1 /* 2 * HyperV Detection code. 3 * 4 * Copyright (C) 2010, Novell, Inc. 5 * Author : K. Y. Srinivasan <[email protected]> 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 <asm/processor.h> 18 #include <asm/hypervisor.h> 19 #include <asm/hyperv.h> 20 #include <asm/mshyperv.h> 21 22 struct ms_hyperv_info ms_hyperv; 23 EXPORT_SYMBOL_GPL(ms_hyperv); 24 25 static bool __init ms_hyperv_platform(void) 26 { 27 u32 eax; 28 u32 hyp_signature[3]; 29 30 if (!boot_cpu_has(X86_FEATURE_HYPERVISOR)) 31 return false; 32 33 cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS, 34 &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]); 35 36 return eax >= HYPERV_CPUID_MIN && 37 eax <= HYPERV_CPUID_MAX && 38 !memcmp("Microsoft Hv", hyp_signature, 12); 39 } 40 41 static cycle_t read_hv_clock(struct clocksource *arg) 42 { 43 cycle_t current_tick; 44 /* 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. 48 */ 49 rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick); 50 return current_tick; 51 } 52 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), 58 }; 59 60 static void __init ms_hyperv_init_platform(void) 61 { 62 /* 63 * Extract the features and hints 64 */ 65 ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES); 66 ms_hyperv.hints = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO); 67 68 printk(KERN_INFO "HyperV: features 0x%x, hints 0x%x\n", 69 ms_hyperv.features, ms_hyperv.hints); 70 71 clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100); 72 } 73 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, 78 }; 79 EXPORT_SYMBOL(x86_hyper_ms_hyperv); 80