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         irq_enter();
  43         exit_idle();
  44
  45         inc_irq_stat(irq_hv_callback_count);
  46         if (vmbus_handler)
  47                 vmbus_handler();
  48
  49         irq_exit();
  50         set_irq_regs(old_regs);
  51 }
  52
  53 void hv_setup_vmbus_irq(void (*handler)(void))
  54 {
  55         vmbus_handler = handler;
  56         /*
  57          * Setup the IDT for hypervisor callback. Prevent reallocation
  58          * at module reload.
  59          */
  60         if (!test_bit(HYPERVISOR_CALLBACK_VECTOR, used_vectors))
  61                 alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR,
  62                                 hyperv_callback_vector);
  63 }
  64
  65 void hv_remove_vmbus_irq(void)
  66 {
  67         /* We have no way to deallocate the interrupt gate */
  68         vmbus_handler = NULL;
  69 }
  70 EXPORT_SYMBOL_GPL(hv_setup_vmbus_irq);
  71 EXPORT_SYMBOL_GPL(hv_remove_vmbus_irq);
  72 #endif
  73
  74 static uint32_t  __init ms_hyperv_platform(void)
  75 {
  76         u32 eax;
  77         u32 hyp_signature[3];
  78
  79         if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
  80                 return 0;
  81
  82         cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
  83               &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
  84
  85         if (eax >= HYPERV_CPUID_MIN &&
  86             eax <= HYPERV_CPUID_MAX &&
  87             !memcmp("Microsoft Hv", hyp_signature, 12))
  88                 return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS;
  89
  90         return 0;
  91 }
  92
  93 static cycle_t read_hv_clock(struct clocksource *arg)
  94 {
  95         cycle_t current_tick;
  96         /*
  97          * Read the partition counter to get the current tick count. This count
  98          * is set to 0 when the partition is created and is incremented in
  99          * 100 nanosecond units.
 100          */
 101         rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
 102         return current_tick;
 103 }
 104
 105 static struct clocksource hyperv_cs = {
 106         .name           = "hyperv_clocksource",
 107         .rating         = 400, /* use this when running on Hyperv*/
 108         .read           = read_hv_clock,
 109         .mask           = CLOCKSOURCE_MASK(64),
 110         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 111 };
 112
 113 static void __init ms_hyperv_init_platform(void)
 114 {
 115         /*
 116          * Extract the features and hints
 117          */
 118         ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
 119         ms_hyperv.hints    = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
 120
 121         printk(KERN_INFO "HyperV: features 0x%x, hints 0x%x\n",
 122                ms_hyperv.features, ms_hyperv.hints);
 123
 124 #ifdef CONFIG_X86_LOCAL_APIC
 125         if (ms_hyperv.features & HV_X64_MSR_APIC_FREQUENCY_AVAILABLE) {
 126                 /*
 127                  * Get the APIC frequency.
 128                  */
 129                 u64     hv_lapic_frequency;
 130
 131                 rdmsrl(HV_X64_MSR_APIC_FREQUENCY, hv_lapic_frequency);
 132                 hv_lapic_frequency = div_u64(hv_lapic_frequency, HZ);
 133                 lapic_timer_frequency = hv_lapic_frequency;
 134                 printk(KERN_INFO "HyperV: LAPIC Timer Frequency: %#x\n",
 135                                 lapic_timer_frequency);
 136         }
 137 #endif
 138
 139         if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
 140                 clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
 141
 142 #ifdef CONFIG_X86_IO_APIC
 143         no_timer_check = 1;
 144 #endif
 145
 146 }
 147
 148 const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
 149         .name                   = "Microsoft HyperV",
 150         .detect                 = ms_hyperv_platform,
 151         .init_platform          = ms_hyperv_init_platform,
 152 };
 153 EXPORT_SYMBOL(x86_hyper_ms_hyperv);