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         schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
 151
 152         exiting_irq();
 153 }
 154
 155 void set_hv_tscchange_cb(void (*cb)(void))
 156 {
 157         struct hv_reenlightenment_control re_ctrl = {
 158                 .vector = HYPERV_REENLIGHTENMENT_VECTOR,
 159                 .enabled = 1,
 160                 .target_vp = hv_vp_index[smp_processor_id()]
 161         };
 162         struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
 163
 164         if (!hv_reenlightenment_available()) {
 165                 pr_warn("Hyper-V: reenlightenment support is unavailable\n");
 166                 return;
 167         }
 168
 169         hv_reenlightenment_cb = cb;
 170
 171         /* Make sure callback is registered before we write to MSRs */
 172         wmb();
 173
 174         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
 175         wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
 176 }
 177 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
 178
 179 void clear_hv_tscchange_cb(void)
 180 {
 181         struct hv_reenlightenment_control re_ctrl;
 182
 183         if (!hv_reenlightenment_available())
 184                 return;
 185
 186         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
 187         re_ctrl.enabled = 0;
 188         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
 189
 190         hv_reenlightenment_cb = NULL;
 191 }
 192 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);
 193
 194 /*
 195  * This function is to be invoked early in the boot sequence after the
 196  * hypervisor has been detected.
 197  *
 198  * 1. Setup the hypercall page.
 199  * 2. Register Hyper-V specific clocksource.
 200  */
 201 void hyperv_init(void)
 202 {
 203         u64 guest_id, required_msrs;
 204         union hv_x64_msr_hypercall_contents hypercall_msr;
 205
 206         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
 207                 return;
 208
 209         /* Absolutely required MSRs */
 210         required_msrs = HV_X64_MSR_HYPERCALL_AVAILABLE |
 211                 HV_X64_MSR_VP_INDEX_AVAILABLE;
 212
 213         if ((ms_hyperv.features & required_msrs) != required_msrs)
 214                 return;
 215
 216         /* Allocate percpu VP index */
 217         hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
 218                                     GFP_KERNEL);
 219         if (!hv_vp_index)
 220                 return;
 221
 222         if (cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
 223                               hv_cpu_init, NULL) < 0)
 224                 goto free_vp_index;
 225
 226         /*
 227          * Setup the hypercall page and enable hypercalls.
 228          * 1. Register the guest ID
 229          * 2. Enable the hypercall and register the hypercall page
 230          */
 231         guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
 232         wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 233
 234         hv_hypercall_pg  = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX);
 235         if (hv_hypercall_pg == NULL) {
 236                 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 237                 goto free_vp_index;
 238         }
 239
 240         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 241         hypercall_msr.enable = 1;
 242         hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
 243         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 244
 245         hyper_alloc_mmu();
 246
 247         /*
 248          * Register Hyper-V specific clocksource.
 249          */
 250 #ifdef CONFIG_HYPERV_TSCPAGE
 251         if (ms_hyperv.features & HV_X64_MSR_REFERENCE_TSC_AVAILABLE) {
 252                 union hv_x64_msr_hypercall_contents tsc_msr;
 253
 254                 tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
 255                 if (!tsc_pg)
 256                         goto register_msr_cs;
 257
 258                 hyperv_cs = &hyperv_cs_tsc;
 259
 260                 rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 261
 262                 tsc_msr.enable = 1;
 263                 tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg);
 264
 265                 wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 266
 267                 hyperv_cs_tsc.archdata.vclock_mode = VCLOCK_HVCLOCK;
 268
 269                 clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
 270                 return;
 271         }
 272 register_msr_cs:
 273 #endif
 274         /*
 275          * For 32 bit guests just use the MSR based mechanism for reading
 276          * the partition counter.
 277          */
 278
 279         hyperv_cs = &hyperv_cs_msr;
 280         if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
 281                 clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
 282
 283         return;
 284
 285 free_vp_index:
 286         kfree(hv_vp_index);
 287         hv_vp_index = NULL;
 288 }
 289
 290 /*
 291  * This routine is called before kexec/kdump, it does the required cleanup.
 292  */
 293 void hyperv_cleanup(void)
 294 {
 295         union hv_x64_msr_hypercall_contents hypercall_msr;
 296
 297         /* Reset our OS id */
 298         wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 299
 300         /* Reset the hypercall page */
 301         hypercall_msr.as_uint64 = 0;
 302         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 303
 304         /* Reset the TSC page */
 305         hypercall_msr.as_uint64 = 0;
 306         wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
 307 }
 308 EXPORT_SYMBOL_GPL(hyperv_cleanup);
 309
 310 void hyperv_report_panic(struct pt_regs *regs, long err)
 311 {
 312         static bool panic_reported;
 313         u64 guest_id;
 314
 315         /*
 316          * We prefer to report panic on 'die' chain as we have proper
 317          * registers to report, but if we miss it (e.g. on BUG()) we need
 318          * to report it on 'panic'.
 319          */
 320         if (panic_reported)
 321                 return;
 322         panic_reported = true;
 323
 324         rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 325
 326         wrmsrl(HV_X64_MSR_CRASH_P0, err);
 327         wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
 328         wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
 329         wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
 330         wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
 331
 332         /*
 333          * Let Hyper-V know there is crash data available
 334          */
 335         wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
 336 }
 337 EXPORT_SYMBOL_GPL(hyperv_report_panic);
 338
 339 bool hv_is_hypercall_page_setup(void)
 340 {
 341         union hv_x64_msr_hypercall_contents hypercall_msr;
 342
 343         /* Check if the hypercall page is setup */
 344         hypercall_msr.as_uint64 = 0;
 345         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 346
 347         if (!hypercall_msr.enable)
 348                 return false;
 349
 350         return true;
 351 }
 352 EXPORT_SYMBOL_GPL(hv_is_hypercall_page_setup);