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