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/efi.h> 11 #include <linux/types.h> 12 #include <linux/bitfield.h> 13 #include <linux/io.h> 14 #include <asm/apic.h> 15 #include <asm/desc.h> 16 #include <asm/hypervisor.h> 17 #include <asm/hyperv-tlfs.h> 18 #include <asm/mshyperv.h> 19 #include <asm/idtentry.h> 20 #include <linux/kexec.h> 21 #include <linux/version.h> 22 #include <linux/vmalloc.h> 23 #include <linux/mm.h> 24 #include <linux/hyperv.h> 25 #include <linux/slab.h> 26 #include <linux/kernel.h> 27 #include <linux/cpuhotplug.h> 28 #include <linux/syscore_ops.h> 29 #include <clocksource/hyperv_timer.h> 30 #include <linux/highmem.h> 31 32 int hyperv_init_cpuhp; 33 u64 hv_current_partition_id = ~0ull; 34 EXPORT_SYMBOL_GPL(hv_current_partition_id); 35 36 void *hv_hypercall_pg; 37 EXPORT_SYMBOL_GPL(hv_hypercall_pg); 38 39 union hv_ghcb __percpu **hv_ghcb_pg; 40 41 /* Storage to save the hypercall page temporarily for hibernation */ 42 static void *hv_hypercall_pg_saved; 43 44 struct hv_vp_assist_page **hv_vp_assist_page; 45 EXPORT_SYMBOL_GPL(hv_vp_assist_page); 46 47 static int hyperv_init_ghcb(void) 48 { 49 u64 ghcb_gpa; 50 void *ghcb_va; 51 void **ghcb_base; 52 53 if (!hv_isolation_type_snp()) 54 return 0; 55 56 if (!hv_ghcb_pg) 57 return -EINVAL; 58 59 /* 60 * GHCB page is allocated by paravisor. The address 61 * returned by MSR_AMD64_SEV_ES_GHCB is above shared 62 * memory boundary and map it here. 63 */ 64 rdmsrl(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa); 65 ghcb_va = memremap(ghcb_gpa, HV_HYP_PAGE_SIZE, MEMREMAP_WB); 66 if (!ghcb_va) 67 return -ENOMEM; 68 69 ghcb_base = (void **)this_cpu_ptr(hv_ghcb_pg); 70 *ghcb_base = ghcb_va; 71 72 return 0; 73 } 74 75 static int hv_cpu_init(unsigned int cpu) 76 { 77 union hv_vp_assist_msr_contents msr = { 0 }; 78 struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()]; 79 int ret; 80 81 ret = hv_common_cpu_init(cpu); 82 if (ret) 83 return ret; 84 85 if (!hv_vp_assist_page) 86 return 0; 87 88 if (!*hvp) { 89 if (hv_root_partition) { 90 /* 91 * For root partition we get the hypervisor provided VP assist 92 * page, instead of allocating a new page. 93 */ 94 rdmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64); 95 *hvp = memremap(msr.pfn << 96 HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT, 97 PAGE_SIZE, MEMREMAP_WB); 98 } else { 99 /* 100 * The VP assist page is an "overlay" page (see Hyper-V TLFS's 101 * Section 5.2.1 "GPA Overlay Pages"). Here it must be zeroed 102 * out to make sure we always write the EOI MSR in 103 * hv_apic_eoi_write() *after* the EOI optimization is disabled 104 * in hv_cpu_die(), otherwise a CPU may not be stopped in the 105 * case of CPU offlining and the VM will hang. 106 */ 107 *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO); 108 if (*hvp) 109 msr.pfn = vmalloc_to_pfn(*hvp); 110 } 111 WARN_ON(!(*hvp)); 112 if (*hvp) { 113 msr.enable = 1; 114 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64); 115 } 116 } 117 118 return hyperv_init_ghcb(); 119 } 120 121 static void (*hv_reenlightenment_cb)(void); 122 123 static void hv_reenlightenment_notify(struct work_struct *dummy) 124 { 125 struct hv_tsc_emulation_status emu_status; 126 127 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 128 129 /* Don't issue the callback if TSC accesses are not emulated */ 130 if (hv_reenlightenment_cb && emu_status.inprogress) 131 hv_reenlightenment_cb(); 132 } 133 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify); 134 135 void hyperv_stop_tsc_emulation(void) 136 { 137 u64 freq; 138 struct hv_tsc_emulation_status emu_status; 139 140 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 141 emu_status.inprogress = 0; 142 wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 143 144 rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq); 145 tsc_khz = div64_u64(freq, 1000); 146 } 147 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation); 148 149 static inline bool hv_reenlightenment_available(void) 150 { 151 /* 152 * Check for required features and privileges to make TSC frequency 153 * change notifications work. 154 */ 155 return ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS && 156 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE && 157 ms_hyperv.features & HV_ACCESS_REENLIGHTENMENT; 158 } 159 160 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_reenlightenment) 161 { 162 ack_APIC_irq(); 163 inc_irq_stat(irq_hv_reenlightenment_count); 164 schedule_delayed_work(&hv_reenlightenment_work, HZ/10); 165 } 166 167 void set_hv_tscchange_cb(void (*cb)(void)) 168 { 169 struct hv_reenlightenment_control re_ctrl = { 170 .vector = HYPERV_REENLIGHTENMENT_VECTOR, 171 .enabled = 1, 172 }; 173 struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1}; 174 175 if (!hv_reenlightenment_available()) { 176 pr_warn("Hyper-V: reenlightenment support is unavailable\n"); 177 return; 178 } 179 180 if (!hv_vp_index) 181 return; 182 183 hv_reenlightenment_cb = cb; 184 185 /* Make sure callback is registered before we write to MSRs */ 186 wmb(); 187 188 re_ctrl.target_vp = hv_vp_index[get_cpu()]; 189 190 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 191 wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl)); 192 193 put_cpu(); 194 } 195 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb); 196 197 void clear_hv_tscchange_cb(void) 198 { 199 struct hv_reenlightenment_control re_ctrl; 200 201 if (!hv_reenlightenment_available()) 202 return; 203 204 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl); 205 re_ctrl.enabled = 0; 206 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl); 207 208 hv_reenlightenment_cb = NULL; 209 } 210 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb); 211 212 static int hv_cpu_die(unsigned int cpu) 213 { 214 struct hv_reenlightenment_control re_ctrl; 215 unsigned int new_cpu; 216 void **ghcb_va; 217 218 if (hv_ghcb_pg) { 219 ghcb_va = (void **)this_cpu_ptr(hv_ghcb_pg); 220 if (*ghcb_va) 221 memunmap(*ghcb_va); 222 *ghcb_va = NULL; 223 } 224 225 hv_common_cpu_die(cpu); 226 227 if (hv_vp_assist_page && hv_vp_assist_page[cpu]) { 228 union hv_vp_assist_msr_contents msr = { 0 }; 229 if (hv_root_partition) { 230 /* 231 * For root partition the VP assist page is mapped to 232 * hypervisor provided page, and thus we unmap the 233 * page here and nullify it, so that in future we have 234 * correct page address mapped in hv_cpu_init. 235 */ 236 memunmap(hv_vp_assist_page[cpu]); 237 hv_vp_assist_page[cpu] = NULL; 238 rdmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64); 239 msr.enable = 0; 240 } 241 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64); 242 } 243 244 if (hv_reenlightenment_cb == NULL) 245 return 0; 246 247 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 248 if (re_ctrl.target_vp == hv_vp_index[cpu]) { 249 /* 250 * Reassign reenlightenment notifications to some other online 251 * CPU or just disable the feature if there are no online CPUs 252 * left (happens on hibernation). 253 */ 254 new_cpu = cpumask_any_but(cpu_online_mask, cpu); 255 256 if (new_cpu < nr_cpu_ids) 257 re_ctrl.target_vp = hv_vp_index[new_cpu]; 258 else 259 re_ctrl.enabled = 0; 260 261 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 262 } 263 264 return 0; 265 } 266 267 static int __init hv_pci_init(void) 268 { 269 int gen2vm = efi_enabled(EFI_BOOT); 270 271 /* 272 * For Generation-2 VM, we exit from pci_arch_init() by returning 0. 273 * The purpose is to suppress the harmless warning: 274 * "PCI: Fatal: No config space access function found" 275 */ 276 if (gen2vm) 277 return 0; 278 279 /* For Generation-1 VM, we'll proceed in pci_arch_init(). */ 280 return 1; 281 } 282 283 static int hv_suspend(void) 284 { 285 union hv_x64_msr_hypercall_contents hypercall_msr; 286 int ret; 287 288 if (hv_root_partition) 289 return -EPERM; 290 291 /* 292 * Reset the hypercall page as it is going to be invalidated 293 * across hibernation. Setting hv_hypercall_pg to NULL ensures 294 * that any subsequent hypercall operation fails safely instead of 295 * crashing due to an access of an invalid page. The hypercall page 296 * pointer is restored on resume. 297 */ 298 hv_hypercall_pg_saved = hv_hypercall_pg; 299 hv_hypercall_pg = NULL; 300 301 /* Disable the hypercall page in the hypervisor */ 302 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 303 hypercall_msr.enable = 0; 304 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 305 306 ret = hv_cpu_die(0); 307 return ret; 308 } 309 310 static void hv_resume(void) 311 { 312 union hv_x64_msr_hypercall_contents hypercall_msr; 313 int ret; 314 315 ret = hv_cpu_init(0); 316 WARN_ON(ret); 317 318 /* Re-enable the hypercall page */ 319 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 320 hypercall_msr.enable = 1; 321 hypercall_msr.guest_physical_address = 322 vmalloc_to_pfn(hv_hypercall_pg_saved); 323 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 324 325 hv_hypercall_pg = hv_hypercall_pg_saved; 326 hv_hypercall_pg_saved = NULL; 327 328 /* 329 * Reenlightenment notifications are disabled by hv_cpu_die(0), 330 * reenable them here if hv_reenlightenment_cb was previously set. 331 */ 332 if (hv_reenlightenment_cb) 333 set_hv_tscchange_cb(hv_reenlightenment_cb); 334 } 335 336 /* Note: when the ops are called, only CPU0 is online and IRQs are disabled. */ 337 static struct syscore_ops hv_syscore_ops = { 338 .suspend = hv_suspend, 339 .resume = hv_resume, 340 }; 341 342 static void (* __initdata old_setup_percpu_clockev)(void); 343 344 static void __init hv_stimer_setup_percpu_clockev(void) 345 { 346 /* 347 * Ignore any errors in setting up stimer clockevents 348 * as we can run with the LAPIC timer as a fallback. 349 */ 350 (void)hv_stimer_alloc(false); 351 352 /* 353 * Still register the LAPIC timer, because the direct-mode STIMER is 354 * not supported by old versions of Hyper-V. This also allows users 355 * to switch to LAPIC timer via /sys, if they want to. 356 */ 357 if (old_setup_percpu_clockev) 358 old_setup_percpu_clockev(); 359 } 360 361 static void __init hv_get_partition_id(void) 362 { 363 struct hv_get_partition_id *output_page; 364 u64 status; 365 unsigned long flags; 366 367 local_irq_save(flags); 368 output_page = *this_cpu_ptr(hyperv_pcpu_output_arg); 369 status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page); 370 if (!hv_result_success(status)) { 371 /* No point in proceeding if this failed */ 372 pr_err("Failed to get partition ID: %lld\n", status); 373 BUG(); 374 } 375 hv_current_partition_id = output_page->partition_id; 376 local_irq_restore(flags); 377 } 378 379 /* 380 * This function is to be invoked early in the boot sequence after the 381 * hypervisor has been detected. 382 * 383 * 1. Setup the hypercall page. 384 * 2. Register Hyper-V specific clocksource. 385 * 3. Setup Hyper-V specific APIC entry points. 386 */ 387 void __init hyperv_init(void) 388 { 389 u64 guest_id; 390 union hv_x64_msr_hypercall_contents hypercall_msr; 391 int cpuhp; 392 393 if (x86_hyper_type != X86_HYPER_MS_HYPERV) 394 return; 395 396 if (hv_common_init()) 397 return; 398 399 hv_vp_assist_page = kcalloc(num_possible_cpus(), 400 sizeof(*hv_vp_assist_page), GFP_KERNEL); 401 if (!hv_vp_assist_page) { 402 ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED; 403 goto common_free; 404 } 405 406 if (hv_isolation_type_snp()) { 407 hv_ghcb_pg = alloc_percpu(union hv_ghcb *); 408 if (!hv_ghcb_pg) 409 goto free_vp_assist_page; 410 } 411 412 cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online", 413 hv_cpu_init, hv_cpu_die); 414 if (cpuhp < 0) 415 goto free_ghcb_page; 416 417 /* 418 * Setup the hypercall page and enable hypercalls. 419 * 1. Register the guest ID 420 * 2. Enable the hypercall and register the hypercall page 421 */ 422 guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0); 423 wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id); 424 425 /* Hyper-V requires to write guest os id via ghcb in SNP IVM. */ 426 hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, guest_id); 427 428 hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START, 429 VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_ROX, 430 VM_FLUSH_RESET_PERMS, NUMA_NO_NODE, 431 __builtin_return_address(0)); 432 if (hv_hypercall_pg == NULL) 433 goto clean_guest_os_id; 434 435 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 436 hypercall_msr.enable = 1; 437 438 if (hv_root_partition) { 439 struct page *pg; 440 void *src, *dst; 441 442 /* 443 * For the root partition, the hypervisor will set up its 444 * hypercall page. The hypervisor guarantees it will not show 445 * up in the root's address space. The root can't change the 446 * location of the hypercall page. 447 * 448 * Order is important here. We must enable the hypercall page 449 * so it is populated with code, then copy the code to an 450 * executable page. 451 */ 452 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 453 454 pg = vmalloc_to_page(hv_hypercall_pg); 455 dst = kmap(pg); 456 src = memremap(hypercall_msr.guest_physical_address << PAGE_SHIFT, PAGE_SIZE, 457 MEMREMAP_WB); 458 BUG_ON(!(src && dst)); 459 memcpy(dst, src, HV_HYP_PAGE_SIZE); 460 memunmap(src); 461 kunmap(pg); 462 } else { 463 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg); 464 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 465 } 466 467 /* 468 * hyperv_init() is called before LAPIC is initialized: see 469 * apic_intr_mode_init() -> x86_platform.apic_post_init() and 470 * apic_bsp_setup() -> setup_local_APIC(). The direct-mode STIMER 471 * depends on LAPIC, so hv_stimer_alloc() should be called from 472 * x86_init.timers.setup_percpu_clockev. 473 */ 474 old_setup_percpu_clockev = x86_init.timers.setup_percpu_clockev; 475 x86_init.timers.setup_percpu_clockev = hv_stimer_setup_percpu_clockev; 476 477 hv_apic_init(); 478 479 x86_init.pci.arch_init = hv_pci_init; 480 481 register_syscore_ops(&hv_syscore_ops); 482 483 hyperv_init_cpuhp = cpuhp; 484 485 if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_ACCESS_PARTITION_ID) 486 hv_get_partition_id(); 487 488 BUG_ON(hv_root_partition && hv_current_partition_id == ~0ull); 489 490 #ifdef CONFIG_PCI_MSI 491 /* 492 * If we're running as root, we want to create our own PCI MSI domain. 493 * We can't set this in hv_pci_init because that would be too late. 494 */ 495 if (hv_root_partition) 496 x86_init.irqs.create_pci_msi_domain = hv_create_pci_msi_domain; 497 #endif 498 499 /* Query the VMs extended capability once, so that it can be cached. */ 500 hv_query_ext_cap(0); 501 return; 502 503 clean_guest_os_id: 504 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); 505 hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, 0); 506 cpuhp_remove_state(cpuhp); 507 free_ghcb_page: 508 free_percpu(hv_ghcb_pg); 509 free_vp_assist_page: 510 kfree(hv_vp_assist_page); 511 hv_vp_assist_page = NULL; 512 common_free: 513 hv_common_free(); 514 } 515 516 /* 517 * This routine is called before kexec/kdump, it does the required cleanup. 518 */ 519 void hyperv_cleanup(void) 520 { 521 union hv_x64_msr_hypercall_contents hypercall_msr; 522 523 unregister_syscore_ops(&hv_syscore_ops); 524 525 /* Reset our OS id */ 526 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); 527 hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, 0); 528 529 /* 530 * Reset hypercall page reference before reset the page, 531 * let hypercall operations fail safely rather than 532 * panic the kernel for using invalid hypercall page 533 */ 534 hv_hypercall_pg = NULL; 535 536 /* Reset the hypercall page */ 537 hypercall_msr.as_uint64 = 0; 538 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 539 540 /* Reset the TSC page */ 541 hypercall_msr.as_uint64 = 0; 542 wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64); 543 } 544 545 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die) 546 { 547 static bool panic_reported; 548 u64 guest_id; 549 550 if (in_die && !panic_on_oops) 551 return; 552 553 /* 554 * We prefer to report panic on 'die' chain as we have proper 555 * registers to report, but if we miss it (e.g. on BUG()) we need 556 * to report it on 'panic'. 557 */ 558 if (panic_reported) 559 return; 560 panic_reported = true; 561 562 rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id); 563 564 wrmsrl(HV_X64_MSR_CRASH_P0, err); 565 wrmsrl(HV_X64_MSR_CRASH_P1, guest_id); 566 wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip); 567 wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax); 568 wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp); 569 570 /* 571 * Let Hyper-V know there is crash data available 572 */ 573 wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY); 574 } 575 EXPORT_SYMBOL_GPL(hyperv_report_panic); 576 577 bool hv_is_hyperv_initialized(void) 578 { 579 union hv_x64_msr_hypercall_contents hypercall_msr; 580 581 /* 582 * Ensure that we're really on Hyper-V, and not a KVM or Xen 583 * emulation of Hyper-V 584 */ 585 if (x86_hyper_type != X86_HYPER_MS_HYPERV) 586 return false; 587 588 /* 589 * Verify that earlier initialization succeeded by checking 590 * that the hypercall page is setup 591 */ 592 hypercall_msr.as_uint64 = 0; 593 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 594 595 return hypercall_msr.enable; 596 } 597 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized); 598