1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * X86 specific Hyper-V initialization code. 4 * 5 * Copyright (C) 2016, Microsoft, Inc. 6 * 7 * Author : K. Y. Srinivasan <kys@microsoft.com> 8 */ 9 10 #include <linux/acpi.h> 11 #include <linux/efi.h> 12 #include <linux/types.h> 13 #include <asm/apic.h> 14 #include <asm/desc.h> 15 #include <asm/hypervisor.h> 16 #include <asm/hyperv-tlfs.h> 17 #include <asm/mshyperv.h> 18 #include <linux/version.h> 19 #include <linux/vmalloc.h> 20 #include <linux/mm.h> 21 #include <linux/hyperv.h> 22 #include <linux/slab.h> 23 #include <linux/cpuhotplug.h> 24 #include <clocksource/hyperv_timer.h> 25 26 void *hv_hypercall_pg; 27 EXPORT_SYMBOL_GPL(hv_hypercall_pg); 28 29 u32 *hv_vp_index; 30 EXPORT_SYMBOL_GPL(hv_vp_index); 31 32 struct hv_vp_assist_page **hv_vp_assist_page; 33 EXPORT_SYMBOL_GPL(hv_vp_assist_page); 34 35 void __percpu **hyperv_pcpu_input_arg; 36 EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg); 37 38 u32 hv_max_vp_index; 39 EXPORT_SYMBOL_GPL(hv_max_vp_index); 40 41 void *hv_alloc_hyperv_page(void) 42 { 43 BUILD_BUG_ON(PAGE_SIZE != HV_HYP_PAGE_SIZE); 44 45 return (void *)__get_free_page(GFP_KERNEL); 46 } 47 EXPORT_SYMBOL_GPL(hv_alloc_hyperv_page); 48 49 void *hv_alloc_hyperv_zeroed_page(void) 50 { 51 BUILD_BUG_ON(PAGE_SIZE != HV_HYP_PAGE_SIZE); 52 53 return (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO); 54 } 55 EXPORT_SYMBOL_GPL(hv_alloc_hyperv_zeroed_page); 56 57 void hv_free_hyperv_page(unsigned long addr) 58 { 59 free_page(addr); 60 } 61 EXPORT_SYMBOL_GPL(hv_free_hyperv_page); 62 63 static int hv_cpu_init(unsigned int cpu) 64 { 65 u64 msr_vp_index; 66 struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()]; 67 void **input_arg; 68 struct page *pg; 69 70 input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg); 71 pg = alloc_page(GFP_KERNEL); 72 if (unlikely(!pg)) 73 return -ENOMEM; 74 *input_arg = page_address(pg); 75 76 hv_get_vp_index(msr_vp_index); 77 78 hv_vp_index[smp_processor_id()] = msr_vp_index; 79 80 if (msr_vp_index > hv_max_vp_index) 81 hv_max_vp_index = msr_vp_index; 82 83 if (!hv_vp_assist_page) 84 return 0; 85 86 /* 87 * The VP ASSIST PAGE is an "overlay" page (see Hyper-V TLFS's Section 88 * 5.2.1 "GPA Overlay Pages"). Here it must be zeroed out to make sure 89 * we always write the EOI MSR in hv_apic_eoi_write() *after* the 90 * EOI optimization is disabled in hv_cpu_die(), otherwise a CPU may 91 * not be stopped in the case of CPU offlining and the VM will hang. 92 */ 93 if (!*hvp) { 94 *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO, 95 PAGE_KERNEL); 96 } 97 98 if (*hvp) { 99 u64 val; 100 101 val = vmalloc_to_pfn(*hvp); 102 val = (val << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT) | 103 HV_X64_MSR_VP_ASSIST_PAGE_ENABLE; 104 105 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, val); 106 } 107 108 return 0; 109 } 110 111 static void (*hv_reenlightenment_cb)(void); 112 113 static void hv_reenlightenment_notify(struct work_struct *dummy) 114 { 115 struct hv_tsc_emulation_status emu_status; 116 117 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 118 119 /* Don't issue the callback if TSC accesses are not emulated */ 120 if (hv_reenlightenment_cb && emu_status.inprogress) 121 hv_reenlightenment_cb(); 122 } 123 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify); 124 125 void hyperv_stop_tsc_emulation(void) 126 { 127 u64 freq; 128 struct hv_tsc_emulation_status emu_status; 129 130 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 131 emu_status.inprogress = 0; 132 wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 133 134 rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq); 135 tsc_khz = div64_u64(freq, 1000); 136 } 137 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation); 138 139 static inline bool hv_reenlightenment_available(void) 140 { 141 /* 142 * Check for required features and priviliges to make TSC frequency 143 * change notifications work. 144 */ 145 return ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS && 146 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE && 147 ms_hyperv.features & HV_X64_ACCESS_REENLIGHTENMENT; 148 } 149 150 __visible void __irq_entry hyperv_reenlightenment_intr(struct pt_regs *regs) 151 { 152 entering_ack_irq(); 153 154 inc_irq_stat(irq_hv_reenlightenment_count); 155 156 schedule_delayed_work(&hv_reenlightenment_work, HZ/10); 157 158 exiting_irq(); 159 } 160 161 void set_hv_tscchange_cb(void (*cb)(void)) 162 { 163 struct hv_reenlightenment_control re_ctrl = { 164 .vector = HYPERV_REENLIGHTENMENT_VECTOR, 165 .enabled = 1, 166 .target_vp = hv_vp_index[smp_processor_id()] 167 }; 168 struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1}; 169 170 if (!hv_reenlightenment_available()) { 171 pr_warn("Hyper-V: reenlightenment support is unavailable\n"); 172 return; 173 } 174 175 hv_reenlightenment_cb = cb; 176 177 /* Make sure callback is registered before we write to MSRs */ 178 wmb(); 179 180 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 181 wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl)); 182 } 183 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb); 184 185 void clear_hv_tscchange_cb(void) 186 { 187 struct hv_reenlightenment_control re_ctrl; 188 189 if (!hv_reenlightenment_available()) 190 return; 191 192 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl); 193 re_ctrl.enabled = 0; 194 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl); 195 196 hv_reenlightenment_cb = NULL; 197 } 198 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb); 199 200 static int hv_cpu_die(unsigned int cpu) 201 { 202 struct hv_reenlightenment_control re_ctrl; 203 unsigned int new_cpu; 204 unsigned long flags; 205 void **input_arg; 206 void *input_pg = NULL; 207 208 local_irq_save(flags); 209 input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg); 210 input_pg = *input_arg; 211 *input_arg = NULL; 212 local_irq_restore(flags); 213 free_page((unsigned long)input_pg); 214 215 if (hv_vp_assist_page && hv_vp_assist_page[cpu]) 216 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0); 217 218 if (hv_reenlightenment_cb == NULL) 219 return 0; 220 221 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 222 if (re_ctrl.target_vp == hv_vp_index[cpu]) { 223 /* Reassign to some other online CPU */ 224 new_cpu = cpumask_any_but(cpu_online_mask, cpu); 225 226 re_ctrl.target_vp = hv_vp_index[new_cpu]; 227 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 228 } 229 230 return 0; 231 } 232 233 static int __init hv_pci_init(void) 234 { 235 int gen2vm = efi_enabled(EFI_BOOT); 236 237 /* 238 * For Generation-2 VM, we exit from pci_arch_init() by returning 0. 239 * The purpose is to suppress the harmless warning: 240 * "PCI: Fatal: No config space access function found" 241 */ 242 if (gen2vm) 243 return 0; 244 245 /* For Generation-1 VM, we'll proceed in pci_arch_init(). */ 246 return 1; 247 } 248 249 /* 250 * This function is to be invoked early in the boot sequence after the 251 * hypervisor has been detected. 252 * 253 * 1. Setup the hypercall page. 254 * 2. Register Hyper-V specific clocksource. 255 * 3. Setup Hyper-V specific APIC entry points. 256 */ 257 void __init hyperv_init(void) 258 { 259 u64 guest_id, required_msrs; 260 union hv_x64_msr_hypercall_contents hypercall_msr; 261 int cpuhp, i; 262 263 if (x86_hyper_type != X86_HYPER_MS_HYPERV) 264 return; 265 266 /* Absolutely required MSRs */ 267 required_msrs = HV_X64_MSR_HYPERCALL_AVAILABLE | 268 HV_X64_MSR_VP_INDEX_AVAILABLE; 269 270 if ((ms_hyperv.features & required_msrs) != required_msrs) 271 return; 272 273 /* 274 * Allocate the per-CPU state for the hypercall input arg. 275 * If this allocation fails, we will not be able to setup 276 * (per-CPU) hypercall input page and thus this failure is 277 * fatal on Hyper-V. 278 */ 279 hyperv_pcpu_input_arg = alloc_percpu(void *); 280 281 BUG_ON(hyperv_pcpu_input_arg == NULL); 282 283 /* Allocate percpu VP index */ 284 hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index), 285 GFP_KERNEL); 286 if (!hv_vp_index) 287 return; 288 289 for (i = 0; i < num_possible_cpus(); i++) 290 hv_vp_index[i] = VP_INVAL; 291 292 hv_vp_assist_page = kcalloc(num_possible_cpus(), 293 sizeof(*hv_vp_assist_page), GFP_KERNEL); 294 if (!hv_vp_assist_page) { 295 ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED; 296 goto free_vp_index; 297 } 298 299 cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online", 300 hv_cpu_init, hv_cpu_die); 301 if (cpuhp < 0) 302 goto free_vp_assist_page; 303 304 /* 305 * Setup the hypercall page and enable hypercalls. 306 * 1. Register the guest ID 307 * 2. Enable the hypercall and register the hypercall page 308 */ 309 guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0); 310 wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id); 311 312 hv_hypercall_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX); 313 if (hv_hypercall_pg == NULL) { 314 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); 315 goto remove_cpuhp_state; 316 } 317 318 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 319 hypercall_msr.enable = 1; 320 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg); 321 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 322 323 /* 324 * Ignore any errors in setting up stimer clockevents 325 * as we can run with the LAPIC timer as a fallback. 326 */ 327 (void)hv_stimer_alloc(); 328 329 hv_apic_init(); 330 331 x86_init.pci.arch_init = hv_pci_init; 332 333 return; 334 335 remove_cpuhp_state: 336 cpuhp_remove_state(cpuhp); 337 free_vp_assist_page: 338 kfree(hv_vp_assist_page); 339 hv_vp_assist_page = NULL; 340 free_vp_index: 341 kfree(hv_vp_index); 342 hv_vp_index = NULL; 343 } 344 345 /* 346 * This routine is called before kexec/kdump, it does the required cleanup. 347 */ 348 void hyperv_cleanup(void) 349 { 350 union hv_x64_msr_hypercall_contents hypercall_msr; 351 352 /* Reset our OS id */ 353 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); 354 355 /* 356 * Reset hypercall page reference before reset the page, 357 * let hypercall operations fail safely rather than 358 * panic the kernel for using invalid hypercall page 359 */ 360 hv_hypercall_pg = NULL; 361 362 /* Reset the hypercall page */ 363 hypercall_msr.as_uint64 = 0; 364 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 365 366 /* Reset the TSC page */ 367 hypercall_msr.as_uint64 = 0; 368 wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64); 369 } 370 EXPORT_SYMBOL_GPL(hyperv_cleanup); 371 372 void hyperv_report_panic(struct pt_regs *regs, long err) 373 { 374 static bool panic_reported; 375 u64 guest_id; 376 377 /* 378 * We prefer to report panic on 'die' chain as we have proper 379 * registers to report, but if we miss it (e.g. on BUG()) we need 380 * to report it on 'panic'. 381 */ 382 if (panic_reported) 383 return; 384 panic_reported = true; 385 386 rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id); 387 388 wrmsrl(HV_X64_MSR_CRASH_P0, err); 389 wrmsrl(HV_X64_MSR_CRASH_P1, guest_id); 390 wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip); 391 wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax); 392 wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp); 393 394 /* 395 * Let Hyper-V know there is crash data available 396 */ 397 wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY); 398 } 399 EXPORT_SYMBOL_GPL(hyperv_report_panic); 400 401 /** 402 * hyperv_report_panic_msg - report panic message to Hyper-V 403 * @pa: physical address of the panic page containing the message 404 * @size: size of the message in the page 405 */ 406 void hyperv_report_panic_msg(phys_addr_t pa, size_t size) 407 { 408 /* 409 * P3 to contain the physical address of the panic page & P4 to 410 * contain the size of the panic data in that page. Rest of the 411 * registers are no-op when the NOTIFY_MSG flag is set. 412 */ 413 wrmsrl(HV_X64_MSR_CRASH_P0, 0); 414 wrmsrl(HV_X64_MSR_CRASH_P1, 0); 415 wrmsrl(HV_X64_MSR_CRASH_P2, 0); 416 wrmsrl(HV_X64_MSR_CRASH_P3, pa); 417 wrmsrl(HV_X64_MSR_CRASH_P4, size); 418 419 /* 420 * Let Hyper-V know there is crash data available along with 421 * the panic message. 422 */ 423 wrmsrl(HV_X64_MSR_CRASH_CTL, 424 (HV_CRASH_CTL_CRASH_NOTIFY | HV_CRASH_CTL_CRASH_NOTIFY_MSG)); 425 } 426 EXPORT_SYMBOL_GPL(hyperv_report_panic_msg); 427 428 bool hv_is_hyperv_initialized(void) 429 { 430 union hv_x64_msr_hypercall_contents hypercall_msr; 431 432 /* 433 * Ensure that we're really on Hyper-V, and not a KVM or Xen 434 * emulation of Hyper-V 435 */ 436 if (x86_hyper_type != X86_HYPER_MS_HYPERV) 437 return false; 438 439 /* 440 * Verify that earlier initialization succeeded by checking 441 * that the hypercall page is setup 442 */ 443 hypercall_msr.as_uint64 = 0; 444 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 445 446 return hypercall_msr.enable; 447 } 448 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized); 449 450 bool hv_is_hibernation_supported(void) 451 { 452 return acpi_sleep_state_supported(ACPI_STATE_S4); 453 } 454 EXPORT_SYMBOL_GPL(hv_is_hibernation_supported); 455