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