arch/x86/kernel/cpu/mshyperv.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * HyperV  Detection code.
   4  *
   5  * Copyright (C) 2010, Novell, Inc.
   6  * Author : K. Y. Srinivasan <[email protected]>
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/time.h>
  11 #include <linux/clocksource.h>
  12 #include <linux/init.h>
  13 #include <linux/export.h>
  14 #include <linux/hardirq.h>
  15 #include <linux/efi.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/irq.h>
  18 #include <linux/kexec.h>
  19 #include <linux/random.h>
  20 #include <asm/processor.h>
  21 #include <asm/hypervisor.h>
  22 #include <asm/hyperv-tlfs.h>
  23 #include <asm/mshyperv.h>
  24 #include <asm/desc.h>
  25 #include <asm/idtentry.h>
  26 #include <asm/irq_regs.h>
  27 #include <asm/i8259.h>
  28 #include <asm/apic.h>
  29 #include <asm/timer.h>
  30 #include <asm/reboot.h>
  31 #include <asm/nmi.h>
  32 #include <clocksource/hyperv_timer.h>
  33 #include <asm/numa.h>
  34 #include <asm/svm.h>
  35
  36 /* Is Linux running as the root partition? */
  37 bool hv_root_partition;
  38 /* Is Linux running on nested Microsoft Hypervisor */
  39 bool hv_nested;
  40 struct ms_hyperv_info ms_hyperv;
  41
  42 /* Used in modules via hv_do_hypercall(): see arch/x86/include/asm/mshyperv.h */
  43 bool hyperv_paravisor_present __ro_after_init;
  44 EXPORT_SYMBOL_GPL(hyperv_paravisor_present);
  45
  46 #if IS_ENABLED(CONFIG_HYPERV)
  47 static inline unsigned int hv_get_nested_msr(unsigned int reg)
  48 {
  49         if (hv_is_sint_msr(reg))
  50                 return reg - HV_X64_MSR_SINT0 + HV_X64_MSR_NESTED_SINT0;
  51
  52         switch (reg) {
  53         case HV_X64_MSR_SIMP:
  54                 return HV_X64_MSR_NESTED_SIMP;
  55         case HV_X64_MSR_SIEFP:
  56                 return HV_X64_MSR_NESTED_SIEFP;
  57         case HV_X64_MSR_SVERSION:
  58                 return HV_X64_MSR_NESTED_SVERSION;
  59         case HV_X64_MSR_SCONTROL:
  60                 return HV_X64_MSR_NESTED_SCONTROL;
  61         case HV_X64_MSR_EOM:
  62                 return HV_X64_MSR_NESTED_EOM;
  63         default:
  64                 return reg;
  65         }
  66 }
  67
  68 u64 hv_get_non_nested_msr(unsigned int reg)
  69 {
  70         u64 value;
  71
  72         if (hv_is_synic_msr(reg) && ms_hyperv.paravisor_present)
  73                 hv_ivm_msr_read(reg, &value);
  74         else
  75                 rdmsrl(reg, value);
  76         return value;
  77 }
  78 EXPORT_SYMBOL_GPL(hv_get_non_nested_msr);
  79
  80 void hv_set_non_nested_msr(unsigned int reg, u64 value)
  81 {
  82         if (hv_is_synic_msr(reg) && ms_hyperv.paravisor_present) {
  83                 hv_ivm_msr_write(reg, value);
  84
  85                 /* Write proxy bit via wrmsl instruction */
  86                 if (hv_is_sint_msr(reg))
  87                         wrmsrl(reg, value | 1 << 20);
  88         } else {
  89                 wrmsrl(reg, value);
  90         }
  91 }
  92 EXPORT_SYMBOL_GPL(hv_set_non_nested_msr);
  93
  94 u64 hv_get_msr(unsigned int reg)
  95 {
  96         if (hv_nested)
  97                 reg = hv_get_nested_msr(reg);
  98
  99         return hv_get_non_nested_msr(reg);
 100 }
 101 EXPORT_SYMBOL_GPL(hv_get_msr);
 102
 103 void hv_set_msr(unsigned int reg, u64 value)
 104 {
 105         if (hv_nested)
 106                 reg = hv_get_nested_msr(reg);
 107
 108         hv_set_non_nested_msr(reg, value);
 109 }
 110 EXPORT_SYMBOL_GPL(hv_set_msr);
 111
 112 static void (*vmbus_handler)(void);
 113 static void (*hv_stimer0_handler)(void);
 114 static void (*hv_kexec_handler)(void);
 115 static void (*hv_crash_handler)(struct pt_regs *regs);
 116
 117 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_callback)
 118 {
 119         struct pt_regs *old_regs = set_irq_regs(regs);
 120
 121         inc_irq_stat(irq_hv_callback_count);
 122         if (vmbus_handler)
 123                 vmbus_handler();
 124
 125         if (ms_hyperv.hints & HV_DEPRECATING_AEOI_RECOMMENDED)
 126                 apic_eoi();
 127
 128         set_irq_regs(old_regs);
 129 }
 130
 131 void hv_setup_vmbus_handler(void (*handler)(void))
 132 {
 133         vmbus_handler = handler;
 134 }
 135
 136 void hv_remove_vmbus_handler(void)
 137 {
 138         /* We have no way to deallocate the interrupt gate */
 139         vmbus_handler = NULL;
 140 }
 141
 142 /*
 143  * Routines to do per-architecture handling of stimer0
 144  * interrupts when in Direct Mode
 145  */
 146 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_stimer0)
 147 {
 148         struct pt_regs *old_regs = set_irq_regs(regs);
 149
 150         inc_irq_stat(hyperv_stimer0_count);
 151         if (hv_stimer0_handler)
 152                 hv_stimer0_handler();
 153         add_interrupt_randomness(HYPERV_STIMER0_VECTOR);
 154         apic_eoi();
 155
 156         set_irq_regs(old_regs);
 157 }
 158
 159 /* For x86/x64, override weak placeholders in hyperv_timer.c */
 160 void hv_setup_stimer0_handler(void (*handler)(void))
 161 {
 162         hv_stimer0_handler = handler;
 163 }
 164
 165 void hv_remove_stimer0_handler(void)
 166 {
 167         /* We have no way to deallocate the interrupt gate */
 168         hv_stimer0_handler = NULL;
 169 }
 170
 171 void hv_setup_kexec_handler(void (*handler)(void))
 172 {
 173         hv_kexec_handler = handler;
 174 }
 175
 176 void hv_remove_kexec_handler(void)
 177 {
 178         hv_kexec_handler = NULL;
 179 }
 180
 181 void hv_setup_crash_handler(void (*handler)(struct pt_regs *regs))
 182 {
 183         hv_crash_handler = handler;
 184 }
 185
 186 void hv_remove_crash_handler(void)
 187 {
 188         hv_crash_handler = NULL;
 189 }
 190
 191 #ifdef CONFIG_KEXEC_CORE
 192 static void hv_machine_shutdown(void)
 193 {
 194         if (kexec_in_progress && hv_kexec_handler)
 195                 hv_kexec_handler();
 196
 197         /*
 198          * Call hv_cpu_die() on all the CPUs, otherwise later the hypervisor
 199          * corrupts the old VP Assist Pages and can crash the kexec kernel.
 200          */
 201         if (kexec_in_progress)
 202                 cpuhp_remove_state(CPUHP_AP_HYPERV_ONLINE);
 203
 204         /* The function calls stop_other_cpus(). */
 205         native_machine_shutdown();
 206
 207         /* Disable the hypercall page when there is only 1 active CPU. */
 208         if (kexec_in_progress)
 209                 hyperv_cleanup();
 210 }
 211 #endif /* CONFIG_KEXEC_CORE */
 212
 213 #ifdef CONFIG_CRASH_DUMP
 214 static void hv_machine_crash_shutdown(struct pt_regs *regs)
 215 {
 216         if (hv_crash_handler)
 217                 hv_crash_handler(regs);
 218
 219         /* The function calls crash_smp_send_stop(). */
 220         native_machine_crash_shutdown(regs);
 221
 222         /* Disable the hypercall page when there is only 1 active CPU. */
 223         hyperv_cleanup();
 224 }
 225 #endif /* CONFIG_CRASH_DUMP */
 226
 227 static u64 hv_ref_counter_at_suspend;
 228 static void (*old_save_sched_clock_state)(void);
 229 static void (*old_restore_sched_clock_state)(void);
 230
 231 /*
 232  * Hyper-V clock counter resets during hibernation. Save and restore clock
 233  * offset during suspend/resume, while also considering the time passed
 234  * before suspend. This is to make sure that sched_clock using hv tsc page
 235  * based clocksource, proceeds from where it left off during suspend and
 236  * it shows correct time for the timestamps of kernel messages after resume.
 237  */
 238 static void save_hv_clock_tsc_state(void)
 239 {
 240         hv_ref_counter_at_suspend = hv_read_reference_counter();
 241 }
 242
 243 static void restore_hv_clock_tsc_state(void)
 244 {
 245         /*
 246          * Adjust the offsets used by hv tsc clocksource to
 247          * account for the time spent before hibernation.
 248          * adjusted value = reference counter (time) at suspend
 249          *                - reference counter (time) now.
 250          */
 251         hv_adj_sched_clock_offset(hv_ref_counter_at_suspend - hv_read_reference_counter());
 252 }
 253
 254 /*
 255  * Functions to override save_sched_clock_state and restore_sched_clock_state
 256  * functions of x86_platform. The Hyper-V clock counter is reset during
 257  * suspend-resume and the offset used to measure time needs to be
 258  * corrected, post resume.
 259  */
 260 static void hv_save_sched_clock_state(void)
 261 {
 262         old_save_sched_clock_state();
 263         save_hv_clock_tsc_state();
 264 }
 265
 266 static void hv_restore_sched_clock_state(void)
 267 {
 268         restore_hv_clock_tsc_state();
 269         old_restore_sched_clock_state();
 270 }
 271
 272 static void __init x86_setup_ops_for_tsc_pg_clock(void)
 273 {
 274         if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))
 275                 return;
 276
 277         old_save_sched_clock_state = x86_platform.save_sched_clock_state;
 278         x86_platform.save_sched_clock_state = hv_save_sched_clock_state;
 279
 280         old_restore_sched_clock_state = x86_platform.restore_sched_clock_state;
 281         x86_platform.restore_sched_clock_state = hv_restore_sched_clock_state;
 282 }
 283 #endif /* CONFIG_HYPERV */
 284
 285 static uint32_t  __init ms_hyperv_platform(void)
 286 {
 287         u32 eax;
 288         u32 hyp_signature[3];
 289
 290         if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
 291                 return 0;
 292
 293         cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
 294               &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
 295
 296         if (eax < HYPERV_CPUID_MIN || eax > HYPERV_CPUID_MAX ||
 297             memcmp("Microsoft Hv", hyp_signature, 12))
 298                 return 0;
 299
 300         /* HYPERCALL and VP_INDEX MSRs are mandatory for all features. */
 301         eax = cpuid_eax(HYPERV_CPUID_FEATURES);
 302         if (!(eax & HV_MSR_HYPERCALL_AVAILABLE)) {
 303                 pr_warn("x86/hyperv: HYPERCALL MSR not available.\n");
 304                 return 0;
 305         }
 306         if (!(eax & HV_MSR_VP_INDEX_AVAILABLE)) {
 307                 pr_warn("x86/hyperv: VP_INDEX MSR not available.\n");
 308                 return 0;
 309         }
 310
 311         return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS;
 312 }
 313
 314 #ifdef CONFIG_X86_LOCAL_APIC
 315 /*
 316  * Prior to WS2016 Debug-VM sends NMIs to all CPUs which makes
 317  * it difficult to process CHANNELMSG_UNLOAD in case of crash. Handle
 318  * unknown NMI on the first CPU which gets it.
 319  */
 320 static int hv_nmi_unknown(unsigned int val, struct pt_regs *regs)
 321 {
 322         static atomic_t nmi_cpu = ATOMIC_INIT(-1);
 323         unsigned int old_cpu, this_cpu;
 324
 325         if (!unknown_nmi_panic)
 326                 return NMI_DONE;
 327
 328         old_cpu = -1;
 329         this_cpu = raw_smp_processor_id();
 330         if (!atomic_try_cmpxchg(&nmi_cpu, &old_cpu, this_cpu))
 331                 return NMI_HANDLED;
 332
 333         return NMI_DONE;
 334 }
 335 #endif
 336
 337 static unsigned long hv_get_tsc_khz(void)
 338 {
 339         unsigned long freq;
 340
 341         rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
 342
 343         return freq / 1000;
 344 }
 345
 346 #if defined(CONFIG_SMP) && IS_ENABLED(CONFIG_HYPERV)
 347 static void __init hv_smp_prepare_boot_cpu(void)
 348 {
 349         native_smp_prepare_boot_cpu();
 350 #if defined(CONFIG_X86_64) && defined(CONFIG_PARAVIRT_SPINLOCKS)
 351         hv_init_spinlocks();
 352 #endif
 353 }
 354
 355 static void __init hv_smp_prepare_cpus(unsigned int max_cpus)
 356 {
 357 #ifdef CONFIG_X86_64
 358         int i;
 359         int ret;
 360 #endif
 361
 362         native_smp_prepare_cpus(max_cpus);
 363
 364         /*
 365          *  Override wakeup_secondary_cpu_64 callback for SEV-SNP
 366          *  enlightened guest.
 367          */
 368         if (!ms_hyperv.paravisor_present && hv_isolation_type_snp()) {
 369                 apic->wakeup_secondary_cpu_64 = hv_snp_boot_ap;
 370                 return;
 371         }
 372
 373 #ifdef CONFIG_X86_64
 374         for_each_present_cpu(i) {
 375                 if (i == 0)
 376                         continue;
 377                 ret = hv_call_add_logical_proc(numa_cpu_node(i), i, cpu_physical_id(i));
 378                 BUG_ON(ret);
 379         }
 380
 381         for_each_present_cpu(i) {
 382                 if (i == 0)
 383                         continue;
 384                 ret = hv_call_create_vp(numa_cpu_node(i), hv_current_partition_id, i, i);
 385                 BUG_ON(ret);
 386         }
 387 #endif
 388 }
 389 #endif
 390
 391 /*
 392  * When a fully enlightened TDX VM runs on Hyper-V, the firmware sets the
 393  * HW_REDUCED flag: refer to acpi_tb_create_local_fadt(). Consequently ttyS0
 394  * interrupts can't work because request_irq() -> ... -> irq_to_desc() returns
 395  * NULL for ttyS0. This happens because mp_config_acpi_legacy_irqs() sees a
 396  * nr_legacy_irqs() of 0, so it doesn't initialize the array 'mp_irqs[]', and
 397  * later setup_IO_APIC_irqs() -> find_irq_entry() fails to find the legacy irqs
 398  * from the array and hence doesn't create the necessary irq description info.
 399  *
 400  * Clone arch/x86/kernel/acpi/boot.c: acpi_generic_reduced_hw_init() here,
 401  * except don't change 'legacy_pic', which keeps its default value
 402  * 'default_legacy_pic'. This way, mp_config_acpi_legacy_irqs() sees a non-zero
 403  * nr_legacy_irqs() and eventually serial console interrupts works properly.
 404  */
 405 static void __init reduced_hw_init(void)
 406 {
 407         x86_init.timers.timer_init      = x86_init_noop;
 408         x86_init.irqs.pre_vector_init   = x86_init_noop;
 409 }
 410
 411 int hv_get_hypervisor_version(union hv_hypervisor_version_info *info)
 412 {
 413         unsigned int hv_max_functions;
 414
 415         hv_max_functions = cpuid_eax(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS);
 416         if (hv_max_functions < HYPERV_CPUID_VERSION) {
 417                 pr_err("%s: Could not detect Hyper-V version\n", __func__);
 418                 return -ENODEV;
 419         }
 420
 421         cpuid(HYPERV_CPUID_VERSION, &info->eax, &info->ebx, &info->ecx, &info->edx);
 422
 423         return 0;
 424 }
 425
 426 static void __init ms_hyperv_init_platform(void)
 427 {
 428         int hv_max_functions_eax;
 429
 430 #ifdef CONFIG_PARAVIRT
 431         pv_info.name = "Hyper-V";
 432 #endif
 433
 434         /*
 435          * Extract the features and hints
 436          */
 437         ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
 438         ms_hyperv.priv_high = cpuid_ebx(HYPERV_CPUID_FEATURES);
 439         ms_hyperv.misc_features = cpuid_edx(HYPERV_CPUID_FEATURES);
 440         ms_hyperv.hints    = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
 441
 442         hv_max_functions_eax = cpuid_eax(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS);
 443
 444         pr_info("Hyper-V: privilege flags low 0x%x, high 0x%x, hints 0x%x, misc 0x%x\n",
 445                 ms_hyperv.features, ms_hyperv.priv_high, ms_hyperv.hints,
 446                 ms_hyperv.misc_features);
 447
 448         ms_hyperv.max_vp_index = cpuid_eax(HYPERV_CPUID_IMPLEMENT_LIMITS);
 449         ms_hyperv.max_lp_index = cpuid_ebx(HYPERV_CPUID_IMPLEMENT_LIMITS);
 450
 451         pr_debug("Hyper-V: max %u virtual processors, %u logical processors\n",
 452                  ms_hyperv.max_vp_index, ms_hyperv.max_lp_index);
 453
 454         /*
 455          * Check CPU management privilege.
 456          *
 457          * To mirror what Windows does we should extract CPU management
 458          * features and use the ReservedIdentityBit to detect if Linux is the
 459          * root partition. But that requires negotiating CPU management
 460          * interface (a process to be finalized). For now, use the privilege
 461          * flag as the indicator for running as root.
 462          *
 463          * Hyper-V should never specify running as root and as a Confidential
 464          * VM. But to protect against a compromised/malicious Hyper-V trying
 465          * to exploit root behavior to expose Confidential VM memory, ignore
 466          * the root partition setting if also a Confidential VM.
 467          */
 468         if ((ms_hyperv.priv_high & HV_CPU_MANAGEMENT) &&
 469             !(ms_hyperv.priv_high & HV_ISOLATION)) {
 470                 hv_root_partition = true;
 471                 pr_info("Hyper-V: running as root partition\n");
 472         }
 473
 474         if (ms_hyperv.hints & HV_X64_HYPERV_NESTED) {
 475                 hv_nested = true;
 476                 pr_info("Hyper-V: running on a nested hypervisor\n");
 477         }
 478
 479         if (ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
 480             ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
 481                 x86_platform.calibrate_tsc = hv_get_tsc_khz;
 482                 x86_platform.calibrate_cpu = hv_get_tsc_khz;
 483                 setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
 484         }
 485
 486         if (ms_hyperv.priv_high & HV_ISOLATION) {
 487                 ms_hyperv.isolation_config_a = cpuid_eax(HYPERV_CPUID_ISOLATION_CONFIG);
 488                 ms_hyperv.isolation_config_b = cpuid_ebx(HYPERV_CPUID_ISOLATION_CONFIG);
 489
 490                 if (ms_hyperv.shared_gpa_boundary_active)
 491                         ms_hyperv.shared_gpa_boundary =
 492                                 BIT_ULL(ms_hyperv.shared_gpa_boundary_bits);
 493
 494                 hyperv_paravisor_present = !!ms_hyperv.paravisor_present;
 495
 496                 pr_info("Hyper-V: Isolation Config: Group A 0x%x, Group B 0x%x\n",
 497                         ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b);
 498
 499
 500                 if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP) {
 501                         static_branch_enable(&isolation_type_snp);
 502                 } else if (hv_get_isolation_type() == HV_ISOLATION_TYPE_TDX) {
 503                         static_branch_enable(&isolation_type_tdx);
 504
 505                         /* A TDX VM must use x2APIC and doesn't use lazy EOI. */
 506                         ms_hyperv.hints &= ~HV_X64_APIC_ACCESS_RECOMMENDED;
 507
 508                         if (!ms_hyperv.paravisor_present) {
 509                                 /*
 510                                  * Mark the Hyper-V TSC page feature as disabled
 511                                  * in a TDX VM without paravisor so that the
 512                                  * Invariant TSC, which is a better clocksource
 513                                  * anyway, is used instead.
 514                                  */
 515                                 ms_hyperv.features &= ~HV_MSR_REFERENCE_TSC_AVAILABLE;
 516
 517                                 /*
 518                                  * The Invariant TSC is expected to be available
 519                                  * in a TDX VM without paravisor, but if not,
 520                                  * print a warning message. The slower Hyper-V MSR-based
 521                                  * Ref Counter should end up being the clocksource.
 522                                  */
 523                                 if (!(ms_hyperv.features & HV_ACCESS_TSC_INVARIANT))
 524                                         pr_warn("Hyper-V: Invariant TSC is unavailable\n");
 525
 526                                 /* HV_MSR_CRASH_CTL is unsupported. */
 527                                 ms_hyperv.misc_features &= ~HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE;
 528
 529                                 /* Don't trust Hyper-V's TLB-flushing hypercalls. */
 530                                 ms_hyperv.hints &= ~HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED;
 531
 532                                 x86_init.acpi.reduced_hw_early_init = reduced_hw_init;
 533                         }
 534                 }
 535         }
 536
 537         if (hv_max_functions_eax >= HYPERV_CPUID_NESTED_FEATURES) {
 538                 ms_hyperv.nested_features =
 539                         cpuid_eax(HYPERV_CPUID_NESTED_FEATURES);
 540                 pr_info("Hyper-V: Nested features: 0x%x\n",
 541                         ms_hyperv.nested_features);
 542         }
 543
 544 #ifdef CONFIG_X86_LOCAL_APIC
 545         if (ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
 546             ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
 547                 /*
 548                  * Get the APIC frequency.
 549                  */
 550                 u64     hv_lapic_frequency;
 551
 552                 rdmsrl(HV_X64_MSR_APIC_FREQUENCY, hv_lapic_frequency);
 553                 hv_lapic_frequency = div_u64(hv_lapic_frequency, HZ);
 554                 lapic_timer_period = hv_lapic_frequency;
 555                 pr_info("Hyper-V: LAPIC Timer Frequency: %#x\n",
 556                         lapic_timer_period);
 557         }
 558
 559         register_nmi_handler(NMI_UNKNOWN, hv_nmi_unknown, NMI_FLAG_FIRST,
 560                              "hv_nmi_unknown");
 561 #endif
 562
 563 #ifdef CONFIG_X86_IO_APIC
 564         no_timer_check = 1;
 565 #endif
 566
 567 #if IS_ENABLED(CONFIG_HYPERV)
 568 #if defined(CONFIG_KEXEC_CORE)
 569         machine_ops.shutdown = hv_machine_shutdown;
 570 #endif
 571 #if defined(CONFIG_CRASH_DUMP)
 572         machine_ops.crash_shutdown = hv_machine_crash_shutdown;
 573 #endif
 574 #endif
 575         if (ms_hyperv.features & HV_ACCESS_TSC_INVARIANT) {
 576                 /*
 577                  * Writing to synthetic MSR 0x40000118 updates/changes the
 578                  * guest visible CPUIDs. Setting bit 0 of this MSR  enables
 579                  * guests to report invariant TSC feature through CPUID
 580                  * instruction, CPUID 0x800000007/EDX, bit 8. See code in
 581                  * early_init_intel() where this bit is examined. The
 582                  * setting of this MSR bit should happen before init_intel()
 583                  * is called.
 584                  */
 585                 wrmsrl(HV_X64_MSR_TSC_INVARIANT_CONTROL, HV_EXPOSE_INVARIANT_TSC);
 586                 setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
 587         }
 588
 589         /*
 590          * Generation 2 instances don't support reading the NMI status from
 591          * 0x61 port.
 592          */
 593         if (efi_enabled(EFI_BOOT))
 594                 x86_platform.get_nmi_reason = hv_get_nmi_reason;
 595
 596 #if IS_ENABLED(CONFIG_HYPERV)
 597         if ((hv_get_isolation_type() == HV_ISOLATION_TYPE_VBS) ||
 598             ms_hyperv.paravisor_present)
 599                 hv_vtom_init();
 600         /*
 601          * Setup the hook to get control post apic initialization.
 602          */
 603         x86_platform.apic_post_init = hyperv_init;
 604         hyperv_setup_mmu_ops();
 605
 606         /* Install system interrupt handler for hypervisor callback */
 607         sysvec_install(HYPERVISOR_CALLBACK_VECTOR, sysvec_hyperv_callback);
 608
 609         /* Install system interrupt handler for reenlightenment notifications */
 610         if (ms_hyperv.features & HV_ACCESS_REENLIGHTENMENT) {
 611                 sysvec_install(HYPERV_REENLIGHTENMENT_VECTOR, sysvec_hyperv_reenlightenment);
 612         }
 613
 614         /* Install system interrupt handler for stimer0 */
 615         if (ms_hyperv.misc_features & HV_STIMER_DIRECT_MODE_AVAILABLE) {
 616                 sysvec_install(HYPERV_STIMER0_VECTOR, sysvec_hyperv_stimer0);
 617         }
 618
 619 # ifdef CONFIG_SMP
 620         smp_ops.smp_prepare_boot_cpu = hv_smp_prepare_boot_cpu;
 621         if (hv_root_partition ||
 622             (!ms_hyperv.paravisor_present && hv_isolation_type_snp()))
 623                 smp_ops.smp_prepare_cpus = hv_smp_prepare_cpus;
 624 # endif
 625
 626         /*
 627          * Hyper-V doesn't provide irq remapping for IO-APIC. To enable x2apic,
 628          * set x2apic destination mode to physical mode when x2apic is available
 629          * and Hyper-V IOMMU driver makes sure cpus assigned with IO-APIC irqs
 630          * have 8-bit APIC id.
 631          */
 632 # ifdef CONFIG_X86_X2APIC
 633         if (x2apic_supported())
 634                 x2apic_phys = 1;
 635 # endif
 636
 637         /* Register Hyper-V specific clocksource */
 638         hv_init_clocksource();
 639         x86_setup_ops_for_tsc_pg_clock();
 640         hv_vtl_init_platform();
 641 #endif
 642         /*
 643          * TSC should be marked as unstable only after Hyper-V
 644          * clocksource has been initialized. This ensures that the
 645          * stability of the sched_clock is not altered.
 646          */
 647         if (!(ms_hyperv.features & HV_ACCESS_TSC_INVARIANT))
 648                 mark_tsc_unstable("running on Hyper-V");
 649
 650         hardlockup_detector_disable();
 651 }
 652
 653 static bool __init ms_hyperv_x2apic_available(void)
 654 {
 655         return x2apic_supported();
 656 }
 657
 658 /*
 659  * If ms_hyperv_msi_ext_dest_id() returns true, hyperv_prepare_irq_remapping()
 660  * returns -ENODEV and the Hyper-V IOMMU driver is not used; instead, the
 661  * generic support of the 15-bit APIC ID is used: see __irq_msi_compose_msg().
 662  *
 663  * Note: for a VM on Hyper-V, the I/O-APIC is the only device which
 664  * (logically) generates MSIs directly to the system APIC irq domain.
 665  * There is no HPET, and PCI MSI/MSI-X interrupts are remapped by the
 666  * pci-hyperv host bridge.
 667  *
 668  * Note: for a Hyper-V root partition, this will always return false.
 669  * The hypervisor doesn't expose these HYPERV_CPUID_VIRT_STACK_* cpuids by
 670  * default, they are implemented as intercepts by the Windows Hyper-V stack.
 671  * Even a nested root partition (L2 root) will not get them because the
 672  * nested (L1) hypervisor filters them out.
 673  */
 674 static bool __init ms_hyperv_msi_ext_dest_id(void)
 675 {
 676         u32 eax;
 677
 678         eax = cpuid_eax(HYPERV_CPUID_VIRT_STACK_INTERFACE);
 679         if (eax != HYPERV_VS_INTERFACE_EAX_SIGNATURE)
 680                 return false;
 681
 682         eax = cpuid_eax(HYPERV_CPUID_VIRT_STACK_PROPERTIES);
 683         return eax & HYPERV_VS_PROPERTIES_EAX_EXTENDED_IOAPIC_RTE;
 684 }
 685
 686 #ifdef CONFIG_AMD_MEM_ENCRYPT
 687 static void hv_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs)
 688 {
 689         /* RAX and CPL are already in the GHCB */
 690         ghcb_set_rcx(ghcb, regs->cx);
 691         ghcb_set_rdx(ghcb, regs->dx);
 692         ghcb_set_r8(ghcb, regs->r8);
 693 }
 694
 695 static bool hv_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs)
 696 {
 697         /* No checking of the return state needed */
 698         return true;
 699 }
 700 #endif
 701
 702 const __initconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
 703         .name                   = "Microsoft Hyper-V",
 704         .detect                 = ms_hyperv_platform,
 705         .type                   = X86_HYPER_MS_HYPERV,
 706         .init.x2apic_available  = ms_hyperv_x2apic_available,
 707         .init.msi_ext_dest_id   = ms_hyperv_msi_ext_dest_id,
 708         .init.init_platform     = ms_hyperv_init_platform,
 709         .init.guest_late_init   = ms_hyperv_late_init,
 710 #ifdef CONFIG_AMD_MEM_ENCRYPT
 711         .runtime.sev_es_hcall_prepare = hv_sev_es_hcall_prepare,
 712         .runtime.sev_es_hcall_finish = hv_sev_es_hcall_finish,
 713 #endif
 714 };