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 <asm/apic.h>
  13 #include <asm/desc.h>
  14 #include <asm/hypervisor.h>
  15 #include <asm/hyperv-tlfs.h>
  16 #include <asm/mshyperv.h>
  17 #include <linux/version.h>
  18 #include <linux/vmalloc.h>
  19 #include <linux/mm.h>
  20 #include <linux/hyperv.h>
  21 #include <linux/slab.h>
  22 #include <linux/cpuhotplug.h>
  23 #include <clocksource/hyperv_timer.h>
  24
  25 void *hv_hypercall_pg;
  26 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
  27
  28 u32 *hv_vp_index;
  29 EXPORT_SYMBOL_GPL(hv_vp_index);
  30
  31 struct hv_vp_assist_page **hv_vp_assist_page;
  32 EXPORT_SYMBOL_GPL(hv_vp_assist_page);
  33
  34 void  __percpu **hyperv_pcpu_input_arg;
  35 EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
  36
  37 u32 hv_max_vp_index;
  38 EXPORT_SYMBOL_GPL(hv_max_vp_index);
  39
  40 void *hv_alloc_hyperv_page(void)
  41 {
  42         BUILD_BUG_ON(PAGE_SIZE != HV_HYP_PAGE_SIZE);
  43
  44         return (void *)__get_free_page(GFP_KERNEL);
  45 }
  46 EXPORT_SYMBOL_GPL(hv_alloc_hyperv_page);
  47
  48 void hv_free_hyperv_page(unsigned long addr)
  49 {
  50         free_page(addr);
  51 }
  52 EXPORT_SYMBOL_GPL(hv_free_hyperv_page);
  53
  54 static int hv_cpu_init(unsigned int cpu)
  55 {
  56         u64 msr_vp_index;
  57         struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
  58         void **input_arg;
  59         struct page *pg;
  60
  61         input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
  62         pg = alloc_page(GFP_KERNEL);
  63         if (unlikely(!pg))
  64                 return -ENOMEM;
  65         *input_arg = page_address(pg);
  66
  67         hv_get_vp_index(msr_vp_index);
  68
  69         hv_vp_index[smp_processor_id()] = msr_vp_index;
  70
  71         if (msr_vp_index > hv_max_vp_index)
  72                 hv_max_vp_index = msr_vp_index;
  73
  74         if (!hv_vp_assist_page)
  75                 return 0;
  76
  77         /*
  78          * The VP ASSIST PAGE is an "overlay" page (see Hyper-V TLFS's Section
  79          * 5.2.1 "GPA Overlay Pages"). Here it must be zeroed out to make sure
  80          * we always write the EOI MSR in hv_apic_eoi_write() *after* the
  81          * EOI optimization is disabled in hv_cpu_die(), otherwise a CPU may
  82          * not be stopped in the case of CPU offlining and the VM will hang.
  83          */
  84         if (!*hvp) {
  85                 *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO,
  86                                  PAGE_KERNEL);
  87         }
  88
  89         if (*hvp) {
  90                 u64 val;
  91
  92                 val = vmalloc_to_pfn(*hvp);
  93                 val = (val << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT) |
  94                         HV_X64_MSR_VP_ASSIST_PAGE_ENABLE;
  95
  96                 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, val);
  97         }
  98
  99         return 0;
 100 }
 101
 102 static void (*hv_reenlightenment_cb)(void);
 103
 104 static void hv_reenlightenment_notify(struct work_struct *dummy)
 105 {
 106         struct hv_tsc_emulation_status emu_status;
 107
 108         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 109
 110         /* Don't issue the callback if TSC accesses are not emulated */
 111         if (hv_reenlightenment_cb && emu_status.inprogress)
 112                 hv_reenlightenment_cb();
 113 }
 114 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify);
 115
 116 void hyperv_stop_tsc_emulation(void)
 117 {
 118         u64 freq;
 119         struct hv_tsc_emulation_status emu_status;
 120
 121         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 122         emu_status.inprogress = 0;
 123         wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 124
 125         rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
 126         tsc_khz = div64_u64(freq, 1000);
 127 }
 128 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation);
 129
 130 static inline bool hv_reenlightenment_available(void)
 131 {
 132         /*
 133          * Check for required features and priviliges to make TSC frequency
 134          * change notifications work.
 135          */
 136         return ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS &&
 137                 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
 138                 ms_hyperv.features & HV_X64_ACCESS_REENLIGHTENMENT;
 139 }
 140
 141 __visible void __irq_entry hyperv_reenlightenment_intr(struct pt_regs *regs)
 142 {
 143         entering_ack_irq();
 144
 145         inc_irq_stat(irq_hv_reenlightenment_count);
 146
 147         schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
 148
 149         exiting_irq();
 150 }
 151
 152 void set_hv_tscchange_cb(void (*cb)(void))
 153 {
 154         struct hv_reenlightenment_control re_ctrl = {
 155                 .vector = HYPERV_REENLIGHTENMENT_VECTOR,
 156                 .enabled = 1,
 157                 .target_vp = hv_vp_index[smp_processor_id()]
 158         };
 159         struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
 160
 161         if (!hv_reenlightenment_available()) {
 162                 pr_warn("Hyper-V: reenlightenment support is unavailable\n");
 163                 return;
 164         }
 165
 166         hv_reenlightenment_cb = cb;
 167
 168         /* Make sure callback is registered before we write to MSRs */
 169         wmb();
 170
 171         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 172         wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
 173 }
 174 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
 175
 176 void clear_hv_tscchange_cb(void)
 177 {
 178         struct hv_reenlightenment_control re_ctrl;
 179
 180         if (!hv_reenlightenment_available())
 181                 return;
 182
 183         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
 184         re_ctrl.enabled = 0;
 185         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
 186
 187         hv_reenlightenment_cb = NULL;
 188 }
 189 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);
 190
 191 static int hv_cpu_die(unsigned int cpu)
 192 {
 193         struct hv_reenlightenment_control re_ctrl;
 194         unsigned int new_cpu;
 195         unsigned long flags;
 196         void **input_arg;
 197         void *input_pg = NULL;
 198
 199         local_irq_save(flags);
 200         input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
 201         input_pg = *input_arg;
 202         *input_arg = NULL;
 203         local_irq_restore(flags);
 204         free_page((unsigned long)input_pg);
 205
 206         if (hv_vp_assist_page && hv_vp_assist_page[cpu])
 207                 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
 208
 209         if (hv_reenlightenment_cb == NULL)
 210                 return 0;
 211
 212         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 213         if (re_ctrl.target_vp == hv_vp_index[cpu]) {
 214                 /* Reassign to some other online CPU */
 215                 new_cpu = cpumask_any_but(cpu_online_mask, cpu);
 216
 217                 re_ctrl.target_vp = hv_vp_index[new_cpu];
 218                 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 219         }
 220
 221         return 0;
 222 }
 223
 224 static int __init hv_pci_init(void)
 225 {
 226         int gen2vm = efi_enabled(EFI_BOOT);
 227
 228         /*
 229          * For Generation-2 VM, we exit from pci_arch_init() by returning 0.
 230          * The purpose is to suppress the harmless warning:
 231          * "PCI: Fatal: No config space access function found"
 232          */
 233         if (gen2vm)
 234                 return 0;
 235
 236         /* For Generation-1 VM, we'll proceed in pci_arch_init().  */
 237         return 1;
 238 }
 239
 240 /*
 241  * This function is to be invoked early in the boot sequence after the
 242  * hypervisor has been detected.
 243  *
 244  * 1. Setup the hypercall page.
 245  * 2. Register Hyper-V specific clocksource.
 246  * 3. Setup Hyper-V specific APIC entry points.
 247  */
 248 void __init hyperv_init(void)
 249 {
 250         u64 guest_id, required_msrs;
 251         union hv_x64_msr_hypercall_contents hypercall_msr;
 252         int cpuhp, i;
 253
 254         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
 255                 return;
 256
 257         /* Absolutely required MSRs */
 258         required_msrs = HV_X64_MSR_HYPERCALL_AVAILABLE |
 259                 HV_X64_MSR_VP_INDEX_AVAILABLE;
 260
 261         if ((ms_hyperv.features & required_msrs) != required_msrs)
 262                 return;
 263
 264         /*
 265          * Allocate the per-CPU state for the hypercall input arg.
 266          * If this allocation fails, we will not be able to setup
 267          * (per-CPU) hypercall input page and thus this failure is
 268          * fatal on Hyper-V.
 269          */
 270         hyperv_pcpu_input_arg = alloc_percpu(void  *);
 271
 272         BUG_ON(hyperv_pcpu_input_arg == NULL);
 273
 274         /* Allocate percpu VP index */
 275         hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
 276                                     GFP_KERNEL);
 277         if (!hv_vp_index)
 278                 return;
 279
 280         for (i = 0; i < num_possible_cpus(); i++)
 281                 hv_vp_index[i] = VP_INVAL;
 282
 283         hv_vp_assist_page = kcalloc(num_possible_cpus(),
 284                                     sizeof(*hv_vp_assist_page), GFP_KERNEL);
 285         if (!hv_vp_assist_page) {
 286                 ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
 287                 goto free_vp_index;
 288         }
 289
 290         cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
 291                                   hv_cpu_init, hv_cpu_die);
 292         if (cpuhp < 0)
 293                 goto free_vp_assist_page;
 294
 295         /*
 296          * Setup the hypercall page and enable hypercalls.
 297          * 1. Register the guest ID
 298          * 2. Enable the hypercall and register the hypercall page
 299          */
 300         guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
 301         wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 302
 303         hv_hypercall_pg  = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX);
 304         if (hv_hypercall_pg == NULL) {
 305                 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 306                 goto remove_cpuhp_state;
 307         }
 308
 309         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 310         hypercall_msr.enable = 1;
 311         hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
 312         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 313
 314         hv_apic_init();
 315
 316         x86_init.pci.arch_init = hv_pci_init;
 317
 318         return;
 319
 320 remove_cpuhp_state:
 321         cpuhp_remove_state(cpuhp);
 322 free_vp_assist_page:
 323         kfree(hv_vp_assist_page);
 324         hv_vp_assist_page = NULL;
 325 free_vp_index:
 326         kfree(hv_vp_index);
 327         hv_vp_index = NULL;
 328 }
 329
 330 /*
 331  * This routine is called before kexec/kdump, it does the required cleanup.
 332  */
 333 void hyperv_cleanup(void)
 334 {
 335         union hv_x64_msr_hypercall_contents hypercall_msr;
 336
 337         /* Reset our OS id */
 338         wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 339
 340         /*
 341          * Reset hypercall page reference before reset the page,
 342          * let hypercall operations fail safely rather than
 343          * panic the kernel for using invalid hypercall page
 344          */
 345         hv_hypercall_pg = NULL;
 346
 347         /* Reset the hypercall page */
 348         hypercall_msr.as_uint64 = 0;
 349         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 350
 351         /* Reset the TSC page */
 352         hypercall_msr.as_uint64 = 0;
 353         wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
 354 }
 355 EXPORT_SYMBOL_GPL(hyperv_cleanup);
 356
 357 void hyperv_report_panic(struct pt_regs *regs, long err)
 358 {
 359         static bool panic_reported;
 360         u64 guest_id;
 361
 362         /*
 363          * We prefer to report panic on 'die' chain as we have proper
 364          * registers to report, but if we miss it (e.g. on BUG()) we need
 365          * to report it on 'panic'.
 366          */
 367         if (panic_reported)
 368                 return;
 369         panic_reported = true;
 370
 371         rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 372
 373         wrmsrl(HV_X64_MSR_CRASH_P0, err);
 374         wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
 375         wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
 376         wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
 377         wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
 378
 379         /*
 380          * Let Hyper-V know there is crash data available
 381          */
 382         wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
 383 }
 384 EXPORT_SYMBOL_GPL(hyperv_report_panic);
 385
 386 /**
 387  * hyperv_report_panic_msg - report panic message to Hyper-V
 388  * @pa: physical address of the panic page containing the message
 389  * @size: size of the message in the page
 390  */
 391 void hyperv_report_panic_msg(phys_addr_t pa, size_t size)
 392 {
 393         /*
 394          * P3 to contain the physical address of the panic page & P4 to
 395          * contain the size of the panic data in that page. Rest of the
 396          * registers are no-op when the NOTIFY_MSG flag is set.
 397          */
 398         wrmsrl(HV_X64_MSR_CRASH_P0, 0);
 399         wrmsrl(HV_X64_MSR_CRASH_P1, 0);
 400         wrmsrl(HV_X64_MSR_CRASH_P2, 0);
 401         wrmsrl(HV_X64_MSR_CRASH_P3, pa);
 402         wrmsrl(HV_X64_MSR_CRASH_P4, size);
 403
 404         /*
 405          * Let Hyper-V know there is crash data available along with
 406          * the panic message.
 407          */
 408         wrmsrl(HV_X64_MSR_CRASH_CTL,
 409                (HV_CRASH_CTL_CRASH_NOTIFY | HV_CRASH_CTL_CRASH_NOTIFY_MSG));
 410 }
 411 EXPORT_SYMBOL_GPL(hyperv_report_panic_msg);
 412
 413 bool hv_is_hyperv_initialized(void)
 414 {
 415         union hv_x64_msr_hypercall_contents hypercall_msr;
 416
 417         /*
 418          * Ensure that we're really on Hyper-V, and not a KVM or Xen
 419          * emulation of Hyper-V
 420          */
 421         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
 422                 return false;
 423
 424         /*
 425          * Verify that earlier initialization succeeded by checking
 426          * that the hypercall page is setup
 427          */
 428         hypercall_msr.as_uint64 = 0;
 429         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 430
 431         return hypercall_msr.enable;
 432 }
 433 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);