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.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 u32 hv_max_vp_index;
  92
  93 static int hv_cpu_init(unsigned int cpu)
  94 {
  95         u64 msr_vp_index;
  96
  97         hv_get_vp_index(msr_vp_index);
  98
  99         hv_vp_index[smp_processor_id()] = msr_vp_index;
 100
 101         if (msr_vp_index > hv_max_vp_index)
 102                 hv_max_vp_index = msr_vp_index;
 103
 104         return 0;
 105 }
 106
 107 static void (*hv_reenlightenment_cb)(void);
 108
 109 static void hv_reenlightenment_notify(struct work_struct *dummy)
 110 {
 111         struct hv_tsc_emulation_status emu_status;
 112
 113         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 114
 115         /* Don't issue the callback if TSC accesses are not emulated */
 116         if (hv_reenlightenment_cb && emu_status.inprogress)
 117                 hv_reenlightenment_cb();
 118 }
 119 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify);
 120
 121 void hyperv_stop_tsc_emulation(void)
 122 {
 123         u64 freq;
 124         struct hv_tsc_emulation_status emu_status;
 125
 126         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 127         emu_status.inprogress = 0;
 128         wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
 129
 130         rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
 131         tsc_khz = div64_u64(freq, 1000);
 132 }
 133 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation);
 134
 135 static inline bool hv_reenlightenment_available(void)
 136 {
 137         /*
 138          * Check for required features and priviliges to make TSC frequency
 139          * change notifications work.
 140          */
 141         return ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS &&
 142                 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
 143                 ms_hyperv.features & HV_X64_ACCESS_REENLIGHTENMENT;
 144 }
 145
 146 __visible void __irq_entry hyperv_reenlightenment_intr(struct pt_regs *regs)
 147 {
 148         entering_ack_irq();
 149
 150         inc_irq_stat(irq_hv_reenlightenment_count);
 151
 152         schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
 153
 154         exiting_irq();
 155 }
 156
 157 void set_hv_tscchange_cb(void (*cb)(void))
 158 {
 159         struct hv_reenlightenment_control re_ctrl = {
 160                 .vector = HYPERV_REENLIGHTENMENT_VECTOR,
 161                 .enabled = 1,
 162                 .target_vp = hv_vp_index[smp_processor_id()]
 163         };
 164         struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
 165
 166         if (!hv_reenlightenment_available()) {
 167                 pr_warn("Hyper-V: reenlightenment support is unavailable\n");
 168                 return;
 169         }
 170
 171         hv_reenlightenment_cb = cb;
 172
 173         /* Make sure callback is registered before we write to MSRs */
 174         wmb();
 175
 176         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 177         wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
 178 }
 179 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
 180
 181 void clear_hv_tscchange_cb(void)
 182 {
 183         struct hv_reenlightenment_control re_ctrl;
 184
 185         if (!hv_reenlightenment_available())
 186                 return;
 187
 188         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
 189         re_ctrl.enabled = 0;
 190         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
 191
 192         hv_reenlightenment_cb = NULL;
 193 }
 194 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);
 195
 196 static int hv_cpu_die(unsigned int cpu)
 197 {
 198         struct hv_reenlightenment_control re_ctrl;
 199         unsigned int new_cpu;
 200
 201         if (hv_reenlightenment_cb == NULL)
 202                 return 0;
 203
 204         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 205         if (re_ctrl.target_vp == hv_vp_index[cpu]) {
 206                 /* Reassign to some other online CPU */
 207                 new_cpu = cpumask_any_but(cpu_online_mask, cpu);
 208
 209                 re_ctrl.target_vp = hv_vp_index[new_cpu];
 210                 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 211         }
 212
 213         return 0;
 214 }
 215
 216 /*
 217  * This function is to be invoked early in the boot sequence after the
 218  * hypervisor has been detected.
 219  *
 220  * 1. Setup the hypercall page.
 221  * 2. Register Hyper-V specific clocksource.
 222  */
 223 void hyperv_init(void)
 224 {
 225         u64 guest_id, required_msrs;
 226         union hv_x64_msr_hypercall_contents hypercall_msr;
 227
 228         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
 229                 return;
 230
 231         /* Absolutely required MSRs */
 232         required_msrs = HV_X64_MSR_HYPERCALL_AVAILABLE |
 233                 HV_X64_MSR_VP_INDEX_AVAILABLE;
 234
 235         if ((ms_hyperv.features & required_msrs) != required_msrs)
 236                 return;
 237
 238         /* Allocate percpu VP index */
 239         hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
 240                                     GFP_KERNEL);
 241         if (!hv_vp_index)
 242                 return;
 243
 244         if (cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
 245                               hv_cpu_init, hv_cpu_die) < 0)
 246                 goto free_vp_index;
 247
 248         /*
 249          * Setup the hypercall page and enable hypercalls.
 250          * 1. Register the guest ID
 251          * 2. Enable the hypercall and register the hypercall page
 252          */
 253         guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
 254         wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 255
 256         hv_hypercall_pg  = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX);
 257         if (hv_hypercall_pg == NULL) {
 258                 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 259                 goto free_vp_index;
 260         }
 261
 262         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 263         hypercall_msr.enable = 1;
 264         hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
 265         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 266
 267         hyper_alloc_mmu();
 268
 269         /*
 270          * Register Hyper-V specific clocksource.
 271          */
 272 #ifdef CONFIG_HYPERV_TSCPAGE
 273         if (ms_hyperv.features & HV_X64_MSR_REFERENCE_TSC_AVAILABLE) {
 274                 union hv_x64_msr_hypercall_contents tsc_msr;
 275
 276                 tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
 277                 if (!tsc_pg)
 278                         goto register_msr_cs;
 279
 280                 hyperv_cs = &hyperv_cs_tsc;
 281
 282                 rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 283
 284                 tsc_msr.enable = 1;
 285                 tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg);
 286
 287                 wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 288
 289                 hyperv_cs_tsc.archdata.vclock_mode = VCLOCK_HVCLOCK;
 290
 291                 clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
 292                 return;
 293         }
 294 register_msr_cs:
 295 #endif
 296         /*
 297          * For 32 bit guests just use the MSR based mechanism for reading
 298          * the partition counter.
 299          */
 300
 301         hyperv_cs = &hyperv_cs_msr;
 302         if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
 303                 clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
 304
 305         return;
 306
 307 free_vp_index:
 308         kfree(hv_vp_index);
 309         hv_vp_index = NULL;
 310 }
 311
 312 /*
 313  * This routine is called before kexec/kdump, it does the required cleanup.
 314  */
 315 void hyperv_cleanup(void)
 316 {
 317         union hv_x64_msr_hypercall_contents hypercall_msr;
 318
 319         /* Reset our OS id */
 320         wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 321
 322         /* Reset the hypercall page */
 323         hypercall_msr.as_uint64 = 0;
 324         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 325
 326         /* Reset the TSC page */
 327         hypercall_msr.as_uint64 = 0;
 328         wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
 329 }
 330 EXPORT_SYMBOL_GPL(hyperv_cleanup);
 331
 332 void hyperv_report_panic(struct pt_regs *regs, long err)
 333 {
 334         static bool panic_reported;
 335         u64 guest_id;
 336
 337         /*
 338          * We prefer to report panic on 'die' chain as we have proper
 339          * registers to report, but if we miss it (e.g. on BUG()) we need
 340          * to report it on 'panic'.
 341          */
 342         if (panic_reported)
 343                 return;
 344         panic_reported = true;
 345
 346         rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 347
 348         wrmsrl(HV_X64_MSR_CRASH_P0, err);
 349         wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
 350         wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
 351         wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
 352         wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
 353
 354         /*
 355          * Let Hyper-V know there is crash data available
 356          */
 357         wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
 358 }
 359 EXPORT_SYMBOL_GPL(hyperv_report_panic);
 360
 361 bool hv_is_hyperv_initialized(void)
 362 {
 363         union hv_x64_msr_hypercall_contents hypercall_msr;
 364
 365         /*
 366          * Ensure that we're really on Hyper-V, and not a KVM or Xen
 367          * emulation of Hyper-V
 368          */
 369         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
 370                 return false;
 371
 372         /*
 373          * Verify that earlier initialization succeeded by checking
 374          * that the hypercall page is setup
 375          */
 376         hypercall_msr.as_uint64 = 0;
 377         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 378
 379         return hypercall_msr.enable;
 380 }
 381 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);