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