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