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