mshyperv.c

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/*
 * HyperV  Detection code.
 *
 * Copyright (C) 2010, Novell, Inc.
 * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 */

#include <linux/types.h>
#include <linux/time.h>
#include <linux/clocksource.h>
#include <linux/module.h>
#include <asm/processor.h>
#include <asm/hypervisor.h>
#include <asm/hyperv.h>
#include <asm/mshyperv.h>

struct ms_hyperv_info ms_hyperv;
EXPORT_SYMBOL_GPL(ms_hyperv);

static bool __init ms_hyperv_platform(void)
{
    u32 eax;
    u32 hyp_signature[3];

    if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
        return false;

    cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
          &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);

    return eax >= HYPERV_CPUID_MIN &&
        eax <= HYPERV_CPUID_MAX &&
        !memcmp("Microsoft Hv", hyp_signature, 12);
}

static cycle_t read_hv_clock(struct clocksource *arg)
{
    cycle_t current_tick;
    /*
     * Read the partition counter to get the current tick count. This count
     * is set to 0 when the partition is created and is incremented in
     * 100 nanosecond units.
     */
    rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
    return current_tick;
}

static struct clocksource hyperv_cs = {
    .name       = "hyperv_clocksource",
    .rating     = 400, /* use this when running on Hyperv*/
    .read       = read_hv_clock,
    .mask       = CLOCKSOURCE_MASK(64),
};

static void __init ms_hyperv_init_platform(void)
{
    /*
     * Extract the features and hints
     */
    ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
    ms_hyperv.hints    = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);

    printk(KERN_INFO "HyperV: features 0x%x, hints 0x%x\n",
           ms_hyperv.features, ms_hyperv.hints);

    clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
}

const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
    .name           = "Microsoft HyperV",
    .detect         = ms_hyperv_platform,
    .init_platform      = ms_hyperv_init_platform,
};
EXPORT_SYMBOL(x86_hyper_ms_hyperv);