock.queued_spin_unlock = 1146 PV_CALLEE_SAVE(__pv_queued_spin_unlock); 1147 pv_ops_lock.wait = kvm_wait; 1148 pv_ops_lock.kick = kvm_kick_cpu; 1149 1150 /* 1151 * When PV spinlock is enabled which is preferred over 1152 * virt_spin_lock(), virt_spin_lock_key's value is meaningless. 1153 * Just disable it anyway. 1154 */ 1155 out: 1156 static_branch_disable(&virt_spin_lock_key); 1157 } 1158 1159 #endif /* CONFIG_PARAVIRT_SPINLOCKS */ 1160 1161 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL 1162 1163 static void kvm_disable_host_haltpoll(void *i) 1164 { 1165 wrmsrq(MSR_KVM_POLL_CONTROL, 0); 1166 } 1167 1168 static void kvm_enable_host_haltpoll(void *i) 1169 { 1170 wrmsrq(MSR_KVM_POLL_CONTROL, 1); 1171 } 1172 1173 void arch_haltpoll_enable(unsigned int cpu) 1174 { 1175 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) { 1176 pr_err_once("host does not support poll control\n"); 1177 pr_err_once("host upgrade recommended\n"); 1178 return; 1179 } 1180 1181 /* Enable guest halt poll disables host halt poll */ 1182 smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1); 1183 } 1184 EXPORT_SYMBOL_GPL(arch_haltpoll_enable); 1185 1186 void arch_haltpoll_disable(unsigned int cpu) 1187 { 1188 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) 1189 return; 1190 1191 /* Disable guest halt poll enables host halt poll */ 1192 smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1); 1193 } 1194 EXPORT_SYMBOL_GPL(arch_haltpoll_disable); 1195 #endif 1196