arch/x86/hyperv/hv_init.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * X86 specific Hyper-V initialization code.
   4  *
   5  * Copyright (C) 2016, Microsoft, Inc.
   6  *
   7  * Author : K. Y. Srinivasan <kys@microsoft.com>
   8  */
   9
  10 #define pr_fmt(fmt)  "Hyper-V: " fmt
  11
  12 #include <linux/efi.h>
  13 #include <linux/types.h>
  14 #include <linux/bitfield.h>
  15 #include <linux/io.h>
  16 #include <asm/apic.h>
  17 #include <asm/desc.h>
  18 #include <asm/e820/api.h>
  19 #include <asm/sev.h>
  20 #include <asm/ibt.h>
  21 #include <asm/hypervisor.h>
  22 #include <asm/hyperv-tlfs.h>
  23 #include <asm/mshyperv.h>
  24 #include <asm/idtentry.h>
  25 #include <asm/set_memory.h>
  26 #include <linux/kexec.h>
  27 #include <linux/version.h>
  28 #include <linux/vmalloc.h>
  29 #include <linux/mm.h>
  30 #include <linux/hyperv.h>
  31 #include <linux/slab.h>
  32 #include <linux/kernel.h>
  33 #include <linux/cpuhotplug.h>
  34 #include <linux/syscore_ops.h>
  35 #include <clocksource/hyperv_timer.h>
  36 #include <linux/highmem.h>
  37
  38 int hyperv_init_cpuhp;
  39 u64 hv_current_partition_id = ~0ull;
  40 EXPORT_SYMBOL_GPL(hv_current_partition_id);
  41
  42 void *hv_hypercall_pg;
  43 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
  44
  45 union hv_ghcb * __percpu *hv_ghcb_pg;
  46
  47 /* Storage to save the hypercall page temporarily for hibernation */
  48 static void *hv_hypercall_pg_saved;
  49
  50 struct hv_vp_assist_page **hv_vp_assist_page;
  51 EXPORT_SYMBOL_GPL(hv_vp_assist_page);
  52
  53 static int hyperv_init_ghcb(void)
  54 {
  55         u64 ghcb_gpa;
  56         void *ghcb_va;
  57         void **ghcb_base;
  58
  59         if (!ms_hyperv.paravisor_present || !hv_isolation_type_snp())
  60                 return 0;
  61
  62         if (!hv_ghcb_pg)
  63                 return -EINVAL;
  64
  65         /*
  66          * GHCB page is allocated by paravisor. The address
  67          * returned by MSR_AMD64_SEV_ES_GHCB is above shared
  68          * memory boundary and map it here.
  69          */
  70         rdmsrl(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa);
  71
  72         /* Mask out vTOM bit. ioremap_cache() maps decrypted */
  73         ghcb_gpa &= ~ms_hyperv.shared_gpa_boundary;
  74         ghcb_va = (void *)ioremap_cache(ghcb_gpa, HV_HYP_PAGE_SIZE);
  75         if (!ghcb_va)
  76                 return -ENOMEM;
  77
  78         ghcb_base = (void **)this_cpu_ptr(hv_ghcb_pg);
  79         *ghcb_base = ghcb_va;
  80
  81         return 0;
  82 }
  83
  84 static int hv_cpu_init(unsigned int cpu)
  85 {
  86         union hv_vp_assist_msr_contents msr = { 0 };
  87         struct hv_vp_assist_page **hvp;
  88         int ret;
  89
  90         ret = hv_common_cpu_init(cpu);
  91         if (ret)
  92                 return ret;
  93
  94         if (!hv_vp_assist_page)
  95                 return 0;
  96
  97         hvp = &hv_vp_assist_page[cpu];
  98         if (hv_root_partition) {
  99                 /*
 100                  * For root partition we get the hypervisor provided VP assist
 101                  * page, instead of allocating a new page.
 102                  */
 103                 rdmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
 104                 *hvp = memremap(msr.pfn << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT,
 105                                 PAGE_SIZE, MEMREMAP_WB);
 106         } else {
 107                 /*
 108                  * The VP assist page is an "overlay" page (see Hyper-V TLFS's
 109                  * Section 5.2.1 "GPA Overlay Pages"). Here it must be zeroed
 110                  * out to make sure we always write the EOI MSR in
 111                  * hv_apic_eoi_write() *after* the EOI optimization is disabled
 112                  * in hv_cpu_die(), otherwise a CPU may not be stopped in the
 113                  * case of CPU offlining and the VM will hang.
 114                  */
 115                 if (!*hvp) {
 116                         *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO);
 117
 118                         /*
 119                          * Hyper-V should never specify a VM that is a Confidential
 120                          * VM and also running in the root partition. Root partition
 121                          * is blocked to run in Confidential VM. So only decrypt assist
 122                          * page in non-root partition here.
 123                          */
 124                         if (*hvp && !ms_hyperv.paravisor_present && hv_isolation_type_snp()) {
 125                                 WARN_ON_ONCE(set_memory_decrypted((unsigned long)(*hvp), 1));
 126                                 memset(*hvp, 0, PAGE_SIZE);
 127                         }
 128                 }
 129
 130                 if (*hvp)
 131                         msr.pfn = vmalloc_to_pfn(*hvp);
 132
 133         }
 134         if (!WARN_ON(!(*hvp))) {
 135                 msr.enable = 1;
 136                 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
 137         }
 138
 139         return hyperv_init_ghcb();
 140 }
 141
 142 static void (*hv_reenlightenment_cb)(void);
 143
 144 static void hv_reenlightenment_notify(struct work_struct *dummy)
 145 {
 146         struct hv_tsc_emulation_status emu_status;
 147
 148         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 149
 150         /* Don't issue the callback if TSC accesses are not emulated */
 151         if (hv_reenlightenment_cb && emu_status.inprogress)
 152                 hv_reenlightenment_cb();
 153 }
 154 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify);
 155
 156 void hyperv_stop_tsc_emulation(void)
 157 {
 158         u64 freq;
 159         struct hv_tsc_emulation_status emu_status;
 160
 161         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 162         emu_status.inprogress = 0;
 163         wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 164
 165         rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
 166         tsc_khz = div64_u64(freq, 1000);
 167 }
 168 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation);
 169
 170 static inline bool hv_reenlightenment_available(void)
 171 {
 172         /*
 173          * Check for required features and privileges to make TSC frequency
 174          * change notifications work.
 175          */
 176         return ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
 177                 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
 178                 ms_hyperv.features & HV_ACCESS_REENLIGHTENMENT;
 179 }
 180
 181 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_reenlightenment)
 182 {
 183         apic_eoi();
 184         inc_irq_stat(irq_hv_reenlightenment_count);
 185         schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
 186 }
 187
 188 void set_hv_tscchange_cb(void (*cb)(void))
 189 {
 190         struct hv_reenlightenment_control re_ctrl = {
 191                 .vector = HYPERV_REENLIGHTENMENT_VECTOR,
 192                 .enabled = 1,
 193         };
 194         struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
 195
 196         if (!hv_reenlightenment_available()) {
 197                 pr_warn("reenlightenment support is unavailable\n");
 198                 return;
 199         }
 200
 201         if (!hv_vp_index)
 202                 return;
 203
 204         hv_reenlightenment_cb = cb;
 205
 206         /* Make sure callback is registered before we write to MSRs */
 207         wmb();
 208
 209         re_ctrl.target_vp = hv_vp_index[get_cpu()];
 210
 211         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 212         wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
 213
 214         put_cpu();
 215 }
 216 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
 217
 218 void clear_hv_tscchange_cb(void)
 219 {
 220         struct hv_reenlightenment_control re_ctrl;
 221
 222         if (!hv_reenlightenment_available())
 223                 return;
 224
 225         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
 226         re_ctrl.enabled = 0;
 227         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
 228
 229         hv_reenlightenment_cb = NULL;
 230 }
 231 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);
 232
 233 static int hv_cpu_die(unsigned int cpu)
 234 {
 235         struct hv_reenlightenment_control re_ctrl;
 236         unsigned int new_cpu;
 237         void **ghcb_va;
 238
 239         if (hv_ghcb_pg) {
 240                 ghcb_va = (void **)this_cpu_ptr(hv_ghcb_pg);
 241                 if (*ghcb_va)
 242                         iounmap(*ghcb_va);
 243                 *ghcb_va = NULL;
 244         }
 245
 246         hv_common_cpu_die(cpu);
 247
 248         if (hv_vp_assist_page && hv_vp_assist_page[cpu]) {
 249                 union hv_vp_assist_msr_contents msr = { 0 };
 250                 if (hv_root_partition) {
 251                         /*
 252                          * For root partition the VP assist page is mapped to
 253                          * hypervisor provided page, and thus we unmap the
 254                          * page here and nullify it, so that in future we have
 255                          * correct page address mapped in hv_cpu_init.
 256                          */
 257                         memunmap(hv_vp_assist_page[cpu]);
 258                         hv_vp_assist_page[cpu] = NULL;
 259                         rdmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
 260                         msr.enable = 0;
 261                 }
 262                 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
 263         }
 264
 265         if (hv_reenlightenment_cb == NULL)
 266                 return 0;
 267
 268         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 269         if (re_ctrl.target_vp == hv_vp_index[cpu]) {
 270                 /*
 271                  * Reassign reenlightenment notifications to some other online
 272                  * CPU or just disable the feature if there are no online CPUs
 273                  * left (happens on hibernation).
 274                  */
 275                 new_cpu = cpumask_any_but(cpu_online_mask, cpu);
 276
 277                 if (new_cpu < nr_cpu_ids)
 278                         re_ctrl.target_vp = hv_vp_index[new_cpu];
 279                 else
 280                         re_ctrl.enabled = 0;
 281
 282                 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 283         }
 284
 285         return 0;
 286 }
 287
 288 static int __init hv_pci_init(void)
 289 {
 290         bool gen2vm = efi_enabled(EFI_BOOT);
 291
 292         /*
 293          * A Generation-2 VM doesn't support legacy PCI/PCIe, so both
 294          * raw_pci_ops and raw_pci_ext_ops are NULL, and pci_subsys_init() ->
 295          * pcibios_init() doesn't call pcibios_resource_survey() ->
 296          * e820__reserve_resources_late(); as a result, any emulated persistent
 297          * memory of E820_TYPE_PRAM (12) via the kernel parameter
 298          * memmap=nn[KMG]!ss is not added into iomem_resource and hence can't be
 299          * detected by register_e820_pmem(). Fix this by directly calling
 300          * e820__reserve_resources_late() here: e820__reserve_resources_late()
 301          * depends on e820__reserve_resources(), which has been called earlier
 302          * from setup_arch(). Note: e820__reserve_resources_late() also adds
 303          * any memory of E820_TYPE_PMEM (7) into iomem_resource, and
 304          * acpi_nfit_register_region() -> acpi_nfit_insert_resource() ->
 305          * region_intersects() returns REGION_INTERSECTS, so the memory of
 306          * E820_TYPE_PMEM won't get added twice.
 307          *
 308          * We return 0 here so that pci_arch_init() won't print the warning:
 309          * "PCI: Fatal: No config space access function found"
 310          */
 311         if (gen2vm) {
 312                 e820__reserve_resources_late();
 313                 return 0;
 314         }
 315
 316         /* For Generation-1 VM, we'll proceed in pci_arch_init().  */
 317         return 1;
 318 }
 319
 320 static int hv_suspend(void)
 321 {
 322         union hv_x64_msr_hypercall_contents hypercall_msr;
 323         int ret;
 324
 325         if (hv_root_partition)
 326                 return -EPERM;
 327
 328         /*
 329          * Reset the hypercall page as it is going to be invalidated
 330          * across hibernation. Setting hv_hypercall_pg to NULL ensures
 331          * that any subsequent hypercall operation fails safely instead of
 332          * crashing due to an access of an invalid page. The hypercall page
 333          * pointer is restored on resume.
 334          */
 335         hv_hypercall_pg_saved = hv_hypercall_pg;
 336         hv_hypercall_pg = NULL;
 337
 338         /* Disable the hypercall page in the hypervisor */
 339         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 340         hypercall_msr.enable = 0;
 341         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 342
 343         ret = hv_cpu_die(0);
 344         return ret;
 345 }
 346
 347 static void hv_resume(void)
 348 {
 349         union hv_x64_msr_hypercall_contents hypercall_msr;
 350         int ret;
 351
 352         ret = hv_cpu_init(0);
 353         WARN_ON(ret);
 354
 355         /* Re-enable the hypercall page */
 356         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 357         hypercall_msr.enable = 1;
 358         hypercall_msr.guest_physical_address =
 359                 vmalloc_to_pfn(hv_hypercall_pg_saved);
 360         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 361
 362         hv_hypercall_pg = hv_hypercall_pg_saved;
 363         hv_hypercall_pg_saved = NULL;
 364
 365         /*
 366          * Reenlightenment notifications are disabled by hv_cpu_die(0),
 367          * reenable them here if hv_reenlightenment_cb was previously set.
 368          */
 369         if (hv_reenlightenment_cb)
 370                 set_hv_tscchange_cb(hv_reenlightenment_cb);
 371 }
 372
 373 /* Note: when the ops are called, only CPU0 is online and IRQs are disabled. */
 374 static struct syscore_ops hv_syscore_ops = {
 375         .suspend        = hv_suspend,
 376         .resume         = hv_resume,
 377 };
 378
 379 static void (* __initdata old_setup_percpu_clockev)(void);
 380
 381 static void __init hv_stimer_setup_percpu_clockev(void)
 382 {
 383         /*
 384          * Ignore any errors in setting up stimer clockevents
 385          * as we can run with the LAPIC timer as a fallback.
 386          */
 387         (void)hv_stimer_alloc(false);
 388
 389         /*
 390          * Still register the LAPIC timer, because the direct-mode STIMER is
 391          * not supported by old versions of Hyper-V. This also allows users
 392          * to switch to LAPIC timer via /sys, if they want to.
 393          */
 394         if (old_setup_percpu_clockev)
 395                 old_setup_percpu_clockev();
 396 }
 397
 398 static void __init hv_get_partition_id(void)
 399 {
 400         struct hv_get_partition_id *output_page;
 401         u64 status;
 402         unsigned long flags;
 403
 404         local_irq_save(flags);
 405         output_page = *this_cpu_ptr(hyperv_pcpu_output_arg);
 406         status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page);
 407         if (!hv_result_success(status)) {
 408                 /* No point in proceeding if this failed */
 409                 pr_err("Failed to get partition ID: %lld\n", status);
 410                 BUG();
 411         }
 412         hv_current_partition_id = output_page->partition_id;
 413         local_irq_restore(flags);
 414 }
 415
 416 #if IS_ENABLED(CONFIG_HYPERV_VTL_MODE)
 417 static u8 __init get_vtl(void)
 418 {
 419         u64 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_REGISTERS;
 420         struct hv_get_vp_registers_input *input;
 421         struct hv_get_vp_registers_output *output;
 422         unsigned long flags;
 423         u64 ret;
 424
 425         local_irq_save(flags);
 426         input = *this_cpu_ptr(hyperv_pcpu_input_arg);
 427         output = (struct hv_get_vp_registers_output *)input;
 428
 429         memset(input, 0, struct_size(input, element, 1));
 430         input->header.partitionid = HV_PARTITION_ID_SELF;
 431         input->header.vpindex = HV_VP_INDEX_SELF;
 432         input->header.inputvtl = 0;
 433         input->element[0].name0 = HV_X64_REGISTER_VSM_VP_STATUS;
 434
 435         ret = hv_do_hypercall(control, input, output);
 436         if (hv_result_success(ret)) {
 437                 ret = output->as64.low & HV_X64_VTL_MASK;
 438         } else {
 439                 pr_err("Failed to get VTL(error: %lld) exiting...\n", ret);
 440                 BUG();
 441         }
 442
 443         local_irq_restore(flags);
 444         return ret;
 445 }
 446 #else
 447 static inline u8 get_vtl(void) { return 0; }
 448 #endif
 449
 450 /*
 451  * This function is to be invoked early in the boot sequence after the
 452  * hypervisor has been detected.
 453  *
 454  * 1. Setup the hypercall page.
 455  * 2. Register Hyper-V specific clocksource.
 456  * 3. Setup Hyper-V specific APIC entry points.
 457  */
 458 void __init hyperv_init(void)
 459 {
 460         u64 guest_id;
 461         union hv_x64_msr_hypercall_contents hypercall_msr;
 462         int cpuhp;
 463
 464         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
 465                 return;
 466
 467         if (hv_common_init())
 468                 return;
 469
 470         /*
 471          * The VP assist page is useless to a TDX guest: the only use we
 472          * would have for it is lazy EOI, which can not be used with TDX.
 473          */
 474         if (hv_isolation_type_tdx())
 475                 hv_vp_assist_page = NULL;
 476         else
 477                 hv_vp_assist_page = kcalloc(num_possible_cpus(),
 478                                             sizeof(*hv_vp_assist_page),
 479                                             GFP_KERNEL);
 480         if (!hv_vp_assist_page) {
 481                 ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
 482
 483                 if (!hv_isolation_type_tdx())
 484                         goto common_free;
 485         }
 486
 487         if (ms_hyperv.paravisor_present && hv_isolation_type_snp()) {
 488                 /* Negotiate GHCB Version. */
 489                 if (!hv_ghcb_negotiate_protocol())
 490                         hv_ghcb_terminate(SEV_TERM_SET_GEN,
 491                                           GHCB_SEV_ES_PROT_UNSUPPORTED);
 492
 493                 hv_ghcb_pg = alloc_percpu(union hv_ghcb *);
 494                 if (!hv_ghcb_pg)
 495                         goto free_vp_assist_page;
 496         }
 497
 498         cpuhp = cpuhp_setup_state(CPUHP_AP_HYPERV_ONLINE, "x86/hyperv_init:online",
 499                                   hv_cpu_init, hv_cpu_die);
 500         if (cpuhp < 0)
 501                 goto free_ghcb_page;
 502
 503         /*
 504          * Setup the hypercall page and enable hypercalls.
 505          * 1. Register the guest ID
 506          * 2. Enable the hypercall and register the hypercall page
 507          *
 508          * A TDX VM with no paravisor only uses TDX GHCI rather than hv_hypercall_pg:
 509          * when the hypercall input is a page, such a VM must pass a decrypted
 510          * page to Hyper-V, e.g. hv_post_message() uses the per-CPU page
 511          * hyperv_pcpu_input_arg, which is decrypted if no paravisor is present.
 512          *
 513          * A TDX VM with the paravisor uses hv_hypercall_pg for most hypercalls,
 514          * which are handled by the paravisor and the VM must use an encrypted
 515          * input page: in such a VM, the hyperv_pcpu_input_arg is encrypted and
 516          * used in the hypercalls, e.g. see hv_mark_gpa_visibility() and
 517          * hv_arch_irq_unmask(). Such a VM uses TDX GHCI for two hypercalls:
 518          * 1. HVCALL_SIGNAL_EVENT: see vmbus_set_event() and _hv_do_fast_hypercall8().
 519          * 2. HVCALL_POST_MESSAGE: the input page must be a decrypted page, i.e.
 520          * hv_post_message() in such a VM can't use the encrypted hyperv_pcpu_input_arg;
 521          * instead, hv_post_message() uses the post_msg_page, which is decrypted
 522          * in such a VM and is only used in such a VM.
 523          */
 524         guest_id = hv_generate_guest_id(LINUX_VERSION_CODE);
 525         wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 526
 527         /* With the paravisor, the VM must also write the ID via GHCB/GHCI */
 528         hv_ivm_msr_write(HV_X64_MSR_GUEST_OS_ID, guest_id);
 529
 530         /* A TDX VM with no paravisor only uses TDX GHCI rather than hv_hypercall_pg */
 531         if (hv_isolation_type_tdx() && !ms_hyperv.paravisor_present)
 532                 goto skip_hypercall_pg_init;
 533
 534         hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START,
 535                         VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_ROX,
 536                         VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
 537                         __builtin_return_address(0));
 538         if (hv_hypercall_pg == NULL)
 539                 goto clean_guest_os_id;
 540
 541         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 542         hypercall_msr.enable = 1;
 543
 544         if (hv_root_partition) {
 545                 struct page *pg;
 546                 void *src;
 547
 548                 /*
 549                  * For the root partition, the hypervisor will set up its
 550                  * hypercall page. The hypervisor guarantees it will not show
 551                  * up in the root's address space. The root can't change the
 552                  * location of the hypercall page.
 553                  *
 554                  * Order is important here. We must enable the hypercall page
 555                  * so it is populated with code, then copy the code to an
 556                  * executable page.
 557                  */
 558                 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 559
 560                 pg = vmalloc_to_page(hv_hypercall_pg);
 561                 src = memremap(hypercall_msr.guest_physical_address << PAGE_SHIFT, PAGE_SIZE,
 562                                 MEMREMAP_WB);
 563                 BUG_ON(!src);
 564                 memcpy_to_page(pg, 0, src, HV_HYP_PAGE_SIZE);
 565                 memunmap(src);
 566
 567                 hv_remap_tsc_clocksource();
 568         } else {
 569                 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
 570                 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 571         }
 572
 573 skip_hypercall_pg_init:
 574         /*
 575          * Some versions of Hyper-V that provide IBT in guest VMs have a bug
 576          * in that there's no ENDBR64 instruction at the entry to the
 577          * hypercall page. Because hypercalls are invoked via an indirect call
 578          * to the hypercall page, all hypercall attempts fail when IBT is
 579          * enabled, and Linux panics. For such buggy versions, disable IBT.
 580          *
 581          * Fixed versions of Hyper-V always provide ENDBR64 on the hypercall
 582          * page, so if future Linux kernel versions enable IBT for 32-bit
 583          * builds, additional hypercall page hackery will be required here
 584          * to provide an ENDBR32.
 585          */
 586 #ifdef CONFIG_X86_KERNEL_IBT
 587         if (cpu_feature_enabled(X86_FEATURE_IBT) &&
 588             *(u32 *)hv_hypercall_pg != gen_endbr()) {
 589                 setup_clear_cpu_cap(X86_FEATURE_IBT);
 590                 pr_warn("Disabling IBT because of Hyper-V bug\n");
 591         }
 592 #endif
 593
 594         /*
 595          * hyperv_init() is called before LAPIC is initialized: see
 596          * apic_intr_mode_init() -> x86_platform.apic_post_init() and
 597          * apic_bsp_setup() -> setup_local_APIC(). The direct-mode STIMER
 598          * depends on LAPIC, so hv_stimer_alloc() should be called from
 599          * x86_init.timers.setup_percpu_clockev.
 600          */
 601         old_setup_percpu_clockev = x86_init.timers.setup_percpu_clockev;
 602         x86_init.timers.setup_percpu_clockev = hv_stimer_setup_percpu_clockev;
 603
 604         hv_apic_init();
 605
 606         x86_init.pci.arch_init = hv_pci_init;
 607
 608         register_syscore_ops(&hv_syscore_ops);
 609
 610         hyperv_init_cpuhp = cpuhp;
 611
 612         if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_ACCESS_PARTITION_ID)
 613                 hv_get_partition_id();
 614
 615         BUG_ON(hv_root_partition && hv_current_partition_id == ~0ull);
 616
 617 #ifdef CONFIG_PCI_MSI
 618         /*
 619          * If we're running as root, we want to create our own PCI MSI domain.
 620          * We can't set this in hv_pci_init because that would be too late.
 621          */
 622         if (hv_root_partition)
 623                 x86_init.irqs.create_pci_msi_domain = hv_create_pci_msi_domain;
 624 #endif
 625
 626         /* Query the VMs extended capability once, so that it can be cached. */
 627         hv_query_ext_cap(0);
 628
 629         /* Find the VTL */
 630         ms_hyperv.vtl = get_vtl();
 631
 632         if (ms_hyperv.vtl > 0) /* non default VTL */
 633                 hv_vtl_early_init();
 634
 635         return;
 636
 637 clean_guest_os_id:
 638         wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 639         hv_ivm_msr_write(HV_X64_MSR_GUEST_OS_ID, 0);
 640         cpuhp_remove_state(cpuhp);
 641 free_ghcb_page:
 642         free_percpu(hv_ghcb_pg);
 643 free_vp_assist_page:
 644         kfree(hv_vp_assist_page);
 645         hv_vp_assist_page = NULL;
 646 common_free:
 647         hv_common_free();
 648 }
 649
 650 /*
 651  * This routine is called before kexec/kdump, it does the required cleanup.
 652  */
 653 void hyperv_cleanup(void)
 654 {
 655         union hv_x64_msr_hypercall_contents hypercall_msr;
 656         union hv_reference_tsc_msr tsc_msr;
 657
 658         /* Reset our OS id */
 659         wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 660         hv_ivm_msr_write(HV_X64_MSR_GUEST_OS_ID, 0);
 661
 662         /*
 663          * Reset hypercall page reference before reset the page,
 664          * let hypercall operations fail safely rather than
 665          * panic the kernel for using invalid hypercall page
 666          */
 667         hv_hypercall_pg = NULL;
 668
 669         /* Reset the hypercall page */
 670         hypercall_msr.as_uint64 = hv_get_register(HV_X64_MSR_HYPERCALL);
 671         hypercall_msr.enable = 0;
 672         hv_set_register(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 673
 674         /* Reset the TSC page */
 675         tsc_msr.as_uint64 = hv_get_register(HV_X64_MSR_REFERENCE_TSC);
 676         tsc_msr.enable = 0;
 677         hv_set_register(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 678 }
 679
 680 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die)
 681 {
 682         static bool panic_reported;
 683         u64 guest_id;
 684
 685         if (in_die && !panic_on_oops)
 686                 return;
 687
 688         /*
 689          * We prefer to report panic on 'die' chain as we have proper
 690          * registers to report, but if we miss it (e.g. on BUG()) we need
 691          * to report it on 'panic'.
 692          */
 693         if (panic_reported)
 694                 return;
 695         panic_reported = true;
 696
 697         rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 698
 699         wrmsrl(HV_X64_MSR_CRASH_P0, err);
 700         wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
 701         wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
 702         wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
 703         wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
 704
 705         /*
 706          * Let Hyper-V know there is crash data available
 707          */
 708         wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
 709 }
 710 EXPORT_SYMBOL_GPL(hyperv_report_panic);
 711
 712 bool hv_is_hyperv_initialized(void)
 713 {
 714         union hv_x64_msr_hypercall_contents hypercall_msr;
 715
 716         /*
 717          * Ensure that we're really on Hyper-V, and not a KVM or Xen
 718          * emulation of Hyper-V
 719          */
 720         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
 721                 return false;
 722
 723         /* A TDX VM with no paravisor uses TDX GHCI call rather than hv_hypercall_pg */
 724         if (hv_isolation_type_tdx() && !ms_hyperv.paravisor_present)
 725                 return true;
 726         /*
 727          * Verify that earlier initialization succeeded by checking
 728          * that the hypercall page is setup
 729          */
 730         hypercall_msr.as_uint64 = 0;
 731         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 732
 733         return hypercall_msr.enable;
 734 }
 735 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);