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