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 static int hv_cpu_init(unsigned int cpu)
  58 {
  59         u64 msr_vp_index;
  60         struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
  61         void **input_arg;
  62         struct page *pg;
  63
  64         /* hv_cpu_init() can be called with IRQs disabled from hv_resume() */
  65         pg = alloc_pages(irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL, hv_root_partition ? 1 : 0);
  66         if (unlikely(!pg))
  67                 return -ENOMEM;
  68
  69         input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
  70         *input_arg = page_address(pg);
  71         if (hv_root_partition) {
  72                 void **output_arg;
  73
  74                 output_arg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
  75                 *output_arg = page_address(pg + 1);
  76         }
  77
  78         msr_vp_index = hv_get_register(HV_REGISTER_VP_INDEX);
  79
  80         hv_vp_index[smp_processor_id()] = msr_vp_index;
  81
  82         if (msr_vp_index > hv_max_vp_index)
  83                 hv_max_vp_index = msr_vp_index;
  84
  85         if (!hv_vp_assist_page)
  86                 return 0;
  87
  88         /*
  89          * The VP ASSIST PAGE is an "overlay" page (see Hyper-V TLFS's Section
  90          * 5.2.1 "GPA Overlay Pages"). Here it must be zeroed out to make sure
  91          * we always write the EOI MSR in hv_apic_eoi_write() *after* the
  92          * EOI optimization is disabled in hv_cpu_die(), otherwise a CPU may
  93          * not be stopped in the case of CPU offlining and the VM will hang.
  94          */
  95         if (!*hvp) {
  96                 *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO);
  97         }
  98
  99         if (*hvp) {
 100                 u64 val;
 101
 102                 val = vmalloc_to_pfn(*hvp);
 103                 val = (val << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT) |
 104                         HV_X64_MSR_VP_ASSIST_PAGE_ENABLE;
 105
 106                 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, val);
 107         }
 108
 109         return 0;
 110 }
 111
 112 static void (*hv_reenlightenment_cb)(void);
 113
 114 static void hv_reenlightenment_notify(struct work_struct *dummy)
 115 {
 116         struct hv_tsc_emulation_status emu_status;
 117
 118         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 119
 120         /* Don't issue the callback if TSC accesses are not emulated */
 121         if (hv_reenlightenment_cb && emu_status.inprogress)
 122                 hv_reenlightenment_cb();
 123 }
 124 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify);
 125
 126 void hyperv_stop_tsc_emulation(void)
 127 {
 128         u64 freq;
 129         struct hv_tsc_emulation_status emu_status;
 130
 131         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 132         emu_status.inprogress = 0;
 133         wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 134
 135         rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
 136         tsc_khz = div64_u64(freq, 1000);
 137 }
 138 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation);
 139
 140 static inline bool hv_reenlightenment_available(void)
 141 {
 142         /*
 143          * Check for required features and privileges to make TSC frequency
 144          * change notifications work.
 145          */
 146         return ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
 147                 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
 148                 ms_hyperv.features & HV_ACCESS_REENLIGHTENMENT;
 149 }
 150
 151 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_reenlightenment)
 152 {
 153         ack_APIC_irq();
 154         inc_irq_stat(irq_hv_reenlightenment_count);
 155         schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
 156 }
 157
 158 void set_hv_tscchange_cb(void (*cb)(void))
 159 {
 160         struct hv_reenlightenment_control re_ctrl = {
 161                 .vector = HYPERV_REENLIGHTENMENT_VECTOR,
 162                 .enabled = 1,
 163                 .target_vp = hv_vp_index[smp_processor_id()]
 164         };
 165         struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
 166
 167         if (!hv_reenlightenment_available()) {
 168                 pr_warn("Hyper-V: reenlightenment support is unavailable\n");
 169                 return;
 170         }
 171
 172         hv_reenlightenment_cb = cb;
 173
 174         /* Make sure callback is registered before we write to MSRs */
 175         wmb();
 176
 177         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 178         wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
 179 }
 180 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
 181
 182 void clear_hv_tscchange_cb(void)
 183 {
 184         struct hv_reenlightenment_control re_ctrl;
 185
 186         if (!hv_reenlightenment_available())
 187                 return;
 188
 189         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
 190         re_ctrl.enabled = 0;
 191         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
 192
 193         hv_reenlightenment_cb = NULL;
 194 }
 195 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);
 196
 197 static int hv_cpu_die(unsigned int cpu)
 198 {
 199         struct hv_reenlightenment_control re_ctrl;
 200         unsigned int new_cpu;
 201         unsigned long flags;
 202         void **input_arg;
 203         void *pg;
 204
 205         local_irq_save(flags);
 206         input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
 207         pg = *input_arg;
 208         *input_arg = NULL;
 209
 210         if (hv_root_partition) {
 211                 void **output_arg;
 212
 213                 output_arg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
 214                 *output_arg = NULL;
 215         }
 216
 217         local_irq_restore(flags);
 218
 219         free_pages((unsigned long)pg, hv_root_partition ? 1 : 0);
 220
 221         if (hv_vp_assist_page && hv_vp_assist_page[cpu])
 222                 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
 223
 224         if (hv_reenlightenment_cb == NULL)
 225                 return 0;
 226
 227         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 228         if (re_ctrl.target_vp == hv_vp_index[cpu]) {
 229                 /*
 230                  * Reassign reenlightenment notifications to some other online
 231                  * CPU or just disable the feature if there are no online CPUs
 232                  * left (happens on hibernation).
 233                  */
 234                 new_cpu = cpumask_any_but(cpu_online_mask, cpu);
 235
 236                 if (new_cpu < nr_cpu_ids)
 237                         re_ctrl.target_vp = hv_vp_index[new_cpu];
 238                 else
 239                         re_ctrl.enabled = 0;
 240
 241                 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 242         }
 243
 244         return 0;
 245 }
 246
 247 static int __init hv_pci_init(void)
 248 {
 249         int gen2vm = efi_enabled(EFI_BOOT);
 250
 251         /*
 252          * For Generation-2 VM, we exit from pci_arch_init() by returning 0.
 253          * The purpose is to suppress the harmless warning:
 254          * "PCI: Fatal: No config space access function found"
 255          */
 256         if (gen2vm)
 257                 return 0;
 258
 259         /* For Generation-1 VM, we'll proceed in pci_arch_init().  */
 260         return 1;
 261 }
 262
 263 static int hv_suspend(void)
 264 {
 265         union hv_x64_msr_hypercall_contents hypercall_msr;
 266         int ret;
 267
 268         if (hv_root_partition)
 269                 return -EPERM;
 270
 271         /*
 272          * Reset the hypercall page as it is going to be invalidated
 273          * across hibernation. Setting hv_hypercall_pg to NULL ensures
 274          * that any subsequent hypercall operation fails safely instead of
 275          * crashing due to an access of an invalid page. The hypercall page
 276          * pointer is restored on resume.
 277          */
 278         hv_hypercall_pg_saved = hv_hypercall_pg;
 279         hv_hypercall_pg = NULL;
 280
 281         /* Disable the hypercall page in the hypervisor */
 282         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 283         hypercall_msr.enable = 0;
 284         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 285
 286         ret = hv_cpu_die(0);
 287         return ret;
 288 }
 289
 290 static void hv_resume(void)
 291 {
 292         union hv_x64_msr_hypercall_contents hypercall_msr;
 293         int ret;
 294
 295         ret = hv_cpu_init(0);
 296         WARN_ON(ret);
 297
 298         /* Re-enable the hypercall page */
 299         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 300         hypercall_msr.enable = 1;
 301         hypercall_msr.guest_physical_address =
 302                 vmalloc_to_pfn(hv_hypercall_pg_saved);
 303         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 304
 305         hv_hypercall_pg = hv_hypercall_pg_saved;
 306         hv_hypercall_pg_saved = NULL;
 307
 308         /*
 309          * Reenlightenment notifications are disabled by hv_cpu_die(0),
 310          * reenable them here if hv_reenlightenment_cb was previously set.
 311          */
 312         if (hv_reenlightenment_cb)
 313                 set_hv_tscchange_cb(hv_reenlightenment_cb);
 314 }
 315
 316 /* Note: when the ops are called, only CPU0 is online and IRQs are disabled. */
 317 static struct syscore_ops hv_syscore_ops = {
 318         .suspend        = hv_suspend,
 319         .resume         = hv_resume,
 320 };
 321
 322 static void (* __initdata old_setup_percpu_clockev)(void);
 323
 324 static void __init hv_stimer_setup_percpu_clockev(void)
 325 {
 326         /*
 327          * Ignore any errors in setting up stimer clockevents
 328          * as we can run with the LAPIC timer as a fallback.
 329          */
 330         (void)hv_stimer_alloc(false);
 331
 332         /*
 333          * Still register the LAPIC timer, because the direct-mode STIMER is
 334          * not supported by old versions of Hyper-V. This also allows users
 335          * to switch to LAPIC timer via /sys, if they want to.
 336          */
 337         if (old_setup_percpu_clockev)
 338                 old_setup_percpu_clockev();
 339 }
 340
 341 static void __init hv_get_partition_id(void)
 342 {
 343         struct hv_get_partition_id *output_page;
 344         u64 status;
 345         unsigned long flags;
 346
 347         local_irq_save(flags);
 348         output_page = *this_cpu_ptr(hyperv_pcpu_output_arg);
 349         status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page);
 350         if (!hv_result_success(status)) {
 351                 /* No point in proceeding if this failed */
 352                 pr_err("Failed to get partition ID: %lld\n", status);
 353                 BUG();
 354         }
 355         hv_current_partition_id = output_page->partition_id;
 356         local_irq_restore(flags);
 357 }
 358
 359 /*
 360  * This function is to be invoked early in the boot sequence after the
 361  * hypervisor has been detected.
 362  *
 363  * 1. Setup the hypercall page.
 364  * 2. Register Hyper-V specific clocksource.
 365  * 3. Setup Hyper-V specific APIC entry points.
 366  */
 367 void __init hyperv_init(void)
 368 {
 369         u64 guest_id, required_msrs;
 370         union hv_x64_msr_hypercall_contents hypercall_msr;
 371         int cpuhp, i;
 372
 373         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
 374                 return;
 375
 376         /* Absolutely required MSRs */
 377         required_msrs = HV_MSR_HYPERCALL_AVAILABLE |
 378                 HV_MSR_VP_INDEX_AVAILABLE;
 379
 380         if ((ms_hyperv.features & required_msrs) != required_msrs)
 381                 return;
 382
 383         /*
 384          * Allocate the per-CPU state for the hypercall input arg.
 385          * If this allocation fails, we will not be able to setup
 386          * (per-CPU) hypercall input page and thus this failure is
 387          * fatal on Hyper-V.
 388          */
 389         hyperv_pcpu_input_arg = alloc_percpu(void  *);
 390
 391         BUG_ON(hyperv_pcpu_input_arg == NULL);
 392
 393         /* Allocate the per-CPU state for output arg for root */
 394         if (hv_root_partition) {
 395                 hyperv_pcpu_output_arg = alloc_percpu(void *);
 396                 BUG_ON(hyperv_pcpu_output_arg == NULL);
 397         }
 398
 399         /* Allocate percpu VP index */
 400         hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
 401                                     GFP_KERNEL);
 402         if (!hv_vp_index)
 403                 return;
 404
 405         for (i = 0; i < num_possible_cpus(); i++)
 406                 hv_vp_index[i] = VP_INVAL;
 407
 408         hv_vp_assist_page = kcalloc(num_possible_cpus(),
 409                                     sizeof(*hv_vp_assist_page), GFP_KERNEL);
 410         if (!hv_vp_assist_page) {
 411                 ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
 412                 goto free_vp_index;
 413         }
 414
 415         cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
 416                                   hv_cpu_init, hv_cpu_die);
 417         if (cpuhp < 0)
 418                 goto free_vp_assist_page;
 419
 420         /*
 421          * Setup the hypercall page and enable hypercalls.
 422          * 1. Register the guest ID
 423          * 2. Enable the hypercall and register the hypercall page
 424          */
 425         guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
 426         wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 427
 428         hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START,
 429                         VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_ROX,
 430                         VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
 431                         __builtin_return_address(0));
 432         if (hv_hypercall_pg == NULL) {
 433                 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 434                 goto remove_cpuhp_state;
 435         }
 436
 437         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 438         hypercall_msr.enable = 1;
 439
 440         if (hv_root_partition) {
 441                 struct page *pg;
 442                 void *src, *dst;
 443
 444                 /*
 445                  * For the root partition, the hypervisor will set up its
 446                  * hypercall page. The hypervisor guarantees it will not show
 447                  * up in the root's address space. The root can't change the
 448                  * location of the hypercall page.
 449                  *
 450                  * Order is important here. We must enable the hypercall page
 451                  * so it is populated with code, then copy the code to an
 452                  * executable page.
 453                  */
 454                 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 455
 456                 pg = vmalloc_to_page(hv_hypercall_pg);
 457                 dst = kmap(pg);
 458                 src = memremap(hypercall_msr.guest_physical_address << PAGE_SHIFT, PAGE_SIZE,
 459                                 MEMREMAP_WB);
 460                 BUG_ON(!(src && dst));
 461                 memcpy(dst, src, HV_HYP_PAGE_SIZE);
 462                 memunmap(src);
 463                 kunmap(pg);
 464         } else {
 465                 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
 466                 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 467         }
 468
 469         /*
 470          * hyperv_init() is called before LAPIC is initialized: see
 471          * apic_intr_mode_init() -> x86_platform.apic_post_init() and
 472          * apic_bsp_setup() -> setup_local_APIC(). The direct-mode STIMER
 473          * depends on LAPIC, so hv_stimer_alloc() should be called from
 474          * x86_init.timers.setup_percpu_clockev.
 475          */
 476         old_setup_percpu_clockev = x86_init.timers.setup_percpu_clockev;
 477         x86_init.timers.setup_percpu_clockev = hv_stimer_setup_percpu_clockev;
 478
 479         hv_apic_init();
 480
 481         x86_init.pci.arch_init = hv_pci_init;
 482
 483         register_syscore_ops(&hv_syscore_ops);
 484
 485         hyperv_init_cpuhp = cpuhp;
 486
 487         if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_ACCESS_PARTITION_ID)
 488                 hv_get_partition_id();
 489
 490         BUG_ON(hv_root_partition && hv_current_partition_id == ~0ull);
 491
 492 #ifdef CONFIG_PCI_MSI
 493         /*
 494          * If we're running as root, we want to create our own PCI MSI domain.
 495          * We can't set this in hv_pci_init because that would be too late.
 496          */
 497         if (hv_root_partition)
 498                 x86_init.irqs.create_pci_msi_domain = hv_create_pci_msi_domain;
 499 #endif
 500
 501         /* Query the VMs extended capability once, so that it can be cached. */
 502         hv_query_ext_cap(0);
 503         return;
 504
 505 remove_cpuhp_state:
 506         cpuhp_remove_state(cpuhp);
 507 free_vp_assist_page:
 508         kfree(hv_vp_assist_page);
 509         hv_vp_assist_page = NULL;
 510 free_vp_index:
 511         kfree(hv_vp_index);
 512         hv_vp_index = NULL;
 513 }
 514
 515 /*
 516  * This routine is called before kexec/kdump, it does the required cleanup.
 517  */
 518 void hyperv_cleanup(void)
 519 {
 520         union hv_x64_msr_hypercall_contents hypercall_msr;
 521
 522         unregister_syscore_ops(&hv_syscore_ops);
 523
 524         /* Reset our OS id */
 525         wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 526
 527         /*
 528          * Reset hypercall page reference before reset the page,
 529          * let hypercall operations fail safely rather than
 530          * panic the kernel for using invalid hypercall page
 531          */
 532         hv_hypercall_pg = NULL;
 533
 534         /* Reset the hypercall page */
 535         hypercall_msr.as_uint64 = 0;
 536         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 537
 538         /* Reset the TSC page */
 539         hypercall_msr.as_uint64 = 0;
 540         wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
 541 }
 542 EXPORT_SYMBOL_GPL(hyperv_cleanup);
 543
 544 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die)
 545 {
 546         static bool panic_reported;
 547         u64 guest_id;
 548
 549         if (in_die && !panic_on_oops)
 550                 return;
 551
 552         /*
 553          * We prefer to report panic on 'die' chain as we have proper
 554          * registers to report, but if we miss it (e.g. on BUG()) we need
 555          * to report it on 'panic'.
 556          */
 557         if (panic_reported)
 558                 return;
 559         panic_reported = true;
 560
 561         rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 562
 563         wrmsrl(HV_X64_MSR_CRASH_P0, err);
 564         wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
 565         wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
 566         wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
 567         wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
 568
 569         /*
 570          * Let Hyper-V know there is crash data available
 571          */
 572         wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
 573 }
 574 EXPORT_SYMBOL_GPL(hyperv_report_panic);
 575
 576 bool hv_is_hyperv_initialized(void)
 577 {
 578         union hv_x64_msr_hypercall_contents hypercall_msr;
 579
 580         /*
 581          * Ensure that we're really on Hyper-V, and not a KVM or Xen
 582          * emulation of Hyper-V
 583          */
 584         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
 585                 return false;
 586
 587         /*
 588          * Verify that earlier initialization succeeded by checking
 589          * that the hypercall page is setup
 590          */
 591         hypercall_msr.as_uint64 = 0;
 592         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 593
 594         return hypercall_msr.enable;
 595 }
 596 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);
 597
 598 bool hv_is_hibernation_supported(void)
 599 {
 600         return !hv_root_partition && acpi_sleep_state_supported(ACPI_STATE_S4);
 601 }
 602 EXPORT_SYMBOL_GPL(hv_is_hibernation_supported);
 603
 604 enum hv_isolation_type hv_get_isolation_type(void)
 605 {
 606         if (!(ms_hyperv.priv_high & HV_ISOLATION))
 607                 return HV_ISOLATION_TYPE_NONE;
 608         return FIELD_GET(HV_ISOLATION_TYPE, ms_hyperv.isolation_config_b);
 609 }
 610 EXPORT_SYMBOL_GPL(hv_get_isolation_type);
 611
 612 bool hv_is_isolation_supported(void)
 613 {
 614         return hv_get_isolation_type() != HV_ISOLATION_TYPE_NONE;
 615 }
 616 EXPORT_SYMBOL_GPL(hv_is_isolation_supported);
 617
 618 /* Bit mask of the extended capability to query: see HV_EXT_CAPABILITY_xxx */
 619 bool hv_query_ext_cap(u64 cap_query)
 620 {
 621         /*
 622          * The address of the 'hv_extended_cap' variable will be used as an
 623          * output parameter to the hypercall below and so it should be
 624          * compatible with 'virt_to_phys'. Which means, it's address should be
 625          * directly mapped. Use 'static' to keep it compatible; stack variables
 626          * can be virtually mapped, making them imcompatible with
 627          * 'virt_to_phys'.
 628          * Hypercall input/output addresses should also be 8-byte aligned.
 629          */
 630         static u64 hv_extended_cap __aligned(8);
 631         static bool hv_extended_cap_queried;
 632         u64 status;
 633
 634         /*
 635          * Querying extended capabilities is an extended hypercall. Check if the
 636          * partition supports extended hypercall, first.
 637          */
 638         if (!(ms_hyperv.priv_high & HV_ENABLE_EXTENDED_HYPERCALLS))
 639                 return false;
 640
 641         /* Extended capabilities do not change at runtime. */
 642         if (hv_extended_cap_queried)
 643                 return hv_extended_cap & cap_query;
 644
 645         status = hv_do_hypercall(HV_EXT_CALL_QUERY_CAPABILITIES, NULL,
 646                                  &hv_extended_cap);
 647
 648         /*
 649          * The query extended capabilities hypercall should not fail under
 650          * any normal circumstances. Avoid repeatedly making the hypercall, on
 651          * error.
 652          */
 653         hv_extended_cap_queried = true;
 654         status &= HV_HYPERCALL_RESULT_MASK;
 655         if (status != HV_STATUS_SUCCESS) {
 656                 pr_err("Hyper-V: Extended query capabilities hypercall failed 0x%llx\n",
 657                        status);
 658                 return false;
 659         }
 660
 661         return hv_extended_cap & cap_query;
 662 }
 663 EXPORT_SYMBOL_GPL(hv_query_ext_cap);