arch/x86/kernel/cpu/mshyperv.c

   1 /*
   2  * HyperV  Detection code.
   3  *
   4  * Copyright (C) 2010, Novell, Inc.
   5  * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; version 2 of the License.
  10  *
  11  */
  12
  13 #include <linux/types.h>
  14 #include <linux/time.h>
  15 #include <linux/clocksource.h>
  16 #include <linux/init.h>
  17 #include <linux/export.h>
  18 #include <linux/hardirq.h>
  19 #include <linux/efi.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/irq.h>
  22 #include <linux/kexec.h>
  23 #include <asm/processor.h>
  24 #include <asm/hypervisor.h>
  25 #include <asm/hyperv.h>
  26 #include <asm/mshyperv.h>
  27 #include <asm/desc.h>
  28 #include <asm/idle.h>
  29 #include <asm/irq_regs.h>
  30 #include <asm/i8259.h>
  31 #include <asm/apic.h>
  32 #include <asm/timer.h>
  33 #include <asm/reboot.h>
  34 #include <asm/nmi.h>
  35
  36 struct ms_hyperv_info ms_hyperv;
  37 EXPORT_SYMBOL_GPL(ms_hyperv);
  38
  39 #if IS_ENABLED(CONFIG_HYPERV)
  40 static void (*vmbus_handler)(void);
  41 static void (*hv_kexec_handler)(void);
  42 static void (*hv_crash_handler)(struct pt_regs *regs);
  43
  44 void hyperv_vector_handler(struct pt_regs *regs)
  45 {
  46         struct pt_regs *old_regs = set_irq_regs(regs);
  47
  48         entering_irq();
  49         inc_irq_stat(irq_hv_callback_count);
  50         if (vmbus_handler)
  51                 vmbus_handler();
  52
  53         exiting_irq();
  54         set_irq_regs(old_regs);
  55 }
  56
  57 void hv_setup_vmbus_irq(void (*handler)(void))
  58 {
  59         vmbus_handler = handler;
  60         /*
  61          * Setup the IDT for hypervisor callback. Prevent reallocation
  62          * at module reload.
  63          */
  64         if (!test_bit(HYPERVISOR_CALLBACK_VECTOR, used_vectors))
  65                 alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR,
  66                                 hyperv_callback_vector);
  67 }
  68
  69 void hv_remove_vmbus_irq(void)
  70 {
  71         /* We have no way to deallocate the interrupt gate */
  72         vmbus_handler = NULL;
  73 }
  74 EXPORT_SYMBOL_GPL(hv_setup_vmbus_irq);
  75 EXPORT_SYMBOL_GPL(hv_remove_vmbus_irq);
  76
  77 void hv_setup_kexec_handler(void (*handler)(void))
  78 {
  79         hv_kexec_handler = handler;
  80 }
  81 EXPORT_SYMBOL_GPL(hv_setup_kexec_handler);
  82
  83 void hv_remove_kexec_handler(void)
  84 {
  85         hv_kexec_handler = NULL;
  86 }
  87 EXPORT_SYMBOL_GPL(hv_remove_kexec_handler);
  88
  89 void hv_setup_crash_handler(void (*handler)(struct pt_regs *regs))
  90 {
  91         hv_crash_handler = handler;
  92 }
  93 EXPORT_SYMBOL_GPL(hv_setup_crash_handler);
  94
  95 void hv_remove_crash_handler(void)
  96 {
  97         hv_crash_handler = NULL;
  98 }
  99 EXPORT_SYMBOL_GPL(hv_remove_crash_handler);
 100
 101 #ifdef CONFIG_KEXEC_CORE
 102 static void hv_machine_shutdown(void)
 103 {
 104         if (kexec_in_progress && hv_kexec_handler)
 105                 hv_kexec_handler();
 106         native_machine_shutdown();
 107 }
 108
 109 static void hv_machine_crash_shutdown(struct pt_regs *regs)
 110 {
 111         if (hv_crash_handler)
 112                 hv_crash_handler(regs);
 113         native_machine_crash_shutdown(regs);
 114 }
 115 #endif /* CONFIG_KEXEC_CORE */
 116 #endif /* CONFIG_HYPERV */
 117
 118 static uint32_t  __init ms_hyperv_platform(void)
 119 {
 120         u32 eax;
 121         u32 hyp_signature[3];
 122
 123         if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
 124                 return 0;
 125
 126         cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
 127               &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
 128
 129         if (eax >= HYPERV_CPUID_MIN &&
 130             eax <= HYPERV_CPUID_MAX &&
 131             !memcmp("Microsoft Hv", hyp_signature, 12))
 132                 return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS;
 133
 134         return 0;
 135 }
 136
 137 static cycle_t read_hv_clock(struct clocksource *arg)
 138 {
 139         cycle_t current_tick;
 140         /*
 141          * Read the partition counter to get the current tick count. This count
 142          * is set to 0 when the partition is created and is incremented in
 143          * 100 nanosecond units.
 144          */
 145         rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
 146         return current_tick;
 147 }
 148
 149 static struct clocksource hyperv_cs = {
 150         .name           = "hyperv_clocksource",
 151         .rating         = 400, /* use this when running on Hyperv*/
 152         .read           = read_hv_clock,
 153         .mask           = CLOCKSOURCE_MASK(64),
 154         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 155 };
 156
 157 static unsigned char hv_get_nmi_reason(void)
 158 {
 159         return 0;
 160 }
 161
 162 #ifdef CONFIG_X86_LOCAL_APIC
 163 /*
 164  * Prior to WS2016 Debug-VM sends NMIs to all CPUs which makes
 165  * it dificult to process CHANNELMSG_UNLOAD in case of crash. Handle
 166  * unknown NMI on the first CPU which gets it.
 167  */
 168 static int hv_nmi_unknown(unsigned int val, struct pt_regs *regs)
 169 {
 170         static atomic_t nmi_cpu = ATOMIC_INIT(-1);
 171
 172         if (!unknown_nmi_panic)
 173                 return NMI_DONE;
 174
 175         if (atomic_cmpxchg(&nmi_cpu, -1, raw_smp_processor_id()) != -1)
 176                 return NMI_HANDLED;
 177
 178         return NMI_DONE;
 179 }
 180 #endif
 181
 182 static void __init ms_hyperv_init_platform(void)
 183 {
 184         /*
 185          * Extract the features and hints
 186          */
 187         ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
 188         ms_hyperv.misc_features = cpuid_edx(HYPERV_CPUID_FEATURES);
 189         ms_hyperv.hints    = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
 190
 191         pr_info("HyperV: features 0x%x, hints 0x%x\n",
 192                 ms_hyperv.features, ms_hyperv.hints);
 193
 194 #ifdef CONFIG_X86_LOCAL_APIC
 195         if (ms_hyperv.features & HV_X64_MSR_APIC_FREQUENCY_AVAILABLE) {
 196                 /*
 197                  * Get the APIC frequency.
 198                  */
 199                 u64     hv_lapic_frequency;
 200
 201                 rdmsrl(HV_X64_MSR_APIC_FREQUENCY, hv_lapic_frequency);
 202                 hv_lapic_frequency = div_u64(hv_lapic_frequency, HZ);
 203                 lapic_timer_frequency = hv_lapic_frequency;
 204                 pr_info("HyperV: LAPIC Timer Frequency: %#x\n",
 205                         lapic_timer_frequency);
 206         }
 207
 208         register_nmi_handler(NMI_UNKNOWN, hv_nmi_unknown, NMI_FLAG_FIRST,
 209                              "hv_nmi_unknown");
 210 #endif
 211
 212         if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
 213                 clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
 214
 215 #ifdef CONFIG_X86_IO_APIC
 216         no_timer_check = 1;
 217 #endif
 218
 219 #if IS_ENABLED(CONFIG_HYPERV) && defined(CONFIG_KEXEC_CORE)
 220         machine_ops.shutdown = hv_machine_shutdown;
 221         machine_ops.crash_shutdown = hv_machine_crash_shutdown;
 222 #endif
 223         mark_tsc_unstable("running on Hyper-V");
 224
 225         /*
 226          * Generation 2 instances don't support reading the NMI status from
 227          * 0x61 port.
 228          */
 229         if (efi_enabled(EFI_BOOT))
 230                 x86_platform.get_nmi_reason = hv_get_nmi_reason;
 231 }
 232
 233 const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
 234         .name                   = "Microsoft HyperV",
 235         .detect                 = ms_hyperv_platform,
 236         .init_platform          = ms_hyperv_init_platform,
 237 };
 238 EXPORT_SYMBOL(x86_hyper_ms_hyperv);