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/sev.h> 17 #include <asm/hypervisor.h> 18 #include <asm/hyperv-tlfs.h> 19 #include <asm/mshyperv.h> 20 #include <asm/idtentry.h> 21 #include <linux/kexec.h> 22 #include <linux/version.h> 23 #include <linux/vmalloc.h> 24 #include <linux/mm.h> 25 #include <linux/hyperv.h> 26 #include <linux/slab.h> 27 #include <linux/kernel.h> 28 #include <linux/cpuhotplug.h> 29 #include <linux/syscore_ops.h> 30 #include <clocksource/hyperv_timer.h> 31 #include <linux/highmem.h> 32 33 int hyperv_init_cpuhp; 34 u64 hv_current_partition_id = ~0ull; 35 EXPORT_SYMBOL_GPL(hv_current_partition_id); 36 37 void *hv_hypercall_pg; 38 EXPORT_SYMBOL_GPL(hv_hypercall_pg); 39 40 union hv_ghcb * __percpu *hv_ghcb_pg; 41 42 /* Storage to save the hypercall page temporarily for hibernation */ 43 static void *hv_hypercall_pg_saved; 44 45 struct hv_vp_assist_page **hv_vp_assist_page; 46 EXPORT_SYMBOL_GPL(hv_vp_assist_page); 47 48 static int hyperv_init_ghcb(void) 49 { 50 u64 ghcb_gpa; 51 void *ghcb_va; 52 void **ghcb_base; 53 54 if (!hv_isolation_type_snp()) 55 return 0; 56 57 if (!hv_ghcb_pg) 58 return -EINVAL; 59 60 /* 61 * GHCB page is allocated by paravisor. The address 62 * returned by MSR_AMD64_SEV_ES_GHCB is above shared 63 * memory boundary and map it here. 64 */ 65 rdmsrl(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa); 66 67 /* Mask out vTOM bit. ioremap_cache() maps decrypted */ 68 ghcb_gpa &= ~ms_hyperv.shared_gpa_boundary; 69 ghcb_va = (void *)ioremap_cache(ghcb_gpa, HV_HYP_PAGE_SIZE); 70 if (!ghcb_va) 71 return -ENOMEM; 72 73 ghcb_base = (void **)this_cpu_ptr(hv_ghcb_pg); 74 *ghcb_base = ghcb_va; 75 76 return 0; 77 } 78 79 static int hv_cpu_init(unsigned int cpu) 80 { 81 union hv_vp_assist_msr_contents msr = { 0 }; 82 struct hv_vp_assist_page **hvp = &hv_vp_assist_page[cpu]; 83 int ret; 84 85 ret = hv_common_cpu_init(cpu); 86 if (ret) 87 return ret; 88 89 if (!hv_vp_assist_page) 90 return 0; 91 92 if (hv_root_partition) { 93 /* 94 * For root partition we get the hypervisor provided VP assist 95 * page, instead of allocating a new page. 96 */ 97 rdmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64); 98 *hvp = memremap(msr.pfn << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT, 99 PAGE_SIZE, MEMREMAP_WB); 100 } else { 101 /* 102 * The VP assist page is an "overlay" page (see Hyper-V TLFS's 103 * Section 5.2.1 "GPA Overlay Pages"). Here it must be zeroed 104 * out to make sure we always write the EOI MSR in 105 * hv_apic_eoi_write() *after* the EOI optimization is disabled 106 * in hv_cpu_die(), otherwise a CPU may not be stopped in the 107 * case of CPU offlining and the VM will hang. 108 */ 109 if (!*hvp) 110 *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO); 111 if (*hvp) 112 msr.pfn = vmalloc_to_pfn(*hvp); 113 114 } 115 if (!WARN_ON(!(*hvp))) { 116 msr.enable = 1; 117 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64); 118 } 119 120 return hyperv_init_ghcb(); 121 } 122 123 static void (*hv_reenlightenment_cb)(void); 124 125 static void hv_reenlightenment_notify(struct work_struct *dummy) 126 { 127 struct hv_tsc_emulation_status emu_status; 128 129 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 130 131 /* Don't issue the callback if TSC accesses are not emulated */ 132 if (hv_reenlightenment_cb && emu_status.inprogress) 133 hv_reenlightenment_cb(); 134 } 135 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify); 136 137 void hyperv_stop_tsc_emulation(void) 138 { 139 u64 freq; 140 struct hv_tsc_emulation_status emu_status; 141 142 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 143 emu_status.inprogress = 0; 144 wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 145 146 rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq); 147 tsc_khz = div64_u64(freq, 1000); 148 } 149 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation); 150 151 static inline bool hv_reenlightenment_available(void) 152 { 153 /* 154 * Check for required features and privileges to make TSC frequency 155 * change notifications work. 156 */ 157 return ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS && 158 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE && 159 ms_hyperv.features & HV_ACCESS_REENLIGHTENMENT; 160 } 161 162 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_reenlightenment) 163 { 164 ack_APIC_irq(); 165 inc_irq_stat(irq_hv_reenlightenment_count); 166 schedule_delayed_work(&hv_reenlightenment_work, HZ/10); 167 } 168 169 void set_hv_tscchange_cb(void (*cb)(void)) 170 { 171 struct hv_reenlightenment_control re_ctrl = { 172 .vector = HYPERV_REENLIGHTENMENT_VECTOR, 173 .enabled = 1, 174 }; 175 struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1}; 176 177 if (!hv_reenlightenment_available()) { 178 pr_warn("Hyper-V: reenlightenment support is unavailable\n"); 179 return; 180 } 181 182 if (!hv_vp_index) 183 return; 184 185 hv_reenlightenment_cb = cb; 186 187 /* Make sure callback is registered before we write to MSRs */ 188 wmb(); 189 190 re_ctrl.target_vp = hv_vp_index[get_cpu()]; 191 192 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 193 wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl)); 194 195 put_cpu(); 196 } 197 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb); 198 199 void clear_hv_tscchange_cb(void) 200 { 201 struct hv_reenlightenment_control re_ctrl; 202 203 if (!hv_reenlightenment_available()) 204 return; 205 206 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl); 207 re_ctrl.enabled = 0; 208 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl); 209 210 hv_reenlightenment_cb = NULL; 211 } 212 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb); 213 214 static int hv_cpu_die(unsigned int cpu) 215 { 216 struct hv_reenlightenment_control re_ctrl; 217 unsigned int new_cpu; 218 void **ghcb_va; 219 220 if (hv_ghcb_pg) { 221 ghcb_va = (void **)this_cpu_ptr(hv_ghcb_pg); 222 if (*ghcb_va) 223 iounmap(*ghcb_va); 224 *ghcb_va = NULL; 225 } 226 227 hv_common_cpu_die(cpu); 228 229 if (hv_vp_assist_page && hv_vp_assist_page[cpu]) { 230 union hv_vp_assist_msr_contents msr = { 0 }; 231 if (hv_root_partition) { 232 /* 233 * For root partition the VP assist page is mapped to 234 * hypervisor provided page, and thus we unmap the 235 * page here and nullify it, so that in future we have 236 * correct page address mapped in hv_cpu_init. 237 */ 238 memunmap(hv_vp_assist_page[cpu]); 239 hv_vp_assist_page[cpu] = NULL; 240 rdmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64); 241 msr.enable = 0; 242 } 243 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64); 244 } 245 246 if (hv_reenlightenment_cb == NULL) 247 return 0; 248 249 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 250 if (re_ctrl.target_vp == hv_vp_index[cpu]) { 251 /* 252 * Reassign reenlightenment notifications to some other online 253 * CPU or just disable the feature if there are no online CPUs 254 * left (happens on hibernation). 255 */ 256 new_cpu = cpumask_any_but(cpu_online_mask, cpu); 257 258 if (new_cpu < nr_cpu_ids) 259 re_ctrl.target_vp = hv_vp_index[new_cpu]; 260 else 261 re_ctrl.enabled = 0; 262 263 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 264 } 265 266 return 0; 267 } 268 269 static int __init hv_pci_init(void) 270 { 271 int gen2vm = efi_enabled(EFI_BOOT); 272 273 /* 274 * For Generation-2 VM, we exit from pci_arch_init() by returning 0. 275 * The purpose is to suppress the harmless warning: 276 * "PCI: Fatal: No config space access function found" 277 */ 278 if (gen2vm) 279 return 0; 280 281 /* For Generation-1 VM, we'll proceed in pci_arch_init(). */ 282 return 1; 283 } 284 285 static int hv_suspend(void) 286 { 287 union hv_x64_msr_hypercall_contents hypercall_msr; 288 int ret; 289 290 if (hv_root_partition) 291 return -EPERM; 292 293 /* 294 * Reset the hypercall page as it is going to be invalidated 295 * across hibernation. Setting hv_hypercall_pg to NULL ensures 296 * that any subsequent hypercall operation fails safely instead of 297 * crashing due to an access of an invalid page. The hypercall page 298 * pointer is restored on resume. 299 */ 300 hv_hypercall_pg_saved = hv_hypercall_pg; 301 hv_hypercall_pg = NULL; 302 303 /* Disable the hypercall page in the hypervisor */ 304 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 305 hypercall_msr.enable = 0; 306 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 307 308 ret = hv_cpu_die(0); 309 return ret; 310 } 311 312 static void hv_resume(void) 313 { 314 union hv_x64_msr_hypercall_contents hypercall_msr; 315 int ret; 316 317 ret = hv_cpu_init(0); 318 WARN_ON(ret); 319 320 /* Re-enable the hypercall page */ 321 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 322 hypercall_msr.enable = 1; 323 hypercall_msr.guest_physical_address = 324 vmalloc_to_pfn(hv_hypercall_pg_saved); 325 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 326 327 hv_hypercall_pg = hv_hypercall_pg_saved; 328 hv_hypercall_pg_saved = NULL; 329 330 /* 331 * Reenlightenment notifications are disabled by hv_cpu_die(0), 332 * reenable them here if hv_reenlightenment_cb was previously set. 333 */ 334 if (hv_reenlightenment_cb) 335 set_hv_tscchange_cb(hv_reenlightenment_cb); 336 } 337 338 /* Note: when the ops are called, only CPU0 is online and IRQs are disabled. */ 339 static struct syscore_ops hv_syscore_ops = { 340 .suspend = hv_suspend, 341 .resume = hv_resume, 342 }; 343 344 static void (* __initdata old_setup_percpu_clockev)(void); 345 346 static void __init hv_stimer_setup_percpu_clockev(void) 347 { 348 /* 349 * Ignore any errors in setting up stimer clockevents 350 * as we can run with the LAPIC timer as a fallback. 351 */ 352 (void)hv_stimer_alloc(false); 353 354 /* 355 * Still register the LAPIC timer, because the direct-mode STIMER is 356 * not supported by old versions of Hyper-V. This also allows users 357 * to switch to LAPIC timer via /sys, if they want to. 358 */ 359 if (old_setup_percpu_clockev) 360 old_setup_percpu_clockev(); 361 } 362 363 static void __init hv_get_partition_id(void) 364 { 365 struct hv_get_partition_id *output_page; 366 u64 status; 367 unsigned long flags; 368 369 local_irq_save(flags); 370 output_page = *this_cpu_ptr(hyperv_pcpu_output_arg); 371 status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page); 372 if (!hv_result_success(status)) { 373 /* No point in proceeding if this failed */ 374 pr_err("Failed to get partition ID: %lld\n", status); 375 BUG(); 376 } 377 hv_current_partition_id = output_page->partition_id; 378 local_irq_restore(flags); 379 } 380 381 /* 382 * This function is to be invoked early in the boot sequence after the 383 * hypervisor has been detected. 384 * 385 * 1. Setup the hypercall page. 386 * 2. Register Hyper-V specific clocksource. 387 * 3. Setup Hyper-V specific APIC entry points. 388 */ 389 void __init hyperv_init(void) 390 { 391 u64 guest_id; 392 union hv_x64_msr_hypercall_contents hypercall_msr; 393 int cpuhp; 394 395 if (x86_hyper_type != X86_HYPER_MS_HYPERV) 396 return; 397 398 if (hv_common_init()) 399 return; 400 401 hv_vp_assist_page = kcalloc(num_possible_cpus(), 402 sizeof(*hv_vp_assist_page), GFP_KERNEL); 403 if (!hv_vp_assist_page) { 404 ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED; 405 goto common_free; 406 } 407 408 if (hv_isolation_type_snp()) { 409 /* Negotiate GHCB Version. */ 410 if (!hv_ghcb_negotiate_protocol()) 411 hv_ghcb_terminate(SEV_TERM_SET_GEN, 412 GHCB_SEV_ES_PROT_UNSUPPORTED); 413 414 hv_ghcb_pg = alloc_percpu(union hv_ghcb *); 415 if (!hv_ghcb_pg) 416 goto free_vp_assist_page; 417 } 418 419 cpuhp = cpuhp_setup_state(CPUHP_AP_HYPERV_ONLINE, "x86/hyperv_init:online", 420 hv_cpu_init, hv_cpu_die); 421 if (cpuhp < 0) 422 goto free_ghcb_page; 423 424 /* 425 * Setup the hypercall page and enable hypercalls. 426 * 1. Register the guest ID 427 * 2. Enable the hypercall and register the hypercall page 428 */ 429 guest_id = hv_generate_guest_id(LINUX_VERSION_CODE); 430 wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id); 431 432 /* Hyper-V requires to write guest os id via ghcb in SNP IVM. */ 433 hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, guest_id); 434 435 hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START, 436 VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_ROX, 437 VM_FLUSH_RESET_PERMS, NUMA_NO_NODE, 438 __builtin_return_address(0)); 439 if (hv_hypercall_pg == NULL) 440 goto clean_guest_os_id; 441 442 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 443 hypercall_msr.enable = 1; 444 445 if (hv_root_partition) { 446 struct page *pg; 447 void *src; 448 449 /* 450 * For the root partition, the hypervisor will set up its 451 * hypercall page. The hypervisor guarantees it will not show 452 * up in the root's address space. The root can't change the 453 * location of the hypercall page. 454 * 455 * Order is important here. We must enable the hypercall page 456 * so it is populated with code, then copy the code to an 457 * executable page. 458 */ 459 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 460 461 pg = vmalloc_to_page(hv_hypercall_pg); 462 src = memremap(hypercall_msr.guest_physical_address << PAGE_SHIFT, PAGE_SIZE, 463 MEMREMAP_WB); 464 BUG_ON(!src); 465 memcpy_to_page(pg, 0, src, HV_HYP_PAGE_SIZE); 466 memunmap(src); 467 468 hv_remap_tsc_clocksource(); 469 } else { 470 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg); 471 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 472 } 473 474 /* 475 * hyperv_init() is called before LAPIC is initialized: see 476 * apic_intr_mode_init() -> x86_platform.apic_post_init() and 477 * apic_bsp_setup() -> setup_local_APIC(). The direct-mode STIMER 478 * depends on LAPIC, so hv_stimer_alloc() should be called from 479 * x86_init.timers.setup_percpu_clockev. 480 */ 481 old_setup_percpu_clockev = x86_init.timers.setup_percpu_clockev; 482 x86_init.timers.setup_percpu_clockev = hv_stimer_setup_percpu_clockev; 483 484 hv_apic_init(); 485 486 x86_init.pci.arch_init = hv_pci_init; 487 488 register_syscore_ops(&hv_syscore_ops); 489 490 hyperv_init_cpuhp = cpuhp; 491 492 if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_ACCESS_PARTITION_ID) 493 hv_get_partition_id(); 494 495 BUG_ON(hv_root_partition && hv_current_partition_id == ~0ull); 496 497 #ifdef CONFIG_PCI_MSI 498 /* 499 * If we're running as root, we want to create our own PCI MSI domain. 500 * We can't set this in hv_pci_init because that would be too late. 501 */ 502 if (hv_root_partition) 503 x86_init.irqs.create_pci_msi_domain = hv_create_pci_msi_domain; 504 #endif 505 506 /* Query the VMs extended capability once, so that it can be cached. */ 507 hv_query_ext_cap(0); 508 509 return; 510 511 clean_guest_os_id: 512 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); 513 hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, 0); 514 cpuhp_remove_state(cpuhp); 515 free_ghcb_page: 516 free_percpu(hv_ghcb_pg); 517 free_vp_assist_page: 518 kfree(hv_vp_assist_page); 519 hv_vp_assist_page = NULL; 520 common_free: 521 hv_common_free(); 522 } 523 524 /* 525 * This routine is called before kexec/kdump, it does the required cleanup. 526 */ 527 void hyperv_cleanup(void) 528 { 529 union hv_x64_msr_hypercall_contents hypercall_msr; 530 union hv_reference_tsc_msr tsc_msr; 531 532 /* Reset our OS id */ 533 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); 534 hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, 0); 535 536 /* 537 * Reset hypercall page reference before reset the page, 538 * let hypercall operations fail safely rather than 539 * panic the kernel for using invalid hypercall page 540 */ 541 hv_hypercall_pg = NULL; 542 543 /* Reset the hypercall page */ 544 hypercall_msr.as_uint64 = hv_get_register(HV_X64_MSR_HYPERCALL); 545 hypercall_msr.enable = 0; 546 hv_set_register(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 547 548 /* Reset the TSC page */ 549 tsc_msr.as_uint64 = hv_get_register(HV_X64_MSR_REFERENCE_TSC); 550 tsc_msr.enable = 0; 551 hv_set_register(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64); 552 } 553 554 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die) 555 { 556 static bool panic_reported; 557 u64 guest_id; 558 559 if (in_die && !panic_on_oops) 560 return; 561 562 /* 563 * We prefer to report panic on 'die' chain as we have proper 564 * registers to report, but if we miss it (e.g. on BUG()) we need 565 * to report it on 'panic'. 566 */ 567 if (panic_reported) 568 return; 569 panic_reported = true; 570 571 rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id); 572 573 wrmsrl(HV_X64_MSR_CRASH_P0, err); 574 wrmsrl(HV_X64_MSR_CRASH_P1, guest_id); 575 wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip); 576 wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax); 577 wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp); 578 579 /* 580 * Let Hyper-V know there is crash data available 581 */ 582 wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY); 583 } 584 EXPORT_SYMBOL_GPL(hyperv_report_panic); 585 586 bool hv_is_hyperv_initialized(void) 587 { 588 union hv_x64_msr_hypercall_contents hypercall_msr; 589 590 /* 591 * Ensure that we're really on Hyper-V, and not a KVM or Xen 592 * emulation of Hyper-V 593 */ 594 if (x86_hyper_type != X86_HYPER_MS_HYPERV) 595 return false; 596 597 /* 598 * Verify that earlier initialization succeeded by checking 599 * that the hypercall page is setup 600 */ 601 hypercall_msr.as_uint64 = 0; 602 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 603 604 return hypercall_msr.enable; 605 } 606 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized); 607