arch/x86/hyperv/hv_init.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * X86 specific Hyper-V initialization code.
   4  *
   5  * Copyright (C) 2016, Microsoft, Inc.
   6  *
   7  * Author : K. Y. Srinivasan <kys@microsoft.com>
   8  */
   9
  10 #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/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 struct hv_vp_assist_page **hv_vp_assist_page;
  43 EXPORT_SYMBOL_GPL(hv_vp_assist_page);
  44
  45 static int hv_cpu_init(unsigned int cpu)
  46 {
  47         union hv_vp_assist_msr_contents msr = { 0 };
  48         struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
  49         int ret;
  50
  51         ret = hv_common_cpu_init(cpu);
  52         if (ret)
  53                 return ret;
  54
  55         if (!hv_vp_assist_page)
  56                 return 0;
  57
  58         if (!*hvp) {
  59                 if (hv_root_partition) {
  60                         /*
  61                          * For root partition we get the hypervisor provided VP assist
  62                          * page, instead of allocating a new page.
  63                          */
  64                         rdmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
  65                         *hvp = memremap(msr.pfn <<
  66                                         HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT,
  67                                         PAGE_SIZE, MEMREMAP_WB);
  68                 } else {
  69                         /*
  70                          * The VP assist page is an "overlay" page (see Hyper-V TLFS's
  71                          * Section 5.2.1 "GPA Overlay Pages"). Here it must be zeroed
  72                          * out to make sure we always write the EOI MSR in
  73                          * hv_apic_eoi_write() *after* the EOI optimization is disabled
  74                          * in hv_cpu_die(), otherwise a CPU may not be stopped in the
  75                          * case of CPU offlining and the VM will hang.
  76                          */
  77                         *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO);
  78                         if (*hvp)
  79                                 msr.pfn = vmalloc_to_pfn(*hvp);
  80                 }
  81                 WARN_ON(!(*hvp));
  82                 if (*hvp) {
  83                         msr.enable = 1;
  84                         wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
  85                 }
  86         }
  87
  88         return 0;
  89 }
  90
  91 static void (*hv_reenlightenment_cb)(void);
  92
  93 static void hv_reenlightenment_notify(struct work_struct *dummy)
  94 {
  95         struct hv_tsc_emulation_status emu_status;
  96
  97         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
  98
  99         /* Don't issue the callback if TSC accesses are not emulated */
 100         if (hv_reenlightenment_cb && emu_status.inprogress)
 101                 hv_reenlightenment_cb();
 102 }
 103 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify);
 104
 105 void hyperv_stop_tsc_emulation(void)
 106 {
 107         u64 freq;
 108         struct hv_tsc_emulation_status emu_status;
 109
 110         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 111         emu_status.inprogress = 0;
 112         wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 113
 114         rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
 115         tsc_khz = div64_u64(freq, 1000);
 116 }
 117 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation);
 118
 119 static inline bool hv_reenlightenment_available(void)
 120 {
 121         /*
 122          * Check for required features and privileges to make TSC frequency
 123          * change notifications work.
 124          */
 125         return ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
 126                 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
 127                 ms_hyperv.features & HV_ACCESS_REENLIGHTENMENT;
 128 }
 129
 130 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_reenlightenment)
 131 {
 132         ack_APIC_irq();
 133         inc_irq_stat(irq_hv_reenlightenment_count);
 134         schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
 135 }
 136
 137 void set_hv_tscchange_cb(void (*cb)(void))
 138 {
 139         struct hv_reenlightenment_control re_ctrl = {
 140                 .vector = HYPERV_REENLIGHTENMENT_VECTOR,
 141                 .enabled = 1,
 142         };
 143         struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
 144
 145         if (!hv_reenlightenment_available()) {
 146                 pr_warn("Hyper-V: reenlightenment support is unavailable\n");
 147                 return;
 148         }
 149
 150         if (!hv_vp_index)
 151                 return;
 152
 153         hv_reenlightenment_cb = cb;
 154
 155         /* Make sure callback is registered before we write to MSRs */
 156         wmb();
 157
 158         re_ctrl.target_vp = hv_vp_index[get_cpu()];
 159
 160         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 161         wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
 162
 163         put_cpu();
 164 }
 165 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
 166
 167 void clear_hv_tscchange_cb(void)
 168 {
 169         struct hv_reenlightenment_control re_ctrl;
 170
 171         if (!hv_reenlightenment_available())
 172                 return;
 173
 174         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
 175         re_ctrl.enabled = 0;
 176         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
 177
 178         hv_reenlightenment_cb = NULL;
 179 }
 180 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);
 181
 182 static int hv_cpu_die(unsigned int cpu)
 183 {
 184         struct hv_reenlightenment_control re_ctrl;
 185         unsigned int new_cpu;
 186
 187         hv_common_cpu_die(cpu);
 188
 189         if (hv_vp_assist_page && hv_vp_assist_page[cpu]) {
 190                 union hv_vp_assist_msr_contents msr = { 0 };
 191                 if (hv_root_partition) {
 192                         /*
 193                          * For root partition the VP assist page is mapped to
 194                          * hypervisor provided page, and thus we unmap the
 195                          * page here and nullify it, so that in future we have
 196                          * correct page address mapped in hv_cpu_init.
 197                          */
 198                         memunmap(hv_vp_assist_page[cpu]);
 199                         hv_vp_assist_page[cpu] = NULL;
 200                         rdmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
 201                         msr.enable = 0;
 202                 }
 203                 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
 204         }
 205
 206         if (hv_reenlightenment_cb == NULL)
 207                 return 0;
 208
 209         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 210         if (re_ctrl.target_vp == hv_vp_index[cpu]) {
 211                 /*
 212                  * Reassign reenlightenment notifications to some other online
 213                  * CPU or just disable the feature if there are no online CPUs
 214                  * left (happens on hibernation).
 215                  */
 216                 new_cpu = cpumask_any_but(cpu_online_mask, cpu);
 217
 218                 if (new_cpu < nr_cpu_ids)
 219                         re_ctrl.target_vp = hv_vp_index[new_cpu];
 220                 else
 221                         re_ctrl.enabled = 0;
 222
 223                 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 224         }
 225
 226         return 0;
 227 }
 228
 229 static int __init hv_pci_init(void)
 230 {
 231         int gen2vm = efi_enabled(EFI_BOOT);
 232
 233         /*
 234          * For Generation-2 VM, we exit from pci_arch_init() by returning 0.
 235          * The purpose is to suppress the harmless warning:
 236          * "PCI: Fatal: No config space access function found"
 237          */
 238         if (gen2vm)
 239                 return 0;
 240
 241         /* For Generation-1 VM, we'll proceed in pci_arch_init().  */
 242         return 1;
 243 }
 244
 245 static int hv_suspend(void)
 246 {
 247         union hv_x64_msr_hypercall_contents hypercall_msr;
 248         int ret;
 249
 250         if (hv_root_partition)
 251                 return -EPERM;
 252
 253         /*
 254          * Reset the hypercall page as it is going to be invalidated
 255          * across hibernation. Setting hv_hypercall_pg to NULL ensures
 256          * that any subsequent hypercall operation fails safely instead of
 257          * crashing due to an access of an invalid page. The hypercall page
 258          * pointer is restored on resume.
 259          */
 260         hv_hypercall_pg_saved = hv_hypercall_pg;
 261         hv_hypercall_pg = NULL;
 262
 263         /* Disable the hypercall page in the hypervisor */
 264         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 265         hypercall_msr.enable = 0;
 266         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 267
 268         ret = hv_cpu_die(0);
 269         return ret;
 270 }
 271
 272 static void hv_resume(void)
 273 {
 274         union hv_x64_msr_hypercall_contents hypercall_msr;
 275         int ret;
 276
 277         ret = hv_cpu_init(0);
 278         WARN_ON(ret);
 279
 280         /* Re-enable the hypercall page */
 281         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 282         hypercall_msr.enable = 1;
 283         hypercall_msr.guest_physical_address =
 284                 vmalloc_to_pfn(hv_hypercall_pg_saved);
 285         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 286
 287         hv_hypercall_pg = hv_hypercall_pg_saved;
 288         hv_hypercall_pg_saved = NULL;
 289
 290         /*
 291          * Reenlightenment notifications are disabled by hv_cpu_die(0),
 292          * reenable them here if hv_reenlightenment_cb was previously set.
 293          */
 294         if (hv_reenlightenment_cb)
 295                 set_hv_tscchange_cb(hv_reenlightenment_cb);
 296 }
 297
 298 /* Note: when the ops are called, only CPU0 is online and IRQs are disabled. */
 299 static struct syscore_ops hv_syscore_ops = {
 300         .suspend        = hv_suspend,
 301         .resume         = hv_resume,
 302 };
 303
 304 static void (* __initdata old_setup_percpu_clockev)(void);
 305
 306 static void __init hv_stimer_setup_percpu_clockev(void)
 307 {
 308         /*
 309          * Ignore any errors in setting up stimer clockevents
 310          * as we can run with the LAPIC timer as a fallback.
 311          */
 312         (void)hv_stimer_alloc(false);
 313
 314         /*
 315          * Still register the LAPIC timer, because the direct-mode STIMER is
 316          * not supported by old versions of Hyper-V. This also allows users
 317          * to switch to LAPIC timer via /sys, if they want to.
 318          */
 319         if (old_setup_percpu_clockev)
 320                 old_setup_percpu_clockev();
 321 }
 322
 323 static void __init hv_get_partition_id(void)
 324 {
 325         struct hv_get_partition_id *output_page;
 326         u64 status;
 327         unsigned long flags;
 328
 329         local_irq_save(flags);
 330         output_page = *this_cpu_ptr(hyperv_pcpu_output_arg);
 331         status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page);
 332         if (!hv_result_success(status)) {
 333                 /* No point in proceeding if this failed */
 334                 pr_err("Failed to get partition ID: %lld\n", status);
 335                 BUG();
 336         }
 337         hv_current_partition_id = output_page->partition_id;
 338         local_irq_restore(flags);
 339 }
 340
 341 /*
 342  * This function is to be invoked early in the boot sequence after the
 343  * hypervisor has been detected.
 344  *
 345  * 1. Setup the hypercall page.
 346  * 2. Register Hyper-V specific clocksource.
 347  * 3. Setup Hyper-V specific APIC entry points.
 348  */
 349 void __init hyperv_init(void)
 350 {
 351         u64 guest_id;
 352         union hv_x64_msr_hypercall_contents hypercall_msr;
 353         int cpuhp;
 354
 355         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
 356                 return;
 357
 358         if (hv_common_init())
 359                 return;
 360
 361         hv_vp_assist_page = kcalloc(num_possible_cpus(),
 362                                     sizeof(*hv_vp_assist_page), GFP_KERNEL);
 363         if (!hv_vp_assist_page) {
 364                 ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
 365                 goto common_free;
 366         }
 367
 368         cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
 369                                   hv_cpu_init, hv_cpu_die);
 370         if (cpuhp < 0)
 371                 goto free_vp_assist_page;
 372
 373         /*
 374          * Setup the hypercall page and enable hypercalls.
 375          * 1. Register the guest ID
 376          * 2. Enable the hypercall and register the hypercall page
 377          */
 378         guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
 379         wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 380
 381         hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START,
 382                         VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_ROX,
 383                         VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
 384                         __builtin_return_address(0));
 385         if (hv_hypercall_pg == NULL) {
 386                 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 387                 goto remove_cpuhp_state;
 388         }
 389
 390         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 391         hypercall_msr.enable = 1;
 392
 393         if (hv_root_partition) {
 394                 struct page *pg;
 395                 void *src, *dst;
 396
 397                 /*
 398                  * For the root partition, the hypervisor will set up its
 399                  * hypercall page. The hypervisor guarantees it will not show
 400                  * up in the root's address space. The root can't change the
 401                  * location of the hypercall page.
 402                  *
 403                  * Order is important here. We must enable the hypercall page
 404                  * so it is populated with code, then copy the code to an
 405                  * executable page.
 406                  */
 407                 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 408
 409                 pg = vmalloc_to_page(hv_hypercall_pg);
 410                 dst = kmap(pg);
 411                 src = memremap(hypercall_msr.guest_physical_address << PAGE_SHIFT, PAGE_SIZE,
 412                                 MEMREMAP_WB);
 413                 BUG_ON(!(src && dst));
 414                 memcpy(dst, src, HV_HYP_PAGE_SIZE);
 415                 memunmap(src);
 416                 kunmap(pg);
 417         } else {
 418                 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
 419                 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 420         }
 421
 422         /*
 423          * hyperv_init() is called before LAPIC is initialized: see
 424          * apic_intr_mode_init() -> x86_platform.apic_post_init() and
 425          * apic_bsp_setup() -> setup_local_APIC(). The direct-mode STIMER
 426          * depends on LAPIC, so hv_stimer_alloc() should be called from
 427          * x86_init.timers.setup_percpu_clockev.
 428          */
 429         old_setup_percpu_clockev = x86_init.timers.setup_percpu_clockev;
 430         x86_init.timers.setup_percpu_clockev = hv_stimer_setup_percpu_clockev;
 431
 432         hv_apic_init();
 433
 434         x86_init.pci.arch_init = hv_pci_init;
 435
 436         register_syscore_ops(&hv_syscore_ops);
 437
 438         hyperv_init_cpuhp = cpuhp;
 439
 440         if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_ACCESS_PARTITION_ID)
 441                 hv_get_partition_id();
 442
 443         BUG_ON(hv_root_partition && hv_current_partition_id == ~0ull);
 444
 445 #ifdef CONFIG_PCI_MSI
 446         /*
 447          * If we're running as root, we want to create our own PCI MSI domain.
 448          * We can't set this in hv_pci_init because that would be too late.
 449          */
 450         if (hv_root_partition)
 451                 x86_init.irqs.create_pci_msi_domain = hv_create_pci_msi_domain;
 452 #endif
 453
 454         /* Query the VMs extended capability once, so that it can be cached. */
 455         hv_query_ext_cap(0);
 456         return;
 457
 458 remove_cpuhp_state:
 459         cpuhp_remove_state(cpuhp);
 460 free_vp_assist_page:
 461         kfree(hv_vp_assist_page);
 462         hv_vp_assist_page = NULL;
 463 common_free:
 464         hv_common_free();
 465 }
 466
 467 /*
 468  * This routine is called before kexec/kdump, it does the required cleanup.
 469  */
 470 void hyperv_cleanup(void)
 471 {
 472         union hv_x64_msr_hypercall_contents hypercall_msr;
 473
 474         unregister_syscore_ops(&hv_syscore_ops);
 475
 476         /* Reset our OS id */
 477         wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 478
 479         /*
 480          * Reset hypercall page reference before reset the page,
 481          * let hypercall operations fail safely rather than
 482          * panic the kernel for using invalid hypercall page
 483          */
 484         hv_hypercall_pg = NULL;
 485
 486         /* Reset the hypercall page */
 487         hypercall_msr.as_uint64 = 0;
 488         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 489
 490         /* Reset the TSC page */
 491         hypercall_msr.as_uint64 = 0;
 492         wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
 493 }
 494
 495 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die)
 496 {
 497         static bool panic_reported;
 498         u64 guest_id;
 499
 500         if (in_die && !panic_on_oops)
 501                 return;
 502
 503         /*
 504          * We prefer to report panic on 'die' chain as we have proper
 505          * registers to report, but if we miss it (e.g. on BUG()) we need
 506          * to report it on 'panic'.
 507          */
 508         if (panic_reported)
 509                 return;
 510         panic_reported = true;
 511
 512         rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 513
 514         wrmsrl(HV_X64_MSR_CRASH_P0, err);
 515         wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
 516         wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
 517         wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
 518         wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
 519
 520         /*
 521          * Let Hyper-V know there is crash data available
 522          */
 523         wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
 524 }
 525 EXPORT_SYMBOL_GPL(hyperv_report_panic);
 526
 527 bool hv_is_hyperv_initialized(void)
 528 {
 529         union hv_x64_msr_hypercall_contents hypercall_msr;
 530
 531         /*
 532          * Ensure that we're really on Hyper-V, and not a KVM or Xen
 533          * emulation of Hyper-V
 534          */
 535         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
 536                 return false;
 537
 538         /*
 539          * Verify that earlier initialization succeeded by checking
 540          * that the hypercall page is setup
 541          */
 542         hypercall_msr.as_uint64 = 0;
 543         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 544
 545         return hypercall_msr.enable;
 546 }
 547 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);
 548
 549 enum hv_isolation_type hv_get_isolation_type(void)
 550 {
 551         if (!(ms_hyperv.priv_high & HV_ISOLATION))
 552                 return HV_ISOLATION_TYPE_NONE;
 553         return FIELD_GET(HV_ISOLATION_TYPE, ms_hyperv.isolation_config_b);
 554 }
 555 EXPORT_SYMBOL_GPL(hv_get_isolation_type);
 556
 557 bool hv_is_isolation_supported(void)
 558 {
 559         return hv_get_isolation_type() != HV_ISOLATION_TYPE_NONE;
 560 }