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 struct psc_entry *e; 362 unsigned int i; 363 364 if (snp_vmpl) 365 svsm_pval_pages(desc); 366 else 367 pval_pages(desc); 368 369 /* 370 * If not affected by the cache-coherency vulnerability there is no need 371 * to perform the cache eviction mitigation. 372 */ 373 if (cpu_feature_enabled(X86_FEATURE_COHERENCY_SFW_NO)) 374 return; 375 376 for (i = 0; i <= desc->hdr.end_entry; i++) { 377 e = &desc->entries[i]; 378 379 /* 380 * If validating memory (making it private) perform the cache 381 * eviction mitigation. 382 */ 383 if (e->operation == SNP_PAGE_STATE_PRIVATE) 384 sev_evict_cache(pfn_to_kaddr(e->gfn), e->pagesize ? 512 : 1); 385 } 386 } 387 388 static int vmgexit_psc(struct ghcb *ghcb, struct snp_psc_desc *desc) 389 { 390 int cur_entry, end_entry, ret = 0; 391 struct snp_psc_desc *data; 392 struct es_em_ctxt ctxt; 393 394 vc_ghcb_invalidate(ghcb); 395 396 /* Copy the input desc into GHCB shared buffer */ 397 data = (struct snp_psc_desc *)ghcb->shared_buffer; 398 memcpy(ghcb->shared_buffer, desc, min_t(int, GHCB_SHARED_BUF_SIZE, sizeof(*desc))); 399 400 /* 401 * As per the GHCB specification, the hypervisor can resume the guest 402 * before processing all the entries. Check whether all the entries 403 * are processed. If not, then keep retrying. Note, the hypervisor 404 * will update the data memory directly to indicate the status, so 405 * reference the data->hdr everywhere. 406 * 407 * The strategy here is to wait for the hypervisor to change the page 408 * state in the RMP table before guest accesses the memory pages. If the 409 * page state change was not successful, then later memory access will 410 * result in a crash. 411 */ 412 cur_entry = data->hdr.cur_entry; 413 end_entry = data->hdr.end_entry; 414 415 while (data->hdr.cur_entry <= data->hdr.end_entry) { 416 ghcb_set_sw_scratch(ghcb, (u64)__pa(data)); 417 418 /* This will advance the shared buffer data points to. */ 419 ret = sev_es_ghcb_hv_call(ghcb, &ctxt, SVM_VMGEXIT_PSC, 0, 0); 420 421 /* 422 * Page State Change VMGEXIT can pass error code through 423 * exit_info_2. 424 */ 425 if (WARN(ret || ghcb->save.sw_exit_info_2, 426 "SNP: PSC failed ret=%d exit_info_2=%llx\n", 427 ret, ghcb->save.sw_exit_info_2)) { 428 ret = 1; 429 goto out; 430 } 431 432 /* Verify that reserved bit is not set */ 433 if (WARN(data->hdr.reserved, "Reserved bit is set in the PSC header\n")) { 434 ret = 1; 435 goto out; 436 } 437 438 /* 439 * Sanity check that entry processing is not going backwards. 440 * This will happen only if hypervisor is tricking us. 441 */ 442 if (WARN(data->hdr.end_entry > end_entry || cur_entry > data->hdr.cur_entry, 443 "SNP: PSC processing going backward, end_entry %d (got %d) cur_entry %d (got %d)\n", 444 end_entry, data->hdr.end_entry, cur_entry, data->hdr.cur_entry)) { 445 ret = 1; 446 goto out; 447 } 448 } 449 450 out: 451 return ret; 452 } 453 454 static unsigned long __set_pages_state(struct snp_psc_desc *data, unsigned long vaddr, 455 unsigned long vaddr_end, int op) 456 { 457 struct ghcb_state state; 458 bool use_large_entry; 459 struct psc_hdr *hdr; 460 struct psc_entry *e; 461 unsigned long flags; 462 unsigned long pfn; 463 struct ghcb *ghcb; 464 int i; 465 466 hdr = &data->hdr; 467 e = data->entries; 468 469 memset(data, 0, sizeof(*data)); 470 i = 0; 471 472 while (vaddr < vaddr_end && i < ARRAY_SIZE(data->entries)) { 473 hdr->end_entry = i; 474 475 if (is_vmalloc_addr((void *)vaddr)) { 476 pfn = vmalloc_to_pfn((void *)vaddr); 477 use_large_entry = false; 478 } else { 479 pfn = __pa(vaddr) >> PAGE_SHIFT; 480 use_large_entry = true; 481 } 482 483 e->gfn = pfn; 484 e->operation = op; 485 486 if (use_large_entry && IS_ALIGNED(vaddr, PMD_SIZE) && 487 (vaddr_end - vaddr) >= PMD_SIZE) { 488 e->pagesize = RMP_PG_SIZE_2M; 489 vaddr += PMD_SIZE; 490 } else { 491 e->pagesize = RMP_PG_SIZE_4K; 492 vaddr += PAGE_SIZE; 493 } 494 495 e++; 496 i++; 497 } 498 499 /* Page validation must be rescinded before changing to shared */ 500 if (op == SNP_PAGE_STATE_SHARED) 501 pvalidate_pages(data); 502 503 local_irq_save(flags); 504 505 if (sev_cfg.ghcbs_initialized) 506 ghcb = __sev_get_ghcb(&state); 507 else 508 ghcb = boot_ghcb; 509 510 /* Invoke the hypervisor to perform the page state changes */ 511 if (!ghcb || vmgexit_psc(ghcb, data)) 512 sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PSC); 513 514 if (sev_cfg.ghcbs_initialized) 515 __sev_put_ghcb(&state); 516 517 local_irq_restore(flags); 518 519 /* Page validation must be performed after changing to private */ 520 if (op == SNP_PAGE_STATE_PRIVATE) 521 pvalidate_pages(data); 522 523 return vaddr; 524 } 525 526 static void set_pages_state(unsigned long vaddr, unsigned long npages, int op) 527 { 528 struct snp_psc_desc desc; 529 unsigned long vaddr_end; 530 531 /* Use the MSR protocol when a GHCB is not available. */ 532 if (!boot_ghcb) 533 return early_set_pages_state(vaddr, __pa(vaddr), npages, op); 534 535 vaddr = vaddr & PAGE_MASK; 536 vaddr_end = vaddr + (npages << PAGE_SHIFT); 537 538 while (vaddr < vaddr_end) 539 vaddr = __set_pages_state(&desc, vaddr, vaddr_end, op); 540 } 541 542 void snp_set_memory_shared(unsigned long vaddr, unsigned long npages) 543 { 544 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 545 return; 546 547 set_pages_state(vaddr, npages, SNP_PAGE_STATE_SHARED); 548 } 549 550 void snp_set_memory_private(unsigned long vaddr, unsigned long npages) 551 { 552 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 553 return; 554 555 set_pages_state(vaddr, npages, SNP_PAGE_STATE_PRIVATE); 556 } 557 558 void snp_accept_memory(phys_addr_t start, phys_addr_t end) 559 { 560 unsigned long vaddr, npages; 561 562 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 563 return; 564 565 vaddr = (unsigned long)__va(start); 566 npages = (end - start) >> PAGE_SHIFT; 567 568 set_pages_state(vaddr, npages, SNP_PAGE_STATE_PRIVATE); 569 } 570 571 static int vmgexit_ap_control(u64 event, struct sev_es_save_area *vmsa, u32 apic_id) 572 { 573 bool create = event != SVM_VMGEXIT_AP_DESTROY; 574 struct ghcb_state state; 575 unsigned long flags; 576 struct ghcb *ghcb; 577 int ret = 0; 578 579 local_irq_save(flags); 580 581 ghcb = __sev_get_ghcb(&state); 582 583 vc_ghcb_invalidate(ghcb); 584 585 if (create) 586 ghcb_set_rax(ghcb, vmsa->sev_features); 587 588 ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_CREATION); 589 ghcb_set_sw_exit_info_1(ghcb, 590 ((u64)apic_id << 32) | 591 ((u64)snp_vmpl << 16) | 592 event); 593 ghcb_set_sw_exit_info_2(ghcb, __pa(vmsa)); 594 595 sev_es_wr_ghcb_msr(__pa(ghcb)); 596 VMGEXIT(); 597 598 if (!ghcb_sw_exit_info_1_is_valid(ghcb) || 599 lower_32_bits(ghcb->save.sw_exit_info_1)) { 600 pr_err("SNP AP %s error\n", (create ? "CREATE" : "DESTROY")); 601 ret = -EINVAL; 602 } 603 604 __sev_put_ghcb(&state); 605 606 local_irq_restore(flags); 607 608 return ret; 609 } 610 611 static int snp_set_vmsa(void *va, void *caa, int apic_id, bool make_vmsa) 612 { 613 int ret; 614 615 if (snp_vmpl) { 616 struct svsm_call call = {}; 617 unsigned long flags; 618 619 local_irq_save(flags); 620 621 call.caa = this_cpu_read(svsm_caa); 622 call.rcx = __pa(va); 623 624 if (make_vmsa) { 625 /* Protocol 0, Call ID 2 */ 626 call.rax = SVSM_CORE_CALL(SVSM_CORE_CREATE_VCPU); 627 call.rdx = __pa(caa); 628 call.r8 = apic_id; 629 } else { 630 /* Protocol 0, Call ID 3 */ 631 call.rax = SVSM_CORE_CALL(SVSM_CORE_DELETE_VCPU); 632 } 633 634 ret = svsm_perform_call_protocol(&call); 635 636 local_irq_restore(flags); 637 } else { 638 /* 639 * If the kernel runs at VMPL0, it can change the VMSA 640 * bit for a page using the RMPADJUST instruction. 641 * However, for the instruction to succeed it must 642 * target the permissions of a lesser privileged (higher 643 * numbered) VMPL level, so use VMPL1. 644 */ 645 u64 attrs = 1; 646 647 if (make_vmsa) 648 attrs |= RMPADJUST_VMSA_PAGE_BIT; 649 650 ret = rmpadjust((unsigned long)va, RMP_PG_SIZE_4K, attrs); 651 } 652 653 return ret; 654 } 655 656 static void snp_cleanup_vmsa(struct sev_es_save_area *vmsa, int apic_id) 657 { 658 int err; 659 660 err = snp_set_vmsa(vmsa, NULL, apic_id, false); 661 if (err) 662 pr_err("clear VMSA page failed (%u), leaking page\n", err); 663 else 664 free_page((unsigned long)vmsa); 665 } 666 667 static void set_pte_enc(pte_t *kpte, int level, void *va) 668 { 669 struct pte_enc_desc d = { 670 .kpte = kpte, 671 .pte_level = level, 672 .va = va, 673 .encrypt = true 674 }; 675 676 prepare_pte_enc(&d); 677 set_pte_enc_mask(kpte, d.pfn, d.new_pgprot); 678 } 679 680 static void unshare_all_memory(void) 681 { 682 unsigned long addr, end, size, ghcb; 683 struct sev_es_runtime_data *data; 684 unsigned int npages, level; 685 bool skipped_addr; 686 pte_t *pte; 687 int cpu; 688 689 /* Unshare the direct mapping. */ 690 addr = PAGE_OFFSET; 691 end = PAGE_OFFSET + get_max_mapped(); 692 693 while (addr < end) { 694 pte = lookup_address(addr, &level); 695 size = page_level_size(level); 696 npages = size / PAGE_SIZE; 697 skipped_addr = false; 698 699 if (!pte || !pte_decrypted(*pte) || pte_none(*pte)) { 700 addr += size; 701 continue; 702 } 703 704 /* 705 * Ensure that all the per-CPU GHCBs are made private at the 706 * end of the unsharing loop so that the switch to the slower 707 * MSR protocol happens last. 708 */ 709 for_each_possible_cpu(cpu) { 710 data = per_cpu(runtime_data, cpu); 711 ghcb = (unsigned long)&data->ghcb_page; 712 713 /* Handle the case of a huge page containing the GHCB page */ 714 if (addr <= ghcb && ghcb < addr + size) { 715 skipped_addr = true; 716 break; 717 } 718 } 719 720 if (!skipped_addr) { 721 set_pte_enc(pte, level, (void *)addr); 722 snp_set_memory_private(addr, npages); 723 } 724 addr += size; 725 } 726 727 /* Unshare all bss decrypted memory. */ 728 addr = (unsigned long)__start_bss_decrypted; 729 end = (unsigned long)__start_bss_decrypted_unused; 730 npages = (end - addr) >> PAGE_SHIFT; 731 732 for (; addr < end; addr += PAGE_SIZE) { 733 pte = lookup_address(addr, &level); 734 if (!pte || !pte_decrypted(*pte) || pte_none(*pte)) 735 continue; 736 737 set_pte_enc(pte, level, (void *)addr); 738 } 739 addr = (unsigned long)__start_bss_decrypted; 740 snp_set_memory_private(addr, npages); 741 742 __flush_tlb_all(); 743 } 744 745 /* Stop new private<->shared conversions */ 746 void snp_kexec_begin(void) 747 { 748 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 749 return; 750 751 if (!IS_ENABLED(CONFIG_KEXEC_CORE)) 752 return; 753 754 /* 755 * Crash kernel ends up here with interrupts disabled: can't wait for 756 * conversions to finish. 757 * 758 * If race happened, just report and proceed. 759 */ 760 if (!set_memory_enc_stop_conversion()) 761 pr_warn("Failed to stop shared<->private conversions\n"); 762 } 763 764 /* 765 * Shutdown all APs except the one handling kexec/kdump and clearing 766 * the VMSA tag on AP's VMSA pages as they are not being used as 767 * VMSA page anymore. 768 */ 769 static void shutdown_all_aps(void) 770 { 771 struct sev_es_save_area *vmsa; 772 int apic_id, this_cpu, cpu; 773 774 this_cpu = get_cpu(); 775 776 /* 777 * APs are already in HLT loop when enc_kexec_finish() callback 778 * is invoked. 779 */ 780 for_each_present_cpu(cpu) { 781 vmsa = per_cpu(sev_vmsa, cpu); 782 783 /* 784 * The BSP or offlined APs do not have guest allocated VMSA 785 * and there is no need to clear the VMSA tag for this page. 786 */ 787 if (!vmsa) 788 continue; 789 790 /* 791 * Cannot clear the VMSA tag for the currently running vCPU. 792 */ 793 if (this_cpu == cpu) { 794 unsigned long pa; 795 struct page *p; 796 797 pa = __pa(vmsa); 798 /* 799 * Mark the VMSA page of the running vCPU as offline 800 * so that is excluded and not touched by makedumpfile 801 * while generating vmcore during kdump. 802 */ 803 p = pfn_to_online_page(pa >> PAGE_SHIFT); 804 if (p) 805 __SetPageOffline(p); 806 continue; 807 } 808 809 apic_id = cpuid_to_apicid[cpu]; 810 811 /* 812 * Issue AP destroy to ensure AP gets kicked out of guest mode 813 * to allow using RMPADJUST to remove the VMSA tag on it's 814 * VMSA page. 815 */ 816 vmgexit_ap_control(SVM_VMGEXIT_AP_DESTROY, vmsa, apic_id); 817 snp_cleanup_vmsa(vmsa, apic_id); 818 } 819 820 put_cpu(); 821 } 822 823 void snp_kexec_finish(void) 824 { 825 struct sev_es_runtime_data *data; 826 unsigned long size, addr; 827 unsigned int level, cpu; 828 struct ghcb *ghcb; 829 pte_t *pte; 830 831 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 832 return; 833 834 if (!IS_ENABLED(CONFIG_KEXEC_CORE)) 835 return; 836 837 shutdown_all_aps(); 838 839 unshare_all_memory(); 840 841 /* 842 * Switch to using the MSR protocol to change per-CPU GHCBs to 843 * private. All the per-CPU GHCBs have been switched back to private, 844 * so can't do any more GHCB calls to the hypervisor beyond this point 845 * until the kexec'ed kernel starts running. 846 */ 847 boot_ghcb = NULL; 848 sev_cfg.ghcbs_initialized = false; 849 850 for_each_possible_cpu(cpu) { 851 data = per_cpu(runtime_data, cpu); 852 ghcb = &data->ghcb_page; 853 pte = lookup_address((unsigned long)ghcb, &level); 854 size = page_level_size(level); 855 /* Handle the case of a huge page containing the GHCB page */ 856 addr = (unsigned long)ghcb & page_level_mask(level); 857 set_pte_enc(pte, level, (void *)addr); 858 snp_set_memory_private(addr, (size / PAGE_SIZE)); 859 } 860 } 861 862 #define __ATTR_BASE (SVM_SELECTOR_P_MASK | SVM_SELECTOR_S_MASK) 863 #define INIT_CS_ATTRIBS (__ATTR_BASE | SVM_SELECTOR_READ_MASK | SVM_SELECTOR_CODE_MASK) 864 #define INIT_DS_ATTRIBS (__ATTR_BASE | SVM_SELECTOR_WRITE_MASK) 865 866 #define INIT_LDTR_ATTRIBS (SVM_SELECTOR_P_MASK | 2) 867 #define INIT_TR_ATTRIBS (SVM_SELECTOR_P_MASK | 3) 868 869 static void *snp_alloc_vmsa_page(int cpu) 870 { 871 struct page *p; 872 873 /* 874 * Allocate VMSA page to work around the SNP erratum where the CPU will 875 * incorrectly signal an RMP violation #PF if a large page (2MB or 1GB) 876 * collides with the RMP entry of VMSA page. The recommended workaround 877 * is to not use a large page. 878 * 879 * Allocate an 8k page which is also 8k-aligned. 880 */ 881 p = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL_ACCOUNT | __GFP_ZERO, 1); 882 if (!p) 883 return NULL; 884 885 split_page(p, 1); 886 887 /* Free the first 4k. This page may be 2M/1G aligned and cannot be used. */ 888 __free_page(p); 889 890 return page_address(p + 1); 891 } 892 893 static int wakeup_cpu_via_vmgexit(u32 apic_id, unsigned long start_ip, unsigned int cpu) 894 { 895 struct sev_es_save_area *cur_vmsa, *vmsa; 896 struct svsm_ca *caa; 897 u8 sipi_vector; 898 int ret; 899 u64 cr4; 900 901 /* 902 * The hypervisor SNP feature support check has happened earlier, just check 903 * the AP_CREATION one here. 904 */ 905 if (!(sev_hv_features & GHCB_HV_FT_SNP_AP_CREATION)) 906 return -EOPNOTSUPP; 907 908 /* 909 * Verify the desired start IP against the known trampoline start IP 910 * to catch any future new trampolines that may be introduced that 911 * would require a new protected guest entry point. 912 */ 913 if (WARN_ONCE(start_ip != real_mode_header->trampoline_start, 914 "Unsupported SNP start_ip: %lx\n", start_ip)) 915 return -EINVAL; 916 917 /* Override start_ip with known protected guest start IP */ 918 start_ip = real_mode_header->sev_es_trampoline_start; 919 cur_vmsa = per_cpu(sev_vmsa, cpu); 920 921 /* 922 * A new VMSA is created each time because there is no guarantee that 923 * the current VMSA is the kernels or that the vCPU is not running. If 924 * an attempt was done to use the current VMSA with a running vCPU, a 925 * #VMEXIT of that vCPU would wipe out all of the settings being done 926 * here. 927 */ 928 vmsa = (struct sev_es_save_area *)snp_alloc_vmsa_page(cpu); 929 if (!vmsa) 930 return -ENOMEM; 931 932 /* If an SVSM is present, the SVSM per-CPU CAA will be !NULL */ 933 caa = per_cpu(svsm_caa, cpu); 934 935 /* CR4 should maintain the MCE value */ 936 cr4 = native_read_cr4() & X86_CR4_MCE; 937 938 /* Set the CS value based on the start_ip converted to a SIPI vector */ 939 sipi_vector = (start_ip >> 12); 940 vmsa->cs.base = sipi_vector << 12; 941 vmsa->cs.limit = AP_INIT_CS_LIMIT; 942 vmsa->cs.attrib = INIT_CS_ATTRIBS; 943 vmsa->cs.selector = sipi_vector << 8; 944 945 /* Set the RIP value based on start_ip */ 946 vmsa->rip = start_ip & 0xfff; 947 948 /* Set AP INIT defaults as documented in the APM */ 949 vmsa->ds.limit = AP_INIT_DS_LIMIT; 950 vmsa->ds.attrib = INIT_DS_ATTRIBS; 951 vmsa->es = vmsa->ds; 952 vmsa->fs = vmsa->ds; 953 vmsa->gs = vmsa->ds; 954 vmsa->ss = vmsa->ds; 955 956 vmsa->gdtr.limit = AP_INIT_GDTR_LIMIT; 957 vmsa->ldtr.limit = AP_INIT_LDTR_LIMIT; 958 vmsa->ldtr.attrib = INIT_LDTR_ATTRIBS; 959 vmsa->idtr.limit = AP_INIT_IDTR_LIMIT; 960 vmsa->tr.limit = AP_INIT_TR_LIMIT; 961 vmsa->tr.attrib = INIT_TR_ATTRIBS; 962 963 vmsa->cr4 = cr4; 964 vmsa->cr0 = AP_INIT_CR0_DEFAULT; 965 vmsa->dr7 = DR7_RESET_VALUE; 966 vmsa->dr6 = AP_INIT_DR6_DEFAULT; 967 vmsa->rflags = AP_INIT_RFLAGS_DEFAULT; 968 vmsa->g_pat = AP_INIT_GPAT_DEFAULT; 969 vmsa->xcr0 = AP_INIT_XCR0_DEFAULT; 970 vmsa->mxcsr = AP_INIT_MXCSR_DEFAULT; 971 vmsa->x87_ftw = AP_INIT_X87_FTW_DEFAULT; 972 vmsa->x87_fcw = AP_INIT_X87_FCW_DEFAULT; 973 974 /* SVME must be set. */ 975 vmsa->efer = EFER_SVME; 976 977 /* 978 * Set the SNP-specific fields for this VMSA: 979 * VMPL level 980 * SEV_FEATURES (matches the SEV STATUS MSR right shifted 2 bits) 981 */ 982 vmsa->vmpl = snp_vmpl; 983 vmsa->sev_features = sev_status >> 2; 984 985 /* Populate AP's TSC scale/offset to get accurate TSC values. */ 986 if (cc_platform_has(CC_ATTR_GUEST_SNP_SECURE_TSC)) { 987 vmsa->tsc_scale = snp_tsc_scale; 988 vmsa->tsc_offset = snp_tsc_offset; 989 } 990 991 /* Switch the page over to a VMSA page now that it is initialized */ 992 ret = snp_set_vmsa(vmsa, caa, apic_id, true); 993 if (ret) { 994 pr_err("set VMSA page failed (%u)\n", ret); 995 free_page((unsigned long)vmsa); 996 997 return -EINVAL; 998 } 999 1000 /* Issue VMGEXIT AP Creation NAE event */ 1001 ret = vmgexit_ap_control(SVM_VMGEXIT_AP_CREATE, vmsa, apic_id); 1002 if (ret) { 1003 snp_cleanup_vmsa(vmsa, apic_id); 1004 vmsa = NULL; 1005 } 1006 1007 /* Free up any previous VMSA page */ 1008 if (cur_vmsa) 1009 snp_cleanup_vmsa(cur_vmsa, apic_id); 1010 1011 /* Record the current VMSA page */ 1012 per_cpu(sev_vmsa, cpu) = vmsa; 1013 1014 return ret; 1015 } 1016 1017 void __init snp_set_wakeup_secondary_cpu(void) 1018 { 1019 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 1020 return; 1021 1022 /* 1023 * Always set this override if SNP is enabled. This makes it the 1024 * required method to start APs under SNP. If the hypervisor does 1025 * not support AP creation, then no APs will be started. 1026 */ 1027 apic_update_callback(wakeup_secondary_cpu, wakeup_cpu_via_vmgexit); 1028 } 1029 1030 int __init sev_es_setup_ap_jump_table(struct real_mode_header *rmh) 1031 { 1032 u16 startup_cs, startup_ip; 1033 phys_addr_t jump_table_pa; 1034 u64 jump_table_addr; 1035 u16 __iomem *jump_table; 1036 1037 jump_table_addr = get_jump_table_addr(); 1038 1039 /* On UP guests there is no jump table so this is not a failure */ 1040 if (!jump_table_addr) 1041 return 0; 1042 1043 /* Check if AP Jump Table is page-aligned */ 1044 if (jump_table_addr & ~PAGE_MASK) 1045 return -EINVAL; 1046 1047 jump_table_pa = jump_table_addr & PAGE_MASK; 1048 1049 startup_cs = (u16)(rmh->trampoline_start >> 4); 1050 startup_ip = (u16)(rmh->sev_es_trampoline_start - 1051 rmh->trampoline_start); 1052 1053 jump_table = ioremap_encrypted(jump_table_pa, PAGE_SIZE); 1054 if (!jump_table) 1055 return -EIO; 1056 1057 writew(startup_ip, &jump_table[0]); 1058 writew(startup_cs, &jump_table[1]); 1059 1060 iounmap(jump_table); 1061 1062 return 0; 1063 } 1064 1065 /* 1066 * This is needed by the OVMF UEFI firmware which will use whatever it finds in 1067 * the GHCB MSR as its GHCB to talk to the hypervisor. So make sure the per-cpu 1068 * runtime GHCBs used by the kernel are also mapped in the EFI page-table. 1069 * 1070 * When running under SVSM the CA page is needed too, so map it as well. 1071 */ 1072 int __init sev_es_efi_map_ghcbs_cas(pgd_t *pgd) 1073 { 1074 unsigned long address, pflags, pflags_enc; 1075 struct sev_es_runtime_data *data; 1076 int cpu; 1077 u64 pfn; 1078 1079 if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) 1080 return 0; 1081 1082 pflags = _PAGE_NX | _PAGE_RW; 1083 pflags_enc = cc_mkenc(pflags); 1084 1085 for_each_possible_cpu(cpu) { 1086 data = per_cpu(runtime_data, cpu); 1087 1088 address = __pa(&data->ghcb_page); 1089 pfn = address >> PAGE_SHIFT; 1090 1091 if (kernel_map_pages_in_pgd(pgd, pfn, address, 1, pflags)) 1092 return 1; 1093 1094 if (snp_vmpl) { 1095 address = per_cpu(svsm_caa_pa, cpu); 1096 if (!address) 1097 return 1; 1098 1099 pfn = address >> PAGE_SHIFT; 1100 if (kernel_map_pages_in_pgd(pgd, pfn, address, 1, pflags_enc)) 1101 return 1; 1102 } 1103 } 1104 1105 return 0; 1106 } 1107 1108 static void snp_register_per_cpu_ghcb(void) 1109 { 1110 struct sev_es_runtime_data *data; 1111 struct ghcb *ghcb; 1112 1113 data = this_cpu_read(runtime_data); 1114 ghcb = &data->ghcb_page; 1115 1116 snp_register_ghcb_early(__pa(ghcb)); 1117 } 1118 1119 void setup_ghcb(void) 1120 { 1121 if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) 1122 return; 1123 1124 /* 1125 * Check whether the runtime #VC exception handler is active. It uses 1126 * the per-CPU GHCB page which is set up by sev_es_init_vc_handling(). 1127 * 1128 * If SNP is active, register the per-CPU GHCB page so that the runtime 1129 * exception handler can use it. 1130 */ 1131 if (initial_vc_handler == (unsigned long)kernel_exc_vmm_communication) { 1132 if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 1133 snp_register_per_cpu_ghcb(); 1134 1135 sev_cfg.ghcbs_initialized = true; 1136 1137 return; 1138 } 1139 1140 /* 1141 * Make sure the hypervisor talks a supported protocol. 1142 * This gets called only in the BSP boot phase. 1143 */ 1144 if (!sev_es_negotiate_protocol()) 1145 sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ); 1146 1147 /* 1148 * Clear the boot_ghcb. The first exception comes in before the bss 1149 * section is cleared. 1150 */ 1151 memset(&boot_ghcb_page, 0, PAGE_SIZE); 1152 1153 /* Alright - Make the boot-ghcb public */ 1154 boot_ghcb = &boot_ghcb_page; 1155 1156 /* SNP guest requires that GHCB GPA must be registered. */ 1157 if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 1158 snp_register_ghcb_early(__pa(&boot_ghcb_page)); 1159 } 1160 1161 #ifdef CONFIG_HOTPLUG_CPU 1162 static void sev_es_ap_hlt_loop(void) 1163 { 1164 struct ghcb_state state; 1165 struct ghcb *ghcb; 1166 1167 ghcb = __sev_get_ghcb(&state); 1168 1169 while (true) { 1170 vc_ghcb_invalidate(ghcb); 1171 ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_HLT_LOOP); 1172 ghcb_set_sw_exit_info_1(ghcb, 0); 1173 ghcb_set_sw_exit_info_2(ghcb, 0); 1174 1175 sev_es_wr_ghcb_msr(__pa(ghcb)); 1176 VMGEXIT(); 1177 1178 /* Wakeup signal? */ 1179 if (ghcb_sw_exit_info_2_is_valid(ghcb) && 1180 ghcb->save.sw_exit_info_2) 1181 break; 1182 } 1183 1184 __sev_put_ghcb(&state); 1185 } 1186 1187 /* 1188 * Play_dead handler when running under SEV-ES. This is needed because 1189 * the hypervisor can't deliver an SIPI request to restart the AP. 1190 * Instead the kernel has to issue a VMGEXIT to halt the VCPU until the 1191 * hypervisor wakes it up again. 1192 */ 1193 static void sev_es_play_dead(void) 1194 { 1195 play_dead_common(); 1196 1197 /* IRQs now disabled */ 1198 1199 sev_es_ap_hlt_loop(); 1200 1201 /* 1202 * If we get here, the VCPU was woken up again. Jump to CPU 1203 * startup code to get it back online. 1204 */ 1205 soft_restart_cpu(); 1206 } 1207 #else /* CONFIG_HOTPLUG_CPU */ 1208 #define sev_es_play_dead native_play_dead 1209 #endif /* CONFIG_HOTPLUG_CPU */ 1210 1211 #ifdef CONFIG_SMP 1212 static void __init sev_es_setup_play_dead(void) 1213 { 1214 smp_ops.play_dead = sev_es_play_dead; 1215 } 1216 #else 1217 static inline void sev_es_setup_play_dead(void) { } 1218 #endif 1219 1220 static void __init alloc_runtime_data(int cpu) 1221 { 1222 struct sev_es_runtime_data *data; 1223 1224 data = memblock_alloc_node(sizeof(*data), PAGE_SIZE, cpu_to_node(cpu)); 1225 if (!data) 1226 panic("Can't allocate SEV-ES runtime data"); 1227 1228 per_cpu(runtime_data, cpu) = data; 1229 1230 if (snp_vmpl) { 1231 struct svsm_ca *caa; 1232 1233 /* Allocate the SVSM CA page if an SVSM is present */ 1234 caa = memblock_alloc_or_panic(sizeof(*caa), PAGE_SIZE); 1235 1236 per_cpu(svsm_caa, cpu) = caa; 1237 per_cpu(svsm_caa_pa, cpu) = __pa(caa); 1238 } 1239 } 1240 1241 static void __init init_ghcb(int cpu) 1242 { 1243 struct sev_es_runtime_data *data; 1244 int err; 1245 1246 data = per_cpu(runtime_data, cpu); 1247 1248 err = early_set_memory_decrypted((unsigned long)&data->ghcb_page, 1249 sizeof(data->ghcb_page)); 1250 if (err) 1251 panic("Can't map GHCBs unencrypted"); 1252 1253 memset(&data->ghcb_page, 0, sizeof(data->ghcb_page)); 1254 1255 data->ghcb_active = false; 1256 data->backup_ghcb_active = false; 1257 } 1258 1259 void __init sev_es_init_vc_handling(void) 1260 { 1261 int cpu; 1262 1263 BUILD_BUG_ON(offsetof(struct sev_es_runtime_data, ghcb_page) % PAGE_SIZE); 1264 1265 if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) 1266 return; 1267 1268 if (!sev_es_check_cpu_features()) 1269 panic("SEV-ES CPU Features missing"); 1270 1271 /* 1272 * SNP is supported in v2 of the GHCB spec which mandates support for HV 1273 * features. 1274 */ 1275 if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) { 1276 sev_hv_features = get_hv_features(); 1277 1278 if (!(sev_hv_features & GHCB_HV_FT_SNP)) 1279 sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED); 1280 } 1281 1282 /* Initialize per-cpu GHCB pages */ 1283 for_each_possible_cpu(cpu) { 1284 alloc_runtime_data(cpu); 1285 init_ghcb(cpu); 1286 } 1287 1288 /* If running under an SVSM, switch to the per-cpu CA */ 1289 if (snp_vmpl) { 1290 struct svsm_call call = {}; 1291 unsigned long flags; 1292 int ret; 1293 1294 local_irq_save(flags); 1295 1296 /* 1297 * SVSM_CORE_REMAP_CA call: 1298 * RAX = 0 (Protocol=0, CallID=0) 1299 * RCX = New CA GPA 1300 */ 1301 call.caa = svsm_get_caa(); 1302 call.rax = SVSM_CORE_CALL(SVSM_CORE_REMAP_CA); 1303 call.rcx = this_cpu_read(svsm_caa_pa); 1304 ret = svsm_perform_call_protocol(&call); 1305 if (ret) 1306 panic("Can't remap the SVSM CA, ret=%d, rax_out=0x%llx\n", 1307 ret, call.rax_out); 1308 1309 sev_cfg.use_cas = true; 1310 1311 local_irq_restore(flags); 1312 } 1313 1314 sev_es_setup_play_dead(); 1315 1316 /* Secondary CPUs use the runtime #VC handler */ 1317 initial_vc_handler = (unsigned long)kernel_exc_vmm_communication; 1318 } 1319 1320 /* 1321 * SEV-SNP guests should only execute dmi_setup() if EFI_CONFIG_TABLES are 1322 * enabled, as the alternative (fallback) logic for DMI probing in the legacy 1323 * ROM region can cause a crash since this region is not pre-validated. 1324 */ 1325 void __init snp_dmi_setup(void) 1326 { 1327 if (efi_enabled(EFI_CONFIG_TABLES)) 1328 dmi_setup(); 1329 } 1330 1331 static void dump_cpuid_table(void) 1332 { 1333 const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table(); 1334 int i = 0; 1335 1336 pr_info("count=%d reserved=0x%x reserved2=0x%llx\n", 1337 cpuid_table->count, cpuid_table->__reserved1, cpuid_table->__reserved2); 1338 1339 for (i = 0; i < SNP_CPUID_COUNT_MAX; i++) { 1340 const struct snp_cpuid_fn *fn = &cpuid_table->fn[i]; 1341 1342 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", 1343 i, fn->eax_in, fn->ecx_in, fn->eax, fn->ebx, fn->ecx, 1344 fn->edx, fn->xcr0_in, fn->xss_in, fn->__reserved); 1345 } 1346 } 1347 1348 /* 1349 * It is useful from an auditing/testing perspective to provide an easy way 1350 * for the guest owner to know that the CPUID table has been initialized as 1351 * expected, but that initialization happens too early in boot to print any 1352 * sort of indicator, and there's not really any other good place to do it, 1353 * so do it here. 1354 * 1355 * If running as an SNP guest, report the current VM privilege level (VMPL). 1356 */ 1357 static int __init report_snp_info(void) 1358 { 1359 const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table(); 1360 1361 if (cpuid_table->count) { 1362 pr_info("Using SNP CPUID table, %d entries present.\n", 1363 cpuid_table->count); 1364 1365 if (sev_cfg.debug) 1366 dump_cpuid_table(); 1367 } 1368 1369 if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 1370 pr_info("SNP running at VMPL%u.\n", snp_vmpl); 1371 1372 return 0; 1373 } 1374 arch_initcall(report_snp_info); 1375 1376 static void update_attest_input(struct svsm_call *call, struct svsm_attest_call *input) 1377 { 1378 /* If (new) lengths have been returned, propagate them up */ 1379 if (call->rcx_out != call->rcx) 1380 input->manifest_buf.len = call->rcx_out; 1381 1382 if (call->rdx_out != call->rdx) 1383 input->certificates_buf.len = call->rdx_out; 1384 1385 if (call->r8_out != call->r8) 1386 input->report_buf.len = call->r8_out; 1387 } 1388 1389 int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call, 1390 struct svsm_attest_call *input) 1391 { 1392 struct svsm_attest_call *ac; 1393 unsigned long flags; 1394 u64 attest_call_pa; 1395 int ret; 1396 1397 if (!snp_vmpl) 1398 return -EINVAL; 1399 1400 local_irq_save(flags); 1401 1402 call->caa = svsm_get_caa(); 1403 1404 ac = (struct svsm_attest_call *)call->caa->svsm_buffer; 1405 attest_call_pa = svsm_get_caa_pa() + offsetof(struct svsm_ca, svsm_buffer); 1406 1407 *ac = *input; 1408 1409 /* 1410 * Set input registers for the request and set RDX and R8 to known 1411 * values in order to detect length values being returned in them. 1412 */ 1413 call->rax = call_id; 1414 call->rcx = attest_call_pa; 1415 call->rdx = -1; 1416 call->r8 = -1; 1417 ret = svsm_perform_call_protocol(call); 1418 update_attest_input(call, input); 1419 1420 local_irq_restore(flags); 1421 1422 return ret; 1423 } 1424 EXPORT_SYMBOL_GPL(snp_issue_svsm_attest_req); 1425 1426 static int snp_issue_guest_request(struct snp_guest_req *req) 1427 { 1428 struct snp_req_data *input = &req->input; 1429 struct ghcb_state state; 1430 struct es_em_ctxt ctxt; 1431 unsigned long flags; 1432 struct ghcb *ghcb; 1433 int ret; 1434 1435 req->exitinfo2 = SEV_RET_NO_FW_CALL; 1436 1437 /* 1438 * __sev_get_ghcb() needs to run with IRQs disabled because it is using 1439 * a per-CPU GHCB. 1440 */ 1441 local_irq_save(flags); 1442 1443 ghcb = __sev_get_ghcb(&state); 1444 if (!ghcb) { 1445 ret = -EIO; 1446 goto e_restore_irq; 1447 } 1448 1449 vc_ghcb_invalidate(ghcb); 1450 1451 if (req->exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) { 1452 ghcb_set_rax(ghcb, input->data_gpa); 1453 ghcb_set_rbx(ghcb, input->data_npages); 1454 } 1455 1456 ret = sev_es_ghcb_hv_call(ghcb, &ctxt, req->exit_code, input->req_gpa, input->resp_gpa); 1457 if (ret) 1458 goto e_put; 1459 1460 req->exitinfo2 = ghcb->save.sw_exit_info_2; 1461 switch (req->exitinfo2) { 1462 case 0: 1463 break; 1464 1465 case SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_BUSY): 1466 ret = -EAGAIN; 1467 break; 1468 1469 case SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN): 1470 /* Number of expected pages are returned in RBX */ 1471 if (req->exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) { 1472 input->data_npages = ghcb_get_rbx(ghcb); 1473 ret = -ENOSPC; 1474 break; 1475 } 1476 fallthrough; 1477 default: 1478 ret = -EIO; 1479 break; 1480 } 1481 1482 e_put: 1483 __sev_put_ghcb(&state); 1484 e_restore_irq: 1485 local_irq_restore(flags); 1486 1487 return ret; 1488 } 1489 1490 /** 1491 * snp_svsm_vtpm_probe() - Probe if SVSM provides a vTPM device 1492 * 1493 * Check that there is SVSM and that it supports at least TPM_SEND_COMMAND 1494 * which is the only request used so far. 1495 * 1496 * Return: true if the platform provides a vTPM SVSM device, false otherwise. 1497 */ 1498 static bool snp_svsm_vtpm_probe(void) 1499 { 1500 struct svsm_call call = {}; 1501 1502 /* The vTPM device is available only if a SVSM is present */ 1503 if (!snp_vmpl) 1504 return false; 1505 1506 call.caa = svsm_get_caa(); 1507 call.rax = SVSM_VTPM_CALL(SVSM_VTPM_QUERY); 1508 1509 if (svsm_perform_call_protocol(&call)) 1510 return false; 1511 1512 /* Check platform commands contains TPM_SEND_COMMAND - platform command 8 */ 1513 return call.rcx_out & BIT_ULL(8); 1514 } 1515 1516 /** 1517 * snp_svsm_vtpm_send_command() - Execute a vTPM operation on SVSM 1518 * @buffer: A buffer used to both send the command and receive the response. 1519 * 1520 * Execute a SVSM_VTPM_CMD call as defined by 1521 * "Secure VM Service Module for SEV-SNP Guests" Publication # 58019 Revision: 1.00 1522 * 1523 * All command request/response buffers have a common structure as specified by 1524 * the following table: 1525 * Byte Size In/Out Description 1526 * Offset (Bytes) 1527 * 0x000 4 In Platform command 1528 * Out Platform command response size 1529 * 1530 * Each command can build upon this common request/response structure to create 1531 * a structure specific to the command. See include/linux/tpm_svsm.h for more 1532 * details. 1533 * 1534 * Return: 0 on success, -errno on failure 1535 */ 1536 int snp_svsm_vtpm_send_command(u8 *buffer) 1537 { 1538 struct svsm_call call = {}; 1539 1540 call.caa = svsm_get_caa(); 1541 call.rax = SVSM_VTPM_CALL(SVSM_VTPM_CMD); 1542 call.rcx = __pa(buffer); 1543 1544 return svsm_perform_call_protocol(&call); 1545 } 1546 EXPORT_SYMBOL_GPL(snp_svsm_vtpm_send_command); 1547 1548 static struct platform_device sev_guest_device = { 1549 .name = "sev-guest", 1550 .id = -1, 1551 }; 1552 1553 static struct platform_device tpm_svsm_device = { 1554 .name = "tpm-svsm", 1555 .id = -1, 1556 }; 1557 1558 static int __init snp_init_platform_device(void) 1559 { 1560 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 1561 return -ENODEV; 1562 1563 if (platform_device_register(&sev_guest_device)) 1564 return -ENODEV; 1565 1566 if (snp_svsm_vtpm_probe() && 1567 platform_device_register(&tpm_svsm_device)) 1568 return -ENODEV; 1569 1570 pr_info("SNP guest platform devices initialized.\n"); 1571 return 0; 1572 } 1573 device_initcall(snp_init_platform_device); 1574 1575 void sev_show_status(void) 1576 { 1577 int i; 1578 1579 pr_info("Status: "); 1580 for (i = 0; i < MSR_AMD64_SNP_RESV_BIT; i++) { 1581 if (sev_status & BIT_ULL(i)) { 1582 if (!sev_status_feat_names[i]) 1583 continue; 1584 1585 pr_cont("%s ", sev_status_feat_names[i]); 1586 } 1587 } 1588 pr_cont("\n"); 1589 } 1590 1591 void __init snp_update_svsm_ca(void) 1592 { 1593 if (!snp_vmpl) 1594 return; 1595 1596 /* Update the CAA to a proper kernel address */ 1597 boot_svsm_caa = &boot_svsm_ca_page; 1598 } 1599 1600 #ifdef CONFIG_SYSFS 1601 static ssize_t vmpl_show(struct kobject *kobj, 1602 struct kobj_attribute *attr, char *buf) 1603 { 1604 return sysfs_emit(buf, "%d\n", snp_vmpl); 1605 } 1606 1607 static struct kobj_attribute vmpl_attr = __ATTR_RO(vmpl); 1608 1609 static struct attribute *vmpl_attrs[] = { 1610 &vmpl_attr.attr, 1611 NULL 1612 }; 1613 1614 static struct attribute_group sev_attr_group = { 1615 .attrs = vmpl_attrs, 1616 }; 1617 1618 static int __init sev_sysfs_init(void) 1619 { 1620 struct kobject *sev_kobj; 1621 struct device *dev_root; 1622 int ret; 1623 1624 if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) 1625 return -ENODEV; 1626 1627 dev_root = bus_get_dev_root(&cpu_subsys); 1628 if (!dev_root) 1629 return -ENODEV; 1630 1631 sev_kobj = kobject_create_and_add("sev", &dev_root->kobj); 1632 put_device(dev_root); 1633 1634 if (!sev_kobj) 1635 return -ENOMEM; 1636 1637 ret = sysfs_create_group(sev_kobj, &sev_attr_group); 1638 if (ret) 1639 kobject_put(sev_kobj); 1640 1641 return ret; 1642 } 1643 arch_initcall(sev_sysfs_init); 1644 #endif // CONFIG_SYSFS 1645 1646 static void free_shared_pages(void *buf, size_t sz) 1647 { 1648 unsigned int npages = PAGE_ALIGN(sz) >> PAGE_SHIFT; 1649 int ret; 1650 1651 if (!buf) 1652 return; 1653 1654 ret = set_memory_encrypted((unsigned long)buf, npages); 1655 if (ret) { 1656 WARN_ONCE(ret, "failed to restore encryption mask (leak it)\n"); 1657 return; 1658 } 1659 1660 __free_pages(virt_to_page(buf), get_order(sz)); 1661 } 1662 1663 static void *alloc_shared_pages(size_t sz) 1664 { 1665 unsigned int npages = PAGE_ALIGN(sz) >> PAGE_SHIFT; 1666 struct page *page; 1667 int ret; 1668 1669 page = alloc_pages(GFP_KERNEL_ACCOUNT, get_order(sz)); 1670 if (!page) 1671 return NULL; 1672 1673 ret = set_memory_decrypted((unsigned long)page_address(page), npages); 1674 if (ret) { 1675 pr_err("failed to mark page shared, ret=%d\n", ret); 1676 __free_pages(page, get_order(sz)); 1677 return NULL; 1678 } 1679 1680 return page_address(page); 1681 } 1682 1683 static u8 *get_vmpck(int id, struct snp_secrets_page *secrets, u32 **seqno) 1684 { 1685 u8 *key = NULL; 1686 1687 switch (id) { 1688 case 0: 1689 *seqno = &secrets->os_area.msg_seqno_0; 1690 key = secrets->vmpck0; 1691 break; 1692 case 1: 1693 *seqno = &secrets->os_area.msg_seqno_1; 1694 key = secrets->vmpck1; 1695 break; 1696 case 2: 1697 *seqno = &secrets->os_area.msg_seqno_2; 1698 key = secrets->vmpck2; 1699 break; 1700 case 3: 1701 *seqno = &secrets->os_area.msg_seqno_3; 1702 key = secrets->vmpck3; 1703 break; 1704 default: 1705 break; 1706 } 1707 1708 return key; 1709 } 1710 1711 static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen) 1712 { 1713 struct aesgcm_ctx *ctx; 1714 1715 ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); 1716 if (!ctx) 1717 return NULL; 1718 1719 if (aesgcm_expandkey(ctx, key, keylen, AUTHTAG_LEN)) { 1720 pr_err("Crypto context initialization failed\n"); 1721 kfree(ctx); 1722 return NULL; 1723 } 1724 1725 return ctx; 1726 } 1727 1728 int snp_msg_init(struct snp_msg_desc *mdesc, int vmpck_id) 1729 { 1730 /* Adjust the default VMPCK key based on the executing VMPL level */ 1731 if (vmpck_id == -1) 1732 vmpck_id = snp_vmpl; 1733 1734 mdesc->vmpck = get_vmpck(vmpck_id, mdesc->secrets, &mdesc->os_area_msg_seqno); 1735 if (!mdesc->vmpck) { 1736 pr_err("Invalid VMPCK%d communication key\n", vmpck_id); 1737 return -EINVAL; 1738 } 1739 1740 /* Verify that VMPCK is not zero. */ 1741 if (!memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN)) { 1742 pr_err("Empty VMPCK%d communication key\n", vmpck_id); 1743 return -EINVAL; 1744 } 1745 1746 mdesc->vmpck_id = vmpck_id; 1747 1748 mdesc->ctx = snp_init_crypto(mdesc->vmpck, VMPCK_KEY_LEN); 1749 if (!mdesc->ctx) 1750 return -ENOMEM; 1751 1752 return 0; 1753 } 1754 EXPORT_SYMBOL_GPL(snp_msg_init); 1755 1756 struct snp_msg_desc *snp_msg_alloc(void) 1757 { 1758 struct snp_msg_desc *mdesc; 1759 void __iomem *mem; 1760 1761 BUILD_BUG_ON(sizeof(struct snp_guest_msg) > PAGE_SIZE); 1762 1763 mdesc = kzalloc(sizeof(struct snp_msg_desc), GFP_KERNEL); 1764 if (!mdesc) 1765 return ERR_PTR(-ENOMEM); 1766 1767 mem = ioremap_encrypted(sev_secrets_pa, PAGE_SIZE); 1768 if (!mem) 1769 goto e_free_mdesc; 1770 1771 mdesc->secrets = (__force struct snp_secrets_page *)mem; 1772 1773 /* Allocate the shared page used for the request and response message. */ 1774 mdesc->request = alloc_shared_pages(sizeof(struct snp_guest_msg)); 1775 if (!mdesc->request) 1776 goto e_unmap; 1777 1778 mdesc->response = alloc_shared_pages(sizeof(struct snp_guest_msg)); 1779 if (!mdesc->response) 1780 goto e_free_request; 1781 1782 return mdesc; 1783 1784 e_free_request: 1785 free_shared_pages(mdesc->request, sizeof(struct snp_guest_msg)); 1786 e_unmap: 1787 iounmap(mem); 1788 e_free_mdesc: 1789 kfree(mdesc); 1790 1791 return ERR_PTR(-ENOMEM); 1792 } 1793 EXPORT_SYMBOL_GPL(snp_msg_alloc); 1794 1795 void snp_msg_free(struct snp_msg_desc *mdesc) 1796 { 1797 if (!mdesc) 1798 return; 1799 1800 kfree(mdesc->ctx); 1801 free_shared_pages(mdesc->response, sizeof(struct snp_guest_msg)); 1802 free_shared_pages(mdesc->request, sizeof(struct snp_guest_msg)); 1803 iounmap((__force void __iomem *)mdesc->secrets); 1804 1805 memset(mdesc, 0, sizeof(*mdesc)); 1806 kfree(mdesc); 1807 } 1808 EXPORT_SYMBOL_GPL(snp_msg_free); 1809 1810 /* Mutex to serialize the shared buffer access and command handling. */ 1811 static DEFINE_MUTEX(snp_cmd_mutex); 1812 1813 /* 1814 * If an error is received from the host or AMD Secure Processor (ASP) there 1815 * are two options. Either retry the exact same encrypted request or discontinue 1816 * using the VMPCK. 1817 * 1818 * This is because in the current encryption scheme GHCB v2 uses AES-GCM to 1819 * encrypt the requests. The IV for this scheme is the sequence number. GCM 1820 * cannot tolerate IV reuse. 1821 * 1822 * The ASP FW v1.51 only increments the sequence numbers on a successful 1823 * guest<->ASP back and forth and only accepts messages at its exact sequence 1824 * number. 1825 * 1826 * So if the sequence number were to be reused the encryption scheme is 1827 * vulnerable. If the sequence number were incremented for a fresh IV the ASP 1828 * will reject the request. 1829 */ 1830 static void snp_disable_vmpck(struct snp_msg_desc *mdesc) 1831 { 1832 pr_alert("Disabling VMPCK%d communication key to prevent IV reuse.\n", 1833 mdesc->vmpck_id); 1834 memzero_explicit(mdesc->vmpck, VMPCK_KEY_LEN); 1835 mdesc->vmpck = NULL; 1836 } 1837 1838 static inline u64 __snp_get_msg_seqno(struct snp_msg_desc *mdesc) 1839 { 1840 u64 count; 1841 1842 lockdep_assert_held(&snp_cmd_mutex); 1843 1844 /* Read the current message sequence counter from secrets pages */ 1845 count = *mdesc->os_area_msg_seqno; 1846 1847 return count + 1; 1848 } 1849 1850 /* Return a non-zero on success */ 1851 static u64 snp_get_msg_seqno(struct snp_msg_desc *mdesc) 1852 { 1853 u64 count = __snp_get_msg_seqno(mdesc); 1854 1855 /* 1856 * The message sequence counter for the SNP guest request is a 64-bit 1857 * value but the version 2 of GHCB specification defines a 32-bit storage 1858 * for it. If the counter exceeds the 32-bit value then return zero. 1859 * The caller should check the return value, but if the caller happens to 1860 * not check the value and use it, then the firmware treats zero as an 1861 * invalid number and will fail the message request. 1862 */ 1863 if (count >= UINT_MAX) { 1864 pr_err("request message sequence counter overflow\n"); 1865 return 0; 1866 } 1867 1868 return count; 1869 } 1870 1871 static void snp_inc_msg_seqno(struct snp_msg_desc *mdesc) 1872 { 1873 /* 1874 * The counter is also incremented by the PSP, so increment it by 2 1875 * and save in secrets page. 1876 */ 1877 *mdesc->os_area_msg_seqno += 2; 1878 } 1879 1880 static int verify_and_dec_payload(struct snp_msg_desc *mdesc, struct snp_guest_req *req) 1881 { 1882 struct snp_guest_msg *resp_msg = &mdesc->secret_response; 1883 struct snp_guest_msg *req_msg = &mdesc->secret_request; 1884 struct snp_guest_msg_hdr *req_msg_hdr = &req_msg->hdr; 1885 struct snp_guest_msg_hdr *resp_msg_hdr = &resp_msg->hdr; 1886 struct aesgcm_ctx *ctx = mdesc->ctx; 1887 u8 iv[GCM_AES_IV_SIZE] = {}; 1888 1889 pr_debug("response [seqno %lld type %d version %d sz %d]\n", 1890 resp_msg_hdr->msg_seqno, resp_msg_hdr->msg_type, resp_msg_hdr->msg_version, 1891 resp_msg_hdr->msg_sz); 1892 1893 /* Copy response from shared memory to encrypted memory. */ 1894 memcpy(resp_msg, mdesc->response, sizeof(*resp_msg)); 1895 1896 /* Verify that the sequence counter is incremented by 1 */ 1897 if (unlikely(resp_msg_hdr->msg_seqno != (req_msg_hdr->msg_seqno + 1))) 1898 return -EBADMSG; 1899 1900 /* Verify response message type and version number. */ 1901 if (resp_msg_hdr->msg_type != (req_msg_hdr->msg_type + 1) || 1902 resp_msg_hdr->msg_version != req_msg_hdr->msg_version) 1903 return -EBADMSG; 1904 1905 /* 1906 * If the message size is greater than our buffer length then return 1907 * an error. 1908 */ 1909 if (unlikely((resp_msg_hdr->msg_sz + ctx->authsize) > req->resp_sz)) 1910 return -EBADMSG; 1911 1912 /* Decrypt the payload */ 1913 memcpy(iv, &resp_msg_hdr->msg_seqno, min(sizeof(iv), sizeof(resp_msg_hdr->msg_seqno))); 1914 if (!aesgcm_decrypt(ctx, req->resp_buf, resp_msg->payload, resp_msg_hdr->msg_sz, 1915 &resp_msg_hdr->algo, AAD_LEN, iv, resp_msg_hdr->authtag)) 1916 return -EBADMSG; 1917 1918 return 0; 1919 } 1920 1921 static int enc_payload(struct snp_msg_desc *mdesc, u64 seqno, struct snp_guest_req *req) 1922 { 1923 struct snp_guest_msg *msg = &mdesc->secret_request; 1924 struct snp_guest_msg_hdr *hdr = &msg->hdr; 1925 struct aesgcm_ctx *ctx = mdesc->ctx; 1926 u8 iv[GCM_AES_IV_SIZE] = {}; 1927 1928 memset(msg, 0, sizeof(*msg)); 1929 1930 hdr->algo = SNP_AEAD_AES_256_GCM; 1931 hdr->hdr_version = MSG_HDR_VER; 1932 hdr->hdr_sz = sizeof(*hdr); 1933 hdr->msg_type = req->msg_type; 1934 hdr->msg_version = req->msg_version; 1935 hdr->msg_seqno = seqno; 1936 hdr->msg_vmpck = req->vmpck_id; 1937 hdr->msg_sz = req->req_sz; 1938 1939 /* Verify the sequence number is non-zero */ 1940 if (!hdr->msg_seqno) 1941 return -ENOSR; 1942 1943 pr_debug("request [seqno %lld type %d version %d sz %d]\n", 1944 hdr->msg_seqno, hdr->msg_type, hdr->msg_version, hdr->msg_sz); 1945 1946 if (WARN_ON((req->req_sz + ctx->authsize) > sizeof(msg->payload))) 1947 return -EBADMSG; 1948 1949 memcpy(iv, &hdr->msg_seqno, min(sizeof(iv), sizeof(hdr->msg_seqno))); 1950 aesgcm_encrypt(ctx, msg->payload, req->req_buf, req->req_sz, &hdr->algo, 1951 AAD_LEN, iv, hdr->authtag); 1952 1953 return 0; 1954 } 1955 1956 static int __handle_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req) 1957 { 1958 unsigned long req_start = jiffies; 1959 unsigned int override_npages = 0; 1960 u64 override_err = 0; 1961 int rc; 1962 1963 retry_request: 1964 /* 1965 * Call firmware to process the request. In this function the encrypted 1966 * message enters shared memory with the host. So after this call the 1967 * sequence number must be incremented or the VMPCK must be deleted to 1968 * prevent reuse of the IV. 1969 */ 1970 rc = snp_issue_guest_request(req); 1971 switch (rc) { 1972 case -ENOSPC: 1973 /* 1974 * If the extended guest request fails due to having too 1975 * small of a certificate data buffer, retry the same 1976 * guest request without the extended data request in 1977 * order to increment the sequence number and thus avoid 1978 * IV reuse. 1979 */ 1980 override_npages = req->input.data_npages; 1981 req->exit_code = SVM_VMGEXIT_GUEST_REQUEST; 1982 1983 /* 1984 * Override the error to inform callers the given extended 1985 * request buffer size was too small and give the caller the 1986 * required buffer size. 1987 */ 1988 override_err = SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN); 1989 1990 /* 1991 * If this call to the firmware succeeds, the sequence number can 1992 * be incremented allowing for continued use of the VMPCK. If 1993 * there is an error reflected in the return value, this value 1994 * is checked further down and the result will be the deletion 1995 * of the VMPCK and the error code being propagated back to the 1996 * user as an ioctl() return code. 1997 */ 1998 goto retry_request; 1999 2000 /* 2001 * The host may return SNP_GUEST_VMM_ERR_BUSY if the request has been 2002 * throttled. Retry in the driver to avoid returning and reusing the 2003 * message sequence number on a different message. 2004 */ 2005 case -EAGAIN: 2006 if (jiffies - req_start > SNP_REQ_MAX_RETRY_DURATION) { 2007 rc = -ETIMEDOUT; 2008 break; 2009 } 2010 schedule_timeout_killable(SNP_REQ_RETRY_DELAY); 2011 goto retry_request; 2012 } 2013 2014 /* 2015 * Increment the message sequence number. There is no harm in doing 2016 * this now because decryption uses the value stored in the response 2017 * structure and any failure will wipe the VMPCK, preventing further 2018 * use anyway. 2019 */ 2020 snp_inc_msg_seqno(mdesc); 2021 2022 if (override_err) { 2023 req->exitinfo2 = override_err; 2024 2025 /* 2026 * If an extended guest request was issued and the supplied certificate 2027 * buffer was not large enough, a standard guest request was issued to 2028 * prevent IV reuse. If the standard request was successful, return -EIO 2029 * back to the caller as would have originally been returned. 2030 */ 2031 if (!rc && override_err == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN)) 2032 rc = -EIO; 2033 } 2034 2035 if (override_npages) 2036 req->input.data_npages = override_npages; 2037 2038 return rc; 2039 } 2040 2041 int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req) 2042 { 2043 u64 seqno; 2044 int rc; 2045 2046 /* 2047 * enc_payload() calls aesgcm_encrypt(), which can potentially offload to HW. 2048 * The offload's DMA SG list of data to encrypt has to be in linear mapping. 2049 */ 2050 if (!virt_addr_valid(req->req_buf) || !virt_addr_valid(req->resp_buf)) { 2051 pr_warn("AES-GSM buffers must be in linear mapping"); 2052 return -EINVAL; 2053 } 2054 2055 guard(mutex)(&snp_cmd_mutex); 2056 2057 /* Check if the VMPCK is not empty */ 2058 if (!mdesc->vmpck || !memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN)) { 2059 pr_err_ratelimited("VMPCK is disabled\n"); 2060 return -ENOTTY; 2061 } 2062 2063 /* Get message sequence and verify that its a non-zero */ 2064 seqno = snp_get_msg_seqno(mdesc); 2065 if (!seqno) 2066 return -EIO; 2067 2068 /* Clear shared memory's response for the host to populate. */ 2069 memset(mdesc->response, 0, sizeof(struct snp_guest_msg)); 2070 2071 /* Encrypt the userspace provided payload in mdesc->secret_request. */ 2072 rc = enc_payload(mdesc, seqno, req); 2073 if (rc) 2074 return rc; 2075 2076 /* 2077 * Write the fully encrypted request to the shared unencrypted 2078 * request page. 2079 */ 2080 memcpy(mdesc->request, &mdesc->secret_request, sizeof(mdesc->secret_request)); 2081 2082 /* Initialize the input address for guest request */ 2083 req->input.req_gpa = __pa(mdesc->request); 2084 req->input.resp_gpa = __pa(mdesc->response); 2085 req->input.data_gpa = req->certs_data ? __pa(req->certs_data) : 0; 2086 2087 rc = __handle_guest_request(mdesc, req); 2088 if (rc) { 2089 if (rc == -EIO && 2090 req->exitinfo2 == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN)) 2091 return rc; 2092 2093 pr_alert("Detected error from ASP request. rc: %d, exitinfo2: 0x%llx\n", 2094 rc, req->exitinfo2); 2095 2096 snp_disable_vmpck(mdesc); 2097 return rc; 2098 } 2099 2100 rc = verify_and_dec_payload(mdesc, req); 2101 if (rc) { 2102 pr_alert("Detected unexpected decode failure from ASP. rc: %d\n", rc); 2103 snp_disable_vmpck(mdesc); 2104 return rc; 2105 } 2106 2107 return 0; 2108 } 2109 EXPORT_SYMBOL_GPL(snp_send_guest_request); 2110 2111 static int __init snp_get_tsc_info(void) 2112 { 2113 struct snp_tsc_info_resp *tsc_resp; 2114 struct snp_tsc_info_req *tsc_req; 2115 struct snp_msg_desc *mdesc; 2116 struct snp_guest_req req = {}; 2117 int rc = -ENOMEM; 2118 2119 tsc_req = kzalloc(sizeof(*tsc_req), GFP_KERNEL); 2120 if (!tsc_req) 2121 return rc; 2122 2123 /* 2124 * The intermediate response buffer is used while decrypting the 2125 * response payload. Make sure that it has enough space to cover 2126 * the authtag. 2127 */ 2128 tsc_resp = kzalloc(sizeof(*tsc_resp) + AUTHTAG_LEN, GFP_KERNEL); 2129 if (!tsc_resp) 2130 goto e_free_tsc_req; 2131 2132 mdesc = snp_msg_alloc(); 2133 if (IS_ERR_OR_NULL(mdesc)) 2134 goto e_free_tsc_resp; 2135 2136 rc = snp_msg_init(mdesc, snp_vmpl); 2137 if (rc) 2138 goto e_free_mdesc; 2139 2140 req.msg_version = MSG_HDR_VER; 2141 req.msg_type = SNP_MSG_TSC_INFO_REQ; 2142 req.vmpck_id = snp_vmpl; 2143 req.req_buf = tsc_req; 2144 req.req_sz = sizeof(*tsc_req); 2145 req.resp_buf = (void *)tsc_resp; 2146 req.resp_sz = sizeof(*tsc_resp) + AUTHTAG_LEN; 2147 req.exit_code = SVM_VMGEXIT_GUEST_REQUEST; 2148 2149 rc = snp_send_guest_request(mdesc, &req); 2150 if (rc) 2151 goto e_request; 2152 2153 pr_debug("%s: response status 0x%x scale 0x%llx offset 0x%llx factor 0x%x\n", 2154 __func__, tsc_resp->status, tsc_resp->tsc_scale, tsc_resp->tsc_offset, 2155 tsc_resp->tsc_factor); 2156 2157 if (!tsc_resp->status) { 2158 snp_tsc_scale = tsc_resp->tsc_scale; 2159 snp_tsc_offset = tsc_resp->tsc_offset; 2160 } else { 2161 pr_err("Failed to get TSC info, response status 0x%x\n", tsc_resp->status); 2162 rc = -EIO; 2163 } 2164 2165 e_request: 2166 /* The response buffer contains sensitive data, explicitly clear it. */ 2167 memzero_explicit(tsc_resp, sizeof(*tsc_resp) + AUTHTAG_LEN); 2168 e_free_mdesc: 2169 snp_msg_free(mdesc); 2170 e_free_tsc_resp: 2171 kfree(tsc_resp); 2172 e_free_tsc_req: 2173 kfree(tsc_req); 2174 2175 return rc; 2176 } 2177 2178 void __init snp_secure_tsc_prepare(void) 2179 { 2180 if (!cc_platform_has(CC_ATTR_GUEST_SNP_SECURE_TSC)) 2181 return; 2182 2183 if (snp_get_tsc_info()) { 2184 pr_alert("Unable to retrieve Secure TSC info from ASP\n"); 2185 sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_SECURE_TSC); 2186 } 2187 2188 pr_debug("SecureTSC enabled"); 2189 } 2190 2191 static unsigned long securetsc_get_tsc_khz(void) 2192 { 2193 return snp_tsc_freq_khz; 2194 } 2195 2196 void __init snp_secure_tsc_init(void) 2197 { 2198 struct snp_secrets_page *secrets; 2199 unsigned long tsc_freq_mhz; 2200 void *mem; 2201 2202 if (!cc_platform_has(CC_ATTR_GUEST_SNP_SECURE_TSC)) 2203 return; 2204 2205 mem = early_memremap_encrypted(sev_secrets_pa, PAGE_SIZE); 2206 if (!mem) { 2207 pr_err("Unable to get TSC_FACTOR: failed to map the SNP secrets page.\n"); 2208 sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_SECURE_TSC); 2209 } 2210 2211 secrets = (__force struct snp_secrets_page *)mem; 2212 2213 setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ); 2214 rdmsrq(MSR_AMD64_GUEST_TSC_FREQ, tsc_freq_mhz); 2215 2216 /* Extract the GUEST TSC MHZ from BIT[17:0], rest is reserved space */ 2217 tsc_freq_mhz &= GENMASK_ULL(17, 0); 2218 2219 snp_tsc_freq_khz = SNP_SCALE_TSC_FREQ(tsc_freq_mhz * 1000, secrets->tsc_factor); 2220 2221 x86_platform.calibrate_cpu = securetsc_get_tsc_khz; 2222 x86_platform.calibrate_tsc = securetsc_get_tsc_khz; 2223 2224 early_memunmap(mem, PAGE_SIZE); 2225 } 2226