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/interrupt.h>
  19 #include <asm/processor.h>
  20 #include <asm/hypervisor.h>
  21 #include <asm/hyperv.h>
  22 #include <asm/mshyperv.h>
  23 #include <asm/desc.h>
  24 #include <asm/idle.h>
  25 #include <asm/irq_regs.h>
  26
  27 struct ms_hyperv_info ms_hyperv;
  28 EXPORT_SYMBOL_GPL(ms_hyperv);
  29
  30 static bool __init ms_hyperv_platform(void)
  31 {
  32         u32 eax;
  33         u32 hyp_signature[3];
  34
  35         if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
  36                 return false;
  37
  38         /*
  39          * Xen emulates Hyper-V to support enlightened Windows.
  40          * Check to see first if we are on a Xen Hypervisor.
  41          */
  42         if (xen_cpuid_base())
  43                 return false;
  44
  45         cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
  46               &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
  47
  48         return eax >= HYPERV_CPUID_MIN &&
  49                 eax <= HYPERV_CPUID_MAX &&
  50                 !memcmp("Microsoft Hv", hyp_signature, 12);
  51 }
  52
  53 static cycle_t read_hv_clock(struct clocksource *arg)
  54 {
  55         cycle_t current_tick;
  56         /*
  57          * Read the partition counter to get the current tick count. This count
  58          * is set to 0 when the partition is created and is incremented in
  59          * 100 nanosecond units.
  60          */
  61         rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
  62         return current_tick;
  63 }
  64
  65 static struct clocksource hyperv_cs = {
  66         .name           = "hyperv_clocksource",
  67         .rating         = 400, /* use this when running on Hyperv*/
  68         .read           = read_hv_clock,
  69         .mask           = CLOCKSOURCE_MASK(64),
  70 };
  71
  72 static void __init ms_hyperv_init_platform(void)
  73 {
  74         /*
  75          * Extract the features and hints
  76          */
  77         ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
  78         ms_hyperv.hints    = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
  79
  80         printk(KERN_INFO "HyperV: features 0x%x, hints 0x%x\n",
  81                ms_hyperv.features, ms_hyperv.hints);
  82
  83         if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
  84                 clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
  85 #if IS_ENABLED(CONFIG_HYPERV)
  86         /*
  87          * Setup the IDT for hypervisor callback.
  88          */
  89         alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, hyperv_callback_vector);
  90 #endif
  91 }
  92
  93 const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
  94         .name                   = "Microsoft HyperV",
  95         .detect                 = ms_hyperv_platform,
  96         .init_platform          = ms_hyperv_init_platform,
  97 };
  98 EXPORT_SYMBOL(x86_hyper_ms_hyperv);
  99
 100 #if IS_ENABLED(CONFIG_HYPERV)
 101 static int vmbus_irq = -1;
 102 static irq_handler_t vmbus_isr;
 103
 104 void hv_register_vmbus_handler(int irq, irq_handler_t handler)
 105 {
 106         vmbus_irq = irq;
 107         vmbus_isr = handler;
 108 }
 109
 110 void hyperv_vector_handler(struct pt_regs *regs)
 111 {
 112         struct pt_regs *old_regs = set_irq_regs(regs);
 113         struct irq_desc *desc;
 114
 115         irq_enter();
 116         exit_idle();
 117
 118         desc = irq_to_desc(vmbus_irq);
 119
 120         if (desc)
 121                 generic_handle_irq_desc(vmbus_irq, desc);
 122
 123         irq_exit();
 124         set_irq_regs(old_regs);
 125 }
 126 #else
 127 void hv_register_vmbus_handler(int irq, irq_handler_t handler)
 128 {
 129 }
 130 #endif
 131 EXPORT_SYMBOL_GPL(hv_register_vmbus_handler);