2 * HyperV Detection code.
4 * Copyright (C) 2010, Novell, Inc.
5 * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
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.
13 #include <linux/types.h>
14 #include <linux/time.h>
15 #include <linux/clocksource.h>
16 #include <linux/module.h>
17 #include <asm/processor.h>
18 #include <asm/hypervisor.h>
19 #include <asm/hyperv.h>
20 #include <asm/mshyperv.h>
21 #include <asm/timer.h>
23 struct ms_hyperv_info ms_hyperv;
24 EXPORT_SYMBOL_GPL(ms_hyperv);
26 static bool __init ms_hyperv_platform(void)
31 if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
34 cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
35 &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
37 return eax >= HYPERV_CPUID_MIN &&
38 eax <= HYPERV_CPUID_MAX &&
39 !memcmp("Microsoft Hv", hyp_signature, 12);
42 static cycle_t read_hv_clock(struct clocksource *arg)
46 * Read the partition counter to get the current tick count. This count
47 * is set to 0 when the partition is created and is incremented in
48 * 100 nanosecond units.
50 rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
54 static struct clocksource hyperv_cs = {
55 .name = "hyperv_clocksource",
56 .rating = 400, /* use this when running on Hyperv*/
57 .read = read_hv_clock,
58 .mask = CLOCKSOURCE_MASK(64),
61 static void __init ms_hyperv_init_platform(void)
64 * Extract the features and hints
66 ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
67 ms_hyperv.hints = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
69 printk(KERN_INFO "HyperV: features 0x%x, hints 0x%x\n",
70 ms_hyperv.features, ms_hyperv.hints);
72 if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
73 clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
75 #ifdef CONFIG_X86_IO_APIC
81 const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
82 .name = "Microsoft HyperV",
83 .detect = ms_hyperv_platform,
84 .init_platform = ms_hyperv_init_platform,
86 EXPORT_SYMBOL(x86_hyper_ms_hyperv);