arch/x86/hyperv/hv_init.c

   1 /*
   2  * X86 specific Hyper-V initialization code.
   3  *
   4  * Copyright (C) 2016, Microsoft, Inc.
   5  *
   6  * Author : K. Y. Srinivasan <kys@microsoft.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU General Public License version 2 as published
  10  * by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  15  * NON INFRINGEMENT.  See the GNU General Public License for more
  16  * details.
  17  *
  18  */
  19
  20 #include <linux/types.h>
  21 #include <asm/apic.h>
  22 #include <asm/desc.h>
  23 #include <asm/hypervisor.h>
  24 #include <asm/hyperv-tlfs.h>
  25 #include <asm/mshyperv.h>
  26 #include <linux/version.h>
  27 #include <linux/vmalloc.h>
  28 #include <linux/mm.h>
  29 #include <linux/clockchips.h>
  30 #include <linux/hyperv.h>
  31 #include <linux/slab.h>
  32 #include <linux/cpuhotplug.h>
  33
  34 #ifdef CONFIG_HYPERV_TSCPAGE
  35
  36 static struct ms_hyperv_tsc_page *tsc_pg;
  37
  38 struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
  39 {
  40         return tsc_pg;
  41 }
  42 EXPORT_SYMBOL_GPL(hv_get_tsc_page);
  43
  44 static u64 read_hv_clock_tsc(struct clocksource *arg)
  45 {
  46         u64 current_tick = hv_read_tsc_page(tsc_pg);
  47
  48         if (current_tick == U64_MAX)
  49                 rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
  50
  51         return current_tick;
  52 }
  53
  54 static struct clocksource hyperv_cs_tsc = {
  55                 .name           = "hyperv_clocksource_tsc_page",
  56                 .rating         = 400,
  57                 .read           = read_hv_clock_tsc,
  58                 .mask           = CLOCKSOURCE_MASK(64),
  59                 .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  60 };
  61 #endif
  62
  63 static u64 read_hv_clock_msr(struct clocksource *arg)
  64 {
  65         u64 current_tick;
  66         /*
  67          * Read the partition counter to get the current tick count. This count
  68          * is set to 0 when the partition is created and is incremented in
  69          * 100 nanosecond units.
  70          */
  71         rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
  72         return current_tick;
  73 }
  74
  75 static struct clocksource hyperv_cs_msr = {
  76         .name           = "hyperv_clocksource_msr",
  77         .rating         = 400,
  78         .read           = read_hv_clock_msr,
  79         .mask           = CLOCKSOURCE_MASK(64),
  80         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  81 };
  82
  83 void *hv_hypercall_pg;
  84 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
  85 struct clocksource *hyperv_cs;
  86 EXPORT_SYMBOL_GPL(hyperv_cs);
  87
  88 u32 *hv_vp_index;
  89 EXPORT_SYMBOL_GPL(hv_vp_index);
  90
  91 struct hv_vp_assist_page **hv_vp_assist_page;
  92 EXPORT_SYMBOL_GPL(hv_vp_assist_page);
  93
  94 void  __percpu **hyperv_pcpu_input_arg;
  95 EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
  96
  97 u32 hv_max_vp_index;
  98
  99 static int hv_cpu_init(unsigned int cpu)
 100 {
 101         u64 msr_vp_index;
 102         struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
 103         void **input_arg;
 104
 105         input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
 106         *input_arg = page_address(alloc_page(GFP_KERNEL));
 107
 108         hv_get_vp_index(msr_vp_index);
 109
 110         hv_vp_index[smp_processor_id()] = msr_vp_index;
 111
 112         if (msr_vp_index > hv_max_vp_index)
 113                 hv_max_vp_index = msr_vp_index;
 114
 115         if (!hv_vp_assist_page)
 116                 return 0;
 117
 118         if (!*hvp)
 119                 *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
 120
 121         if (*hvp) {
 122                 u64 val;
 123
 124                 val = vmalloc_to_pfn(*hvp);
 125                 val = (val << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT) |
 126                         HV_X64_MSR_VP_ASSIST_PAGE_ENABLE;
 127
 128                 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, val);
 129         }
 130
 131         return 0;
 132 }
 133
 134 static void (*hv_reenlightenment_cb)(void);
 135
 136 static void hv_reenlightenment_notify(struct work_struct *dummy)
 137 {
 138         struct hv_tsc_emulation_status emu_status;
 139
 140         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 141
 142         /* Don't issue the callback if TSC accesses are not emulated */
 143         if (hv_reenlightenment_cb && emu_status.inprogress)
 144                 hv_reenlightenment_cb();
 145 }
 146 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify);
 147
 148 void hyperv_stop_tsc_emulation(void)
 149 {
 150         u64 freq;
 151         struct hv_tsc_emulation_status emu_status;
 152
 153         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 154         emu_status.inprogress = 0;
 155         wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 156
 157         rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
 158         tsc_khz = div64_u64(freq, 1000);
 159 }
 160 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation);
 161
 162 static inline bool hv_reenlightenment_available(void)
 163 {
 164         /*
 165          * Check for required features and priviliges to make TSC frequency
 166          * change notifications work.
 167          */
 168         return ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS &&
 169                 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
 170                 ms_hyperv.features & HV_X64_ACCESS_REENLIGHTENMENT;
 171 }
 172
 173 __visible void __irq_entry hyperv_reenlightenment_intr(struct pt_regs *regs)
 174 {
 175         entering_ack_irq();
 176
 177         inc_irq_stat(irq_hv_reenlightenment_count);
 178
 179         schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
 180
 181         exiting_irq();
 182 }
 183
 184 void set_hv_tscchange_cb(void (*cb)(void))
 185 {
 186         struct hv_reenlightenment_control re_ctrl = {
 187                 .vector = HYPERV_REENLIGHTENMENT_VECTOR,
 188                 .enabled = 1,
 189                 .target_vp = hv_vp_index[smp_processor_id()]
 190         };
 191         struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
 192
 193         if (!hv_reenlightenment_available()) {
 194                 pr_warn("Hyper-V: reenlightenment support is unavailable\n");
 195                 return;
 196         }
 197
 198         hv_reenlightenment_cb = cb;
 199
 200         /* Make sure callback is registered before we write to MSRs */
 201         wmb();
 202
 203         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 204         wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
 205 }
 206 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
 207
 208 void clear_hv_tscchange_cb(void)
 209 {
 210         struct hv_reenlightenment_control re_ctrl;
 211
 212         if (!hv_reenlightenment_available())
 213                 return;
 214
 215         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
 216         re_ctrl.enabled = 0;
 217         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
 218
 219         hv_reenlightenment_cb = NULL;
 220 }
 221 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);
 222
 223 static int hv_cpu_die(unsigned int cpu)
 224 {
 225         struct hv_reenlightenment_control re_ctrl;
 226         unsigned int new_cpu;
 227         unsigned long flags;
 228         void **input_arg;
 229         void *input_pg = NULL;
 230
 231         local_irq_save(flags);
 232         input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
 233         input_pg = *input_arg;
 234         *input_arg = NULL;
 235         local_irq_restore(flags);
 236         free_page((unsigned long)input_pg);
 237
 238         if (hv_vp_assist_page && hv_vp_assist_page[cpu])
 239                 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
 240
 241         if (hv_reenlightenment_cb == NULL)
 242                 return 0;
 243
 244         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 245         if (re_ctrl.target_vp == hv_vp_index[cpu]) {
 246                 /* Reassign to some other online CPU */
 247                 new_cpu = cpumask_any_but(cpu_online_mask, cpu);
 248
 249                 re_ctrl.target_vp = hv_vp_index[new_cpu];
 250                 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 251         }
 252
 253         return 0;
 254 }
 255
 256 /*
 257  * This function is to be invoked early in the boot sequence after the
 258  * hypervisor has been detected.
 259  *
 260  * 1. Setup the hypercall page.
 261  * 2. Register Hyper-V specific clocksource.
 262  * 3. Setup Hyper-V specific APIC entry points.
 263  */
 264 void __init hyperv_init(void)
 265 {
 266         u64 guest_id, required_msrs;
 267         union hv_x64_msr_hypercall_contents hypercall_msr;
 268         int cpuhp;
 269
 270         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
 271                 return;
 272
 273         /* Absolutely required MSRs */
 274         required_msrs = HV_X64_MSR_HYPERCALL_AVAILABLE |
 275                 HV_X64_MSR_VP_INDEX_AVAILABLE;
 276
 277         if ((ms_hyperv.features & required_msrs) != required_msrs)
 278                 return;
 279
 280         /*
 281          * Allocate the per-CPU state for the hypercall input arg.
 282          * If this allocation fails, we will not be able to setup
 283          * (per-CPU) hypercall input page and thus this failure is
 284          * fatal on Hyper-V.
 285          */
 286         hyperv_pcpu_input_arg = alloc_percpu(void  *);
 287
 288         BUG_ON(hyperv_pcpu_input_arg == NULL);
 289
 290         /* Allocate percpu VP index */
 291         hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
 292                                     GFP_KERNEL);
 293         if (!hv_vp_index)
 294                 return;
 295
 296         hv_vp_assist_page = kcalloc(num_possible_cpus(),
 297                                     sizeof(*hv_vp_assist_page), GFP_KERNEL);
 298         if (!hv_vp_assist_page) {
 299                 ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
 300                 goto free_vp_index;
 301         }
 302
 303         cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
 304                                   hv_cpu_init, hv_cpu_die);
 305         if (cpuhp < 0)
 306                 goto free_vp_assist_page;
 307
 308         /*
 309          * Setup the hypercall page and enable hypercalls.
 310          * 1. Register the guest ID
 311          * 2. Enable the hypercall and register the hypercall page
 312          */
 313         guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
 314         wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 315
 316         hv_hypercall_pg  = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX);
 317         if (hv_hypercall_pg == NULL) {
 318                 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 319                 goto remove_cpuhp_state;
 320         }
 321
 322         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 323         hypercall_msr.enable = 1;
 324         hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
 325         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 326
 327         hv_apic_init();
 328
 329         /*
 330          * Register Hyper-V specific clocksource.
 331          */
 332 #ifdef CONFIG_HYPERV_TSCPAGE
 333         if (ms_hyperv.features & HV_X64_MSR_REFERENCE_TSC_AVAILABLE) {
 334                 union hv_x64_msr_hypercall_contents tsc_msr;
 335
 336                 tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
 337                 if (!tsc_pg)
 338                         goto register_msr_cs;
 339
 340                 hyperv_cs = &hyperv_cs_tsc;
 341
 342                 rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 343
 344                 tsc_msr.enable = 1;
 345                 tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg);
 346
 347                 wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 348
 349                 hyperv_cs_tsc.archdata.vclock_mode = VCLOCK_HVCLOCK;
 350
 351                 clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
 352                 return;
 353         }
 354 register_msr_cs:
 355 #endif
 356         /*
 357          * For 32 bit guests just use the MSR based mechanism for reading
 358          * the partition counter.
 359          */
 360
 361         hyperv_cs = &hyperv_cs_msr;
 362         if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
 363                 clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
 364
 365         return;
 366
 367 remove_cpuhp_state:
 368         cpuhp_remove_state(cpuhp);
 369 free_vp_assist_page:
 370         kfree(hv_vp_assist_page);
 371         hv_vp_assist_page = NULL;
 372 free_vp_index:
 373         kfree(hv_vp_index);
 374         hv_vp_index = NULL;
 375 }
 376
 377 /*
 378  * This routine is called before kexec/kdump, it does the required cleanup.
 379  */
 380 void hyperv_cleanup(void)
 381 {
 382         union hv_x64_msr_hypercall_contents hypercall_msr;
 383
 384         /* Reset our OS id */
 385         wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 386
 387         /* Reset the hypercall page */
 388         hypercall_msr.as_uint64 = 0;
 389         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 390
 391         /* Reset the TSC page */
 392         hypercall_msr.as_uint64 = 0;
 393         wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
 394 }
 395 EXPORT_SYMBOL_GPL(hyperv_cleanup);
 396
 397 void hyperv_report_panic(struct pt_regs *regs, long err)
 398 {
 399         static bool panic_reported;
 400         u64 guest_id;
 401
 402         /*
 403          * We prefer to report panic on 'die' chain as we have proper
 404          * registers to report, but if we miss it (e.g. on BUG()) we need
 405          * to report it on 'panic'.
 406          */
 407         if (panic_reported)
 408                 return;
 409         panic_reported = true;
 410
 411         rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 412
 413         wrmsrl(HV_X64_MSR_CRASH_P0, err);
 414         wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
 415         wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
 416         wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
 417         wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
 418
 419         /*
 420          * Let Hyper-V know there is crash data available
 421          */
 422         wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
 423 }
 424 EXPORT_SYMBOL_GPL(hyperv_report_panic);
 425
 426 bool hv_is_hyperv_initialized(void)
 427 {
 428         union hv_x64_msr_hypercall_contents hypercall_msr;
 429
 430         /*
 431          * Ensure that we're really on Hyper-V, and not a KVM or Xen
 432          * emulation of Hyper-V
 433          */
 434         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
 435                 return false;
 436
 437         /*
 438          * Verify that earlier initialization succeeded by checking
 439          * that the hypercall page is setup
 440          */
 441         hypercall_msr.as_uint64 = 0;
 442         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 443
 444         return hypercall_msr.enable;
 445 }
 446 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);