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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;
/*
* Xen emulates Hyper-V to support enlightened Windows.
* Check to see first if we are on a Xen Hypervisor.
*/
if (xen_cpuid_base())
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);
if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
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);
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