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/apic.h> 22 #include <asm/desc.h> 23 #include <asm/hypervisor.h> 24 #include <asm/hyperv.h> 25 #include <asm/mshyperv.h> 26 #include <linux/version.h> 27 #include <linux/vmalloc.h> 28 #include <linux/mm.h> 29 #include <linux/clockchips.h> 30 #include <linux/hyperv.h> 31 #include <linux/slab.h> 32 #include <linux/cpuhotplug.h> 33 34 #ifdef CONFIG_HYPERV_TSCPAGE 35 36 static struct ms_hyperv_tsc_page *tsc_pg; 37 38 struct ms_hyperv_tsc_page *hv_get_tsc_page(void) 39 { 40 return tsc_pg; 41 } 42 EXPORT_SYMBOL_GPL(hv_get_tsc_page); 43 44 static u64 read_hv_clock_tsc(struct clocksource *arg) 45 { 46 u64 current_tick = hv_read_tsc_page(tsc_pg); 47 48 if (current_tick == U64_MAX) 49 rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick); 50 51 return current_tick; 52 } 53 54 static struct clocksource hyperv_cs_tsc = { 55 .name = "hyperv_clocksource_tsc_page", 56 .rating = 400, 57 .read = read_hv_clock_tsc, 58 .mask = CLOCKSOURCE_MASK(64), 59 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 60 }; 61 #endif 62 63 static u64 read_hv_clock_msr(struct clocksource *arg) 64 { 65 u64 current_tick; 66 /* 67 * Read the partition counter to get the current tick count. This count 68 * is set to 0 when the partition is created and is incremented in 69 * 100 nanosecond units. 70 */ 71 rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick); 72 return current_tick; 73 } 74 75 static struct clocksource hyperv_cs_msr = { 76 .name = "hyperv_clocksource_msr", 77 .rating = 400, 78 .read = read_hv_clock_msr, 79 .mask = CLOCKSOURCE_MASK(64), 80 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 81 }; 82 83 void *hv_hypercall_pg; 84 EXPORT_SYMBOL_GPL(hv_hypercall_pg); 85 struct clocksource *hyperv_cs; 86 EXPORT_SYMBOL_GPL(hyperv_cs); 87 88 u32 *hv_vp_index; 89 EXPORT_SYMBOL_GPL(hv_vp_index); 90 91 u32 hv_max_vp_index; 92 93 static int hv_cpu_init(unsigned int cpu) 94 { 95 u64 msr_vp_index; 96 97 hv_get_vp_index(msr_vp_index); 98 99 hv_vp_index[smp_processor_id()] = msr_vp_index; 100 101 if (msr_vp_index > hv_max_vp_index) 102 hv_max_vp_index = msr_vp_index; 103 104 return 0; 105 } 106 107 static void (*hv_reenlightenment_cb)(void); 108 109 static void hv_reenlightenment_notify(struct work_struct *dummy) 110 { 111 struct hv_tsc_emulation_status emu_status; 112 113 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 114 115 /* Don't issue the callback if TSC accesses are not emulated */ 116 if (hv_reenlightenment_cb && emu_status.inprogress) 117 hv_reenlightenment_cb(); 118 } 119 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify); 120 121 void hyperv_stop_tsc_emulation(void) 122 { 123 u64 freq; 124 struct hv_tsc_emulation_status emu_status; 125 126 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 127 emu_status.inprogress = 0; 128 wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 129 130 rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq); 131 tsc_khz = div64_u64(freq, 1000); 132 } 133 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation); 134 135 static inline bool hv_reenlightenment_available(void) 136 { 137 /* 138 * Check for required features and priviliges to make TSC frequency 139 * change notifications work. 140 */ 141 return ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS && 142 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE && 143 ms_hyperv.features & HV_X64_ACCESS_REENLIGHTENMENT; 144 } 145 146 __visible void __irq_entry hyperv_reenlightenment_intr(struct pt_regs *regs) 147 { 148 entering_ack_irq(); 149 150 inc_irq_stat(irq_hv_reenlightenment_count); 151 152 schedule_delayed_work(&hv_reenlightenment_work, HZ/10); 153 154 exiting_irq(); 155 } 156 157 void set_hv_tscchange_cb(void (*cb)(void)) 158 { 159 struct hv_reenlightenment_control re_ctrl = { 160 .vector = HYPERV_REENLIGHTENMENT_VECTOR, 161 .enabled = 1, 162 .target_vp = hv_vp_index[smp_processor_id()] 163 }; 164 struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1}; 165 166 if (!hv_reenlightenment_available()) { 167 pr_warn("Hyper-V: reenlightenment support is unavailable\n"); 168 return; 169 } 170 171 hv_reenlightenment_cb = cb; 172 173 /* Make sure callback is registered before we write to MSRs */ 174 wmb(); 175 176 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 177 wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl)); 178 } 179 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb); 180 181 void clear_hv_tscchange_cb(void) 182 { 183 struct hv_reenlightenment_control re_ctrl; 184 185 if (!hv_reenlightenment_available()) 186 return; 187 188 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl); 189 re_ctrl.enabled = 0; 190 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl); 191 192 hv_reenlightenment_cb = NULL; 193 } 194 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb); 195 196 static int hv_cpu_die(unsigned int cpu) 197 { 198 struct hv_reenlightenment_control re_ctrl; 199 unsigned int new_cpu; 200 201 if (hv_reenlightenment_cb == NULL) 202 return 0; 203 204 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 205 if (re_ctrl.target_vp == hv_vp_index[cpu]) { 206 /* Reassign to some other online CPU */ 207 new_cpu = cpumask_any_but(cpu_online_mask, cpu); 208 209 re_ctrl.target_vp = hv_vp_index[new_cpu]; 210 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 211 } 212 213 return 0; 214 } 215 216 /* 217 * This function is to be invoked early in the boot sequence after the 218 * hypervisor has been detected. 219 * 220 * 1. Setup the hypercall page. 221 * 2. Register Hyper-V specific clocksource. 222 */ 223 void hyperv_init(void) 224 { 225 u64 guest_id, required_msrs; 226 union hv_x64_msr_hypercall_contents hypercall_msr; 227 228 if (x86_hyper_type != X86_HYPER_MS_HYPERV) 229 return; 230 231 /* Absolutely required MSRs */ 232 required_msrs = HV_X64_MSR_HYPERCALL_AVAILABLE | 233 HV_X64_MSR_VP_INDEX_AVAILABLE; 234 235 if ((ms_hyperv.features & required_msrs) != required_msrs) 236 return; 237 238 /* Allocate percpu VP index */ 239 hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index), 240 GFP_KERNEL); 241 if (!hv_vp_index) 242 return; 243 244 if (cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online", 245 hv_cpu_init, hv_cpu_die) < 0) 246 goto free_vp_index; 247 248 /* 249 * Setup the hypercall page and enable hypercalls. 250 * 1. Register the guest ID 251 * 2. Enable the hypercall and register the hypercall page 252 */ 253 guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0); 254 wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id); 255 256 hv_hypercall_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX); 257 if (hv_hypercall_pg == NULL) { 258 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); 259 goto free_vp_index; 260 } 261 262 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 263 hypercall_msr.enable = 1; 264 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg); 265 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 266 267 hyper_alloc_mmu(); 268 269 /* 270 * Register Hyper-V specific clocksource. 271 */ 272 #ifdef CONFIG_HYPERV_TSCPAGE 273 if (ms_hyperv.features & HV_X64_MSR_REFERENCE_TSC_AVAILABLE) { 274 union hv_x64_msr_hypercall_contents tsc_msr; 275 276 tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL); 277 if (!tsc_pg) 278 goto register_msr_cs; 279 280 hyperv_cs = &hyperv_cs_tsc; 281 282 rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64); 283 284 tsc_msr.enable = 1; 285 tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg); 286 287 wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64); 288 289 hyperv_cs_tsc.archdata.vclock_mode = VCLOCK_HVCLOCK; 290 291 clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100); 292 return; 293 } 294 register_msr_cs: 295 #endif 296 /* 297 * For 32 bit guests just use the MSR based mechanism for reading 298 * the partition counter. 299 */ 300 301 hyperv_cs = &hyperv_cs_msr; 302 if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE) 303 clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100); 304 305 return; 306 307 free_vp_index: 308 kfree(hv_vp_index); 309 hv_vp_index = NULL; 310 } 311 312 /* 313 * This routine is called before kexec/kdump, it does the required cleanup. 314 */ 315 void hyperv_cleanup(void) 316 { 317 union hv_x64_msr_hypercall_contents hypercall_msr; 318 319 /* Reset our OS id */ 320 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); 321 322 /* Reset the hypercall page */ 323 hypercall_msr.as_uint64 = 0; 324 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 325 326 /* Reset the TSC page */ 327 hypercall_msr.as_uint64 = 0; 328 wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64); 329 } 330 EXPORT_SYMBOL_GPL(hyperv_cleanup); 331 332 void hyperv_report_panic(struct pt_regs *regs, long err) 333 { 334 static bool panic_reported; 335 u64 guest_id; 336 337 /* 338 * We prefer to report panic on 'die' chain as we have proper 339 * registers to report, but if we miss it (e.g. on BUG()) we need 340 * to report it on 'panic'. 341 */ 342 if (panic_reported) 343 return; 344 panic_reported = true; 345 346 rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id); 347 348 wrmsrl(HV_X64_MSR_CRASH_P0, err); 349 wrmsrl(HV_X64_MSR_CRASH_P1, guest_id); 350 wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip); 351 wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax); 352 wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp); 353 354 /* 355 * Let Hyper-V know there is crash data available 356 */ 357 wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY); 358 } 359 EXPORT_SYMBOL_GPL(hyperv_report_panic); 360 361 bool hv_is_hyperv_initialized(void) 362 { 363 union hv_x64_msr_hypercall_contents hypercall_msr; 364 365 /* 366 * Ensure that we're really on Hyper-V, and not a KVM or Xen 367 * emulation of Hyper-V 368 */ 369 if (x86_hyper_type != X86_HYPER_MS_HYPERV) 370 return false; 371 372 /* 373 * Verify that earlier initialization succeeded by checking 374 * that the hypercall page is setup 375 */ 376 hypercall_msr.as_uint64 = 0; 377 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 378 379 return hypercall_msr.enable; 380 } 381 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized); 382