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/acpi.h>
  11 #include <linux/efi.h>
  12 #include <linux/types.h>
  13 #include <linux/bitfield.h>
  14 #include <asm/apic.h>
  15 #include <asm/desc.h>
  16 #include <asm/hypervisor.h>
  17 #include <asm/hyperv-tlfs.h>
  18 #include <asm/mshyperv.h>
  19 #include <asm/idtentry.h>
  20 #include <linux/kexec.h>
  21 #include <linux/version.h>
  22 #include <linux/vmalloc.h>
  23 #include <linux/mm.h>
  24 #include <linux/hyperv.h>
  25 #include <linux/slab.h>
  26 #include <linux/kernel.h>
  27 #include <linux/cpuhotplug.h>
  28 #include <linux/syscore_ops.h>
  29 #include <clocksource/hyperv_timer.h>
  30 #include <linux/highmem.h>
  31
  32 int hyperv_init_cpuhp;
  33 u64 hv_current_partition_id = ~0ull;
  34 EXPORT_SYMBOL_GPL(hv_current_partition_id);
  35
  36 void *hv_hypercall_pg;
  37 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
  38
  39 /* Storage to save the hypercall page temporarily for hibernation */
  40 static void *hv_hypercall_pg_saved;
  41
  42 u32 *hv_vp_index;
  43 EXPORT_SYMBOL_GPL(hv_vp_index);
  44
  45 struct hv_vp_assist_page **hv_vp_assist_page;
  46 EXPORT_SYMBOL_GPL(hv_vp_assist_page);
  47
  48 void  __percpu **hyperv_pcpu_input_arg;
  49 EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
  50
  51 void  __percpu **hyperv_pcpu_output_arg;
  52 EXPORT_SYMBOL_GPL(hyperv_pcpu_output_arg);
  53
  54 u32 hv_max_vp_index;
  55 EXPORT_SYMBOL_GPL(hv_max_vp_index);
  56
  57 void *hv_alloc_hyperv_page(void)
  58 {
  59         BUILD_BUG_ON(PAGE_SIZE != HV_HYP_PAGE_SIZE);
  60
  61         return (void *)__get_free_page(GFP_KERNEL);
  62 }
  63 EXPORT_SYMBOL_GPL(hv_alloc_hyperv_page);
  64
  65 void *hv_alloc_hyperv_zeroed_page(void)
  66 {
  67         BUILD_BUG_ON(PAGE_SIZE != HV_HYP_PAGE_SIZE);
  68
  69         return (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
  70 }
  71 EXPORT_SYMBOL_GPL(hv_alloc_hyperv_zeroed_page);
  72
  73 void hv_free_hyperv_page(unsigned long addr)
  74 {
  75         free_page(addr);
  76 }
  77 EXPORT_SYMBOL_GPL(hv_free_hyperv_page);
  78
  79 static int hv_cpu_init(unsigned int cpu)
  80 {
  81         u64 msr_vp_index;
  82         struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
  83         void **input_arg;
  84         struct page *pg;
  85
  86         /* hv_cpu_init() can be called with IRQs disabled from hv_resume() */
  87         pg = alloc_pages(irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL, hv_root_partition ? 1 : 0);
  88         if (unlikely(!pg))
  89                 return -ENOMEM;
  90
  91         input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
  92         *input_arg = page_address(pg);
  93         if (hv_root_partition) {
  94                 void **output_arg;
  95
  96                 output_arg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
  97                 *output_arg = page_address(pg + 1);
  98         }
  99
 100         hv_get_vp_index(msr_vp_index);
 101
 102         hv_vp_index[smp_processor_id()] = msr_vp_index;
 103
 104         if (msr_vp_index > hv_max_vp_index)
 105                 hv_max_vp_index = msr_vp_index;
 106
 107         if (!hv_vp_assist_page)
 108                 return 0;
 109
 110         /*
 111          * The VP ASSIST PAGE is an "overlay" page (see Hyper-V TLFS's Section
 112          * 5.2.1 "GPA Overlay Pages"). Here it must be zeroed out to make sure
 113          * we always write the EOI MSR in hv_apic_eoi_write() *after* the
 114          * EOI optimization is disabled in hv_cpu_die(), otherwise a CPU may
 115          * not be stopped in the case of CPU offlining and the VM will hang.
 116          */
 117         if (!*hvp) {
 118                 *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO);
 119         }
 120
 121         if (*hvp) {
 122                 u64 val;
 123
 124                 val = vmalloc_to_pfn(*hvp);
 125                 val = (val << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT) |
 126                         HV_X64_MSR_VP_ASSIST_PAGE_ENABLE;
 127
 128                 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, val);
 129         }
 130
 131         return 0;
 132 }
 133
 134 static void (*hv_reenlightenment_cb)(void);
 135
 136 static void hv_reenlightenment_notify(struct work_struct *dummy)
 137 {
 138         struct hv_tsc_emulation_status emu_status;
 139
 140         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 141
 142         /* Don't issue the callback if TSC accesses are not emulated */
 143         if (hv_reenlightenment_cb && emu_status.inprogress)
 144                 hv_reenlightenment_cb();
 145 }
 146 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify);
 147
 148 void hyperv_stop_tsc_emulation(void)
 149 {
 150         u64 freq;
 151         struct hv_tsc_emulation_status emu_status;
 152
 153         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 154         emu_status.inprogress = 0;
 155         wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 156
 157         rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
 158         tsc_khz = div64_u64(freq, 1000);
 159 }
 160 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation);
 161
 162 static inline bool hv_reenlightenment_available(void)
 163 {
 164         /*
 165          * Check for required features and priviliges to make TSC frequency
 166          * change notifications work.
 167          */
 168         return ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
 169                 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
 170                 ms_hyperv.features & HV_ACCESS_REENLIGHTENMENT;
 171 }
 172
 173 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_reenlightenment)
 174 {
 175         ack_APIC_irq();
 176         inc_irq_stat(irq_hv_reenlightenment_count);
 177         schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
 178 }
 179
 180 void set_hv_tscchange_cb(void (*cb)(void))
 181 {
 182         struct hv_reenlightenment_control re_ctrl = {
 183                 .vector = HYPERV_REENLIGHTENMENT_VECTOR,
 184                 .enabled = 1,
 185                 .target_vp = hv_vp_index[smp_processor_id()]
 186         };
 187         struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
 188
 189         if (!hv_reenlightenment_available()) {
 190                 pr_warn("Hyper-V: reenlightenment support is unavailable\n");
 191                 return;
 192         }
 193
 194         hv_reenlightenment_cb = cb;
 195
 196         /* Make sure callback is registered before we write to MSRs */
 197         wmb();
 198
 199         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 200         wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
 201 }
 202 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
 203
 204 void clear_hv_tscchange_cb(void)
 205 {
 206         struct hv_reenlightenment_control re_ctrl;
 207
 208         if (!hv_reenlightenment_available())
 209                 return;
 210
 211         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
 212         re_ctrl.enabled = 0;
 213         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
 214
 215         hv_reenlightenment_cb = NULL;
 216 }
 217 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);
 218
 219 static int hv_cpu_die(unsigned int cpu)
 220 {
 221         struct hv_reenlightenment_control re_ctrl;
 222         unsigned int new_cpu;
 223         unsigned long flags;
 224         void **input_arg;
 225         void *pg;
 226
 227         local_irq_save(flags);
 228         input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
 229         pg = *input_arg;
 230         *input_arg = NULL;
 231
 232         if (hv_root_partition) {
 233                 void **output_arg;
 234
 235                 output_arg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
 236                 *output_arg = NULL;
 237         }
 238
 239         local_irq_restore(flags);
 240
 241         free_pages((unsigned long)pg, hv_root_partition ? 1 : 0);
 242
 243         if (hv_vp_assist_page && hv_vp_assist_page[cpu])
 244                 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
 245
 246         if (hv_reenlightenment_cb == NULL)
 247                 return 0;
 248
 249         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 250         if (re_ctrl.target_vp == hv_vp_index[cpu]) {
 251                 /*
 252                  * Reassign reenlightenment notifications to some other online
 253                  * CPU or just disable the feature if there are no online CPUs
 254                  * left (happens on hibernation).
 255                  */
 256                 new_cpu = cpumask_any_but(cpu_online_mask, cpu);
 257
 258                 if (new_cpu < nr_cpu_ids)
 259                         re_ctrl.target_vp = hv_vp_index[new_cpu];
 260                 else
 261                         re_ctrl.enabled = 0;
 262
 263                 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 264         }
 265
 266         return 0;
 267 }
 268
 269 static int __init hv_pci_init(void)
 270 {
 271         int gen2vm = efi_enabled(EFI_BOOT);
 272
 273         /*
 274          * For Generation-2 VM, we exit from pci_arch_init() by returning 0.
 275          * The purpose is to suppress the harmless warning:
 276          * "PCI: Fatal: No config space access function found"
 277          */
 278         if (gen2vm)
 279                 return 0;
 280
 281         /* For Generation-1 VM, we'll proceed in pci_arch_init().  */
 282         return 1;
 283 }
 284
 285 static int hv_suspend(void)
 286 {
 287         union hv_x64_msr_hypercall_contents hypercall_msr;
 288         int ret;
 289
 290         if (hv_root_partition)
 291                 return -EPERM;
 292
 293         /*
 294          * Reset the hypercall page as it is going to be invalidated
 295          * accross hibernation. Setting hv_hypercall_pg to NULL ensures
 296          * that any subsequent hypercall operation fails safely instead of
 297          * crashing due to an access of an invalid page. The hypercall page
 298          * pointer is restored on resume.
 299          */
 300         hv_hypercall_pg_saved = hv_hypercall_pg;
 301         hv_hypercall_pg = NULL;
 302
 303         /* Disable the hypercall page in the hypervisor */
 304         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 305         hypercall_msr.enable = 0;
 306         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 307
 308         ret = hv_cpu_die(0);
 309         return ret;
 310 }
 311
 312 static void hv_resume(void)
 313 {
 314         union hv_x64_msr_hypercall_contents hypercall_msr;
 315         int ret;
 316
 317         ret = hv_cpu_init(0);
 318         WARN_ON(ret);
 319
 320         /* Re-enable the hypercall page */
 321         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 322         hypercall_msr.enable = 1;
 323         hypercall_msr.guest_physical_address =
 324                 vmalloc_to_pfn(hv_hypercall_pg_saved);
 325         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 326
 327         hv_hypercall_pg = hv_hypercall_pg_saved;
 328         hv_hypercall_pg_saved = NULL;
 329
 330         /*
 331          * Reenlightenment notifications are disabled by hv_cpu_die(0),
 332          * reenable them here if hv_reenlightenment_cb was previously set.
 333          */
 334         if (hv_reenlightenment_cb)
 335                 set_hv_tscchange_cb(hv_reenlightenment_cb);
 336 }
 337
 338 /* Note: when the ops are called, only CPU0 is online and IRQs are disabled. */
 339 static struct syscore_ops hv_syscore_ops = {
 340         .suspend        = hv_suspend,
 341         .resume         = hv_resume,
 342 };
 343
 344 static void (* __initdata old_setup_percpu_clockev)(void);
 345
 346 static void __init hv_stimer_setup_percpu_clockev(void)
 347 {
 348         /*
 349          * Ignore any errors in setting up stimer clockevents
 350          * as we can run with the LAPIC timer as a fallback.
 351          */
 352         (void)hv_stimer_alloc();
 353
 354         /*
 355          * Still register the LAPIC timer, because the direct-mode STIMER is
 356          * not supported by old versions of Hyper-V. This also allows users
 357          * to switch to LAPIC timer via /sys, if they want to.
 358          */
 359         if (old_setup_percpu_clockev)
 360                 old_setup_percpu_clockev();
 361 }
 362
 363 static void __init hv_get_partition_id(void)
 364 {
 365         struct hv_get_partition_id *output_page;
 366         u64 status;
 367         unsigned long flags;
 368
 369         local_irq_save(flags);
 370         output_page = *this_cpu_ptr(hyperv_pcpu_output_arg);
 371         status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page);
 372         if ((status & HV_HYPERCALL_RESULT_MASK) != HV_STATUS_SUCCESS) {
 373                 /* No point in proceeding if this failed */
 374                 pr_err("Failed to get partition ID: %lld\n", status);
 375                 BUG();
 376         }
 377         hv_current_partition_id = output_page->partition_id;
 378         local_irq_restore(flags);
 379 }
 380
 381 /*
 382  * This function is to be invoked early in the boot sequence after the
 383  * hypervisor has been detected.
 384  *
 385  * 1. Setup the hypercall page.
 386  * 2. Register Hyper-V specific clocksource.
 387  * 3. Setup Hyper-V specific APIC entry points.
 388  */
 389 void __init hyperv_init(void)
 390 {
 391         u64 guest_id, required_msrs;
 392         union hv_x64_msr_hypercall_contents hypercall_msr;
 393         int cpuhp, i;
 394
 395         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
 396                 return;
 397
 398         /* Absolutely required MSRs */
 399         required_msrs = HV_MSR_HYPERCALL_AVAILABLE |
 400                 HV_MSR_VP_INDEX_AVAILABLE;
 401
 402         if ((ms_hyperv.features & required_msrs) != required_msrs)
 403                 return;
 404
 405         /*
 406          * Allocate the per-CPU state for the hypercall input arg.
 407          * If this allocation fails, we will not be able to setup
 408          * (per-CPU) hypercall input page and thus this failure is
 409          * fatal on Hyper-V.
 410          */
 411         hyperv_pcpu_input_arg = alloc_percpu(void  *);
 412
 413         BUG_ON(hyperv_pcpu_input_arg == NULL);
 414
 415         /* Allocate the per-CPU state for output arg for root */
 416         if (hv_root_partition) {
 417                 hyperv_pcpu_output_arg = alloc_percpu(void *);
 418                 BUG_ON(hyperv_pcpu_output_arg == NULL);
 419         }
 420
 421         /* Allocate percpu VP index */
 422         hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
 423                                     GFP_KERNEL);
 424         if (!hv_vp_index)
 425                 return;
 426
 427         for (i = 0; i < num_possible_cpus(); i++)
 428                 hv_vp_index[i] = VP_INVAL;
 429
 430         hv_vp_assist_page = kcalloc(num_possible_cpus(),
 431                                     sizeof(*hv_vp_assist_page), GFP_KERNEL);
 432         if (!hv_vp_assist_page) {
 433                 ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
 434                 goto free_vp_index;
 435         }
 436
 437         cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
 438                                   hv_cpu_init, hv_cpu_die);
 439         if (cpuhp < 0)
 440                 goto free_vp_assist_page;
 441
 442         /*
 443          * Setup the hypercall page and enable hypercalls.
 444          * 1. Register the guest ID
 445          * 2. Enable the hypercall and register the hypercall page
 446          */
 447         guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
 448         wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 449
 450         hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START,
 451                         VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_ROX,
 452                         VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
 453                         __builtin_return_address(0));
 454         if (hv_hypercall_pg == NULL) {
 455                 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 456                 goto remove_cpuhp_state;
 457         }
 458
 459         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 460         hypercall_msr.enable = 1;
 461
 462         if (hv_root_partition) {
 463                 struct page *pg;
 464                 void *src, *dst;
 465
 466                 /*
 467                  * For the root partition, the hypervisor will set up its
 468                  * hypercall page. The hypervisor guarantees it will not show
 469                  * up in the root's address space. The root can't change the
 470                  * location of the hypercall page.
 471                  *
 472                  * Order is important here. We must enable the hypercall page
 473                  * so it is populated with code, then copy the code to an
 474                  * executable page.
 475                  */
 476                 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 477
 478                 pg = vmalloc_to_page(hv_hypercall_pg);
 479                 dst = kmap(pg);
 480                 src = memremap(hypercall_msr.guest_physical_address << PAGE_SHIFT, PAGE_SIZE,
 481                                 MEMREMAP_WB);
 482                 BUG_ON(!(src && dst));
 483                 memcpy(dst, src, HV_HYP_PAGE_SIZE);
 484                 memunmap(src);
 485                 kunmap(pg);
 486         } else {
 487                 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
 488                 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 489         }
 490
 491         /*
 492          * hyperv_init() is called before LAPIC is initialized: see
 493          * apic_intr_mode_init() -> x86_platform.apic_post_init() and
 494          * apic_bsp_setup() -> setup_local_APIC(). The direct-mode STIMER
 495          * depends on LAPIC, so hv_stimer_alloc() should be called from
 496          * x86_init.timers.setup_percpu_clockev.
 497          */
 498         old_setup_percpu_clockev = x86_init.timers.setup_percpu_clockev;
 499         x86_init.timers.setup_percpu_clockev = hv_stimer_setup_percpu_clockev;
 500
 501         hv_apic_init();
 502
 503         x86_init.pci.arch_init = hv_pci_init;
 504
 505         register_syscore_ops(&hv_syscore_ops);
 506
 507         hyperv_init_cpuhp = cpuhp;
 508
 509         if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_ACCESS_PARTITION_ID)
 510                 hv_get_partition_id();
 511
 512         BUG_ON(hv_root_partition && hv_current_partition_id == ~0ull);
 513
 514 #ifdef CONFIG_PCI_MSI
 515         /*
 516          * If we're running as root, we want to create our own PCI MSI domain.
 517          * We can't set this in hv_pci_init because that would be too late.
 518          */
 519         if (hv_root_partition)
 520                 x86_init.irqs.create_pci_msi_domain = hv_create_pci_msi_domain;
 521 #endif
 522
 523         return;
 524
 525 remove_cpuhp_state:
 526         cpuhp_remove_state(cpuhp);
 527 free_vp_assist_page:
 528         kfree(hv_vp_assist_page);
 529         hv_vp_assist_page = NULL;
 530 free_vp_index:
 531         kfree(hv_vp_index);
 532         hv_vp_index = NULL;
 533 }
 534
 535 /*
 536  * This routine is called before kexec/kdump, it does the required cleanup.
 537  */
 538 void hyperv_cleanup(void)
 539 {
 540         union hv_x64_msr_hypercall_contents hypercall_msr;
 541
 542         unregister_syscore_ops(&hv_syscore_ops);
 543
 544         /* Reset our OS id */
 545         wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 546
 547         /*
 548          * Reset hypercall page reference before reset the page,
 549          * let hypercall operations fail safely rather than
 550          * panic the kernel for using invalid hypercall page
 551          */
 552         hv_hypercall_pg = NULL;
 553
 554         /* Reset the hypercall page */
 555         hypercall_msr.as_uint64 = 0;
 556         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 557
 558         /* Reset the TSC page */
 559         hypercall_msr.as_uint64 = 0;
 560         wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
 561 }
 562 EXPORT_SYMBOL_GPL(hyperv_cleanup);
 563
 564 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die)
 565 {
 566         static bool panic_reported;
 567         u64 guest_id;
 568
 569         if (in_die && !panic_on_oops)
 570                 return;
 571
 572         /*
 573          * We prefer to report panic on 'die' chain as we have proper
 574          * registers to report, but if we miss it (e.g. on BUG()) we need
 575          * to report it on 'panic'.
 576          */
 577         if (panic_reported)
 578                 return;
 579         panic_reported = true;
 580
 581         rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 582
 583         wrmsrl(HV_X64_MSR_CRASH_P0, err);
 584         wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
 585         wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
 586         wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
 587         wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
 588
 589         /*
 590          * Let Hyper-V know there is crash data available
 591          */
 592         wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
 593 }
 594 EXPORT_SYMBOL_GPL(hyperv_report_panic);
 595
 596 /**
 597  * hyperv_report_panic_msg - report panic message to Hyper-V
 598  * @pa: physical address of the panic page containing the message
 599  * @size: size of the message in the page
 600  */
 601 void hyperv_report_panic_msg(phys_addr_t pa, size_t size)
 602 {
 603         /*
 604          * P3 to contain the physical address of the panic page & P4 to
 605          * contain the size of the panic data in that page. Rest of the
 606          * registers are no-op when the NOTIFY_MSG flag is set.
 607          */
 608         wrmsrl(HV_X64_MSR_CRASH_P0, 0);
 609         wrmsrl(HV_X64_MSR_CRASH_P1, 0);
 610         wrmsrl(HV_X64_MSR_CRASH_P2, 0);
 611         wrmsrl(HV_X64_MSR_CRASH_P3, pa);
 612         wrmsrl(HV_X64_MSR_CRASH_P4, size);
 613
 614         /*
 615          * Let Hyper-V know there is crash data available along with
 616          * the panic message.
 617          */
 618         wrmsrl(HV_X64_MSR_CRASH_CTL,
 619                (HV_CRASH_CTL_CRASH_NOTIFY | HV_CRASH_CTL_CRASH_NOTIFY_MSG));
 620 }
 621 EXPORT_SYMBOL_GPL(hyperv_report_panic_msg);
 622
 623 bool hv_is_hyperv_initialized(void)
 624 {
 625         union hv_x64_msr_hypercall_contents hypercall_msr;
 626
 627         /*
 628          * Ensure that we're really on Hyper-V, and not a KVM or Xen
 629          * emulation of Hyper-V
 630          */
 631         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
 632                 return false;
 633
 634         /*
 635          * Verify that earlier initialization succeeded by checking
 636          * that the hypercall page is setup
 637          */
 638         hypercall_msr.as_uint64 = 0;
 639         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 640
 641         return hypercall_msr.enable;
 642 }
 643 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);
 644
 645 bool hv_is_hibernation_supported(void)
 646 {
 647         return !hv_root_partition && acpi_sleep_state_supported(ACPI_STATE_S4);
 648 }
 649 EXPORT_SYMBOL_GPL(hv_is_hibernation_supported);
 650
 651 enum hv_isolation_type hv_get_isolation_type(void)
 652 {
 653         if (!(ms_hyperv.features_b & HV_ISOLATION))
 654                 return HV_ISOLATION_TYPE_NONE;
 655         return FIELD_GET(HV_ISOLATION_TYPE, ms_hyperv.isolation_config_b);
 656 }
 657 EXPORT_SYMBOL_GPL(hv_get_isolation_type);
 658
 659 bool hv_is_isolation_supported(void)
 660 {
 661         return hv_get_isolation_type() != HV_ISOLATION_TYPE_NONE;
 662 }
 663 EXPORT_SYMBOL_GPL(hv_is_isolation_supported);