1 /* 2 * X86 specific Hyper-V initialization code. 3 * 4 * Copyright (C) 2016, Microsoft, Inc. 5 * 6 * Author : K. Y. Srinivasan <kys@microsoft.com> 7 * 8 * This program is free software; you can redistribute it and/or modify it 9 * under the terms of the GNU General Public License version 2 as published 10 * by the Free Software Foundation. 11 * 12 * This program is distributed in the hope that it will be useful, but 13 * WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or 15 * NON INFRINGEMENT. See the GNU General Public License for more 16 * details. 17 * 18 */ 19 20 #include <linux/types.h> 21 #include <asm/hypervisor.h> 22 #include <asm/hyperv.h> 23 #include <asm/mshyperv.h> 24 #include <linux/version.h> 25 #include <linux/vmalloc.h> 26 #include <linux/mm.h> 27 #include <linux/clockchips.h> 28 29 30 #ifdef CONFIG_X86_64 31 32 static struct ms_hyperv_tsc_page *tsc_pg; 33 34 static u64 read_hv_clock_tsc(struct clocksource *arg) 35 { 36 u64 current_tick; 37 38 if (tsc_pg->tsc_sequence != 0) { 39 /* 40 * Use the tsc page to compute the value. 41 */ 42 43 while (1) { 44 u64 tmp; 45 u32 sequence = tsc_pg->tsc_sequence; 46 u64 cur_tsc; 47 u64 scale = tsc_pg->tsc_scale; 48 s64 offset = tsc_pg->tsc_offset; 49 50 rdtscll(cur_tsc); 51 /* current_tick = ((cur_tsc *scale) >> 64) + offset */ 52 asm("mulq %3" 53 : "=d" (current_tick), "=a" (tmp) 54 : "a" (cur_tsc), "r" (scale)); 55 56 current_tick += offset; 57 if (tsc_pg->tsc_sequence == sequence) 58 return current_tick; 59 60 if (tsc_pg->tsc_sequence != 0) 61 continue; 62 /* 63 * Fallback using MSR method. 64 */ 65 break; 66 } 67 } 68 rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick); 69 return current_tick; 70 } 71 72 static struct clocksource hyperv_cs_tsc = { 73 .name = "hyperv_clocksource_tsc_page", 74 .rating = 400, 75 .read = read_hv_clock_tsc, 76 .mask = CLOCKSOURCE_MASK(64), 77 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 78 }; 79 #endif 80 81 static u64 read_hv_clock_msr(struct clocksource *arg) 82 { 83 u64 current_tick; 84 /* 85 * Read the partition counter to get the current tick count. This count 86 * is set to 0 when the partition is created and is incremented in 87 * 100 nanosecond units. 88 */ 89 rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick); 90 return current_tick; 91 } 92 93 static struct clocksource hyperv_cs_msr = { 94 .name = "hyperv_clocksource_msr", 95 .rating = 400, 96 .read = read_hv_clock_msr, 97 .mask = CLOCKSOURCE_MASK(64), 98 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 99 }; 100 101 static void *hypercall_pg; 102 /* 103 * This function is to be invoked early in the boot sequence after the 104 * hypervisor has been detected. 105 * 106 * 1. Setup the hypercall page. 107 * 2. Register Hyper-V specific clocksource. 108 */ 109 void hyperv_init(void) 110 { 111 u64 guest_id; 112 union hv_x64_msr_hypercall_contents hypercall_msr; 113 114 if (x86_hyper != &x86_hyper_ms_hyperv) 115 return; 116 117 /* 118 * Setup the hypercall page and enable hypercalls. 119 * 1. Register the guest ID 120 * 2. Enable the hypercall and register the hypercall page 121 */ 122 guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0); 123 wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id); 124 125 hypercall_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_EXEC); 126 if (hypercall_pg == NULL) { 127 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); 128 return; 129 } 130 131 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 132 hypercall_msr.enable = 1; 133 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hypercall_pg); 134 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 135 136 /* 137 * Register Hyper-V specific clocksource. 138 */ 139 #ifdef CONFIG_X86_64 140 if (ms_hyperv.features & HV_X64_MSR_REFERENCE_TSC_AVAILABLE) { 141 union hv_x64_msr_hypercall_contents tsc_msr; 142 143 tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL); 144 if (!tsc_pg) { 145 clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100); 146 return; 147 } 148 149 rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64); 150 151 tsc_msr.enable = 1; 152 tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg); 153 154 wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64); 155 clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100); 156 return; 157 } 158 #endif 159 /* 160 * For 32 bit guests just use the MSR based mechanism for reading 161 * the partition counter. 162 */ 163 164 if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE) 165 clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100); 166 } 167 168 /* 169 * hv_do_hypercall- Invoke the specified hypercall 170 */ 171 u64 hv_do_hypercall(u64 control, void *input, void *output) 172 { 173 u64 input_address = (input) ? virt_to_phys(input) : 0; 174 u64 output_address = (output) ? virt_to_phys(output) : 0; 175 #ifdef CONFIG_X86_64 176 u64 hv_status = 0; 177 178 if (!hypercall_pg) 179 return (u64)ULLONG_MAX; 180 181 __asm__ __volatile__("mov %0, %%r8" : : "r" (output_address) : "r8"); 182 __asm__ __volatile__("call *%3" : "=a" (hv_status) : 183 "c" (control), "d" (input_address), 184 "m" (hypercall_pg)); 185 186 return hv_status; 187 188 #else 189 190 u32 control_hi = control >> 32; 191 u32 control_lo = control & 0xFFFFFFFF; 192 u32 hv_status_hi = 1; 193 u32 hv_status_lo = 1; 194 u32 input_address_hi = input_address >> 32; 195 u32 input_address_lo = input_address & 0xFFFFFFFF; 196 u32 output_address_hi = output_address >> 32; 197 u32 output_address_lo = output_address & 0xFFFFFFFF; 198 199 if (!hypercall_pg) 200 return (u64)ULLONG_MAX; 201 202 __asm__ __volatile__ ("call *%8" : "=d"(hv_status_hi), 203 "=a"(hv_status_lo) : "d" (control_hi), 204 "a" (control_lo), "b" (input_address_hi), 205 "c" (input_address_lo), "D"(output_address_hi), 206 "S"(output_address_lo), "m" (hypercall_pg)); 207 208 return hv_status_lo | ((u64)hv_status_hi << 32); 209 #endif /* !x86_64 */ 210 } 211 EXPORT_SYMBOL_GPL(hv_do_hypercall); 212