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