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