1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * AMD Memory Encryption Support 4 * 5 * Copyright (C) 2019 SUSE 6 * 7 * Author: Joerg Roedel <jroedel@suse.de> 8 */ 9 10 #define pr_fmt(fmt) "SEV: " fmt 11 12 #include <linux/sched/debug.h> /* For show_regs() */ 13 #include <linux/percpu-defs.h> 14 #include <linux/cc_platform.h> 15 #include <linux/printk.h> 16 #include <linux/mm_types.h> 17 #include <linux/set_memory.h> 18 #include <linux/memblock.h> 19 #include <linux/kernel.h> 20 #include <linux/mm.h> 21 #include <linux/cpumask.h> 22 #include <linux/efi.h> 23 #include <linux/platform_device.h> 24 #include <linux/io.h> 25 #include <linux/psp-sev.h> 26 #include <linux/dmi.h> 27 #include <uapi/linux/sev-guest.h> 28 #include <crypto/gcm.h> 29 30 #include <asm/init.h> 31 #include <asm/cpu_entry_area.h> 32 #include <asm/stacktrace.h> 33 #include <asm/sev.h> 34 #include <asm/sev-internal.h> 35 #include <asm/insn-eval.h> 36 #include <asm/fpu/xcr.h> 37 #include <asm/processor.h> 38 #include <asm/realmode.h> 39 #include <asm/setup.h> 40 #include <asm/traps.h> 41 #include <asm/svm.h> 42 #include <asm/smp.h> 43 #include <asm/cpu.h> 44 #include <asm/apic.h> 45 #include <asm/cpuid/api.h> 46 #include <asm/cmdline.h> 47 #include <asm/msr.h> 48 49 /* AP INIT values as documented in the APM2 section "Processor Initialization State" */ 50 #define AP_INIT_CS_LIMIT 0xffff 51 #define AP_INIT_DS_LIMIT 0xffff 52 #define AP_INIT_LDTR_LIMIT 0xffff 53 #define AP_INIT_GDTR_LIMIT 0xffff 54 #define AP_INIT_IDTR_LIMIT 0xffff 55 #define AP_INIT_TR_LIMIT 0xffff 56 #define AP_INIT_RFLAGS_DEFAULT 0x2 57 #define AP_INIT_DR6_DEFAULT 0xffff0ff0 58 #define AP_INIT_GPAT_DEFAULT 0x0007040600070406ULL 59 #define AP_INIT_XCR0_DEFAULT 0x1 60 #define AP_INIT_X87_FTW_DEFAULT 0x5555 61 #define AP_INIT_X87_FCW_DEFAULT 0x0040 62 #define AP_INIT_CR0_DEFAULT 0x60000010 63 #define AP_INIT_MXCSR_DEFAULT 0x1f80 64 65 static const char * const sev_status_feat_names[] = { 66 [MSR_AMD64_SEV_ENABLED_BIT] = "SEV", 67 [MSR_AMD64_SEV_ES_ENABLED_BIT] = "SEV-ES", 68 [MSR_AMD64_SEV_SNP_ENABLED_BIT] = "SEV-SNP", 69 [MSR_AMD64_SNP_VTOM_BIT] = "vTom", 70 [MSR_AMD64_SNP_REFLECT_VC_BIT] = "ReflectVC", 71 [MSR_AMD64_SNP_RESTRICTED_INJ_BIT] = "RI", 72 [MSR_AMD64_SNP_ALT_INJ_BIT] = "AI", 73 [MSR_AMD64_SNP_DEBUG_SWAP_BIT] = "DebugSwap", 74 [MSR_AMD64_SNP_PREVENT_HOST_IBS_BIT] = "NoHostIBS", 75 [MSR_AMD64_SNP_BTB_ISOLATION_BIT] = "BTBIsol", 76 [MSR_AMD64_SNP_VMPL_SSS_BIT] = "VmplSSS", 77 [MSR_AMD64_SNP_SECURE_TSC_BIT] = "SecureTSC", 78 [MSR_AMD64_SNP_VMGEXIT_PARAM_BIT] = "VMGExitParam", 79 [MSR_AMD64_SNP_IBS_VIRT_BIT] = "IBSVirt", 80 [MSR_AMD64_SNP_VMSA_REG_PROT_BIT] = "VMSARegProt", 81 [MSR_AMD64_SNP_SMT_PROT_BIT] = "SMTProt", 82 }; 83 84 /* 85 * For Secure TSC guests, the BSP fetches TSC_INFO using SNP guest messaging and 86 * initializes snp_tsc_scale and snp_tsc_offset. These values are replicated 87 * across the APs VMSA fields (TSC_SCALE and TSC_OFFSET). 88 */ 89 static u64 snp_tsc_scale __ro_after_init; 90 static u64 snp_tsc_offset __ro_after_init; 91 static unsigned long snp_tsc_freq_khz __ro_after_init; 92 93 DEFINE_PER_CPU(struct sev_es_runtime_data*, runtime_data); 94 DEFINE_PER_CPU(struct sev_es_save_area *, sev_vmsa); 95 96 /* 97 * SVSM related information: 98 * When running under an SVSM, the VMPL that Linux is executing at must be 99 * non-zero. The VMPL is therefore used to indicate the presence of an SVSM. 100 */ 101 u8 snp_vmpl __ro_after_init; 102 EXPORT_SYMBOL_GPL(snp_vmpl); 103 104 static u64 __init get_snp_jump_table_addr(void) 105 { 106 struct snp_secrets_page *secrets; 107 void __iomem *mem; 108 u64 addr; 109 110 mem = ioremap_encrypted(sev_secrets_pa, PAGE_SIZE); 111 if (!mem) { 112 pr_err("Unable to locate AP jump table address: failed to map the SNP secrets page.\n"); 113 return 0; 114 } 115 116 secrets = (__force struct snp_secrets_page *)mem; 117 118 addr = secrets->os_area.ap_jump_table_pa; 119 iounmap(mem); 120 121 return addr; 122 } 123 124 static u64 __init get_jump_table_addr(void) 125 { 126 struct ghcb_state state; 127 unsigned long flags; 128 struct ghcb *ghcb; 129 u64 ret = 0; 130 131 if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 132 return get_snp_jump_table_addr(); 133 134 local_irq_save(flags); 135 136 ghcb = __sev_get_ghcb(&state); 137 138 vc_ghcb_invalidate(ghcb); 139 ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_JUMP_TABLE); 140 ghcb_set_sw_exit_info_1(ghcb, SVM_VMGEXIT_GET_AP_JUMP_TABLE); 141 ghcb_set_sw_exit_info_2(ghcb, 0); 142 143 sev_es_wr_ghcb_msr(__pa(ghcb)); 144 VMGEXIT(); 145 146 if (ghcb_sw_exit_info_1_is_valid(ghcb) && 147 ghcb_sw_exit_info_2_is_valid(ghcb)) 148 ret = ghcb->save.sw_exit_info_2; 149 150 __sev_put_ghcb(&state); 151 152 local_irq_restore(flags); 153 154 return ret; 155 } 156 157 static inline void __pval_terminate(u64 pfn, bool action, unsigned int page_size, 158 int ret, u64 svsm_ret) 159 { 160 WARN(1, "PVALIDATE failure: pfn: 0x%llx, action: %u, size: %u, ret: %d, svsm_ret: 0x%llx\n", 161 pfn, action, page_size, ret, svsm_ret); 162 163 sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PVALIDATE); 164 } 165 166 static void svsm_pval_terminate(struct svsm_pvalidate_call *pc, int ret, u64 svsm_ret) 167 { 168 unsigned int page_size; 169 bool action; 170 u64 pfn; 171 172 pfn = pc->entry[pc->cur_index].pfn; 173 action = pc->entry[pc->cur_index].action; 174 page_size = pc->entry[pc->cur_index].page_size; 175 176 __pval_terminate(pfn, action, page_size, ret, svsm_ret); 177 } 178 179 static void pval_pages(struct snp_psc_desc *desc) 180 { 181 struct psc_entry *e; 182 unsigned long vaddr; 183 unsigned int size; 184 unsigned int i; 185 bool validate; 186 u64 pfn; 187 int rc; 188 189 for (i = 0; i <= desc->hdr.end_entry; i++) { 190 e = &desc->entries[i]; 191 192 pfn = e->gfn; 193 vaddr = (unsigned long)pfn_to_kaddr(pfn); 194 size = e->pagesize ? RMP_PG_SIZE_2M : RMP_PG_SIZE_4K; 195 validate = e->operation == SNP_PAGE_STATE_PRIVATE; 196 197 rc = pvalidate(vaddr, size, validate); 198 if (!rc) 199 continue; 200 201 if (rc == PVALIDATE_FAIL_SIZEMISMATCH && size == RMP_PG_SIZE_2M) { 202 unsigned long vaddr_end = vaddr + PMD_SIZE; 203 204 for (; vaddr < vaddr_end; vaddr += PAGE_SIZE, pfn++) { 205 rc = pvalidate(vaddr, RMP_PG_SIZE_4K, validate); 206 if (rc) 207 __pval_terminate(pfn, validate, RMP_PG_SIZE_4K, rc, 0); 208 } 209 } else { 210 __pval_terminate(pfn, validate, size, rc, 0); 211 } 212 } 213 } 214 215 static u64 svsm_build_ca_from_pfn_range(u64 pfn, u64 pfn_end, bool action, 216 struct svsm_pvalidate_call *pc) 217 { 218 struct svsm_pvalidate_entry *pe; 219 220 /* Nothing in the CA yet */ 221 pc->num_entries = 0; 222 pc->cur_index = 0; 223 224 pe = &pc->entry[0]; 225 226 while (pfn < pfn_end) { 227 pe->page_size = RMP_PG_SIZE_4K; 228 pe->action = action; 229 pe->ignore_cf = 0; 230 pe->rsvd = 0; 231 pe->pfn = pfn; 232 233 pe++; 234 pfn++; 235 236 pc->num_entries++; 237 if (pc->num_entries == SVSM_PVALIDATE_MAX_COUNT) 238 break; 239 } 240 241 return pfn; 242 } 243 244 static int svsm_build_ca_from_psc_desc(struct snp_psc_desc *desc, unsigned int desc_entry, 245 struct svsm_pvalidate_call *pc) 246 { 247 struct svsm_pvalidate_entry *pe; 248 struct psc_entry *e; 249 250 /* Nothing in the CA yet */ 251 pc->num_entries = 0; 252 pc->cur_index = 0; 253 254 pe = &pc->entry[0]; 255 e = &desc->entries[desc_entry]; 256 257 while (desc_entry <= desc->hdr.end_entry) { 258 pe->page_size = e->pagesize ? RMP_PG_SIZE_2M : RMP_PG_SIZE_4K; 259 pe->action = e->operation == SNP_PAGE_STATE_PRIVATE; 260 pe->ignore_cf = 0; 261 pe->rsvd = 0; 262 pe->pfn = e->gfn; 263 264 pe++; 265 e++; 266 267 desc_entry++; 268 pc->num_entries++; 269 if (pc->num_entries == SVSM_PVALIDATE_MAX_COUNT) 270 break; 271 } 272 273 return desc_entry; 274 } 275 276 static void svsm_pval_pages(struct snp_psc_desc *desc) 277 { 278 struct svsm_pvalidate_entry pv_4k[VMGEXIT_PSC_MAX_ENTRY]; 279 unsigned int i, pv_4k_count = 0; 280 struct svsm_pvalidate_call *pc; 281 struct svsm_call call = {}; 282 unsigned long flags; 283 bool action; 284 u64 pc_pa; 285 int ret; 286 287 /* 288 * This can be called very early in the boot, use native functions in 289 * order to avoid paravirt issues. 290 */ 291 flags = native_local_irq_save(); 292 293 /* 294 * The SVSM calling area (CA) can support processing 510 entries at a 295 * time. Loop through the Page State Change descriptor until the CA is 296 * full or the last entry in the descriptor is reached, at which time 297 * the SVSM is invoked. This repeats until all entries in the descriptor 298 * are processed. 299 */ 300 call.caa = svsm_get_caa(); 301 302 pc = (struct svsm_pvalidate_call *)call.caa->svsm_buffer; 303 pc_pa = svsm_get_caa_pa() + offsetof(struct svsm_ca, svsm_buffer); 304 305 /* Protocol 0, Call ID 1 */ 306 call.rax = SVSM_CORE_CALL(SVSM_CORE_PVALIDATE); 307 call.rcx = pc_pa; 308 309 for (i = 0; i <= desc->hdr.end_entry;) { 310 i = svsm_build_ca_from_psc_desc(desc, i, pc); 311 312 do { 313 ret = svsm_perform_call_protocol(&call); 314 if (!ret) 315 continue; 316 317 /* 318 * Check if the entry failed because of an RMP mismatch (a 319 * PVALIDATE at 2M was requested, but the page is mapped in 320 * the RMP as 4K). 321 */ 322 323 if (call.rax_out == SVSM_PVALIDATE_FAIL_SIZEMISMATCH && 324 pc->entry[pc->cur_index].page_size == RMP_PG_SIZE_2M) { 325 /* Save this entry for post-processing at 4K */ 326 pv_4k[pv_4k_count++] = pc->entry[pc->cur_index]; 327 328 /* Skip to the next one unless at the end of the list */ 329 pc->cur_index++; 330 if (pc->cur_index < pc->num_entries) 331 ret = -EAGAIN; 332 else 333 ret = 0; 334 } 335 } while (ret == -EAGAIN); 336 337 if (ret) 338 svsm_pval_terminate(pc, ret, call.rax_out); 339 } 340 341 /* Process any entries that failed to be validated at 2M and validate them at 4K */ 342 for (i = 0; i < pv_4k_count; i++) { 343 u64 pfn, pfn_end; 344 345 action = pv_4k[i].action; 346 pfn = pv_4k[i].pfn; 347 pfn_end = pfn + 512; 348 349 while (pfn < pfn_end) { 350 pfn = svsm_build_ca_from_pfn_range(pfn, pfn_end, action, pc); 351 352 ret = svsm_perform_call_protocol(&call); 353 if (ret) 354 svsm_pval_terminate(pc, ret, call.rax_out); 355 } 356 } 357 358 native_local_irq_restore(flags); 359 } 360 361 static void pvalidate_pages(struct snp_psc_desc *desc) 362 { 363 if (snp_vmpl) 364 svsm_pval_pages(desc); 365 else 366 pval_pages(desc); 367 } 368 369 static int vmgexit_psc(struct ghcb *ghcb, struct snp_psc_desc *desc) 370 { 371 int cur_entry, end_entry, ret = 0; 372 struct snp_psc_desc *data; 373 struct es_em_ctxt ctxt; 374 375 vc_ghcb_invalidate(ghcb); 376 377 /* Copy the input desc into GHCB shared buffer */ 378 data = (struct snp_psc_desc *)ghcb->shared_buffer; 379 memcpy(ghcb->shared_buffer, desc, min_t(int, GHCB_SHARED_BUF_SIZE, sizeof(*desc))); 380 381 /* 382 * As per the GHCB specification, the hypervisor can resume the guest 383 * before processing all the entries. Check whether all the entries 384 * are processed. If not, then keep retrying. Note, the hypervisor 385 * will update the data memory directly to indicate the status, so 386 * reference the data->hdr everywhere. 387 * 388 * The strategy here is to wait for the hypervisor to change the page 389 * state in the RMP table before guest accesses the memory pages. If the 390 * page state change was not successful, then later memory access will 391 * result in a crash. 392 */ 393 cur_entry = data->hdr.cur_entry; 394 end_entry = data->hdr.end_entry; 395 396 while (data->hdr.cur_entry <= data->hdr.end_entry) { 397 ghcb_set_sw_scratch(ghcb, (u64)__pa(data)); 398 399 /* This will advance the shared buffer data points to. */ 400 ret = sev_es_ghcb_hv_call(ghcb, &ctxt, SVM_VMGEXIT_PSC, 0, 0); 401 402 /* 403 * Page State Change VMGEXIT can pass error code through 404 * exit_info_2. 405 */ 406 if (WARN(ret || ghcb->save.sw_exit_info_2, 407 "SNP: PSC failed ret=%d exit_info_2=%llx\n", 408 ret, ghcb->save.sw_exit_info_2)) { 409 ret = 1; 410 goto out; 411 } 412 413 /* Verify that reserved bit is not set */ 414 if (WARN(data->hdr.reserved, "Reserved bit is set in the PSC header\n")) { 415 ret = 1; 416 goto out; 417 } 418 419 /* 420 * Sanity check that entry processing is not going backwards. 421 * This will happen only if hypervisor is tricking us. 422 */ 423 if (WARN(data->hdr.end_entry > end_entry || cur_entry > data->hdr.cur_entry, 424 "SNP: PSC processing going backward, end_entry %d (got %d) cur_entry %d (got %d)\n", 425 end_entry, data->hdr.end_entry, cur_entry, data->hdr.cur_entry)) { 426 ret = 1; 427 goto out; 428 } 429 } 430 431 out: 432 return ret; 433 } 434 435 static unsigned long __set_pages_state(struct snp_psc_desc *data, unsigned long vaddr, 436 unsigned long vaddr_end, int op) 437 { 438 struct ghcb_state state; 439 bool use_large_entry; 440 struct psc_hdr *hdr; 441 struct psc_entry *e; 442 unsigned long flags; 443 unsigned long pfn; 444 struct ghcb *ghcb; 445 int i; 446 447 hdr = &data->hdr; 448 e = data->entries; 449 450 memset(data, 0, sizeof(*data)); 451 i = 0; 452 453 while (vaddr < vaddr_end && i < ARRAY_SIZE(data->entries)) { 454 hdr->end_entry = i; 455 456 if (is_vmalloc_addr((void *)vaddr)) { 457 pfn = vmalloc_to_pfn((void *)vaddr); 458 use_large_entry = false; 459 } else { 460 pfn = __pa(vaddr) >> PAGE_SHIFT; 461 use_large_entry = true; 462 } 463 464 e->gfn = pfn; 465 e->operation = op; 466 467 if (use_large_entry && IS_ALIGNED(vaddr, PMD_SIZE) && 468 (vaddr_end - vaddr) >= PMD_SIZE) { 469 e->pagesize = RMP_PG_SIZE_2M; 470 vaddr += PMD_SIZE; 471 } else { 472 e->pagesize = RMP_PG_SIZE_4K; 473 vaddr += PAGE_SIZE; 474 } 475 476 e++; 477 i++; 478 } 479 480 /* Page validation must be rescinded before changing to shared */ 481 if (op == SNP_PAGE_STATE_SHARED) 482 pvalidate_pages(data); 483 484 local_irq_save(flags); 485 486 if (sev_cfg.ghcbs_initialized) 487 ghcb = __sev_get_ghcb(&state); 488 else 489 ghcb = boot_ghcb; 490 491 /* Invoke the hypervisor to perform the page state changes */ 492 if (!ghcb || vmgexit_psc(ghcb, data)) 493 sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PSC); 494 495 if (sev_cfg.ghcbs_initialized) 496 __sev_put_ghcb(&state); 497 498 local_irq_restore(flags); 499 500 /* Page validation must be performed after changing to private */ 501 if (op == SNP_PAGE_STATE_PRIVATE) 502 pvalidate_pages(data); 503 504 return vaddr; 505 } 506 507 static void set_pages_state(unsigned long vaddr, unsigned long npages, int op) 508 { 509 struct snp_psc_desc desc; 510 unsigned long vaddr_end; 511 512 /* Use the MSR protocol when a GHCB is not available. */ 513 if (!boot_ghcb) 514 return early_set_pages_state(vaddr, __pa(vaddr), npages, op); 515 516 vaddr = vaddr & PAGE_MASK; 517 vaddr_end = vaddr + (npages << PAGE_SHIFT); 518 519 while (vaddr < vaddr_end) 520 vaddr = __set_pages_state(&desc, vaddr, vaddr_end, op); 521 } 522 523 void snp_set_memory_shared(unsigned long vaddr, unsigned long npages) 524 { 525 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 526 return; 527 528 set_pages_state(vaddr, npages, SNP_PAGE_STATE_SHARED); 529 } 530 531 void snp_set_memory_private(unsigned long vaddr, unsigned long npages) 532 { 533 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 534 return; 535 536 set_pages_state(vaddr, npages, SNP_PAGE_STATE_PRIVATE); 537 } 538 539 void snp_accept_memory(phys_addr_t start, phys_addr_t end) 540 { 541 unsigned long vaddr, npages; 542 543 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 544 return; 545 546 vaddr = (unsigned long)__va(start); 547 npages = (end - start) >> PAGE_SHIFT; 548 549 set_pages_state(vaddr, npages, SNP_PAGE_STATE_PRIVATE); 550 } 551 552 static int vmgexit_ap_control(u64 event, struct sev_es_save_area *vmsa, u32 apic_id) 553 { 554 bool create = event != SVM_VMGEXIT_AP_DESTROY; 555 struct ghcb_state state; 556 unsigned long flags; 557 struct ghcb *ghcb; 558 int ret = 0; 559 560 local_irq_save(flags); 561 562 ghcb = __sev_get_ghcb(&state); 563 564 vc_ghcb_invalidate(ghcb); 565 566 if (create) 567 ghcb_set_rax(ghcb, vmsa->sev_features); 568 569 ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_CREATION); 570 ghcb_set_sw_exit_info_1(ghcb, 571 ((u64)apic_id << 32) | 572 ((u64)snp_vmpl << 16) | 573 event); 574 ghcb_set_sw_exit_info_2(ghcb, __pa(vmsa)); 575 576 sev_es_wr_ghcb_msr(__pa(ghcb)); 577 VMGEXIT(); 578 579 if (!ghcb_sw_exit_info_1_is_valid(ghcb) || 580 lower_32_bits(ghcb->save.sw_exit_info_1)) { 581 pr_err("SNP AP %s error\n", (create ? "CREATE" : "DESTROY")); 582 ret = -EINVAL; 583 } 584 585 __sev_put_ghcb(&state); 586 587 local_irq_restore(flags); 588 589 return ret; 590 } 591 592 static int snp_set_vmsa(void *va, void *caa, int apic_id, bool make_vmsa) 593 { 594 int ret; 595 596 if (snp_vmpl) { 597 struct svsm_call call = {}; 598 unsigned long flags; 599 600 local_irq_save(flags); 601 602 call.caa = this_cpu_read(svsm_caa); 603 call.rcx = __pa(va); 604 605 if (make_vmsa) { 606 /* Protocol 0, Call ID 2 */ 607 call.rax = SVSM_CORE_CALL(SVSM_CORE_CREATE_VCPU); 608 call.rdx = __pa(caa); 609 call.r8 = apic_id; 610 } else { 611 /* Protocol 0, Call ID 3 */ 612 call.rax = SVSM_CORE_CALL(SVSM_CORE_DELETE_VCPU); 613 } 614 615 ret = svsm_perform_call_protocol(&call); 616 617 local_irq_restore(flags); 618 } else { 619 /* 620 * If the kernel runs at VMPL0, it can change the VMSA 621 * bit for a page using the RMPADJUST instruction. 622 * However, for the instruction to succeed it must 623 * target the permissions of a lesser privileged (higher 624 * numbered) VMPL level, so use VMPL1. 625 */ 626 u64 attrs = 1; 627 628 if (make_vmsa) 629 attrs |= RMPADJUST_VMSA_PAGE_BIT; 630 631 ret = rmpadjust((unsigned long)va, RMP_PG_SIZE_4K, attrs); 632 } 633 634 return ret; 635 } 636 637 static void snp_cleanup_vmsa(struct sev_es_save_area *vmsa, int apic_id) 638 { 639 int err; 640 641 err = snp_set_vmsa(vmsa, NULL, apic_id, false); 642 if (err) 643 pr_err("clear VMSA page failed (%u), leaking page\n", err); 644 else 645 free_page((unsigned long)vmsa); 646 } 647 648 static void set_pte_enc(pte_t *kpte, int level, void *va) 649 { 650 struct pte_enc_desc d = { 651 .kpte = kpte, 652 .pte_level = level, 653 .va = va, 654 .encrypt = true 655 }; 656 657 prepare_pte_enc(&d); 658 set_pte_enc_mask(kpte, d.pfn, d.new_pgprot); 659 } 660 661 static void unshare_all_memory(void) 662 { 663 unsigned long addr, end, size, ghcb; 664 struct sev_es_runtime_data *data; 665 unsigned int npages, level; 666 bool skipped_addr; 667 pte_t *pte; 668 int cpu; 669 670 /* Unshare the direct mapping. */ 671 addr = PAGE_OFFSET; 672 end = PAGE_OFFSET + get_max_mapped(); 673 674 while (addr < end) { 675 pte = lookup_address(addr, &level); 676 size = page_level_size(level); 677 npages = size / PAGE_SIZE; 678 skipped_addr = false; 679 680 if (!pte || !pte_decrypted(*pte) || pte_none(*pte)) { 681 addr += size; 682 continue; 683 } 684 685 /* 686 * Ensure that all the per-CPU GHCBs are made private at the 687 * end of the unsharing loop so that the switch to the slower 688 * MSR protocol happens last. 689 */ 690 for_each_possible_cpu(cpu) { 691 data = per_cpu(runtime_data, cpu); 692 ghcb = (unsigned long)&data->ghcb_page; 693 694 /* Handle the case of a huge page containing the GHCB page */ 695 if (addr <= ghcb && ghcb < addr + size) { 696 skipped_addr = true; 697 break; 698 } 699 } 700 701 if (!skipped_addr) { 702 set_pte_enc(pte, level, (void *)addr); 703 snp_set_memory_private(addr, npages); 704 } 705 addr += size; 706 } 707 708 /* Unshare all bss decrypted memory. */ 709 addr = (unsigned long)__start_bss_decrypted; 710 end = (unsigned long)__start_bss_decrypted_unused; 711 npages = (end - addr) >> PAGE_SHIFT; 712 713 for (; addr < end; addr += PAGE_SIZE) { 714 pte = lookup_address(addr, &level); 715 if (!pte || !pte_decrypted(*pte) || pte_none(*pte)) 716 continue; 717 718 set_pte_enc(pte, level, (void *)addr); 719 } 720 addr = (unsigned long)__start_bss_decrypted; 721 snp_set_memory_private(addr, npages); 722 723 __flush_tlb_all(); 724 } 725 726 /* Stop new private<->shared conversions */ 727 void snp_kexec_begin(void) 728 { 729 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 730 return; 731 732 if (!IS_ENABLED(CONFIG_KEXEC_CORE)) 733 return; 734 735 /* 736 * Crash kernel ends up here with interrupts disabled: can't wait for 737 * conversions to finish. 738 * 739 * If race happened, just report and proceed. 740 */ 741 if (!set_memory_enc_stop_conversion()) 742 pr_warn("Failed to stop shared<->private conversions\n"); 743 } 744 745 /* 746 * Shutdown all APs except the one handling kexec/kdump and clearing 747 * the VMSA tag on AP's VMSA pages as they are not being used as 748 * VMSA page anymore. 749 */ 750 static void shutdown_all_aps(void) 751 { 752 struct sev_es_save_area *vmsa; 753 int apic_id, this_cpu, cpu; 754 755 this_cpu = get_cpu(); 756 757 /* 758 * APs are already in HLT loop when enc_kexec_finish() callback 759 * is invoked. 760 */ 761 for_each_present_cpu(cpu) { 762 vmsa = per_cpu(sev_vmsa, cpu); 763 764 /* 765 * The BSP or offlined APs do not have guest allocated VMSA 766 * and there is no need to clear the VMSA tag for this page. 767 */ 768 if (!vmsa) 769 continue; 770 771 /* 772 * Cannot clear the VMSA tag for the currently running vCPU. 773 */ 774 if (this_cpu == cpu) { 775 unsigned long pa; 776 struct page *p; 777 778 pa = __pa(vmsa); 779 /* 780 * Mark the VMSA page of the running vCPU as offline 781 * so that is excluded and not touched by makedumpfile 782 * while generating vmcore during kdump. 783 */ 784 p = pfn_to_online_page(pa >> PAGE_SHIFT); 785 if (p) 786 __SetPageOffline(p); 787 continue; 788 } 789 790 apic_id = cpuid_to_apicid[cpu]; 791 792 /* 793 * Issue AP destroy to ensure AP gets kicked out of guest mode 794 * to allow using RMPADJUST to remove the VMSA tag on it's 795 * VMSA page. 796 */ 797 vmgexit_ap_control(SVM_VMGEXIT_AP_DESTROY, vmsa, apic_id); 798 snp_cleanup_vmsa(vmsa, apic_id); 799 } 800 801 put_cpu(); 802 } 803 804 void snp_kexec_finish(void) 805 { 806 struct sev_es_runtime_data *data; 807 unsigned long size, addr; 808 unsigned int level, cpu; 809 struct ghcb *ghcb; 810 pte_t *pte; 811 812 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 813 return; 814 815 if (!IS_ENABLED(CONFIG_KEXEC_CORE)) 816 return; 817 818 shutdown_all_aps(); 819 820 unshare_all_memory(); 821 822 /* 823 * Switch to using the MSR protocol to change per-CPU GHCBs to 824 * private. All the per-CPU GHCBs have been switched back to private, 825 * so can't do any more GHCB calls to the hypervisor beyond this point 826 * until the kexec'ed kernel starts running. 827 */ 828 boot_ghcb = NULL; 829 sev_cfg.ghcbs_initialized = false; 830 831 for_each_possible_cpu(cpu) { 832 data = per_cpu(runtime_data, cpu); 833 ghcb = &data->ghcb_page; 834 pte = lookup_address((unsigned long)ghcb, &level); 835 size = page_level_size(level); 836 /* Handle the case of a huge page containing the GHCB page */ 837 addr = (unsigned long)ghcb & page_level_mask(level); 838 set_pte_enc(pte, level, (void *)addr); 839 snp_set_memory_private(addr, (size / PAGE_SIZE)); 840 } 841 } 842 843 #define __ATTR_BASE (SVM_SELECTOR_P_MASK | SVM_SELECTOR_S_MASK) 844 #define INIT_CS_ATTRIBS (__ATTR_BASE | SVM_SELECTOR_READ_MASK | SVM_SELECTOR_CODE_MASK) 845 #define INIT_DS_ATTRIBS (__ATTR_BASE | SVM_SELECTOR_WRITE_MASK) 846 847 #define INIT_LDTR_ATTRIBS (SVM_SELECTOR_P_MASK | 2) 848 #define INIT_TR_ATTRIBS (SVM_SELECTOR_P_MASK | 3) 849 850 static void *snp_alloc_vmsa_page(int cpu) 851 { 852 struct page *p; 853 854 /* 855 * Allocate VMSA page to work around the SNP erratum where the CPU will 856 * incorrectly signal an RMP violation #PF if a large page (2MB or 1GB) 857 * collides with the RMP entry of VMSA page. The recommended workaround 858 * is to not use a large page. 859 * 860 * Allocate an 8k page which is also 8k-aligned. 861 */ 862 p = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL_ACCOUNT | __GFP_ZERO, 1); 863 if (!p) 864 return NULL; 865 866 split_page(p, 1); 867 868 /* Free the first 4k. This page may be 2M/1G aligned and cannot be used. */ 869 __free_page(p); 870 871 return page_address(p + 1); 872 } 873 874 static int wakeup_cpu_via_vmgexit(u32 apic_id, unsigned long start_ip, unsigned int cpu) 875 { 876 struct sev_es_save_area *cur_vmsa, *vmsa; 877 struct svsm_ca *caa; 878 u8 sipi_vector; 879 int ret; 880 u64 cr4; 881 882 /* 883 * The hypervisor SNP feature support check has happened earlier, just check 884 * the AP_CREATION one here. 885 */ 886 if (!(sev_hv_features & GHCB_HV_FT_SNP_AP_CREATION)) 887 return -EOPNOTSUPP; 888 889 /* 890 * Verify the desired start IP against the known trampoline start IP 891 * to catch any future new trampolines that may be introduced that 892 * would require a new protected guest entry point. 893 */ 894 if (WARN_ONCE(start_ip != real_mode_header->trampoline_start, 895 "Unsupported SNP start_ip: %lx\n", start_ip)) 896 return -EINVAL; 897 898 /* Override start_ip with known protected guest start IP */ 899 start_ip = real_mode_header->sev_es_trampoline_start; 900 cur_vmsa = per_cpu(sev_vmsa, cpu); 901 902 /* 903 * A new VMSA is created each time because there is no guarantee that 904 * the current VMSA is the kernels or that the vCPU is not running. If 905 * an attempt was done to use the current VMSA with a running vCPU, a 906 * #VMEXIT of that vCPU would wipe out all of the settings being done 907 * here. 908 */ 909 vmsa = (struct sev_es_save_area *)snp_alloc_vmsa_page(cpu); 910 if (!vmsa) 911 return -ENOMEM; 912 913 /* If an SVSM is present, the SVSM per-CPU CAA will be !NULL */ 914 caa = per_cpu(svsm_caa, cpu); 915 916 /* CR4 should maintain the MCE value */ 917 cr4 = native_read_cr4() & X86_CR4_MCE; 918 919 /* Set the CS value based on the start_ip converted to a SIPI vector */ 920 sipi_vector = (start_ip >> 12); 921 vmsa->cs.base = sipi_vector << 12; 922 vmsa->cs.limit = AP_INIT_CS_LIMIT; 923 vmsa->cs.attrib = INIT_CS_ATTRIBS; 924 vmsa->cs.selector = sipi_vector << 8; 925 926 /* Set the RIP value based on start_ip */ 927 vmsa->rip = start_ip & 0xfff; 928 929 /* Set AP INIT defaults as documented in the APM */ 930 vmsa->ds.limit = AP_INIT_DS_LIMIT; 931 vmsa->ds.attrib = INIT_DS_ATTRIBS; 932 vmsa->es = vmsa->ds; 933 vmsa->fs = vmsa->ds; 934 vmsa->gs = vmsa->ds; 935 vmsa->ss = vmsa->ds; 936 937 vmsa->gdtr.limit = AP_INIT_GDTR_LIMIT; 938 vmsa->ldtr.limit = AP_INIT_LDTR_LIMIT; 939 vmsa->ldtr.attrib = INIT_LDTR_ATTRIBS; 940 vmsa->idtr.limit = AP_INIT_IDTR_LIMIT; 941 vmsa->tr.limit = AP_INIT_TR_LIMIT; 942 vmsa->tr.attrib = INIT_TR_ATTRIBS; 943 944 vmsa->cr4 = cr4; 945 vmsa->cr0 = AP_INIT_CR0_DEFAULT; 946 vmsa->dr7 = DR7_RESET_VALUE; 947 vmsa->dr6 = AP_INIT_DR6_DEFAULT; 948 vmsa->rflags = AP_INIT_RFLAGS_DEFAULT; 949 vmsa->g_pat = AP_INIT_GPAT_DEFAULT; 950 vmsa->xcr0 = AP_INIT_XCR0_DEFAULT; 951 vmsa->mxcsr = AP_INIT_MXCSR_DEFAULT; 952 vmsa->x87_ftw = AP_INIT_X87_FTW_DEFAULT; 953 vmsa->x87_fcw = AP_INIT_X87_FCW_DEFAULT; 954 955 /* SVME must be set. */ 956 vmsa->efer = EFER_SVME; 957 958 /* 959 * Set the SNP-specific fields for this VMSA: 960 * VMPL level 961 * SEV_FEATURES (matches the SEV STATUS MSR right shifted 2 bits) 962 */ 963 vmsa->vmpl = snp_vmpl; 964 vmsa->sev_features = sev_status >> 2; 965 966 /* Populate AP's TSC scale/offset to get accurate TSC values. */ 967 if (cc_platform_has(CC_ATTR_GUEST_SNP_SECURE_TSC)) { 968 vmsa->tsc_scale = snp_tsc_scale; 969 vmsa->tsc_offset = snp_tsc_offset; 970 } 971 972 /* Switch the page over to a VMSA page now that it is initialized */ 973 ret = snp_set_vmsa(vmsa, caa, apic_id, true); 974 if (ret) { 975 pr_err("set VMSA page failed (%u)\n", ret); 976 free_page((unsigned long)vmsa); 977 978 return -EINVAL; 979 } 980 981 /* Issue VMGEXIT AP Creation NAE event */ 982 ret = vmgexit_ap_control(SVM_VMGEXIT_AP_CREATE, vmsa, apic_id); 983 if (ret) { 984 snp_cleanup_vmsa(vmsa, apic_id); 985 vmsa = NULL; 986 } 987 988 /* Free up any previous VMSA page */ 989 if (cur_vmsa) 990 snp_cleanup_vmsa(cur_vmsa, apic_id); 991 992 /* Record the current VMSA page */ 993 per_cpu(sev_vmsa, cpu) = vmsa; 994 995 return ret; 996 } 997 998 void __init snp_set_wakeup_secondary_cpu(void) 999 { 1000 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 1001 return; 1002 1003 /* 1004 * Always set this override if SNP is enabled. This makes it the 1005 * required method to start APs under SNP. If the hypervisor does 1006 * not support AP creation, then no APs will be started. 1007 */ 1008 apic_update_callback(wakeup_secondary_cpu, wakeup_cpu_via_vmgexit); 1009 } 1010 1011 int __init sev_es_setup_ap_jump_table(struct real_mode_header *rmh) 1012 { 1013 u16 startup_cs, startup_ip; 1014 phys_addr_t jump_table_pa; 1015 u64 jump_table_addr; 1016 u16 __iomem *jump_table; 1017 1018 jump_table_addr = get_jump_table_addr(); 1019 1020 /* On UP guests there is no jump table so this is not a failure */ 1021 if (!jump_table_addr) 1022 return 0; 1023 1024 /* Check if AP Jump Table is page-aligned */ 1025 if (jump_table_addr & ~PAGE_MASK) 1026 return -EINVAL; 1027 1028 jump_table_pa = jump_table_addr & PAGE_MASK; 1029 1030 startup_cs = (u16)(rmh->trampoline_start >> 4); 1031 startup_ip = (u16)(rmh->sev_es_trampoline_start - 1032 rmh->trampoline_start); 1033 1034 jump_table = ioremap_encrypted(jump_table_pa, PAGE_SIZE); 1035 if (!jump_table) 1036 return -EIO; 1037 1038 writew(startup_ip, &jump_table[0]); 1039 writew(startup_cs, &jump_table[1]); 1040 1041 iounmap(jump_table); 1042 1043 return 0; 1044 } 1045 1046 /* 1047 * This is needed by the OVMF UEFI firmware which will use whatever it finds in 1048 * the GHCB MSR as its GHCB to talk to the hypervisor. So make sure the per-cpu 1049 * runtime GHCBs used by the kernel are also mapped in the EFI page-table. 1050 * 1051 * When running under SVSM the CA page is needed too, so map it as well. 1052 */ 1053 int __init sev_es_efi_map_ghcbs_cas(pgd_t *pgd) 1054 { 1055 unsigned long address, pflags, pflags_enc; 1056 struct sev_es_runtime_data *data; 1057 int cpu; 1058 u64 pfn; 1059 1060 if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) 1061 return 0; 1062 1063 pflags = _PAGE_NX | _PAGE_RW; 1064 pflags_enc = cc_mkenc(pflags); 1065 1066 for_each_possible_cpu(cpu) { 1067 data = per_cpu(runtime_data, cpu); 1068 1069 address = __pa(&data->ghcb_page); 1070 pfn = address >> PAGE_SHIFT; 1071 1072 if (kernel_map_pages_in_pgd(pgd, pfn, address, 1, pflags)) 1073 return 1; 1074 1075 if (snp_vmpl) { 1076 address = per_cpu(svsm_caa_pa, cpu); 1077 if (!address) 1078 return 1; 1079 1080 pfn = address >> PAGE_SHIFT; 1081 if (kernel_map_pages_in_pgd(pgd, pfn, address, 1, pflags_enc)) 1082 return 1; 1083 } 1084 } 1085 1086 return 0; 1087 } 1088 1089 static void snp_register_per_cpu_ghcb(void) 1090 { 1091 struct sev_es_runtime_data *data; 1092 struct ghcb *ghcb; 1093 1094 data = this_cpu_read(runtime_data); 1095 ghcb = &data->ghcb_page; 1096 1097 snp_register_ghcb_early(__pa(ghcb)); 1098 } 1099 1100 void setup_ghcb(void) 1101 { 1102 if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) 1103 return; 1104 1105 /* 1106 * Check whether the runtime #VC exception handler is active. It uses 1107 * the per-CPU GHCB page which is set up by sev_es_init_vc_handling(). 1108 * 1109 * If SNP is active, register the per-CPU GHCB page so that the runtime 1110 * exception handler can use it. 1111 */ 1112 if (initial_vc_handler == (unsigned long)kernel_exc_vmm_communication) { 1113 if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 1114 snp_register_per_cpu_ghcb(); 1115 1116 sev_cfg.ghcbs_initialized = true; 1117 1118 return; 1119 } 1120 1121 /* 1122 * Make sure the hypervisor talks a supported protocol. 1123 * This gets called only in the BSP boot phase. 1124 */ 1125 if (!sev_es_negotiate_protocol()) 1126 sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ); 1127 1128 /* 1129 * Clear the boot_ghcb. The first exception comes in before the bss 1130 * section is cleared. 1131 */ 1132 memset(&boot_ghcb_page, 0, PAGE_SIZE); 1133 1134 /* Alright - Make the boot-ghcb public */ 1135 boot_ghcb = &boot_ghcb_page; 1136 1137 /* SNP guest requires that GHCB GPA must be registered. */ 1138 if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 1139 snp_register_ghcb_early(__pa(&boot_ghcb_page)); 1140 } 1141 1142 #ifdef CONFIG_HOTPLUG_CPU 1143 static void sev_es_ap_hlt_loop(void) 1144 { 1145 struct ghcb_state state; 1146 struct ghcb *ghcb; 1147 1148 ghcb = __sev_get_ghcb(&state); 1149 1150 while (true) { 1151 vc_ghcb_invalidate(ghcb); 1152 ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_HLT_LOOP); 1153 ghcb_set_sw_exit_info_1(ghcb, 0); 1154 ghcb_set_sw_exit_info_2(ghcb, 0); 1155 1156 sev_es_wr_ghcb_msr(__pa(ghcb)); 1157 VMGEXIT(); 1158 1159 /* Wakeup signal? */ 1160 if (ghcb_sw_exit_info_2_is_valid(ghcb) && 1161 ghcb->save.sw_exit_info_2) 1162 break; 1163 } 1164 1165 __sev_put_ghcb(&state); 1166 } 1167 1168 /* 1169 * Play_dead handler when running under SEV-ES. This is needed because 1170 * the hypervisor can't deliver an SIPI request to restart the AP. 1171 * Instead the kernel has to issue a VMGEXIT to halt the VCPU until the 1172 * hypervisor wakes it up again. 1173 */ 1174 static void sev_es_play_dead(void) 1175 { 1176 play_dead_common(); 1177 1178 /* IRQs now disabled */ 1179 1180 sev_es_ap_hlt_loop(); 1181 1182 /* 1183 * If we get here, the VCPU was woken up again. Jump to CPU 1184 * startup code to get it back online. 1185 */ 1186 soft_restart_cpu(); 1187 } 1188 #else /* CONFIG_HOTPLUG_CPU */ 1189 #define sev_es_play_dead native_play_dead 1190 #endif /* CONFIG_HOTPLUG_CPU */ 1191 1192 #ifdef CONFIG_SMP 1193 static void __init sev_es_setup_play_dead(void) 1194 { 1195 smp_ops.play_dead = sev_es_play_dead; 1196 } 1197 #else 1198 static inline void sev_es_setup_play_dead(void) { } 1199 #endif 1200 1201 static void __init alloc_runtime_data(int cpu) 1202 { 1203 struct sev_es_runtime_data *data; 1204 1205 data = memblock_alloc_node(sizeof(*data), PAGE_SIZE, cpu_to_node(cpu)); 1206 if (!data) 1207 panic("Can't allocate SEV-ES runtime data"); 1208 1209 per_cpu(runtime_data, cpu) = data; 1210 1211 if (snp_vmpl) { 1212 struct svsm_ca *caa; 1213 1214 /* Allocate the SVSM CA page if an SVSM is present */ 1215 caa = memblock_alloc_or_panic(sizeof(*caa), PAGE_SIZE); 1216 1217 per_cpu(svsm_caa, cpu) = caa; 1218 per_cpu(svsm_caa_pa, cpu) = __pa(caa); 1219 } 1220 } 1221 1222 static void __init init_ghcb(int cpu) 1223 { 1224 struct sev_es_runtime_data *data; 1225 int err; 1226 1227 data = per_cpu(runtime_data, cpu); 1228 1229 err = early_set_memory_decrypted((unsigned long)&data->ghcb_page, 1230 sizeof(data->ghcb_page)); 1231 if (err) 1232 panic("Can't map GHCBs unencrypted"); 1233 1234 memset(&data->ghcb_page, 0, sizeof(data->ghcb_page)); 1235 1236 data->ghcb_active = false; 1237 data->backup_ghcb_active = false; 1238 } 1239 1240 void __init sev_es_init_vc_handling(void) 1241 { 1242 int cpu; 1243 1244 BUILD_BUG_ON(offsetof(struct sev_es_runtime_data, ghcb_page) % PAGE_SIZE); 1245 1246 if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) 1247 return; 1248 1249 if (!sev_es_check_cpu_features()) 1250 panic("SEV-ES CPU Features missing"); 1251 1252 /* 1253 * SNP is supported in v2 of the GHCB spec which mandates support for HV 1254 * features. 1255 */ 1256 if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) { 1257 sev_hv_features = get_hv_features(); 1258 1259 if (!(sev_hv_features & GHCB_HV_FT_SNP)) 1260 sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED); 1261 } 1262 1263 /* Initialize per-cpu GHCB pages */ 1264 for_each_possible_cpu(cpu) { 1265 alloc_runtime_data(cpu); 1266 init_ghcb(cpu); 1267 } 1268 1269 /* If running under an SVSM, switch to the per-cpu CA */ 1270 if (snp_vmpl) { 1271 struct svsm_call call = {}; 1272 unsigned long flags; 1273 int ret; 1274 1275 local_irq_save(flags); 1276 1277 /* 1278 * SVSM_CORE_REMAP_CA call: 1279 * RAX = 0 (Protocol=0, CallID=0) 1280 * RCX = New CA GPA 1281 */ 1282 call.caa = svsm_get_caa(); 1283 call.rax = SVSM_CORE_CALL(SVSM_CORE_REMAP_CA); 1284 call.rcx = this_cpu_read(svsm_caa_pa); 1285 ret = svsm_perform_call_protocol(&call); 1286 if (ret) 1287 panic("Can't remap the SVSM CA, ret=%d, rax_out=0x%llx\n", 1288 ret, call.rax_out); 1289 1290 sev_cfg.use_cas = true; 1291 1292 local_irq_restore(flags); 1293 } 1294 1295 sev_es_setup_play_dead(); 1296 1297 /* Secondary CPUs use the runtime #VC handler */ 1298 initial_vc_handler = (unsigned long)kernel_exc_vmm_communication; 1299 } 1300 1301 /* 1302 * SEV-SNP guests should only execute dmi_setup() if EFI_CONFIG_TABLES are 1303 * enabled, as the alternative (fallback) logic for DMI probing in the legacy 1304 * ROM region can cause a crash since this region is not pre-validated. 1305 */ 1306 void __init snp_dmi_setup(void) 1307 { 1308 if (efi_enabled(EFI_CONFIG_TABLES)) 1309 dmi_setup(); 1310 } 1311 1312 static void dump_cpuid_table(void) 1313 { 1314 const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table(); 1315 int i = 0; 1316 1317 pr_info("count=%d reserved=0x%x reserved2=0x%llx\n", 1318 cpuid_table->count, cpuid_table->__reserved1, cpuid_table->__reserved2); 1319 1320 for (i = 0; i < SNP_CPUID_COUNT_MAX; i++) { 1321 const struct snp_cpuid_fn *fn = &cpuid_table->fn[i]; 1322 1323 pr_info("index=%3d fn=0x%08x subfn=0x%08x: eax=0x%08x ebx=0x%08x ecx=0x%08x edx=0x%08x xcr0_in=0x%016llx xss_in=0x%016llx reserved=0x%016llx\n", 1324 i, fn->eax_in, fn->ecx_in, fn->eax, fn->ebx, fn->ecx, 1325 fn->edx, fn->xcr0_in, fn->xss_in, fn->__reserved); 1326 } 1327 } 1328 1329 /* 1330 * It is useful from an auditing/testing perspective to provide an easy way 1331 * for the guest owner to know that the CPUID table has been initialized as 1332 * expected, but that initialization happens too early in boot to print any 1333 * sort of indicator, and there's not really any other good place to do it, 1334 * so do it here. 1335 * 1336 * If running as an SNP guest, report the current VM privilege level (VMPL). 1337 */ 1338 static int __init report_snp_info(void) 1339 { 1340 const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table(); 1341 1342 if (cpuid_table->count) { 1343 pr_info("Using SNP CPUID table, %d entries present.\n", 1344 cpuid_table->count); 1345 1346 if (sev_cfg.debug) 1347 dump_cpuid_table(); 1348 } 1349 1350 if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 1351 pr_info("SNP running at VMPL%u.\n", snp_vmpl); 1352 1353 return 0; 1354 } 1355 arch_initcall(report_snp_info); 1356 1357 static void update_attest_input(struct svsm_call *call, struct svsm_attest_call *input) 1358 { 1359 /* If (new) lengths have been returned, propagate them up */ 1360 if (call->rcx_out != call->rcx) 1361 input->manifest_buf.len = call->rcx_out; 1362 1363 if (call->rdx_out != call->rdx) 1364 input->certificates_buf.len = call->rdx_out; 1365 1366 if (call->r8_out != call->r8) 1367 input->report_buf.len = call->r8_out; 1368 } 1369 1370 int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call, 1371 struct svsm_attest_call *input) 1372 { 1373 struct svsm_attest_call *ac; 1374 unsigned long flags; 1375 u64 attest_call_pa; 1376 int ret; 1377 1378 if (!snp_vmpl) 1379 return -EINVAL; 1380 1381 local_irq_save(flags); 1382 1383 call->caa = svsm_get_caa(); 1384 1385 ac = (struct svsm_attest_call *)call->caa->svsm_buffer; 1386 attest_call_pa = svsm_get_caa_pa() + offsetof(struct svsm_ca, svsm_buffer); 1387 1388 *ac = *input; 1389 1390 /* 1391 * Set input registers for the request and set RDX and R8 to known 1392 * values in order to detect length values being returned in them. 1393 */ 1394 call->rax = call_id; 1395 call->rcx = attest_call_pa; 1396 call->rdx = -1; 1397 call->r8 = -1; 1398 ret = svsm_perform_call_protocol(call); 1399 update_attest_input(call, input); 1400 1401 local_irq_restore(flags); 1402 1403 return ret; 1404 } 1405 EXPORT_SYMBOL_GPL(snp_issue_svsm_attest_req); 1406 1407 static int snp_issue_guest_request(struct snp_guest_req *req) 1408 { 1409 struct snp_req_data *input = &req->input; 1410 struct ghcb_state state; 1411 struct es_em_ctxt ctxt; 1412 unsigned long flags; 1413 struct ghcb *ghcb; 1414 int ret; 1415 1416 req->exitinfo2 = SEV_RET_NO_FW_CALL; 1417 1418 /* 1419 * __sev_get_ghcb() needs to run with IRQs disabled because it is using 1420 * a per-CPU GHCB. 1421 */ 1422 local_irq_save(flags); 1423 1424 ghcb = __sev_get_ghcb(&state); 1425 if (!ghcb) { 1426 ret = -EIO; 1427 goto e_restore_irq; 1428 } 1429 1430 vc_ghcb_invalidate(ghcb); 1431 1432 if (req->exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) { 1433 ghcb_set_rax(ghcb, input->data_gpa); 1434 ghcb_set_rbx(ghcb, input->data_npages); 1435 } 1436 1437 ret = sev_es_ghcb_hv_call(ghcb, &ctxt, req->exit_code, input->req_gpa, input->resp_gpa); 1438 if (ret) 1439 goto e_put; 1440 1441 req->exitinfo2 = ghcb->save.sw_exit_info_2; 1442 switch (req->exitinfo2) { 1443 case 0: 1444 break; 1445 1446 case SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_BUSY): 1447 ret = -EAGAIN; 1448 break; 1449 1450 case SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN): 1451 /* Number of expected pages are returned in RBX */ 1452 if (req->exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) { 1453 input->data_npages = ghcb_get_rbx(ghcb); 1454 ret = -ENOSPC; 1455 break; 1456 } 1457 fallthrough; 1458 default: 1459 ret = -EIO; 1460 break; 1461 } 1462 1463 e_put: 1464 __sev_put_ghcb(&state); 1465 e_restore_irq: 1466 local_irq_restore(flags); 1467 1468 return ret; 1469 } 1470 1471 /** 1472 * snp_svsm_vtpm_probe() - Probe if SVSM provides a vTPM device 1473 * 1474 * Check that there is SVSM and that it supports at least TPM_SEND_COMMAND 1475 * which is the only request used so far. 1476 * 1477 * Return: true if the platform provides a vTPM SVSM device, false otherwise. 1478 */ 1479 static bool snp_svsm_vtpm_probe(void) 1480 { 1481 struct svsm_call call = {}; 1482 1483 /* The vTPM device is available only if a SVSM is present */ 1484 if (!snp_vmpl) 1485 return false; 1486 1487 call.caa = svsm_get_caa(); 1488 call.rax = SVSM_VTPM_CALL(SVSM_VTPM_QUERY); 1489 1490 if (svsm_perform_call_protocol(&call)) 1491 return false; 1492 1493 /* Check platform commands contains TPM_SEND_COMMAND - platform command 8 */ 1494 return call.rcx_out & BIT_ULL(8); 1495 } 1496 1497 /** 1498 * snp_svsm_vtpm_send_command() - Execute a vTPM operation on SVSM 1499 * @buffer: A buffer used to both send the command and receive the response. 1500 * 1501 * Execute a SVSM_VTPM_CMD call as defined by 1502 * "Secure VM Service Module for SEV-SNP Guests" Publication # 58019 Revision: 1.00 1503 * 1504 * All command request/response buffers have a common structure as specified by 1505 * the following table: 1506 * Byte Size In/Out Description 1507 * Offset (Bytes) 1508 * 0x000 4 In Platform command 1509 * Out Platform command response size 1510 * 1511 * Each command can build upon this common request/response structure to create 1512 * a structure specific to the command. See include/linux/tpm_svsm.h for more 1513 * details. 1514 * 1515 * Return: 0 on success, -errno on failure 1516 */ 1517 int snp_svsm_vtpm_send_command(u8 *buffer) 1518 { 1519 struct svsm_call call = {}; 1520 1521 call.caa = svsm_get_caa(); 1522 call.rax = SVSM_VTPM_CALL(SVSM_VTPM_CMD); 1523 call.rcx = __pa(buffer); 1524 1525 return svsm_perform_call_protocol(&call); 1526 } 1527 EXPORT_SYMBOL_GPL(snp_svsm_vtpm_send_command); 1528 1529 static struct platform_device sev_guest_device = { 1530 .name = "sev-guest", 1531 .id = -1, 1532 }; 1533 1534 static struct platform_device tpm_svsm_device = { 1535 .name = "tpm-svsm", 1536 .id = -1, 1537 }; 1538 1539 static int __init snp_init_platform_device(void) 1540 { 1541 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 1542 return -ENODEV; 1543 1544 if (platform_device_register(&sev_guest_device)) 1545 return -ENODEV; 1546 1547 if (snp_svsm_vtpm_probe() && 1548 platform_device_register(&tpm_svsm_device)) 1549 return -ENODEV; 1550 1551 pr_info("SNP guest platform devices initialized.\n"); 1552 return 0; 1553 } 1554 device_initcall(snp_init_platform_device); 1555 1556 void sev_show_status(void) 1557 { 1558 int i; 1559 1560 pr_info("Status: "); 1561 for (i = 0; i < MSR_AMD64_SNP_RESV_BIT; i++) { 1562 if (sev_status & BIT_ULL(i)) { 1563 if (!sev_status_feat_names[i]) 1564 continue; 1565 1566 pr_cont("%s ", sev_status_feat_names[i]); 1567 } 1568 } 1569 pr_cont("\n"); 1570 } 1571 1572 void __init snp_update_svsm_ca(void) 1573 { 1574 if (!snp_vmpl) 1575 return; 1576 1577 /* Update the CAA to a proper kernel address */ 1578 boot_svsm_caa = &boot_svsm_ca_page; 1579 } 1580 1581 #ifdef CONFIG_SYSFS 1582 static ssize_t vmpl_show(struct kobject *kobj, 1583 struct kobj_attribute *attr, char *buf) 1584 { 1585 return sysfs_emit(buf, "%d\n", snp_vmpl); 1586 } 1587 1588 static struct kobj_attribute vmpl_attr = __ATTR_RO(vmpl); 1589 1590 static struct attribute *vmpl_attrs[] = { 1591 &vmpl_attr.attr, 1592 NULL 1593 }; 1594 1595 static struct attribute_group sev_attr_group = { 1596 .attrs = vmpl_attrs, 1597 }; 1598 1599 static int __init sev_sysfs_init(void) 1600 { 1601 struct kobject *sev_kobj; 1602 struct device *dev_root; 1603 int ret; 1604 1605 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 1606 return -ENODEV; 1607 1608 dev_root = bus_get_dev_root(&cpu_subsys); 1609 if (!dev_root) 1610 return -ENODEV; 1611 1612 sev_kobj = kobject_create_and_add("sev", &dev_root->kobj); 1613 put_device(dev_root); 1614 1615 if (!sev_kobj) 1616 return -ENOMEM; 1617 1618 ret = sysfs_create_group(sev_kobj, &sev_attr_group); 1619 if (ret) 1620 kobject_put(sev_kobj); 1621 1622 return ret; 1623 } 1624 arch_initcall(sev_sysfs_init); 1625 #endif // CONFIG_SYSFS 1626 1627 static void free_shared_pages(void *buf, size_t sz) 1628 { 1629 unsigned int npages = PAGE_ALIGN(sz) >> PAGE_SHIFT; 1630 int ret; 1631 1632 if (!buf) 1633 return; 1634 1635 ret = set_memory_encrypted((unsigned long)buf, npages); 1636 if (ret) { 1637 WARN_ONCE(ret, "failed to restore encryption mask (leak it)\n"); 1638 return; 1639 } 1640 1641 __free_pages(virt_to_page(buf), get_order(sz)); 1642 } 1643 1644 static void *alloc_shared_pages(size_t sz) 1645 { 1646 unsigned int npages = PAGE_ALIGN(sz) >> PAGE_SHIFT; 1647 struct page *page; 1648 int ret; 1649 1650 page = alloc_pages(GFP_KERNEL_ACCOUNT, get_order(sz)); 1651 if (!page) 1652 return NULL; 1653 1654 ret = set_memory_decrypted((unsigned long)page_address(page), npages); 1655 if (ret) { 1656 pr_err("failed to mark page shared, ret=%d\n", ret); 1657 __free_pages(page, get_order(sz)); 1658 return NULL; 1659 } 1660 1661 return page_address(page); 1662 } 1663 1664 static u8 *get_vmpck(int id, struct snp_secrets_page *secrets, u32 **seqno) 1665 { 1666 u8 *key = NULL; 1667 1668 switch (id) { 1669 case 0: 1670 *seqno = &secrets->os_area.msg_seqno_0; 1671 key = secrets->vmpck0; 1672 break; 1673 case 1: 1674 *seqno = &secrets->os_area.msg_seqno_1; 1675 key = secrets->vmpck1; 1676 break; 1677 case 2: 1678 *seqno = &secrets->os_area.msg_seqno_2; 1679 key = secrets->vmpck2; 1680 break; 1681 case 3: 1682 *seqno = &secrets->os_area.msg_seqno_3; 1683 key = secrets->vmpck3; 1684 break; 1685 default: 1686 break; 1687 } 1688 1689 return key; 1690 } 1691 1692 static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen) 1693 { 1694 struct aesgcm_ctx *ctx; 1695 1696 ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); 1697 if (!ctx) 1698 return NULL; 1699 1700 if (aesgcm_expandkey(ctx, key, keylen, AUTHTAG_LEN)) { 1701 pr_err("Crypto context initialization failed\n"); 1702 kfree(ctx); 1703 return NULL; 1704 } 1705 1706 return ctx; 1707 } 1708 1709 int snp_msg_init(struct snp_msg_desc *mdesc, int vmpck_id) 1710 { 1711 /* Adjust the default VMPCK key based on the executing VMPL level */ 1712 if (vmpck_id == -1) 1713 vmpck_id = snp_vmpl; 1714 1715 mdesc->vmpck = get_vmpck(vmpck_id, mdesc->secrets, &mdesc->os_area_msg_seqno); 1716 if (!mdesc->vmpck) { 1717 pr_err("Invalid VMPCK%d communication key\n", vmpck_id); 1718 return -EINVAL; 1719 } 1720 1721 /* Verify that VMPCK is not zero. */ 1722 if (!memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN)) { 1723 pr_err("Empty VMPCK%d communication key\n", vmpck_id); 1724 return -EINVAL; 1725 } 1726 1727 mdesc->vmpck_id = vmpck_id; 1728 1729 mdesc->ctx = snp_init_crypto(mdesc->vmpck, VMPCK_KEY_LEN); 1730 if (!mdesc->ctx) 1731 return -ENOMEM; 1732 1733 return 0; 1734 } 1735 EXPORT_SYMBOL_GPL(snp_msg_init); 1736 1737 struct snp_msg_desc *snp_msg_alloc(void) 1738 { 1739 struct snp_msg_desc *mdesc; 1740 void __iomem *mem; 1741 1742 BUILD_BUG_ON(sizeof(struct snp_guest_msg) > PAGE_SIZE); 1743 1744 mdesc = kzalloc(sizeof(struct snp_msg_desc), GFP_KERNEL); 1745 if (!mdesc) 1746 return ERR_PTR(-ENOMEM); 1747 1748 mem = ioremap_encrypted(sev_secrets_pa, PAGE_SIZE); 1749 if (!mem) 1750 goto e_free_mdesc; 1751 1752 mdesc->secrets = (__force struct snp_secrets_page *)mem; 1753 1754 /* Allocate the shared page used for the request and response message. */ 1755 mdesc->request = alloc_shared_pages(sizeof(struct snp_guest_msg)); 1756 if (!mdesc->request) 1757 goto e_unmap; 1758 1759 mdesc->response = alloc_shared_pages(sizeof(struct snp_guest_msg)); 1760 if (!mdesc->response) 1761 goto e_free_request; 1762 1763 return mdesc; 1764 1765 e_free_request: 1766 free_shared_pages(mdesc->request, sizeof(struct snp_guest_msg)); 1767 e_unmap: 1768 iounmap(mem); 1769 e_free_mdesc: 1770 kfree(mdesc); 1771 1772 return ERR_PTR(-ENOMEM); 1773 } 1774 EXPORT_SYMBOL_GPL(snp_msg_alloc); 1775 1776 void snp_msg_free(struct snp_msg_desc *mdesc) 1777 { 1778 if (!mdesc) 1779 return; 1780 1781 kfree(mdesc->ctx); 1782 free_shared_pages(mdesc->response, sizeof(struct snp_guest_msg)); 1783 free_shared_pages(mdesc->request, sizeof(struct snp_guest_msg)); 1784 iounmap((__force void __iomem *)mdesc->secrets); 1785 1786 memset(mdesc, 0, sizeof(*mdesc)); 1787 kfree(mdesc); 1788 } 1789 EXPORT_SYMBOL_GPL(snp_msg_free); 1790 1791 /* Mutex to serialize the shared buffer access and command handling. */ 1792 static DEFINE_MUTEX(snp_cmd_mutex); 1793 1794 /* 1795 * If an error is received from the host or AMD Secure Processor (ASP) there 1796 * are two options. Either retry the exact same encrypted request or discontinue 1797 * using the VMPCK. 1798 * 1799 * This is because in the current encryption scheme GHCB v2 uses AES-GCM to 1800 * encrypt the requests. The IV for this scheme is the sequence number. GCM 1801 * cannot tolerate IV reuse. 1802 * 1803 * The ASP FW v1.51 only increments the sequence numbers on a successful 1804 * guest<->ASP back and forth and only accepts messages at its exact sequence 1805 * number. 1806 * 1807 * So if the sequence number were to be reused the encryption scheme is 1808 * vulnerable. If the sequence number were incremented for a fresh IV the ASP 1809 * will reject the request. 1810 */ 1811 static void snp_disable_vmpck(struct snp_msg_desc *mdesc) 1812 { 1813 pr_alert("Disabling VMPCK%d communication key to prevent IV reuse.\n", 1814 mdesc->vmpck_id); 1815 memzero_explicit(mdesc->vmpck, VMPCK_KEY_LEN); 1816 mdesc->vmpck = NULL; 1817 } 1818 1819 static inline u64 __snp_get_msg_seqno(struct snp_msg_desc *mdesc) 1820 { 1821 u64 count; 1822 1823 lockdep_assert_held(&snp_cmd_mutex); 1824 1825 /* Read the current message sequence counter from secrets pages */ 1826 count = *mdesc->os_area_msg_seqno; 1827 1828 return count + 1; 1829 } 1830 1831 /* Return a non-zero on success */ 1832 static u64 snp_get_msg_seqno(struct snp_msg_desc *mdesc) 1833 { 1834 u64 count = __snp_get_msg_seqno(mdesc); 1835 1836 /* 1837 * The message sequence counter for the SNP guest request is a 64-bit 1838 * value but the version 2 of GHCB specification defines a 32-bit storage 1839 * for it. If the counter exceeds the 32-bit value then return zero. 1840 * The caller should check the return value, but if the caller happens to 1841 * not check the value and use it, then the firmware treats zero as an 1842 * invalid number and will fail the message request. 1843 */ 1844 if (count >= UINT_MAX) { 1845 pr_err("request message sequence counter overflow\n"); 1846 return 0; 1847 } 1848 1849 return count; 1850 } 1851 1852 static void snp_inc_msg_seqno(struct snp_msg_desc *mdesc) 1853 { 1854 /* 1855 * The counter is also incremented by the PSP, so increment it by 2 1856 * and save in secrets page. 1857 */ 1858 *mdesc->os_area_msg_seqno += 2; 1859 } 1860 1861 static int verify_and_dec_payload(struct snp_msg_desc *mdesc, struct snp_guest_req *req) 1862 { 1863 struct snp_guest_msg *resp_msg = &mdesc->secret_response; 1864 struct snp_guest_msg *req_msg = &mdesc->secret_request; 1865 struct snp_guest_msg_hdr *req_msg_hdr = &req_msg->hdr; 1866 struct snp_guest_msg_hdr *resp_msg_hdr = &resp_msg->hdr; 1867 struct aesgcm_ctx *ctx = mdesc->ctx; 1868 u8 iv[GCM_AES_IV_SIZE] = {}; 1869 1870 pr_debug("response [seqno %lld type %d version %d sz %d]\n", 1871 resp_msg_hdr->msg_seqno, resp_msg_hdr->msg_type, resp_msg_hdr->msg_version, 1872 resp_msg_hdr->msg_sz); 1873 1874 /* Copy response from shared memory to encrypted memory. */ 1875 memcpy(resp_msg, mdesc->response, sizeof(*resp_msg)); 1876 1877 /* Verify that the sequence counter is incremented by 1 */ 1878 if (unlikely(resp_msg_hdr->msg_seqno != (req_msg_hdr->msg_seqno + 1))) 1879 return -EBADMSG; 1880 1881 /* Verify response message type and version number. */ 1882 if (resp_msg_hdr->msg_type != (req_msg_hdr->msg_type + 1) || 1883 resp_msg_hdr->msg_version != req_msg_hdr->msg_version) 1884 return -EBADMSG; 1885 1886 /* 1887 * If the message size is greater than our buffer length then return 1888 * an error. 1889 */ 1890 if (unlikely((resp_msg_hdr->msg_sz + ctx->authsize) > req->resp_sz)) 1891 return -EBADMSG; 1892 1893 /* Decrypt the payload */ 1894 memcpy(iv, &resp_msg_hdr->msg_seqno, min(sizeof(iv), sizeof(resp_msg_hdr->msg_seqno))); 1895 if (!aesgcm_decrypt(ctx, req->resp_buf, resp_msg->payload, resp_msg_hdr->msg_sz, 1896 &resp_msg_hdr->algo, AAD_LEN, iv, resp_msg_hdr->authtag)) 1897 return -EBADMSG; 1898 1899 return 0; 1900 } 1901 1902 static int enc_payload(struct snp_msg_desc *mdesc, u64 seqno, struct snp_guest_req *req) 1903 { 1904 struct snp_guest_msg *msg = &mdesc->secret_request; 1905 struct snp_guest_msg_hdr *hdr = &msg->hdr; 1906 struct aesgcm_ctx *ctx = mdesc->ctx; 1907 u8 iv[GCM_AES_IV_SIZE] = {}; 1908 1909 memset(msg, 0, sizeof(*msg)); 1910 1911 hdr->algo = SNP_AEAD_AES_256_GCM; 1912 hdr->hdr_version = MSG_HDR_VER; 1913 hdr->hdr_sz = sizeof(*hdr); 1914 hdr->msg_type = req->msg_type; 1915 hdr->msg_version = req->msg_version; 1916 hdr->msg_seqno = seqno; 1917 hdr->msg_vmpck = req->vmpck_id; 1918 hdr->msg_sz = req->req_sz; 1919 1920 /* Verify the sequence number is non-zero */ 1921 if (!hdr->msg_seqno) 1922 return -ENOSR; 1923 1924 pr_debug("request [seqno %lld type %d version %d sz %d]\n", 1925 hdr->msg_seqno, hdr->msg_type, hdr->msg_version, hdr->msg_sz); 1926 1927 if (WARN_ON((req->req_sz + ctx->authsize) > sizeof(msg->payload))) 1928 return -EBADMSG; 1929 1930 memcpy(iv, &hdr->msg_seqno, min(sizeof(iv), sizeof(hdr->msg_seqno))); 1931 aesgcm_encrypt(ctx, msg->payload, req->req_buf, req->req_sz, &hdr->algo, 1932 AAD_LEN, iv, hdr->authtag); 1933 1934 return 0; 1935 } 1936 1937 static int __handle_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req) 1938 { 1939 unsigned long req_start = jiffies; 1940 unsigned int override_npages = 0; 1941 u64 override_err = 0; 1942 int rc; 1943 1944 retry_request: 1945 /* 1946 * Call firmware to process the request. In this function the encrypted 1947 * message enters shared memory with the host. So after this call the 1948 * sequence number must be incremented or the VMPCK must be deleted to 1949 * prevent reuse of the IV. 1950 */ 1951 rc = snp_issue_guest_request(req); 1952 switch (rc) { 1953 case -ENOSPC: 1954 /* 1955 * If the extended guest request fails due to having too 1956 * small of a certificate data buffer, retry the same 1957 * guest request without the extended data request in 1958 * order to increment the sequence number and thus avoid 1959 * IV reuse. 1960 */ 1961 override_npages = req->input.data_npages; 1962 req->exit_code = SVM_VMGEXIT_GUEST_REQUEST; 1963 1964 /* 1965 * Override the error to inform callers the given extended 1966 * request buffer size was too small and give the caller the 1967 * required buffer size. 1968 */ 1969 override_err = SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN); 1970 1971 /* 1972 * If this call to the firmware succeeds, the sequence number can 1973 * be incremented allowing for continued use of the VMPCK. If 1974 * there is an error reflected in the return value, this value 1975 * is checked further down and the result will be the deletion 1976 * of the VMPCK and the error code being propagated back to the 1977 * user as an ioctl() return code. 1978 */ 1979 goto retry_request; 1980 1981 /* 1982 * The host may return SNP_GUEST_VMM_ERR_BUSY if the request has been 1983 * throttled. Retry in the driver to avoid returning and reusing the 1984 * message sequence number on a different message. 1985 */ 1986 case -EAGAIN: 1987 if (jiffies - req_start > SNP_REQ_MAX_RETRY_DURATION) { 1988 rc = -ETIMEDOUT; 1989 break; 1990 } 1991 schedule_timeout_killable(SNP_REQ_RETRY_DELAY); 1992 goto retry_request; 1993 } 1994 1995 /* 1996 * Increment the message sequence number. There is no harm in doing 1997 * this now because decryption uses the value stored in the response 1998 * structure and any failure will wipe the VMPCK, preventing further 1999 * use anyway. 2000 */ 2001 snp_inc_msg_seqno(mdesc); 2002 2003 if (override_err) { 2004 req->exitinfo2 = override_err; 2005 2006 /* 2007 * If an extended guest request was issued and the supplied certificate 2008 * buffer was not large enough, a standard guest request was issued to 2009 * prevent IV reuse. If the standard request was successful, return -EIO 2010 * back to the caller as would have originally been returned. 2011 */ 2012 if (!rc && override_err == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN)) 2013 rc = -EIO; 2014 } 2015 2016 if (override_npages) 2017 req->input.data_npages = override_npages; 2018 2019 return rc; 2020 } 2021 2022 int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req) 2023 { 2024 u64 seqno; 2025 int rc; 2026 2027 /* 2028 * enc_payload() calls aesgcm_encrypt(), which can potentially offload to HW. 2029 * The offload's DMA SG list of data to encrypt has to be in linear mapping. 2030 */ 2031 if (!virt_addr_valid(req->req_buf) || !virt_addr_valid(req->resp_buf)) { 2032 pr_warn("AES-GSM buffers must be in linear mapping"); 2033 return -EINVAL; 2034 } 2035 2036 guard(mutex)(&snp_cmd_mutex); 2037 2038 /* Check if the VMPCK is not empty */ 2039 if (!mdesc->vmpck || !memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN)) { 2040 pr_err_ratelimited("VMPCK is disabled\n"); 2041 return -ENOTTY; 2042 } 2043 2044 /* Get message sequence and verify that its a non-zero */ 2045 seqno = snp_get_msg_seqno(mdesc); 2046 if (!seqno) 2047 return -EIO; 2048 2049 /* Clear shared memory's response for the host to populate. */ 2050 memset(mdesc->response, 0, sizeof(struct snp_guest_msg)); 2051 2052 /* Encrypt the userspace provided payload in mdesc->secret_request. */ 2053 rc = enc_payload(mdesc, seqno, req); 2054 if (rc) 2055 return rc; 2056 2057 /* 2058 * Write the fully encrypted request to the shared unencrypted 2059 * request page. 2060 */ 2061 memcpy(mdesc->request, &mdesc->secret_request, sizeof(mdesc->secret_request)); 2062 2063 /* Initialize the input address for guest request */ 2064 req->input.req_gpa = __pa(mdesc->request); 2065 req->input.resp_gpa = __pa(mdesc->response); 2066 req->input.data_gpa = req->certs_data ? __pa(req->certs_data) : 0; 2067 2068 rc = __handle_guest_request(mdesc, req); 2069 if (rc) { 2070 if (rc == -EIO && 2071 req->exitinfo2 == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN)) 2072 return rc; 2073 2074 pr_alert("Detected error from ASP request. rc: %d, exitinfo2: 0x%llx\n", 2075 rc, req->exitinfo2); 2076 2077 snp_disable_vmpck(mdesc); 2078 return rc; 2079 } 2080 2081 rc = verify_and_dec_payload(mdesc, req); 2082 if (rc) { 2083 pr_alert("Detected unexpected decode failure from ASP. rc: %d\n", rc); 2084 snp_disable_vmpck(mdesc); 2085 return rc; 2086 } 2087 2088 return 0; 2089 } 2090 EXPORT_SYMBOL_GPL(snp_send_guest_request); 2091 2092 static int __init snp_get_tsc_info(void) 2093 { 2094 struct snp_tsc_info_resp *tsc_resp; 2095 struct snp_tsc_info_req *tsc_req; 2096 struct snp_msg_desc *mdesc; 2097 struct snp_guest_req req = {}; 2098 int rc = -ENOMEM; 2099 2100 tsc_req = kzalloc(sizeof(*tsc_req), GFP_KERNEL); 2101 if (!tsc_req) 2102 return rc; 2103 2104 /* 2105 * The intermediate response buffer is used while decrypting the 2106 * response payload. Make sure that it has enough space to cover 2107 * the authtag. 2108 */ 2109 tsc_resp = kzalloc(sizeof(*tsc_resp) + AUTHTAG_LEN, GFP_KERNEL); 2110 if (!tsc_resp) 2111 goto e_free_tsc_req; 2112 2113 mdesc = snp_msg_alloc(); 2114 if (IS_ERR_OR_NULL(mdesc)) 2115 goto e_free_tsc_resp; 2116 2117 rc = snp_msg_init(mdesc, snp_vmpl); 2118 if (rc) 2119 goto e_free_mdesc; 2120 2121 req.msg_version = MSG_HDR_VER; 2122 req.msg_type = SNP_MSG_TSC_INFO_REQ; 2123 req.vmpck_id = snp_vmpl; 2124 req.req_buf = tsc_req; 2125 req.req_sz = sizeof(*tsc_req); 2126 req.resp_buf = (void *)tsc_resp; 2127 req.resp_sz = sizeof(*tsc_resp) + AUTHTAG_LEN; 2128 req.exit_code = SVM_VMGEXIT_GUEST_REQUEST; 2129 2130 rc = snp_send_guest_request(mdesc, &req); 2131 if (rc) 2132 goto e_request; 2133 2134 pr_debug("%s: response status 0x%x scale 0x%llx offset 0x%llx factor 0x%x\n", 2135 __func__, tsc_resp->status, tsc_resp->tsc_scale, tsc_resp->tsc_offset, 2136 tsc_resp->tsc_factor); 2137 2138 if (!tsc_resp->status) { 2139 snp_tsc_scale = tsc_resp->tsc_scale; 2140 snp_tsc_offset = tsc_resp->tsc_offset; 2141 } else { 2142 pr_err("Failed to get TSC info, response status 0x%x\n", tsc_resp->status); 2143 rc = -EIO; 2144 } 2145 2146 e_request: 2147 /* The response buffer contains sensitive data, explicitly clear it. */ 2148 memzero_explicit(tsc_resp, sizeof(*tsc_resp) + AUTHTAG_LEN); 2149 e_free_mdesc: 2150 snp_msg_free(mdesc); 2151 e_free_tsc_resp: 2152 kfree(tsc_resp); 2153 e_free_tsc_req: 2154 kfree(tsc_req); 2155 2156 return rc; 2157 } 2158 2159 void __init snp_secure_tsc_prepare(void) 2160 { 2161 if (!cc_platform_has(CC_ATTR_GUEST_SNP_SECURE_TSC)) 2162 return; 2163 2164 if (snp_get_tsc_info()) { 2165 pr_alert("Unable to retrieve Secure TSC info from ASP\n"); 2166 sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_SECURE_TSC); 2167 } 2168 2169 pr_debug("SecureTSC enabled"); 2170 } 2171 2172 static unsigned long securetsc_get_tsc_khz(void) 2173 { 2174 return snp_tsc_freq_khz; 2175 } 2176 2177 void __init snp_secure_tsc_init(void) 2178 { 2179 struct snp_secrets_page *secrets; 2180 unsigned long tsc_freq_mhz; 2181 void *mem; 2182 2183 if (!cc_platform_has(CC_ATTR_GUEST_SNP_SECURE_TSC)) 2184 return; 2185 2186 mem = early_memremap_encrypted(sev_secrets_pa, PAGE_SIZE); 2187 if (!mem) { 2188 pr_err("Unable to get TSC_FACTOR: failed to map the SNP secrets page.\n"); 2189 sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_SECURE_TSC); 2190 } 2191 2192 secrets = (__force struct snp_secrets_page *)mem; 2193 2194 setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ); 2195 rdmsrq(MSR_AMD64_GUEST_TSC_FREQ, tsc_freq_mhz); 2196 2197 /* Extract the GUEST TSC MHZ from BIT[17:0], rest is reserved space */ 2198 tsc_freq_mhz &= GENMASK_ULL(17, 0); 2199 2200 snp_tsc_freq_khz = SNP_SCALE_TSC_FREQ(tsc_freq_mhz * 1000, secrets->tsc_factor); 2201 2202 x86_platform.calibrate_cpu = securetsc_get_tsc_khz; 2203 x86_platform.calibrate_tsc = securetsc_get_tsc_khz; 2204 2205 early_memunmap(mem, PAGE_SIZE); 2206 } 2207