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/cpuid/api.h> 45 #include <asm/cpuidle_haltpoll.h> 46 #include <asm/msr.h> 47 #include <asm/ptrace.h> 48 #include <asm/reboot.h> 49 #include <asm/svm.h> 50 #include <asm/e820/api.h> 51 52 DEFINE_STATIC_KEY_FALSE_RO(kvm_async_pf_enabled); 53 54 static int kvmapf = 1; 55 56 static int __init parse_no_kvmapf(char *arg) 57 { 58 kvmapf = 0; 59 return 0; 60 } 61 62 early_param("no-kvmapf", parse_no_kvmapf); 63 64 static int steal_acc = 1; 65 static int __init parse_no_stealacc(char *arg) 66 { 67 steal_acc = 0; 68 return 0; 69 } 70 71 early_param("no-steal-acc", parse_no_stealacc); 72 73 static DEFINE_PER_CPU_READ_MOSTLY(bool, async_pf_enabled); 74 static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64); 75 DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64) __visible; 76 static int has_steal_clock = 0; 77 78 static int has_guest_poll = 0; 79 80 #define KVM_TASK_SLEEP_HASHBITS 8 81 #define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS) 82 83 struct kvm_task_sleep_node { 84 struct hlist_node link; 85 struct swait_queue_head wq; 86 u32 token; 87 int cpu; 88 bool dummy; 89 }; 90 91 static struct kvm_task_sleep_head { 92 raw_spinlock_t lock; 93 struct hlist_head list; 94 } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE]; 95 96 static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b, 97 u32 token) 98 { 99 struct hlist_node *p; 100 101 hlist_for_each(p, &b->list) { 102 struct kvm_task_sleep_node *n = 103 hlist_entry(p, typeof(*n), link); 104 if (n->token == token) 105 return n; 106 } 107 108 return NULL; 109 } 110 111 static bool kvm_async_pf_queue_task(u32 token, struct kvm_task_sleep_node *n) 112 { 113 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS); 114 struct kvm_task_sleep_head *b = &async_pf_sleepers[key]; 115 struct kvm_task_sleep_node *e; 116 117 raw_spin_lock(&b->lock); 118 e = _find_apf_task(b, token); 119 if (e) { 120 struct kvm_task_sleep_node *dummy = NULL; 121 122 /* 123 * The entry can either be a 'dummy' entry (which is put on the 124 * list when wake-up happens ahead of APF handling completion) 125 * or a token from another task which should not be touched. 126 */ 127 if (e->dummy) { 128 hlist_del(&e->link); 129 dummy = e; 130 } 131 132 raw_spin_unlock(&b->lock); 133 kfree(dummy); 134 return false; 135 } 136 137 n->token = token; 138 n->cpu = smp_processor_id(); 139 n->dummy = false; 140 init_swait_queue_head(&n->wq); 141 hlist_add_head(&n->link, &b->list); 142 raw_spin_unlock(&b->lock); 143 return true; 144 } 145 146 /* 147 * kvm_async_pf_task_wait_schedule - Wait for pagefault to be handled 148 * @token: Token to identify the sleep node entry 149 * 150 * Invoked from the async pagefault handling code or from the VM exit page 151 * fault handler. In both cases RCU is watching. 152 */ 153 void kvm_async_pf_task_wait_schedule(u32 token) 154 { 155 struct kvm_task_sleep_node n; 156 DECLARE_SWAITQUEUE(wait); 157 158 lockdep_assert_irqs_disabled(); 159 160 if (!kvm_async_pf_queue_task(token, &n)) 161 return; 162 163 for (;;) { 164 prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE); 165 if (hlist_unhashed(&n.link)) 166 break; 167 168 local_irq_enable(); 169 schedule(); 170 local_irq_disable(); 171 } 172 finish_swait(&n.wq, &wait); 173 } 174 EXPORT_SYMBOL_FOR_KVM(kvm_async_pf_task_wait_schedule); 175 176 static void apf_task_wake_one(struct kvm_task_sleep_node *n) 177 { 178 hlist_del_init(&n->link); 179 if (swq_has_sleeper(&n->wq)) 180 swake_up_one(&n->wq); 181 } 182 183 static void apf_task_wake_all(void) 184 { 185 int i; 186 187 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) { 188 struct kvm_task_sleep_head *b = &async_pf_sleepers[i]; 189 struct kvm_task_sleep_node *n; 190 struct hlist_node *p, *next; 191 192 raw_spin_lock(&b->lock); 193 hlist_for_each_safe(p, next, &b->list) { 194 n = hlist_entry(p, typeof(*n), link); 195 if (n->cpu == smp_processor_id()) 196 apf_task_wake_one(n); 197 } 198 raw_spin_unlock(&b->lock); 199 } 200 } 201 202 static void kvm_async_pf_task_wake(u32 token) 203 { 204 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS); 205 struct kvm_task_sleep_head *b = &async_pf_sleepers[key]; 206 struct kvm_task_sleep_node *n, *dummy = NULL; 207 208 if (token == ~0) { 209 apf_task_wake_all(); 210 return; 211 } 212 213 again: 214 raw_spin_lock(&b->lock); 215 n = _find_apf_task(b, token); 216 if (!n) { 217 /* 218 * Async #PF not yet handled, add a dummy entry for the token. 219 * Allocating the token must be down outside of the raw lock 220 * as the allocator is preemptible on PREEMPT_RT kernels. 221 */ 222 if (!dummy) { 223 raw_spin_unlock(&b->lock); 224 dummy = kzalloc_obj(*dummy, GFP_ATOMIC); 225 226 /* 227 * Continue looping on allocation failure, eventually 228 * the async #PF will be handled and allocating a new 229 * node will be unnecessary. 230 */ 231 if (!dummy) 232 cpu_relax(); 233 234 /* 235 * Recheck for async #PF completion before enqueueing 236 * the dummy token to avoid duplicate list entries. 237 */ 238 goto again; 239 } 240 dummy->token = token; 241 dummy->cpu = smp_processor_id(); 242 dummy->dummy = true; 243 init_swait_queue_head(&dummy->wq); 244 hlist_add_head(&dummy->link, &b->list); 245 dummy = NULL; 246 } else { 247 apf_task_wake_one(n); 248 } 249 raw_spin_unlock(&b->lock); 250 251 /* A dummy token might be allocated and ultimately not used. */ 252 kfree(dummy); 253 } 254 255 noinstr u32 kvm_read_and_reset_apf_flags(void) 256 { 257 u32 flags = 0; 258 259 if (__this_cpu_read(async_pf_enabled)) { 260 flags = __this_cpu_read(apf_reason.flags); 261 __this_cpu_write(apf_reason.flags, 0); 262 } 263 264 return flags; 265 } 266 EXPORT_SYMBOL_FOR_KVM(kvm_read_and_reset_apf_flags); 267 268 static __always_inline bool kvm_apf_reason_pending(void) 269 { 270 return __this_cpu_read(async_pf_enabled) && 271 __this_cpu_read(apf_reason.flags); 272 } 273 274 noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token) 275 { 276 irqentry_state_t state; 277 u32 flags; 278 279 if (!kvm_apf_reason_pending()) 280 return false; 281 282 /* 283 * The guest does not enable KVM_ASYNC_PF_SEND_ALWAYS, so the host 284 * delivers async #PF only to user mode (or as a #PF VM-exit, which KVM 285 * reads itself). A #PF from kernel mode can still arrive between that 286 * delivery and the read of the reason flags, inside an NMI that 287 * interrupted it, for instance perf reading user memory for a call 288 * chain. Such a fault is not async, so leave the async PF flags 289 * untouched for the outer handler. Outside NMI context, on the other 290 * hand, async PF flags on a kernel-mode fault mean the host is broken. 291 */ 292 if (!user_mode(regs)) { 293 if (likely(in_nmi())) 294 return false; 295 state = irqentry_enter(regs); 296 instrumentation_begin(); 297 panic("Host injected async #PF in kernel mode\n"); 298 } 299 300 flags = kvm_read_and_reset_apf_flags(); 301 if (!flags) 302 return false; 303 304 state = irqentry_enter(regs); 305 instrumentation_begin(); 306 307 /* 308 * If the host managed to inject an async #PF into an interrupt 309 * disabled region, then die hard as this is not going to end well 310 * and the host side is seriously broken. 311 */ 312 if (unlikely(!(regs->flags & X86_EFLAGS_IF))) 313 panic("Host injected async #PF in interrupt disabled region\n"); 314 315 if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) { 316 /* Page is swapped out by the host. */ 317 kvm_async_pf_task_wait_schedule(token); 318 } else { 319 WARN_ONCE(1, "Unexpected async PF flags: %x\n", flags); 320 } 321 322 instrumentation_end(); 323 irqentry_exit(regs, state); 324 return true; 325 } 326 327 DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt) 328 { 329 struct pt_regs *old_regs = set_irq_regs(regs); 330 u32 token; 331 332 apic_eoi(); 333 334 inc_irq_stat(HYPERVISOR_CALLBACK); 335 336 if (__this_cpu_read(async_pf_enabled)) { 337 token = __this_cpu_read(apf_reason.token); 338 kvm_async_pf_task_wake(token); 339 __this_cpu_write(apf_reason.token, 0); 340 wrmsrq(MSR_KVM_ASYNC_PF_ACK, 1); 341 } 342 343 set_irq_regs(old_regs); 344 } 345 346 static void __init paravirt_ops_setup(void) 347 { 348 pv_info.name = "KVM"; 349 350 if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY)) 351 pv_info.io_delay = false; 352 353 #ifdef CONFIG_X86_IO_APIC 354 no_timer_check = 1; 355 #endif 356 } 357 358 static void kvm_register_steal_time(void) 359 { 360 int cpu = smp_processor_id(); 361 struct kvm_steal_time *st = &per_cpu(steal_time, cpu); 362 363 if (!has_steal_clock) 364 return; 365 366 wrmsrq(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED)); 367 pr_debug("stealtime: cpu %d, msr %llx\n", cpu, 368 (unsigned long long) slow_virt_to_phys(st)); 369 } 370 371 static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED; 372 373 static notrace __maybe_unused void kvm_guest_apic_eoi_write(void) 374 { 375 /** 376 * This relies on __test_and_clear_bit to modify the memory 377 * in a way that is atomic with respect to the local CPU. 378 * The hypervisor only accesses this memory from the local CPU so 379 * there's no need for lock or memory barriers. 380 * An optimization barrier is implied in apic write. 381 */ 382 if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi))) 383 return; 384 apic_native_eoi(); 385 } 386 387 static void kvm_guest_cpu_init(void) 388 { 389 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) { 390 u64 pa; 391 392 WARN_ON_ONCE(!static_branch_likely(&kvm_async_pf_enabled)); 393 394 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason)); 395 pa |= KVM_ASYNC_PF_ENABLED | KVM_ASYNC_PF_DELIVERY_AS_INT; 396 397 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT)) 398 pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT; 399 400 wrmsrq(MSR_KVM_ASYNC_PF_INT, HYPERVISOR_CALLBACK_VECTOR); 401 402 wrmsrq(MSR_KVM_ASYNC_PF_EN, pa); 403 __this_cpu_write(async_pf_enabled, true); 404 pr_debug("setup async PF for cpu %d\n", smp_processor_id()); 405 } 406 407 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) { 408 unsigned long pa; 409 410 /* Size alignment is implied but just to make it explicit. */ 411 BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4); 412 __this_cpu_write(kvm_apic_eoi, 0); 413 pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi)) 414 | KVM_MSR_ENABLED; 415 wrmsrq(MSR_KVM_PV_EOI_EN, pa); 416 } 417 418 if (has_steal_clock) 419 kvm_register_steal_time(); 420 } 421 422 static void kvm_pv_disable_apf(void) 423 { 424 if (!__this_cpu_read(async_pf_enabled)) 425 return; 426 427 wrmsrq(MSR_KVM_ASYNC_PF_EN, 0); 428 __this_cpu_write(async_pf_enabled, false); 429 430 pr_debug("disable async PF for cpu %d\n", smp_processor_id()); 431 } 432 433 static void kvm_disable_steal_time(void) 434 { 435 if (!has_steal_clock) 436 return; 437 438 wrmsrq(MSR_KVM_STEAL_TIME, 0); 439 } 440 441 static u64 kvm_steal_clock(int cpu) 442 { 443 u64 steal; 444 struct kvm_steal_time *src; 445 int version; 446 447 src = &per_cpu(steal_time, cpu); 448 do { 449 version = src->version; 450 virt_rmb(); 451 steal = src->steal; 452 virt_rmb(); 453 } while ((version & 1) || (version != src->version)); 454 455 return steal; 456 } 457 458 static inline __init void __set_percpu_decrypted(void *ptr, unsigned long size) 459 { 460 early_set_memory_decrypted((unsigned long) ptr, size); 461 } 462 463 /* 464 * Iterate through all possible CPUs and map the memory region pointed 465 * by apf_reason, steal_time and kvm_apic_eoi as decrypted at once. 466 * 467 * Note: we iterate through all possible CPUs to ensure that CPUs 468 * hotplugged will have their per-cpu variable already mapped as 469 * decrypted. 470 */ 471 static void __init sev_map_percpu_data(void) 472 { 473 int cpu; 474 475 if (cc_vendor != CC_VENDOR_AMD || 476 !cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)) 477 return; 478 479 for_each_possible_cpu(cpu) { 480 __set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason)); 481 __set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time)); 482 __set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi)); 483 } 484 } 485 486 static void kvm_guest_cpu_offline(bool shutdown) 487 { 488 kvm_disable_steal_time(); 489 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) 490 wrmsrq(MSR_KVM_PV_EOI_EN, 0); 491 if (kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) 492 wrmsrq(MSR_KVM_MIGRATION_CONTROL, 0); 493 kvm_pv_disable_apf(); 494 if (!shutdown) 495 apf_task_wake_all(); 496 kvmclock_disable(); 497 } 498 499 static int kvm_cpu_online(unsigned int cpu) 500 { 501 unsigned long flags; 502 503 local_irq_save(flags); 504 kvm_guest_cpu_init(); 505 local_irq_restore(flags); 506 return 0; 507 } 508 509 #ifdef CONFIG_SMP 510 511 static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask); 512 513 static bool pv_tlb_flush_supported(void) 514 { 515 return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) && 516 !kvm_para_has_hint(KVM_HINTS_REALTIME) && 517 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) && 518 !boot_cpu_has(X86_FEATURE_MWAIT) && 519 (num_possible_cpus() != 1)); 520 } 521 522 static bool pv_ipi_supported(void) 523 { 524 return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) && 525 (num_possible_cpus() != 1)); 526 } 527 528 static bool pv_sched_yield_supported(void) 529 { 530 return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) && 531 !kvm_para_has_hint(KVM_HINTS_REALTIME) && 532 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) && 533 !boot_cpu_has(X86_FEATURE_MWAIT) && 534 (num_possible_cpus() != 1)); 535 } 536 537 #define KVM_IPI_CLUSTER_SIZE (2 * BITS_PER_LONG) 538 539 static void __send_ipi_mask(const struct cpumask *mask, int vector) 540 { 541 unsigned long flags; 542 int cpu, min = 0, max = 0; 543 #ifdef CONFIG_X86_64 544 __uint128_t ipi_bitmap = 0; 545 #else 546 u64 ipi_bitmap = 0; 547 #endif 548 u32 apic_id, icr; 549 long ret; 550 551 if (cpumask_empty(mask)) 552 return; 553 554 local_irq_save(flags); 555 556 switch (vector) { 557 default: 558 icr = APIC_DM_FIXED | vector; 559 break; 560 case NMI_VECTOR: 561 icr = APIC_DM_NMI; 562 break; 563 } 564 565 for_each_cpu(cpu, mask) { 566 apic_id = per_cpu(x86_cpu_to_apicid, cpu); 567 if (!ipi_bitmap) { 568 min = max = apic_id; 569 } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) { 570 ipi_bitmap <<= min - apic_id; 571 min = apic_id; 572 } else if (apic_id > min && apic_id < min + KVM_IPI_CLUSTER_SIZE) { 573 max = apic_id < max ? max : apic_id; 574 } else { 575 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap, 576 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr); 577 WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld", 578 ret); 579 min = max = apic_id; 580 ipi_bitmap = 0; 581 } 582 __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap); 583 } 584 585 if (ipi_bitmap) { 586 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap, 587 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr); 588 WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld", 589 ret); 590 } 591 592 local_irq_restore(flags); 593 } 594 595 static void kvm_send_ipi_mask(const struct cpumask *mask, int vector) 596 { 597 __send_ipi_mask(mask, vector); 598 } 599 600 static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector) 601 { 602 unsigned int this_cpu = smp_processor_id(); 603 struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); 604 const struct cpumask *local_mask; 605 606 cpumask_copy(new_mask, mask); 607 cpumask_clear_cpu(this_cpu, new_mask); 608 local_mask = new_mask; 609 __send_ipi_mask(local_mask, vector); 610 } 611 612 static int __init setup_efi_kvm_sev_migration(void) 613 { 614 efi_char16_t efi_sev_live_migration_enabled[] = L"SevLiveMigrationEnabled"; 615 efi_guid_t efi_variable_guid = AMD_SEV_MEM_ENCRYPT_GUID; 616 efi_status_t status; 617 unsigned long size; 618 bool enabled; 619 620 if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) || 621 !kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) 622 return 0; 623 624 if (!efi_enabled(EFI_BOOT)) 625 return 0; 626 627 if (!efi_enabled(EFI_RUNTIME_SERVICES)) { 628 pr_info("%s : EFI runtime services are not enabled\n", __func__); 629 return 0; 630 } 631 632 size = sizeof(enabled); 633 634 /* Get variable contents into buffer */ 635 status = efi.get_variable(efi_sev_live_migration_enabled, 636 &efi_variable_guid, NULL, &size, &enabled); 637 638 if (status == EFI_NOT_FOUND) { 639 pr_info("%s : EFI live migration variable not found\n", __func__); 640 return 0; 641 } 642 643 if (status != EFI_SUCCESS) { 644 pr_info("%s : EFI variable retrieval failed\n", __func__); 645 return 0; 646 } 647 648 if (enabled == 0) { 649 pr_info("%s: live migration disabled in EFI\n", __func__); 650 return 0; 651 } 652 653 pr_info("%s : live migration enabled in EFI\n", __func__); 654 wrmsrq(MSR_KVM_MIGRATION_CONTROL, KVM_MIGRATION_READY); 655 656 return 1; 657 } 658 659 late_initcall(setup_efi_kvm_sev_migration); 660 661 /* 662 * Set the IPI entry points 663 */ 664 static __init void kvm_setup_pv_ipi(void) 665 { 666 apic_update_callback(send_IPI_mask, kvm_send_ipi_mask); 667 apic_update_callback(send_IPI_mask_allbutself, kvm_send_ipi_mask_allbutself); 668 pr_info("setup PV IPIs\n"); 669 } 670 671 static void kvm_smp_send_call_func_ipi(const struct cpumask *mask) 672 { 673 int cpu; 674 675 native_send_call_func_ipi(mask); 676 677 /* Make sure other vCPUs get a chance to run if they need to. */ 678 for_each_cpu(cpu, mask) { 679 if (!idle_cpu(cpu) && vcpu_is_preempted(cpu)) { 680 kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu)); 681 break; 682 } 683 } 684 } 685 686 static void kvm_flush_tlb_multi(const struct cpumask *cpumask, 687 const struct flush_tlb_info *info) 688 { 689 u8 state; 690 int cpu; 691 struct kvm_steal_time *src; 692 struct cpumask *flushmask; 693 694 guard(preempt)(); 695 flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); 696 cpumask_copy(flushmask, cpumask); 697 /* 698 * We have to call flush only on online vCPUs. And 699 * queue flush_on_enter for pre-empted vCPUs 700 */ 701 for_each_cpu(cpu, flushmask) { 702 /* 703 * The local vCPU is never preempted, so we do not explicitly 704 * skip check for local vCPU - it will never be cleared from 705 * flushmask. 706 */ 707 src = &per_cpu(steal_time, cpu); 708 state = READ_ONCE(src->preempted); 709 if ((state & KVM_VCPU_PREEMPTED)) { 710 if (try_cmpxchg(&src->preempted, &state, 711 state | KVM_VCPU_FLUSH_TLB)) 712 __cpumask_clear_cpu(cpu, flushmask); 713 } 714 } 715 716 native_flush_tlb_multi(flushmask, info); 717 } 718 719 static __init int kvm_alloc_cpumask(void) 720 { 721 int cpu; 722 723 if (!kvm_para_available() || nopv) 724 return 0; 725 726 if (pv_tlb_flush_supported() || pv_ipi_supported()) 727 for_each_possible_cpu(cpu) { 728 zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu), 729 GFP_KERNEL, cpu_to_node(cpu)); 730 } 731 732 return 0; 733 } 734 arch_initcall(kvm_alloc_cpumask); 735 736 static void __init kvm_smp_prepare_boot_cpu(void) 737 { 738 /* 739 * Map the per-cpu variables as decrypted before kvm_guest_cpu_init() 740 * shares the guest physical address with the hypervisor. 741 */ 742 sev_map_percpu_data(); 743 744 kvm_guest_cpu_init(); 745 native_smp_prepare_boot_cpu(); 746 kvm_spinlock_init(); 747 } 748 749 static int kvm_cpu_down_prepare(unsigned int cpu) 750 { 751 unsigned long flags; 752 753 local_irq_save(flags); 754 kvm_guest_cpu_offline(false); 755 local_irq_restore(flags); 756 return 0; 757 } 758 759 #endif 760 761 static int kvm_suspend(void *data) 762 { 763 u64 val = 0; 764 765 kvm_guest_cpu_offline(false); 766 767 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL 768 if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) 769 rdmsrq(MSR_KVM_POLL_CONTROL, val); 770 has_guest_poll = !(val & 1); 771 #endif 772 return 0; 773 } 774 775 static void kvm_resume(void *data) 776 { 777 kvm_cpu_online(raw_smp_processor_id()); 778 779 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL 780 if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL) && has_guest_poll) 781 wrmsrq(MSR_KVM_POLL_CONTROL, 0); 782 #endif 783 } 784 785 static const struct syscore_ops kvm_syscore_ops = { 786 .suspend = kvm_suspend, 787 .resume = kvm_resume, 788 }; 789 790 static struct syscore kvm_syscore = { 791 .ops = &kvm_syscore_ops, 792 }; 793 794 static void kvm_pv_guest_cpu_reboot(void *unused) 795 { 796 kvm_guest_cpu_offline(true); 797 } 798 799 static int kvm_pv_reboot_notify(struct notifier_block *nb, 800 unsigned long code, void *unused) 801 { 802 if (code == SYS_RESTART) 803 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1); 804 return NOTIFY_DONE; 805 } 806 807 static struct notifier_block kvm_pv_reboot_nb = { 808 .notifier_call = kvm_pv_reboot_notify, 809 }; 810 811 /* 812 * After a PV feature is registered, the host will keep writing to the 813 * registered memory location. If the guest happens to shutdown, this memory 814 * won't be valid. In cases like kexec, in which you install a new kernel, this 815 * means a random memory location will be kept being written. 816 */ 817 #ifdef CONFIG_CRASH_DUMP 818 static void kvm_crash_shutdown(struct pt_regs *regs) 819 { 820 kvm_guest_cpu_offline(true); 821 native_machine_crash_shutdown(regs); 822 } 823 #endif 824 825 #if defined(CONFIG_X86_32) || !defined(CONFIG_SMP) 826 bool __kvm_vcpu_is_preempted(long cpu); 827 828 __visible bool __kvm_vcpu_is_preempted(long cpu) 829 { 830 struct kvm_steal_time *src = &per_cpu(steal_time, cpu); 831 832 return !!(src->preempted & KVM_VCPU_PREEMPTED); 833 } 834 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted); 835 836 #else 837 838 #include <asm/asm-offsets.h> 839 840 extern bool __raw_callee_save___kvm_vcpu_is_preempted(long); 841 842 /* 843 * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and 844 * restoring to/from the stack. 845 */ 846 #define PV_VCPU_PREEMPTED_ASM \ 847 "movq __per_cpu_offset(,%rdi,8), %rax\n\t" \ 848 "cmpb $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax)\n\t" \ 849 "setne %al\n\t" 850 851 DEFINE_ASM_FUNC(__raw_callee_save___kvm_vcpu_is_preempted, 852 PV_VCPU_PREEMPTED_ASM, .text); 853 #endif 854 855 static void __init kvm_guest_init(void) 856 { 857 int i; 858 859 paravirt_ops_setup(); 860 register_reboot_notifier(&kvm_pv_reboot_nb); 861 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) 862 raw_spin_lock_init(&async_pf_sleepers[i].lock); 863 864 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) { 865 has_steal_clock = 1; 866 static_call_update(pv_steal_clock, kvm_steal_clock); 867 868 #ifdef CONFIG_PARAVIRT_SPINLOCKS 869 pv_ops_lock.vcpu_is_preempted = 870 PV_CALLEE_SAVE(__kvm_vcpu_is_preempted); 871 #endif 872 } 873 874 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) 875 apic_update_callback(eoi, kvm_guest_apic_eoi_write); 876 877 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) { 878 static_branch_enable(&kvm_async_pf_enabled); 879 sysvec_install(HYPERVISOR_CALLBACK_VECTOR, sysvec_kvm_asyncpf_interrupt); 880 } 881 882 #ifdef CONFIG_SMP 883 if (pv_tlb_flush_supported()) { 884 pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi; 885 pr_info("KVM setup pv remote TLB flush\n"); 886 } 887 888 smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; 889 if (pv_sched_yield_supported()) { 890 smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi; 891 pr_info("setup PV sched yield\n"); 892 } 893 if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online", 894 kvm_cpu_online, kvm_cpu_down_prepare) < 0) 895 pr_err("failed to install cpu hotplug callbacks\n"); 896 #else 897 sev_map_percpu_data(); 898 kvm_guest_cpu_init(); 899 #endif 900 901 #ifdef CONFIG_CRASH_DUMP 902 machine_ops.crash_shutdown = kvm_crash_shutdown; 903 #endif 904 905 register_syscore(&kvm_syscore); 906 907 /* 908 * Hard lockup detection is enabled by default. Disable it, as guests 909 * can get false positives too easily, for example if the host is 910 * overcommitted. 911 */ 912 hardlockup_detector_disable(); 913 } 914 915 static noinline uint32_t __kvm_cpuid_base(void) 916 { 917 if (boot_cpu_data.cpuid_level < 0) 918 return 0; /* So we don't blow up on old processors */ 919 920 if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) 921 return cpuid_base_hypervisor(KVM_SIGNATURE, 0); 922 923 return 0; 924 } 925 926 static inline uint32_t kvm_cpuid_base(void) 927 { 928 static int kvm_cpuid_base = -1; 929 930 if (kvm_cpuid_base == -1) 931 kvm_cpuid_base = __kvm_cpuid_base(); 932 933 return kvm_cpuid_base; 934 } 935 936 bool kvm_para_available(void) 937 { 938 return kvm_cpuid_base() != 0; 939 } 940 EXPORT_SYMBOL_GPL(kvm_para_available); 941 942 unsigned int kvm_arch_para_features(void) 943 { 944 return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES); 945 } 946 947 unsigned int kvm_arch_para_hints(void) 948 { 949 return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES); 950 } 951 EXPORT_SYMBOL_GPL(kvm_arch_para_hints); 952 953 static uint32_t __init kvm_detect(void) 954 { 955 return kvm_cpuid_base(); 956 } 957 958 static void __init kvm_apic_init(void) 959 { 960 #ifdef CONFIG_SMP 961 if (pv_ipi_supported()) 962 kvm_setup_pv_ipi(); 963 #endif 964 } 965 966 static bool __init kvm_msi_ext_dest_id(void) 967 { 968 return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID); 969 } 970 971 static void kvm_sev_hc_page_enc_status(unsigned long pfn, int npages, bool enc) 972 { 973 kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, pfn << PAGE_SHIFT, npages, 974 KVM_MAP_GPA_RANGE_ENC_STAT(enc) | KVM_MAP_GPA_RANGE_PAGE_SZ_4K); 975 } 976 977 static void __init kvm_init_platform(void) 978 { 979 u64 tolud = PFN_PHYS(e820__end_of_low_ram_pfn()); 980 /* 981 * Note, hardware requires variable MTRR ranges to be power-of-2 sized 982 * and naturally aligned. But when forcing guest MTRR state, Linux 983 * doesn't program the forced ranges into hardware. Don't bother doing 984 * the math to generate a technically-legal range. 985 */ 986 struct mtrr_var_range pci_hole = { 987 .base_lo = tolud | X86_MEMTYPE_UC, 988 .mask_lo = (u32)(~(SZ_4G - tolud - 1)) | MTRR_PHYSMASK_V, 989 .mask_hi = (BIT_ULL(boot_cpu_data.x86_phys_bits) - 1) >> 32, 990 }; 991 992 if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) && 993 kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) { 994 unsigned long nr_pages; 995 int i; 996 997 pv_ops.mmu.notify_page_enc_status_changed = 998 kvm_sev_hc_page_enc_status; 999 1000 /* 1001 * Reset the host's shared pages list related to kernel 1002 * specific page encryption status settings before we load a 1003 * new kernel by kexec. Reset the page encryption status 1004 * during early boot instead of just before kexec to avoid SMP 1005 * races during kvm_pv_guest_cpu_reboot(). 1006 * NOTE: We cannot reset the complete shared pages list 1007 * here as we need to retain the UEFI/OVMF firmware 1008 * specific settings. 1009 */ 1010 1011 for (i = 0; i < e820_table->nr_entries; i++) { 1012 struct e820_entry *entry = &e820_table->entries[i]; 1013 1014 if (entry->type != E820_TYPE_RAM) 1015 continue; 1016 1017 nr_pages = DIV_ROUND_UP(entry->size, PAGE_SIZE); 1018 1019 kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, entry->addr, 1020 nr_pages, 1021 KVM_MAP_GPA_RANGE_ENCRYPTED | KVM_MAP_GPA_RANGE_PAGE_SZ_4K); 1022 } 1023 1024 /* 1025 * Ensure that _bss_decrypted section is marked as decrypted in the 1026 * shared pages list. 1027 */ 1028 early_set_mem_enc_dec_hypercall((unsigned long)__start_bss_decrypted, 1029 __end_bss_decrypted - __start_bss_decrypted, 0); 1030 1031 /* 1032 * If not booted using EFI, enable Live migration support. 1033 */ 1034 if (!efi_enabled(EFI_BOOT)) 1035 wrmsrq(MSR_KVM_MIGRATION_CONTROL, 1036 KVM_MIGRATION_READY); 1037 } 1038 kvmclock_init(); 1039 x86_platform.apic_post_init = kvm_apic_init; 1040 1041 /* 1042 * Set WB as the default cache mode for SEV-SNP and TDX, with a single 1043 * UC range for the legacy PCI hole, e.g. so that devices that expect 1044 * to get UC/WC mappings don't get surprised with WB. 1045 */ 1046 guest_force_mtrr_state(&pci_hole, 1, MTRR_TYPE_WRBACK); 1047 } 1048 1049 #if defined(CONFIG_AMD_MEM_ENCRYPT) 1050 static void kvm_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs) 1051 { 1052 /* RAX and CPL are already in the GHCB */ 1053 ghcb_set_rbx(ghcb, regs->bx); 1054 ghcb_set_rcx(ghcb, regs->cx); 1055 ghcb_set_rdx(ghcb, regs->dx); 1056 ghcb_set_rsi(ghcb, regs->si); 1057 } 1058 1059 static bool kvm_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs) 1060 { 1061 /* No checking of the return state needed */ 1062 return true; 1063 } 1064 #endif 1065 1066 const __initconst struct hypervisor_x86 x86_hyper_kvm = { 1067 .name = "KVM", 1068 .detect = kvm_detect, 1069 .type = X86_HYPER_KVM, 1070 .init.guest_late_init = kvm_guest_init, 1071 .init.x2apic_available = kvm_para_available, 1072 .init.msi_ext_dest_id = kvm_msi_ext_dest_id, 1073 .init.init_platform = kvm_init_platform, 1074 #if defined(CONFIG_AMD_MEM_ENCRYPT) 1075 .runtime.sev_es_hcall_prepare = kvm_sev_es_hcall_prepare, 1076 .runtime.sev_es_hcall_finish = kvm_sev_es_hcall_finish, 1077 #endif 1078 }; 1079 1080 static __init int activate_jump_labels(void) 1081 { 1082 if (has_steal_clock) { 1083 static_branch_inc(¶virt_steal_enabled); 1084 if (steal_acc) 1085 static_branch_inc(¶virt_steal_rq_enabled); 1086 } 1087 1088 return 0; 1089 } 1090 arch_initcall(activate_jump_labels); 1091 1092 #ifdef CONFIG_PARAVIRT_SPINLOCKS 1093 1094 /* Kick a cpu by its apicid. Used to wake up a halted vcpu */ 1095 static void kvm_kick_cpu(int cpu) 1096 { 1097 unsigned long flags = 0; 1098 u32 apicid; 1099 1100 apicid = per_cpu(x86_cpu_to_apicid, cpu); 1101 kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid); 1102 } 1103 1104 #include <asm/qspinlock.h> 1105 1106 static void kvm_wait(u8 *ptr, u8 val) 1107 { 1108 if (in_nmi()) 1109 return; 1110 1111 /* 1112 * halt until it's our turn and kicked. Note that we do safe halt 1113 * for irq enabled case to avoid hang when lock info is overwritten 1114 * in irq spinlock slowpath and no spurious interrupt occur to save us. 1115 */ 1116 if (irqs_disabled()) { 1117 if (READ_ONCE(*ptr) == val) 1118 halt(); 1119 } else { 1120 local_irq_disable(); 1121 1122 /* safe_halt() will enable IRQ */ 1123 if (READ_ONCE(*ptr) == val) 1124 safe_halt(); 1125 else 1126 local_irq_enable(); 1127 } 1128 } 1129 1130 /* 1131 * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present. 1132 */ 1133 void __init kvm_spinlock_init(void) 1134 { 1135 /* 1136 * Disable PV spinlocks and use native qspinlock when dedicated pCPUs 1137 * are available. 1138 */ 1139 if (kvm_para_has_hint(KVM_HINTS_REALTIME)) { 1140 pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n"); 1141 goto out; 1142 } 1143 1144 if (num_possible_cpus() == 1) { 1145 pr_info("PV spinlocks disabled, single CPU\n"); 1146 goto out; 1147 } 1148 1149 if (nopvspin) { 1150 pr_info("PV spinlocks disabled, forced by \"nopvspin\" parameter\n"); 1151 goto out; 1152 } 1153 1154 /* 1155 * In case host doesn't support KVM_FEATURE_PV_UNHALT there is still an 1156 * advantage of keeping virt_spin_lock_key enabled: virt_spin_lock() is 1157 * preferred over native qspinlock when vCPU is preempted. 1158 */ 1159 if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) { 1160 pr_info("PV spinlocks disabled, no host support\n"); 1161 return; 1162 } 1163 1164 pr_info("PV spinlocks enabled\n"); 1165 1166 __pv_init_lock_hash(); 1167 static_call_update(queued_spin_lock_slowpath, __pv_queued_spin_lock_slowpath); 1168 static_call_update(queued_spin_unlock, __raw_callee_save___pv_queued_spin_unlock); 1169 pv_ops_lock.wait = kvm_wait; 1170 pv_ops_lock.kick = kvm_kick_cpu; 1171 1172 /* 1173 * When PV spinlock is enabled which is preferred over 1174 * virt_spin_lock(), virt_spin_lock_key's value is meaningless. 1175 * Just disable it anyway. 1176 */ 1177 out: 1178 static_branch_disable(&virt_spin_lock_key); 1179 } 1180 1181 #endif /* CONFIG_PARAVIRT_SPINLOCKS */ 1182 1183 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL 1184 1185 static void kvm_disable_host_haltpoll(void *i) 1186 { 1187 wrmsrq(MSR_KVM_POLL_CONTROL, 0); 1188 } 1189 1190 static void kvm_enable_host_haltpoll(void *i) 1191 { 1192 wrmsrq(MSR_KVM_POLL_CONTROL, 1); 1193 } 1194 1195 void arch_haltpoll_enable(unsigned int cpu) 1196 { 1197 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) { 1198 pr_err_once("host does not support poll control\n"); 1199 pr_err_once("host upgrade recommended\n"); 1200 return; 1201 } 1202 1203 /* Enable guest halt poll disables host halt poll */ 1204 smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1); 1205 } 1206 EXPORT_SYMBOL_GPL(arch_haltpoll_enable); 1207 1208 void arch_haltpoll_disable(unsigned int cpu) 1209 { 1210 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) 1211 return; 1212 1213 /* Disable guest halt poll enables host halt poll */ 1214 smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1); 1215 } 1216 EXPORT_SYMBOL_GPL(arch_haltpoll_disable); 1217 #endif 1218