Linux 3.8-rc7
[cris-mirror.git] / arch / x86 / kernel / cpu / mshyperv.c
blob0a630dd4b62061ae713803ba29684fbe35a96312
1 /*
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>
22 struct ms_hyperv_info ms_hyperv;
23 EXPORT_SYMBOL_GPL(ms_hyperv);
25 static bool __init ms_hyperv_platform(void)
27 u32 eax;
28 u32 hyp_signature[3];
30 if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
31 return false;
33 cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
34 &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
36 return eax >= HYPERV_CPUID_MIN &&
37 eax <= HYPERV_CPUID_MAX &&
38 !memcmp("Microsoft Hv", hyp_signature, 12);
41 static cycle_t read_hv_clock(struct clocksource *arg)
43 cycle_t current_tick;
45 * Read the partition counter to get the current tick count. This count
46 * is set to 0 when the partition is created and is incremented in
47 * 100 nanosecond units.
49 rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
50 return current_tick;
53 static struct clocksource hyperv_cs = {
54 .name = "hyperv_clocksource",
55 .rating = 400, /* use this when running on Hyperv*/
56 .read = read_hv_clock,
57 .mask = CLOCKSOURCE_MASK(64),
60 static void __init ms_hyperv_init_platform(void)
63 * Extract the features and hints
65 ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
66 ms_hyperv.hints = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
68 printk(KERN_INFO "HyperV: features 0x%x, hints 0x%x\n",
69 ms_hyperv.features, ms_hyperv.hints);
71 clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
74 const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
75 .name = "Microsoft HyperV",
76 .detect = ms_hyperv_platform,
77 .init_platform = ms_hyperv_init_platform,
79 EXPORT_SYMBOL(x86_hyper_ms_hyperv);