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 struct clocksource *hyperv_cs; 103 EXPORT_SYMBOL_GPL(hyperv_cs); 104 105 /* 106 * This function is to be invoked early in the boot sequence after the 107 * hypervisor has been detected. 108 * 109 * 1. Setup the hypercall page. 110 * 2. Register Hyper-V specific clocksource. 111 */ 112 void hyperv_init(void) 113 { 114 u64 guest_id; 115 union hv_x64_msr_hypercall_contents hypercall_msr; 116 117 if (x86_hyper != &x86_hyper_ms_hyperv) 118 return; 119 120 /* 121 * Setup the hypercall page and enable hypercalls. 122 * 1. Register the guest ID 123 * 2. Enable the hypercall and register the hypercall page 124 */ 125 guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0); 126 wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id); 127 128 hypercall_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX); 129 if (hypercall_pg == NULL) { 130 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); 131 return; 132 } 133 134 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 135 hypercall_msr.enable = 1; 136 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hypercall_pg); 137 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 138 139 /* 140 * Register Hyper-V specific clocksource. 141 */ 142 #ifdef CONFIG_X86_64 143 if (ms_hyperv.features & HV_X64_MSR_REFERENCE_TSC_AVAILABLE) { 144 union hv_x64_msr_hypercall_contents tsc_msr; 145 146 tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL); 147 if (!tsc_pg) 148 goto register_msr_cs; 149 150 hyperv_cs = &hyperv_cs_tsc; 151 152 rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64); 153 154 tsc_msr.enable = 1; 155 tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg); 156 157 wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64); 158 clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100); 159 return; 160 } 161 register_msr_cs: 162 #endif 163 /* 164 * For 32 bit guests just use the MSR based mechanism for reading 165 * the partition counter. 166 */ 167 168 hyperv_cs = &hyperv_cs_msr; 169 if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE) 170 clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100); 171 } 172 173 /* 174 * This routine is called before kexec/kdump, it does the required cleanup. 175 */ 176 void hyperv_cleanup(void) 177 { 178 union hv_x64_msr_hypercall_contents hypercall_msr; 179 180 /* Reset our OS id */ 181 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); 182 183 /* Reset the hypercall page */ 184 hypercall_msr.as_uint64 = 0; 185 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 186 187 /* Reset the TSC page */ 188 hypercall_msr.as_uint64 = 0; 189 wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64); 190 } 191 EXPORT_SYMBOL_GPL(hyperv_cleanup); 192 193 /* 194 * hv_do_hypercall- Invoke the specified hypercall 195 */ 196 u64 hv_do_hypercall(u64 control, void *input, void *output) 197 { 198 u64 input_address = (input) ? virt_to_phys(input) : 0; 199 u64 output_address = (output) ? virt_to_phys(output) : 0; 200 #ifdef CONFIG_X86_64 201 u64 hv_status = 0; 202 203 if (!hypercall_pg) 204 return (u64)ULLONG_MAX; 205 206 __asm__ __volatile__("mov %0, %%r8" : : "r" (output_address) : "r8"); 207 __asm__ __volatile__("call *%3" : "=a" (hv_status) : 208 "c" (control), "d" (input_address), 209 "m" (hypercall_pg)); 210 211 return hv_status; 212 213 #else 214 215 u32 control_hi = control >> 32; 216 u32 control_lo = control & 0xFFFFFFFF; 217 u32 hv_status_hi = 1; 218 u32 hv_status_lo = 1; 219 u32 input_address_hi = input_address >> 32; 220 u32 input_address_lo = input_address & 0xFFFFFFFF; 221 u32 output_address_hi = output_address >> 32; 222 u32 output_address_lo = output_address & 0xFFFFFFFF; 223 224 if (!hypercall_pg) 225 return (u64)ULLONG_MAX; 226 227 __asm__ __volatile__ ("call *%8" : "=d"(hv_status_hi), 228 "=a"(hv_status_lo) : "d" (control_hi), 229 "a" (control_lo), "b" (input_address_hi), 230 "c" (input_address_lo), "D"(output_address_hi), 231 "S"(output_address_lo), "m" (hypercall_pg)); 232 233 return hv_status_lo | ((u64)hv_status_hi << 32); 234 #endif /* !x86_64 */ 235 } 236 EXPORT_SYMBOL_GPL(hv_do_hypercall); 237 238 void hyperv_report_panic(struct pt_regs *regs) 239 { 240 static bool panic_reported; 241 242 /* 243 * We prefer to report panic on 'die' chain as we have proper 244 * registers to report, but if we miss it (e.g. on BUG()) we need 245 * to report it on 'panic'. 246 */ 247 if (panic_reported) 248 return; 249 panic_reported = true; 250 251 wrmsrl(HV_X64_MSR_CRASH_P0, regs->ip); 252 wrmsrl(HV_X64_MSR_CRASH_P1, regs->ax); 253 wrmsrl(HV_X64_MSR_CRASH_P2, regs->bx); 254 wrmsrl(HV_X64_MSR_CRASH_P3, regs->cx); 255 wrmsrl(HV_X64_MSR_CRASH_P4, regs->dx); 256 257 /* 258 * Let Hyper-V know there is crash data available 259 */ 260 wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY); 261 } 262 EXPORT_SYMBOL_GPL(hyperv_report_panic); 263 264 bool hv_is_hypercall_page_setup(void) 265 { 266 union hv_x64_msr_hypercall_contents hypercall_msr; 267 268 /* Check if the hypercall page is setup */ 269 hypercall_msr.as_uint64 = 0; 270 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 271 272 if (!hypercall_msr.enable) 273 return false; 274 275 return true; 276 } 277 EXPORT_SYMBOL_GPL(hv_is_hypercall_page_setup); 278