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
  29
  30 #ifdef CONFIG_X86_64
  31
  32 static struct ms_hyperv_tsc_page *tsc_pg;
  33
  34 static u64 read_hv_clock_tsc(struct clocksource *arg)
  35 {
  36         u64 current_tick;
  37
  38         if (tsc_pg->tsc_sequence != 0) {
  39                 /*
  40                  * Use the tsc page to compute the value.
  41                  */
  42
  43                 while (1) {
  44                         u64 tmp;
  45                         u32 sequence = tsc_pg->tsc_sequence;
  46                         u64 cur_tsc;
  47                         u64 scale = tsc_pg->tsc_scale;
  48                         s64 offset = tsc_pg->tsc_offset;
  49
  50                         rdtscll(cur_tsc);
  51                         /* current_tick = ((cur_tsc *scale) >> 64) + offset */
  52                         asm("mulq %3"
  53                                 : "=d" (current_tick), "=a" (tmp)
  54                                 : "a" (cur_tsc), "r" (scale));
  55
  56                         current_tick += offset;
  57                         if (tsc_pg->tsc_sequence == sequence)
  58                                 return current_tick;
  59
  60                         if (tsc_pg->tsc_sequence != 0)
  61                                 continue;
  62                         /*
  63                          * Fallback using MSR method.
  64                          */
  65                         break;
  66                 }
  67         }
  68         rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
  69         return current_tick;
  70 }
  71
  72 static struct clocksource hyperv_cs_tsc = {
  73                 .name           = "hyperv_clocksource_tsc_page",
  74                 .rating         = 400,
  75                 .read           = read_hv_clock_tsc,
  76                 .mask           = CLOCKSOURCE_MASK(64),
  77                 .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  78 };
  79 #endif
  80
  81 static u64 read_hv_clock_msr(struct clocksource *arg)
  82 {
  83         u64 current_tick;
  84         /*
  85          * Read the partition counter to get the current tick count. This count
  86          * is set to 0 when the partition is created and is incremented in
  87          * 100 nanosecond units.
  88          */
  89         rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
  90         return current_tick;
  91 }
  92
  93 static struct clocksource hyperv_cs_msr = {
  94         .name           = "hyperv_clocksource_msr",
  95         .rating         = 400,
  96         .read           = read_hv_clock_msr,
  97         .mask           = CLOCKSOURCE_MASK(64),
  98         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  99 };
 100
 101 static void *hypercall_pg;
 102 struct clocksource *hyperv_cs;
 103 EXPORT_SYMBOL_GPL(hyperv_cs);
 104
 105 /*
 106  * This function is to be invoked early in the boot sequence after the
 107  * hypervisor has been detected.
 108  *
 109  * 1. Setup the hypercall page.
 110  * 2. Register Hyper-V specific clocksource.
 111  */
 112 void hyperv_init(void)
 113 {
 114         u64 guest_id;
 115         union hv_x64_msr_hypercall_contents hypercall_msr;
 116
 117         if (x86_hyper != &x86_hyper_ms_hyperv)
 118                 return;
 119
 120         /*
 121          * Setup the hypercall page and enable hypercalls.
 122          * 1. Register the guest ID
 123          * 2. Enable the hypercall and register the hypercall page
 124          */
 125         guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
 126         wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 127
 128         hypercall_pg  = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX);
 129         if (hypercall_pg == NULL) {
 130                 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 131                 return;
 132         }
 133
 134         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 135         hypercall_msr.enable = 1;
 136         hypercall_msr.guest_physical_address = vmalloc_to_pfn(hypercall_pg);
 137         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 138
 139         /*
 140          * Register Hyper-V specific clocksource.
 141          */
 142 #ifdef CONFIG_X86_64
 143         if (ms_hyperv.features & HV_X64_MSR_REFERENCE_TSC_AVAILABLE) {
 144                 union hv_x64_msr_hypercall_contents tsc_msr;
 145
 146                 tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
 147                 if (!tsc_pg)
 148                         goto register_msr_cs;
 149
 150                 hyperv_cs = &hyperv_cs_tsc;
 151
 152                 rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 153
 154                 tsc_msr.enable = 1;
 155                 tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg);
 156
 157                 wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
 158                 clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
 159                 return;
 160         }
 161 #endif
 162         /*
 163          * For 32 bit guests just use the MSR based mechanism for reading
 164          * the partition counter.
 165          */
 166
 167 register_msr_cs:
 168         hyperv_cs = &hyperv_cs_msr;
 169         if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
 170                 clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
 171 }
 172
 173 /*
 174  * This routine is called before kexec/kdump, it does the required cleanup.
 175  */
 176 void hyperv_cleanup(void)
 177 {
 178         union hv_x64_msr_hypercall_contents hypercall_msr;
 179
 180         /* Reset our OS id */
 181         wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 182
 183         /* Reset the hypercall page */
 184         hypercall_msr.as_uint64 = 0;
 185         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 186
 187         /* Reset the TSC page */
 188         hypercall_msr.as_uint64 = 0;
 189         wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
 190 }
 191 EXPORT_SYMBOL_GPL(hyperv_cleanup);
 192
 193 /*
 194  * hv_do_hypercall- Invoke the specified hypercall
 195  */
 196 u64 hv_do_hypercall(u64 control, void *input, void *output)
 197 {
 198         u64 input_address = (input) ? virt_to_phys(input) : 0;
 199         u64 output_address = (output) ? virt_to_phys(output) : 0;
 200 #ifdef CONFIG_X86_64
 201         u64 hv_status = 0;
 202
 203         if (!hypercall_pg)
 204                 return (u64)ULLONG_MAX;
 205
 206         __asm__ __volatile__("mov %0, %%r8" : : "r" (output_address) : "r8");
 207         __asm__ __volatile__("call *%3" : "=a" (hv_status) :
 208                              "c" (control), "d" (input_address),
 209                              "m" (hypercall_pg));
 210
 211         return hv_status;
 212
 213 #else
 214
 215         u32 control_hi = control >> 32;
 216         u32 control_lo = control & 0xFFFFFFFF;
 217         u32 hv_status_hi = 1;
 218         u32 hv_status_lo = 1;
 219         u32 input_address_hi = input_address >> 32;
 220         u32 input_address_lo = input_address & 0xFFFFFFFF;
 221         u32 output_address_hi = output_address >> 32;
 222         u32 output_address_lo = output_address & 0xFFFFFFFF;
 223
 224         if (!hypercall_pg)
 225                 return (u64)ULLONG_MAX;
 226
 227         __asm__ __volatile__ ("call *%8" : "=d"(hv_status_hi),
 228                               "=a"(hv_status_lo) : "d" (control_hi),
 229                               "a" (control_lo), "b" (input_address_hi),
 230                               "c" (input_address_lo), "D"(output_address_hi),
 231                               "S"(output_address_lo), "m" (hypercall_pg));
 232
 233         return hv_status_lo | ((u64)hv_status_hi << 32);
 234 #endif /* !x86_64 */
 235 }
 236 EXPORT_SYMBOL_GPL(hv_do_hypercall);
 237
 238 void hyperv_report_panic(struct pt_regs *regs)
 239 {
 240         static bool panic_reported;
 241
 242         /*
 243          * We prefer to report panic on 'die' chain as we have proper
 244          * registers to report, but if we miss it (e.g. on BUG()) we need
 245          * to report it on 'panic'.
 246          */
 247         if (panic_reported)
 248                 return;
 249         panic_reported = true;
 250
 251         wrmsrl(HV_X64_MSR_CRASH_P0, regs->ip);
 252         wrmsrl(HV_X64_MSR_CRASH_P1, regs->ax);
 253         wrmsrl(HV_X64_MSR_CRASH_P2, regs->bx);
 254         wrmsrl(HV_X64_MSR_CRASH_P3, regs->cx);
 255         wrmsrl(HV_X64_MSR_CRASH_P4, regs->dx);
 256
 257         /*
 258          * Let Hyper-V know there is crash data available
 259          */
 260         wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
 261 }
 262 EXPORT_SYMBOL_GPL(hyperv_report_panic);
 263
 264 bool hv_is_hypercall_page_setup(void)
 265 {
 266         union hv_x64_msr_hypercall_contents hypercall_msr;
 267
 268         /* Check if the hypercall page is setup */
 269         hypercall_msr.as_uint64 = 0;
 270         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 271
 272         if (!hypercall_msr.enable)
 273                 return false;
 274
 275         return true;
 276 }
 277 EXPORT_SYMBOL_GPL(hv_is_hypercall_page_setup);