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/module.h>
  17 #include <linux/hardirq.h>
  18 #include <linux/efi.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/irq.h>
  21 #include <asm/processor.h>
  22 #include <asm/hypervisor.h>
  23 #include <asm/hyperv.h>
  24 #include <asm/mshyperv.h>
  25 #include <asm/desc.h>
  26 #include <asm/idle.h>
  27 #include <asm/irq_regs.h>
  28 #include <asm/i8259.h>
  29 #include <asm/apic.h>
  30 #include <asm/timer.h>
  31
  32 struct ms_hyperv_info ms_hyperv;
  33 EXPORT_SYMBOL_GPL(ms_hyperv);
  34
  35 #if IS_ENABLED(CONFIG_HYPERV)
  36 static void (*vmbus_handler)(void);
  37
  38 void hyperv_vector_handler(struct pt_regs *regs)
  39 {
  40         struct pt_regs *old_regs = set_irq_regs(regs);
  41
  42         entering_irq();
  43         inc_irq_stat(irq_hv_callback_count);
  44         if (vmbus_handler)
  45                 vmbus_handler();
  46
  47         exiting_irq();
  48         set_irq_regs(old_regs);
  49 }
  50
  51 void hv_setup_vmbus_irq(void (*handler)(void))
  52 {
  53         vmbus_handler = handler;
  54         /*
  55          * Setup the IDT for hypervisor callback. Prevent reallocation
  56          * at module reload.
  57          */
  58         if (!test_bit(HYPERVISOR_CALLBACK_VECTOR, used_vectors))
  59                 alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR,
  60                                 hyperv_callback_vector);
  61 }
  62
  63 void hv_remove_vmbus_irq(void)
  64 {
  65         /* We have no way to deallocate the interrupt gate */
  66         vmbus_handler = NULL;
  67 }
  68 EXPORT_SYMBOL_GPL(hv_setup_vmbus_irq);
  69 EXPORT_SYMBOL_GPL(hv_remove_vmbus_irq);
  70 #endif
  71
  72 static uint32_t  __init ms_hyperv_platform(void)
  73 {
  74         u32 eax;
  75         u32 hyp_signature[3];
  76
  77         if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
  78                 return 0;
  79
  80         cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
  81               &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
  82
  83         if (eax >= HYPERV_CPUID_MIN &&
  84             eax <= HYPERV_CPUID_MAX &&
  85             !memcmp("Microsoft Hv", hyp_signature, 12))
  86                 return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS;
  87
  88         return 0;
  89 }
  90
  91 static cycle_t read_hv_clock(struct clocksource *arg)
  92 {
  93         cycle_t current_tick;
  94         /*
  95          * Read the partition counter to get the current tick count. This count
  96          * is set to 0 when the partition is created and is incremented in
  97          * 100 nanosecond units.
  98          */
  99         rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
 100         return current_tick;
 101 }
 102
 103 static struct clocksource hyperv_cs = {
 104         .name           = "hyperv_clocksource",
 105         .rating         = 400, /* use this when running on Hyperv*/
 106         .read           = read_hv_clock,
 107         .mask           = CLOCKSOURCE_MASK(64),
 108         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 109 };
 110
 111 static void __init ms_hyperv_init_platform(void)
 112 {
 113         /*
 114          * Extract the features and hints
 115          */
 116         ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
 117         ms_hyperv.hints    = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
 118
 119         printk(KERN_INFO "HyperV: features 0x%x, hints 0x%x\n",
 120                ms_hyperv.features, ms_hyperv.hints);
 121
 122 #ifdef CONFIG_X86_LOCAL_APIC
 123         if (ms_hyperv.features & HV_X64_MSR_APIC_FREQUENCY_AVAILABLE) {
 124                 /*
 125                  * Get the APIC frequency.
 126                  */
 127                 u64     hv_lapic_frequency;
 128
 129                 rdmsrl(HV_X64_MSR_APIC_FREQUENCY, hv_lapic_frequency);
 130                 hv_lapic_frequency = div_u64(hv_lapic_frequency, HZ);
 131                 lapic_timer_frequency = hv_lapic_frequency;
 132                 printk(KERN_INFO "HyperV: LAPIC Timer Frequency: %#x\n",
 133                                 lapic_timer_frequency);
 134         }
 135 #endif
 136
 137         if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
 138                 clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
 139
 140 #ifdef CONFIG_X86_IO_APIC
 141         no_timer_check = 1;
 142 #endif
 143
 144 }
 145
 146 const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
 147         .name                   = "Microsoft HyperV",
 148         .detect                 = ms_hyperv_platform,
 149         .init_platform          = ms_hyperv_init_platform,
 150 };
 151 EXPORT_SYMBOL(x86_hyper_ms_hyperv);