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/hypervisor.h>
  22 #include <asm/hyperv.h>
  23 #include <asm/mshyperv.h>
  24 #include <linux/version.h>
  25 #include <linux/vmalloc.h>
  26 #include <linux/mm.h>
  27 #include <linux/clockchips.h>
  28 #include <linux/hyperv.h>
  29 #include <linux/slab.h>
  30 #include <linux/cpuhotplug.h>
  31
  32 #ifdef CONFIG_HYPERV_TSCPAGE
  33
  34 static struct ms_hyperv_tsc_page *tsc_pg;
  35
  36 struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
  37 {
  38         return tsc_pg;
  39 }
  40
  41 static u64 read_hv_clock_tsc(struct clocksource *arg)
  42 {
  43         u64 current_tick = hv_read_tsc_page(tsc_pg);
  44
  45         if (current_tick == U64_MAX)
  46                 rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
  47
  48         return current_tick;
  49 }
  50
  51 static struct clocksource hyperv_cs_tsc = {
  52                 .name           = "hyperv_clocksource_tsc_page",
  53                 .rating         = 400,
  54                 .read           = read_hv_clock_tsc,
  55                 .mask           = CLOCKSOURCE_MASK(64),
  56                 .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  57 };
  58 #endif
  59
  60 static u64 read_hv_clock_msr(struct clocksource *arg)
  61 {
  62         u64 current_tick;
  63         /*
  64          * Read the partition counter to get the current tick count. This count
  65          * is set to 0 when the partition is created and is incremented in
  66          * 100 nanosecond units.
  67          */
  68         rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
  69         return current_tick;
  70 }
  71
  72 static struct clocksource hyperv_cs_msr = {
  73         .name           = "hyperv_clocksource_msr",
  74         .rating         = 400,
  75         .read           = read_hv_clock_msr,
  76         .mask           = CLOCKSOURCE_MASK(64),
  77         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  78 };
  79
  80 void *hv_hypercall_pg;
  81 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
  82 struct clocksource *hyperv_cs;
  83 EXPORT_SYMBOL_GPL(hyperv_cs);
  84
  85 u32 *hv_vp_index;
  86 EXPORT_SYMBOL_GPL(hv_vp_index);
  87
  88 u32 hv_max_vp_index;
  89
  90 static int hv_cpu_init(unsigned int cpu)
  91 {
  92         u64 msr_vp_index;
  93
  94         hv_get_vp_index(msr_vp_index);
  95
  96         hv_vp_index[smp_processor_id()] = msr_vp_index;
  97
  98         if (msr_vp_index > hv_max_vp_index)
  99                 hv_max_vp_index = msr_vp_index;
 100
 101         return 0;
 102 }
 103
 104 /*
 105  * This function is to be invoked early in the boot sequence after the
 106  * hypervisor has been detected.
 107  *
 108  * 1. Setup the hypercall page.
 109  * 2. Register Hyper-V specific clocksource.
 110  */
 111 void hyperv_init(void)
 112 {
 113         u64 guest_id, required_msrs;
 114         union hv_x64_msr_hypercall_contents hypercall_msr;
 115
 116         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
 117                 return;
 118
 119         /* Absolutely required MSRs */
 120         required_msrs = HV_X64_MSR_HYPERCALL_AVAILABLE |
 121                 HV_X64_MSR_VP_INDEX_AVAILABLE;
 122
 123         if ((ms_hyperv.features & required_msrs) != required_msrs)
 124                 return;
 125
 126         /* Allocate percpu VP index */
 127         hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
 128                                     GFP_KERNEL);
 129         if (!hv_vp_index)
 130                 return;
 131
 132         if (cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
 133                               hv_cpu_init, NULL) < 0)
 134                 goto free_vp_index;
 135
 136         /*
 137          * Setup the hypercall page and enable hypercalls.
 138          * 1. Register the guest ID
 139          * 2. Enable the hypercall and register the hypercall page
 140          */
 141         guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
 142         wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 143
 144         hv_hypercall_pg  = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX);
 145         if (hv_hypercall_pg == NULL) {
 146                 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 147                 goto free_vp_index;
 148         }
 149
 150         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 151         hypercall_msr.enable = 1;
 152         hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
 153         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 154
 155         hyper_alloc_mmu();
 156
 157         /*
 158          * Register Hyper-V specific clocksource.
 159          */
 160 #ifdef CONFIG_HYPERV_TSCPAGE
 161         if (ms_hyperv.features & HV_X64_MSR_REFERENCE_TSC_AVAILABLE) {
 162                 union hv_x64_msr_hypercall_contents tsc_msr;
 163
 164                 tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
 165                 if (!tsc_pg)
 166                         goto register_msr_cs;
 167
 168                 hyperv_cs = &hyperv_cs_tsc;
 169
 170                 rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 171
 172                 tsc_msr.enable = 1;
 173                 tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg);
 174
 175                 wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 176
 177                 hyperv_cs_tsc.archdata.vclock_mode = VCLOCK_HVCLOCK;
 178
 179                 clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
 180                 return;
 181         }
 182 register_msr_cs:
 183 #endif
 184         /*
 185          * For 32 bit guests just use the MSR based mechanism for reading
 186          * the partition counter.
 187          */
 188
 189         hyperv_cs = &hyperv_cs_msr;
 190         if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
 191                 clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
 192
 193         return;
 194
 195 free_vp_index:
 196         kfree(hv_vp_index);
 197         hv_vp_index = NULL;
 198 }
 199
 200 /*
 201  * This routine is called before kexec/kdump, it does the required cleanup.
 202  */
 203 void hyperv_cleanup(void)
 204 {
 205         union hv_x64_msr_hypercall_contents hypercall_msr;
 206
 207         /* Reset our OS id */
 208         wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 209
 210         /* Reset the hypercall page */
 211         hypercall_msr.as_uint64 = 0;
 212         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 213
 214         /* Reset the TSC page */
 215         hypercall_msr.as_uint64 = 0;
 216         wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
 217 }
 218 EXPORT_SYMBOL_GPL(hyperv_cleanup);
 219
 220 void hyperv_report_panic(struct pt_regs *regs)
 221 {
 222         static bool panic_reported;
 223
 224         /*
 225          * We prefer to report panic on 'die' chain as we have proper
 226          * registers to report, but if we miss it (e.g. on BUG()) we need
 227          * to report it on 'panic'.
 228          */
 229         if (panic_reported)
 230                 return;
 231         panic_reported = true;
 232
 233         wrmsrl(HV_X64_MSR_CRASH_P0, regs->ip);
 234         wrmsrl(HV_X64_MSR_CRASH_P1, regs->ax);
 235         wrmsrl(HV_X64_MSR_CRASH_P2, regs->bx);
 236         wrmsrl(HV_X64_MSR_CRASH_P3, regs->cx);
 237         wrmsrl(HV_X64_MSR_CRASH_P4, regs->dx);
 238
 239         /*
 240          * Let Hyper-V know there is crash data available
 241          */
 242         wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
 243 }
 244 EXPORT_SYMBOL_GPL(hyperv_report_panic);
 245
 246 bool hv_is_hypercall_page_setup(void)
 247 {
 248         union hv_x64_msr_hypercall_contents hypercall_msr;
 249
 250         /* Check if the hypercall page is setup */
 251         hypercall_msr.as_uint64 = 0;
 252         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 253
 254         if (!hypercall_msr.enable)
 255                 return false;
 256
 257         return true;
 258 }
 259 EXPORT_SYMBOL_GPL(hv_is_hypercall_page_setup);