arch/x86/kernel/cpu/bugs.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  Copyright (C) 1994  Linus Torvalds
   4  *
   5  *  Cyrix stuff, June 1998 by:
   6  *      - Rafael R. Reilova (moved everything from head.S),
   7  *        <rreilova@ececs.uc.edu>
   8  *      - Channing Corn (tests & fixes),
   9  *      - Andrew D. Balsa (code cleanup).
  10  */
  11 #include <linux/init.h>
  12 #include <linux/utsname.h>
  13 #include <linux/cpu.h>
  14 #include <linux/module.h>
  15 #include <linux/nospec.h>
  16 #include <linux/prctl.h>
  17 #include <linux/sched/smt.h>
  18 #include <linux/pgtable.h>
  19 #include <linux/bpf.h>
  20
  21 #include <asm/spec-ctrl.h>
  22 #include <asm/cmdline.h>
  23 #include <asm/bugs.h>
  24 #include <asm/processor.h>
  25 #include <asm/processor-flags.h>
  26 #include <asm/fpu/api.h>
  27 #include <asm/msr.h>
  28 #include <asm/vmx.h>
  29 #include <asm/paravirt.h>
  30 #include <asm/alternative.h>
  31 #include <asm/set_memory.h>
  32 #include <asm/intel-family.h>
  33 #include <asm/e820/api.h>
  34 #include <asm/hypervisor.h>
  35 #include <asm/tlbflush.h>
  36
  37 #include "cpu.h"
  38
  39 static void __init spectre_v1_select_mitigation(void);
  40 static void __init spectre_v2_select_mitigation(void);
  41 static void __init retbleed_select_mitigation(void);
  42 static void __init spectre_v2_user_select_mitigation(void);
  43 static void __init ssb_select_mitigation(void);
  44 static void __init l1tf_select_mitigation(void);
  45 static void __init mds_select_mitigation(void);
  46 static void __init md_clear_update_mitigation(void);
  47 static void __init md_clear_select_mitigation(void);
  48 static void __init taa_select_mitigation(void);
  49 static void __init mmio_select_mitigation(void);
  50 static void __init srbds_select_mitigation(void);
  51 static void __init l1d_flush_select_mitigation(void);
  52
  53 /* The base value of the SPEC_CTRL MSR without task-specific bits set */
  54 u64 x86_spec_ctrl_base;
  55 EXPORT_SYMBOL_GPL(x86_spec_ctrl_base);
  56
  57 /* The current value of the SPEC_CTRL MSR with task-specific bits set */
  58 DEFINE_PER_CPU(u64, x86_spec_ctrl_current);
  59 EXPORT_SYMBOL_GPL(x86_spec_ctrl_current);
  60
  61 static DEFINE_MUTEX(spec_ctrl_mutex);
  62
  63 /*
  64  * Keep track of the SPEC_CTRL MSR value for the current task, which may differ
  65  * from x86_spec_ctrl_base due to STIBP/SSB in __speculation_ctrl_update().
  66  */
  67 void write_spec_ctrl_current(u64 val, bool force)
  68 {
  69         if (this_cpu_read(x86_spec_ctrl_current) == val)
  70                 return;
  71
  72         this_cpu_write(x86_spec_ctrl_current, val);
  73
  74         /*
  75          * When KERNEL_IBRS this MSR is written on return-to-user, unless
  76          * forced the update can be delayed until that time.
  77          */
  78         if (force || !cpu_feature_enabled(X86_FEATURE_KERNEL_IBRS))
  79                 wrmsrl(MSR_IA32_SPEC_CTRL, val);
  80 }
  81
  82 u64 spec_ctrl_current(void)
  83 {
  84         return this_cpu_read(x86_spec_ctrl_current);
  85 }
  86 EXPORT_SYMBOL_GPL(spec_ctrl_current);
  87
  88 /*
  89  * AMD specific MSR info for Speculative Store Bypass control.
  90  * x86_amd_ls_cfg_ssbd_mask is initialized in identify_boot_cpu().
  91  */
  92 u64 __ro_after_init x86_amd_ls_cfg_base;
  93 u64 __ro_after_init x86_amd_ls_cfg_ssbd_mask;
  94
  95 /* Control conditional STIBP in switch_to() */
  96 DEFINE_STATIC_KEY_FALSE(switch_to_cond_stibp);
  97 /* Control conditional IBPB in switch_mm() */
  98 DEFINE_STATIC_KEY_FALSE(switch_mm_cond_ibpb);
  99 /* Control unconditional IBPB in switch_mm() */
 100 DEFINE_STATIC_KEY_FALSE(switch_mm_always_ibpb);
 101
 102 /* Control MDS CPU buffer clear before returning to user space */
 103 DEFINE_STATIC_KEY_FALSE(mds_user_clear);
 104 EXPORT_SYMBOL_GPL(mds_user_clear);
 105 /* Control MDS CPU buffer clear before idling (halt, mwait) */
 106 DEFINE_STATIC_KEY_FALSE(mds_idle_clear);
 107 EXPORT_SYMBOL_GPL(mds_idle_clear);
 108
 109 /*
 110  * Controls whether l1d flush based mitigations are enabled,
 111  * based on hw features and admin setting via boot parameter
 112  * defaults to false
 113  */
 114 DEFINE_STATIC_KEY_FALSE(switch_mm_cond_l1d_flush);
 115
 116 /* Controls CPU Fill buffer clear before KVM guest MMIO accesses */
 117 DEFINE_STATIC_KEY_FALSE(mmio_stale_data_clear);
 118 EXPORT_SYMBOL_GPL(mmio_stale_data_clear);
 119
 120 void __init check_bugs(void)
 121 {
 122         identify_boot_cpu();
 123
 124         /*
 125          * identify_boot_cpu() initialized SMT support information, let the
 126          * core code know.
 127          */
 128         cpu_smt_check_topology();
 129
 130         if (!IS_ENABLED(CONFIG_SMP)) {
 131                 pr_info("CPU: ");
 132                 print_cpu_info(&boot_cpu_data);
 133         }
 134
 135         /*
 136          * Read the SPEC_CTRL MSR to account for reserved bits which may
 137          * have unknown values. AMD64_LS_CFG MSR is cached in the early AMD
 138          * init code as it is not enumerated and depends on the family.
 139          */
 140         if (boot_cpu_has(X86_FEATURE_MSR_SPEC_CTRL))
 141                 rdmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
 142
 143         /* Select the proper CPU mitigations before patching alternatives: */
 144         spectre_v1_select_mitigation();
 145         spectre_v2_select_mitigation();
 146         /*
 147          * retbleed_select_mitigation() relies on the state set by
 148          * spectre_v2_select_mitigation(); specifically it wants to know about
 149          * spectre_v2=ibrs.
 150          */
 151         retbleed_select_mitigation();
 152         /*
 153          * spectre_v2_user_select_mitigation() relies on the state set by
 154          * retbleed_select_mitigation(); specifically the STIBP selection is
 155          * forced for UNRET.
 156          */
 157         spectre_v2_user_select_mitigation();
 158         ssb_select_mitigation();
 159         l1tf_select_mitigation();
 160         md_clear_select_mitigation();
 161         srbds_select_mitigation();
 162         l1d_flush_select_mitigation();
 163
 164         arch_smt_update();
 165
 166 #ifdef CONFIG_X86_32
 167         /*
 168          * Check whether we are able to run this kernel safely on SMP.
 169          *
 170          * - i386 is no longer supported.
 171          * - In order to run on anything without a TSC, we need to be
 172          *   compiled for a i486.
 173          */
 174         if (boot_cpu_data.x86 < 4)
 175                 panic("Kernel requires i486+ for 'invlpg' and other features");
 176
 177         init_utsname()->machine[1] =
 178                 '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
 179         alternative_instructions();
 180
 181         fpu__init_check_bugs();
 182 #else /* CONFIG_X86_64 */
 183         alternative_instructions();
 184
 185         /*
 186          * Make sure the first 2MB area is not mapped by huge pages
 187          * There are typically fixed size MTRRs in there and overlapping
 188          * MTRRs into large pages causes slow downs.
 189          *
 190          * Right now we don't do that with gbpages because there seems
 191          * very little benefit for that case.
 192          */
 193         if (!direct_gbpages)
 194                 set_memory_4k((unsigned long)__va(0), 1);
 195 #endif
 196 }
 197
 198 /*
 199  * NOTE: This function is *only* called for SVM.  VMX spec_ctrl handling is
 200  * done in vmenter.S.
 201  */
 202 void
 203 x86_virt_spec_ctrl(u64 guest_spec_ctrl, u64 guest_virt_spec_ctrl, bool setguest)
 204 {
 205         u64 msrval, guestval = guest_spec_ctrl, hostval = spec_ctrl_current();
 206         struct thread_info *ti = current_thread_info();
 207
 208         if (static_cpu_has(X86_FEATURE_MSR_SPEC_CTRL)) {
 209                 if (hostval != guestval) {
 210                         msrval = setguest ? guestval : hostval;
 211                         wrmsrl(MSR_IA32_SPEC_CTRL, msrval);
 212                 }
 213         }
 214
 215         /*
 216          * If SSBD is not handled in MSR_SPEC_CTRL on AMD, update
 217          * MSR_AMD64_L2_CFG or MSR_VIRT_SPEC_CTRL if supported.
 218          */
 219         if (!static_cpu_has(X86_FEATURE_LS_CFG_SSBD) &&
 220             !static_cpu_has(X86_FEATURE_VIRT_SSBD))
 221                 return;
 222
 223         /*
 224          * If the host has SSBD mitigation enabled, force it in the host's
 225          * virtual MSR value. If its not permanently enabled, evaluate
 226          * current's TIF_SSBD thread flag.
 227          */
 228         if (static_cpu_has(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE))
 229                 hostval = SPEC_CTRL_SSBD;
 230         else
 231                 hostval = ssbd_tif_to_spec_ctrl(ti->flags);
 232
 233         /* Sanitize the guest value */
 234         guestval = guest_virt_spec_ctrl & SPEC_CTRL_SSBD;
 235
 236         if (hostval != guestval) {
 237                 unsigned long tif;
 238
 239                 tif = setguest ? ssbd_spec_ctrl_to_tif(guestval) :
 240                                  ssbd_spec_ctrl_to_tif(hostval);
 241
 242                 speculation_ctrl_update(tif);
 243         }
 244 }
 245 EXPORT_SYMBOL_GPL(x86_virt_spec_ctrl);
 246
 247 static void x86_amd_ssb_disable(void)
 248 {
 249         u64 msrval = x86_amd_ls_cfg_base | x86_amd_ls_cfg_ssbd_mask;
 250
 251         if (boot_cpu_has(X86_FEATURE_VIRT_SSBD))
 252                 wrmsrl(MSR_AMD64_VIRT_SPEC_CTRL, SPEC_CTRL_SSBD);
 253         else if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD))
 254                 wrmsrl(MSR_AMD64_LS_CFG, msrval);
 255 }
 256
 257 #undef pr_fmt
 258 #define pr_fmt(fmt)     "MDS: " fmt
 259
 260 /* Default mitigation for MDS-affected CPUs */
 261 static enum mds_mitigations mds_mitigation __ro_after_init = MDS_MITIGATION_FULL;
 262 static bool mds_nosmt __ro_after_init = false;
 263
 264 static const char * const mds_strings[] = {
 265         [MDS_MITIGATION_OFF]    = "Vulnerable",
 266         [MDS_MITIGATION_FULL]   = "Mitigation: Clear CPU buffers",
 267         [MDS_MITIGATION_VMWERV] = "Vulnerable: Clear CPU buffers attempted, no microcode",
 268 };
 269
 270 static void __init mds_select_mitigation(void)
 271 {
 272         if (!boot_cpu_has_bug(X86_BUG_MDS) || cpu_mitigations_off()) {
 273                 mds_mitigation = MDS_MITIGATION_OFF;
 274                 return;
 275         }
 276
 277         if (mds_mitigation == MDS_MITIGATION_FULL) {
 278                 if (!boot_cpu_has(X86_FEATURE_MD_CLEAR))
 279                         mds_mitigation = MDS_MITIGATION_VMWERV;
 280
 281                 static_branch_enable(&mds_user_clear);
 282
 283                 if (!boot_cpu_has(X86_BUG_MSBDS_ONLY) &&
 284                     (mds_nosmt || cpu_mitigations_auto_nosmt()))
 285                         cpu_smt_disable(false);
 286         }
 287 }
 288
 289 static int __init mds_cmdline(char *str)
 290 {
 291         if (!boot_cpu_has_bug(X86_BUG_MDS))
 292                 return 0;
 293
 294         if (!str)
 295                 return -EINVAL;
 296
 297         if (!strcmp(str, "off"))
 298                 mds_mitigation = MDS_MITIGATION_OFF;
 299         else if (!strcmp(str, "full"))
 300                 mds_mitigation = MDS_MITIGATION_FULL;
 301         else if (!strcmp(str, "full,nosmt")) {
 302                 mds_mitigation = MDS_MITIGATION_FULL;
 303                 mds_nosmt = true;
 304         }
 305
 306         return 0;
 307 }
 308 early_param("mds", mds_cmdline);
 309
 310 #undef pr_fmt
 311 #define pr_fmt(fmt)     "TAA: " fmt
 312
 313 enum taa_mitigations {
 314         TAA_MITIGATION_OFF,
 315         TAA_MITIGATION_UCODE_NEEDED,
 316         TAA_MITIGATION_VERW,
 317         TAA_MITIGATION_TSX_DISABLED,
 318 };
 319
 320 /* Default mitigation for TAA-affected CPUs */
 321 static enum taa_mitigations taa_mitigation __ro_after_init = TAA_MITIGATION_VERW;
 322 static bool taa_nosmt __ro_after_init;
 323
 324 static const char * const taa_strings[] = {
 325         [TAA_MITIGATION_OFF]            = "Vulnerable",
 326         [TAA_MITIGATION_UCODE_NEEDED]   = "Vulnerable: Clear CPU buffers attempted, no microcode",
 327         [TAA_MITIGATION_VERW]           = "Mitigation: Clear CPU buffers",
 328         [TAA_MITIGATION_TSX_DISABLED]   = "Mitigation: TSX disabled",
 329 };
 330
 331 static void __init taa_select_mitigation(void)
 332 {
 333         u64 ia32_cap;
 334
 335         if (!boot_cpu_has_bug(X86_BUG_TAA)) {
 336                 taa_mitigation = TAA_MITIGATION_OFF;
 337                 return;
 338         }
 339
 340         /* TSX previously disabled by tsx=off */
 341         if (!boot_cpu_has(X86_FEATURE_RTM)) {
 342                 taa_mitigation = TAA_MITIGATION_TSX_DISABLED;
 343                 return;
 344         }
 345
 346         if (cpu_mitigations_off()) {
 347                 taa_mitigation = TAA_MITIGATION_OFF;
 348                 return;
 349         }
 350
 351         /*
 352          * TAA mitigation via VERW is turned off if both
 353          * tsx_async_abort=off and mds=off are specified.
 354          */
 355         if (taa_mitigation == TAA_MITIGATION_OFF &&
 356             mds_mitigation == MDS_MITIGATION_OFF)
 357                 return;
 358
 359         if (boot_cpu_has(X86_FEATURE_MD_CLEAR))
 360                 taa_mitigation = TAA_MITIGATION_VERW;
 361         else
 362                 taa_mitigation = TAA_MITIGATION_UCODE_NEEDED;
 363
 364         /*
 365          * VERW doesn't clear the CPU buffers when MD_CLEAR=1 and MDS_NO=1.
 366          * A microcode update fixes this behavior to clear CPU buffers. It also
 367          * adds support for MSR_IA32_TSX_CTRL which is enumerated by the
 368          * ARCH_CAP_TSX_CTRL_MSR bit.
 369          *
 370          * On MDS_NO=1 CPUs if ARCH_CAP_TSX_CTRL_MSR is not set, microcode
 371          * update is required.
 372          */
 373         ia32_cap = x86_read_arch_cap_msr();
 374         if ( (ia32_cap & ARCH_CAP_MDS_NO) &&
 375             !(ia32_cap & ARCH_CAP_TSX_CTRL_MSR))
 376                 taa_mitigation = TAA_MITIGATION_UCODE_NEEDED;
 377
 378         /*
 379          * TSX is enabled, select alternate mitigation for TAA which is
 380          * the same as MDS. Enable MDS static branch to clear CPU buffers.
 381          *
 382          * For guests that can't determine whether the correct microcode is
 383          * present on host, enable the mitigation for UCODE_NEEDED as well.
 384          */
 385         static_branch_enable(&mds_user_clear);
 386
 387         if (taa_nosmt || cpu_mitigations_auto_nosmt())
 388                 cpu_smt_disable(false);
 389 }
 390
 391 static int __init tsx_async_abort_parse_cmdline(char *str)
 392 {
 393         if (!boot_cpu_has_bug(X86_BUG_TAA))
 394                 return 0;
 395
 396         if (!str)
 397                 return -EINVAL;
 398
 399         if (!strcmp(str, "off")) {
 400                 taa_mitigation = TAA_MITIGATION_OFF;
 401         } else if (!strcmp(str, "full")) {
 402                 taa_mitigation = TAA_MITIGATION_VERW;
 403         } else if (!strcmp(str, "full,nosmt")) {
 404                 taa_mitigation = TAA_MITIGATION_VERW;
 405                 taa_nosmt = true;
 406         }
 407
 408         return 0;
 409 }
 410 early_param("tsx_async_abort", tsx_async_abort_parse_cmdline);
 411
 412 #undef pr_fmt
 413 #define pr_fmt(fmt)     "MMIO Stale Data: " fmt
 414
 415 enum mmio_mitigations {
 416         MMIO_MITIGATION_OFF,
 417         MMIO_MITIGATION_UCODE_NEEDED,
 418         MMIO_MITIGATION_VERW,
 419 };
 420
 421 /* Default mitigation for Processor MMIO Stale Data vulnerabilities */
 422 static enum mmio_mitigations mmio_mitigation __ro_after_init = MMIO_MITIGATION_VERW;
 423 static bool mmio_nosmt __ro_after_init = false;
 424
 425 static const char * const mmio_strings[] = {
 426         [MMIO_MITIGATION_OFF]           = "Vulnerable",
 427         [MMIO_MITIGATION_UCODE_NEEDED]  = "Vulnerable: Clear CPU buffers attempted, no microcode",
 428         [MMIO_MITIGATION_VERW]          = "Mitigation: Clear CPU buffers",
 429 };
 430
 431 static void __init mmio_select_mitigation(void)
 432 {
 433         u64 ia32_cap;
 434
 435         if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA) ||
 436             cpu_mitigations_off()) {
 437                 mmio_mitigation = MMIO_MITIGATION_OFF;
 438                 return;
 439         }
 440
 441         if (mmio_mitigation == MMIO_MITIGATION_OFF)
 442                 return;
 443
 444         ia32_cap = x86_read_arch_cap_msr();
 445
 446         /*
 447          * Enable CPU buffer clear mitigation for host and VMM, if also affected
 448          * by MDS or TAA. Otherwise, enable mitigation for VMM only.
 449          */
 450         if (boot_cpu_has_bug(X86_BUG_MDS) || (boot_cpu_has_bug(X86_BUG_TAA) &&
 451                                               boot_cpu_has(X86_FEATURE_RTM)))
 452                 static_branch_enable(&mds_user_clear);
 453         else
 454                 static_branch_enable(&mmio_stale_data_clear);
 455
 456         /*
 457          * If Processor-MMIO-Stale-Data bug is present and Fill Buffer data can
 458          * be propagated to uncore buffers, clearing the Fill buffers on idle
 459          * is required irrespective of SMT state.
 460          */
 461         if (!(ia32_cap & ARCH_CAP_FBSDP_NO))
 462                 static_branch_enable(&mds_idle_clear);
 463
 464         /*
 465          * Check if the system has the right microcode.
 466          *
 467          * CPU Fill buffer clear mitigation is enumerated by either an explicit
 468          * FB_CLEAR or by the presence of both MD_CLEAR and L1D_FLUSH on MDS
 469          * affected systems.
 470          */
 471         if ((ia32_cap & ARCH_CAP_FB_CLEAR) ||
 472             (boot_cpu_has(X86_FEATURE_MD_CLEAR) &&
 473              boot_cpu_has(X86_FEATURE_FLUSH_L1D) &&
 474              !(ia32_cap & ARCH_CAP_MDS_NO)))
 475                 mmio_mitigation = MMIO_MITIGATION_VERW;
 476         else
 477                 mmio_mitigation = MMIO_MITIGATION_UCODE_NEEDED;
 478
 479         if (mmio_nosmt || cpu_mitigations_auto_nosmt())
 480                 cpu_smt_disable(false);
 481 }
 482
 483 static int __init mmio_stale_data_parse_cmdline(char *str)
 484 {
 485         if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA))
 486                 return 0;
 487
 488         if (!str)
 489                 return -EINVAL;
 490
 491         if (!strcmp(str, "off")) {
 492                 mmio_mitigation = MMIO_MITIGATION_OFF;
 493         } else if (!strcmp(str, "full")) {
 494                 mmio_mitigation = MMIO_MITIGATION_VERW;
 495         } else if (!strcmp(str, "full,nosmt")) {
 496                 mmio_mitigation = MMIO_MITIGATION_VERW;
 497                 mmio_nosmt = true;
 498         }
 499
 500         return 0;
 501 }
 502 early_param("mmio_stale_data", mmio_stale_data_parse_cmdline);
 503
 504 #undef pr_fmt
 505 #define pr_fmt(fmt)     "" fmt
 506
 507 static void __init md_clear_update_mitigation(void)
 508 {
 509         if (cpu_mitigations_off())
 510                 return;
 511
 512         if (!static_key_enabled(&mds_user_clear))
 513                 goto out;
 514
 515         /*
 516          * mds_user_clear is now enabled. Update MDS, TAA and MMIO Stale Data
 517          * mitigation, if necessary.
 518          */
 519         if (mds_mitigation == MDS_MITIGATION_OFF &&
 520             boot_cpu_has_bug(X86_BUG_MDS)) {
 521                 mds_mitigation = MDS_MITIGATION_FULL;
 522                 mds_select_mitigation();
 523         }
 524         if (taa_mitigation == TAA_MITIGATION_OFF &&
 525             boot_cpu_has_bug(X86_BUG_TAA)) {
 526                 taa_mitigation = TAA_MITIGATION_VERW;
 527                 taa_select_mitigation();
 528         }
 529         if (mmio_mitigation == MMIO_MITIGATION_OFF &&
 530             boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA)) {
 531                 mmio_mitigation = MMIO_MITIGATION_VERW;
 532                 mmio_select_mitigation();
 533         }
 534 out:
 535         if (boot_cpu_has_bug(X86_BUG_MDS))
 536                 pr_info("MDS: %s\n", mds_strings[mds_mitigation]);
 537         if (boot_cpu_has_bug(X86_BUG_TAA))
 538                 pr_info("TAA: %s\n", taa_strings[taa_mitigation]);
 539         if (boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA))
 540                 pr_info("MMIO Stale Data: %s\n", mmio_strings[mmio_mitigation]);
 541 }
 542
 543 static void __init md_clear_select_mitigation(void)
 544 {
 545         mds_select_mitigation();
 546         taa_select_mitigation();
 547         mmio_select_mitigation();
 548
 549         /*
 550          * As MDS, TAA and MMIO Stale Data mitigations are inter-related, update
 551          * and print their mitigation after MDS, TAA and MMIO Stale Data
 552          * mitigation selection is done.
 553          */
 554         md_clear_update_mitigation();
 555 }
 556
 557 #undef pr_fmt
 558 #define pr_fmt(fmt)     "SRBDS: " fmt
 559
 560 enum srbds_mitigations {
 561         SRBDS_MITIGATION_OFF,
 562         SRBDS_MITIGATION_UCODE_NEEDED,
 563         SRBDS_MITIGATION_FULL,
 564         SRBDS_MITIGATION_TSX_OFF,
 565         SRBDS_MITIGATION_HYPERVISOR,
 566 };
 567
 568 static enum srbds_mitigations srbds_mitigation __ro_after_init = SRBDS_MITIGATION_FULL;
 569
 570 static const char * const srbds_strings[] = {
 571         [SRBDS_MITIGATION_OFF]          = "Vulnerable",
 572         [SRBDS_MITIGATION_UCODE_NEEDED] = "Vulnerable: No microcode",
 573         [SRBDS_MITIGATION_FULL]         = "Mitigation: Microcode",
 574         [SRBDS_MITIGATION_TSX_OFF]      = "Mitigation: TSX disabled",
 575         [SRBDS_MITIGATION_HYPERVISOR]   = "Unknown: Dependent on hypervisor status",
 576 };
 577
 578 static bool srbds_off;
 579
 580 void update_srbds_msr(void)
 581 {
 582         u64 mcu_ctrl;
 583
 584         if (!boot_cpu_has_bug(X86_BUG_SRBDS))
 585                 return;
 586
 587         if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
 588                 return;
 589
 590         if (srbds_mitigation == SRBDS_MITIGATION_UCODE_NEEDED)
 591                 return;
 592
 593         /*
 594          * A MDS_NO CPU for which SRBDS mitigation is not needed due to TSX
 595          * being disabled and it hasn't received the SRBDS MSR microcode.
 596          */
 597         if (!boot_cpu_has(X86_FEATURE_SRBDS_CTRL))
 598                 return;
 599
 600         rdmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl);
 601
 602         switch (srbds_mitigation) {
 603         case SRBDS_MITIGATION_OFF:
 604         case SRBDS_MITIGATION_TSX_OFF:
 605                 mcu_ctrl |= RNGDS_MITG_DIS;
 606                 break;
 607         case SRBDS_MITIGATION_FULL:
 608                 mcu_ctrl &= ~RNGDS_MITG_DIS;
 609                 break;
 610         default:
 611                 break;
 612         }
 613
 614         wrmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl);
 615 }
 616
 617 static void __init srbds_select_mitigation(void)
 618 {
 619         u64 ia32_cap;
 620
 621         if (!boot_cpu_has_bug(X86_BUG_SRBDS))
 622                 return;
 623
 624         /*
 625          * Check to see if this is one of the MDS_NO systems supporting TSX that
 626          * are only exposed to SRBDS when TSX is enabled or when CPU is affected
 627          * by Processor MMIO Stale Data vulnerability.
 628          */
 629         ia32_cap = x86_read_arch_cap_msr();
 630         if ((ia32_cap & ARCH_CAP_MDS_NO) && !boot_cpu_has(X86_FEATURE_RTM) &&
 631             !boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA))
 632                 srbds_mitigation = SRBDS_MITIGATION_TSX_OFF;
 633         else if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
 634                 srbds_mitigation = SRBDS_MITIGATION_HYPERVISOR;
 635         else if (!boot_cpu_has(X86_FEATURE_SRBDS_CTRL))
 636                 srbds_mitigation = SRBDS_MITIGATION_UCODE_NEEDED;
 637         else if (cpu_mitigations_off() || srbds_off)
 638                 srbds_mitigation = SRBDS_MITIGATION_OFF;
 639
 640         update_srbds_msr();
 641         pr_info("%s\n", srbds_strings[srbds_mitigation]);
 642 }
 643
 644 static int __init srbds_parse_cmdline(char *str)
 645 {
 646         if (!str)
 647                 return -EINVAL;
 648
 649         if (!boot_cpu_has_bug(X86_BUG_SRBDS))
 650                 return 0;
 651
 652         srbds_off = !strcmp(str, "off");
 653         return 0;
 654 }
 655 early_param("srbds", srbds_parse_cmdline);
 656
 657 #undef pr_fmt
 658 #define pr_fmt(fmt)     "L1D Flush : " fmt
 659
 660 enum l1d_flush_mitigations {
 661         L1D_FLUSH_OFF = 0,
 662         L1D_FLUSH_ON,
 663 };
 664
 665 static enum l1d_flush_mitigations l1d_flush_mitigation __initdata = L1D_FLUSH_OFF;
 666
 667 static void __init l1d_flush_select_mitigation(void)
 668 {
 669         if (!l1d_flush_mitigation || !boot_cpu_has(X86_FEATURE_FLUSH_L1D))
 670                 return;
 671
 672         static_branch_enable(&switch_mm_cond_l1d_flush);
 673         pr_info("Conditional flush on switch_mm() enabled\n");
 674 }
 675
 676 static int __init l1d_flush_parse_cmdline(char *str)
 677 {
 678         if (!strcmp(str, "on"))
 679                 l1d_flush_mitigation = L1D_FLUSH_ON;
 680
 681         return 0;
 682 }
 683 early_param("l1d_flush", l1d_flush_parse_cmdline);
 684
 685 #undef pr_fmt
 686 #define pr_fmt(fmt)     "Spectre V1 : " fmt
 687
 688 enum spectre_v1_mitigation {
 689         SPECTRE_V1_MITIGATION_NONE,
 690         SPECTRE_V1_MITIGATION_AUTO,
 691 };
 692
 693 static enum spectre_v1_mitigation spectre_v1_mitigation __ro_after_init =
 694         SPECTRE_V1_MITIGATION_AUTO;
 695
 696 static const char * const spectre_v1_strings[] = {
 697         [SPECTRE_V1_MITIGATION_NONE] = "Vulnerable: __user pointer sanitization and usercopy barriers only; no swapgs barriers",
 698         [SPECTRE_V1_MITIGATION_AUTO] = "Mitigation: usercopy/swapgs barriers and __user pointer sanitization",
 699 };
 700
 701 /*
 702  * Does SMAP provide full mitigation against speculative kernel access to
 703  * userspace?
 704  */
 705 static bool smap_works_speculatively(void)
 706 {
 707         if (!boot_cpu_has(X86_FEATURE_SMAP))
 708                 return false;
 709
 710         /*
 711          * On CPUs which are vulnerable to Meltdown, SMAP does not
 712          * prevent speculative access to user data in the L1 cache.
 713          * Consider SMAP to be non-functional as a mitigation on these
 714          * CPUs.
 715          */
 716         if (boot_cpu_has(X86_BUG_CPU_MELTDOWN))
 717                 return false;
 718
 719         return true;
 720 }
 721
 722 static void __init spectre_v1_select_mitigation(void)
 723 {
 724         if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V1) || cpu_mitigations_off()) {
 725                 spectre_v1_mitigation = SPECTRE_V1_MITIGATION_NONE;
 726                 return;
 727         }
 728
 729         if (spectre_v1_mitigation == SPECTRE_V1_MITIGATION_AUTO) {
 730                 /*
 731                  * With Spectre v1, a user can speculatively control either
 732                  * path of a conditional swapgs with a user-controlled GS
 733                  * value.  The mitigation is to add lfences to both code paths.
 734                  *
 735                  * If FSGSBASE is enabled, the user can put a kernel address in
 736                  * GS, in which case SMAP provides no protection.
 737                  *
 738                  * If FSGSBASE is disabled, the user can only put a user space
 739                  * address in GS.  That makes an attack harder, but still
 740                  * possible if there's no SMAP protection.
 741                  */
 742                 if (boot_cpu_has(X86_FEATURE_FSGSBASE) ||
 743                     !smap_works_speculatively()) {
 744                         /*
 745                          * Mitigation can be provided from SWAPGS itself or
 746                          * PTI as the CR3 write in the Meltdown mitigation
 747                          * is serializing.
 748                          *
 749                          * If neither is there, mitigate with an LFENCE to
 750                          * stop speculation through swapgs.
 751                          */
 752                         if (boot_cpu_has_bug(X86_BUG_SWAPGS) &&
 753                             !boot_cpu_has(X86_FEATURE_PTI))
 754                                 setup_force_cpu_cap(X86_FEATURE_FENCE_SWAPGS_USER);
 755
 756                         /*
 757                          * Enable lfences in the kernel entry (non-swapgs)
 758                          * paths, to prevent user entry from speculatively
 759                          * skipping swapgs.
 760                          */
 761                         setup_force_cpu_cap(X86_FEATURE_FENCE_SWAPGS_KERNEL);
 762                 }
 763         }
 764
 765         pr_info("%s\n", spectre_v1_strings[spectre_v1_mitigation]);
 766 }
 767
 768 static int __init nospectre_v1_cmdline(char *str)
 769 {
 770         spectre_v1_mitigation = SPECTRE_V1_MITIGATION_NONE;
 771         return 0;
 772 }
 773 early_param("nospectre_v1", nospectre_v1_cmdline);
 774
 775 static enum spectre_v2_mitigation spectre_v2_enabled __ro_after_init =
 776         SPECTRE_V2_NONE;
 777
 778 #undef pr_fmt
 779 #define pr_fmt(fmt)     "RETBleed: " fmt
 780
 781 enum retbleed_mitigation {
 782         RETBLEED_MITIGATION_NONE,
 783         RETBLEED_MITIGATION_UNRET,
 784         RETBLEED_MITIGATION_IBPB,
 785         RETBLEED_MITIGATION_IBRS,
 786         RETBLEED_MITIGATION_EIBRS,
 787 };
 788
 789 enum retbleed_mitigation_cmd {
 790         RETBLEED_CMD_OFF,
 791         RETBLEED_CMD_AUTO,
 792         RETBLEED_CMD_UNRET,
 793         RETBLEED_CMD_IBPB,
 794 };
 795
 796 static const char * const retbleed_strings[] = {
 797         [RETBLEED_MITIGATION_NONE]      = "Vulnerable",
 798         [RETBLEED_MITIGATION_UNRET]     = "Mitigation: untrained return thunk",
 799         [RETBLEED_MITIGATION_IBPB]      = "Mitigation: IBPB",
 800         [RETBLEED_MITIGATION_IBRS]      = "Mitigation: IBRS",
 801         [RETBLEED_MITIGATION_EIBRS]     = "Mitigation: Enhanced IBRS",
 802 };
 803
 804 static enum retbleed_mitigation retbleed_mitigation __ro_after_init =
 805         RETBLEED_MITIGATION_NONE;
 806 static enum retbleed_mitigation_cmd retbleed_cmd __ro_after_init =
 807         RETBLEED_CMD_AUTO;
 808
 809 static int __ro_after_init retbleed_nosmt = false;
 810
 811 static int __init retbleed_parse_cmdline(char *str)
 812 {
 813         if (!str)
 814                 return -EINVAL;
 815
 816         while (str) {
 817                 char *next = strchr(str, ',');
 818                 if (next) {
 819                         *next = 0;
 820                         next++;
 821                 }
 822
 823                 if (!strcmp(str, "off")) {
 824                         retbleed_cmd = RETBLEED_CMD_OFF;
 825                 } else if (!strcmp(str, "auto")) {
 826                         retbleed_cmd = RETBLEED_CMD_AUTO;
 827                 } else if (!strcmp(str, "unret")) {
 828                         retbleed_cmd = RETBLEED_CMD_UNRET;
 829                 } else if (!strcmp(str, "ibpb")) {
 830                         retbleed_cmd = RETBLEED_CMD_IBPB;
 831                 } else if (!strcmp(str, "nosmt")) {
 832                         retbleed_nosmt = true;
 833                 } else {
 834                         pr_err("Ignoring unknown retbleed option (%s).", str);
 835                 }
 836
 837                 str = next;
 838         }
 839
 840         return 0;
 841 }
 842 early_param("retbleed", retbleed_parse_cmdline);
 843
 844 #define RETBLEED_UNTRAIN_MSG "WARNING: BTB untrained return thunk mitigation is only effective on AMD/Hygon!\n"
 845 #define RETBLEED_INTEL_MSG "WARNING: Spectre v2 mitigation leaves CPU vulnerable to RETBleed attacks, data leaks possible!\n"
 846
 847 static void __init retbleed_select_mitigation(void)
 848 {
 849         bool mitigate_smt = false;
 850
 851         if (!boot_cpu_has_bug(X86_BUG_RETBLEED) || cpu_mitigations_off())
 852                 return;
 853
 854         switch (retbleed_cmd) {
 855         case RETBLEED_CMD_OFF:
 856                 return;
 857
 858         case RETBLEED_CMD_UNRET:
 859                 if (IS_ENABLED(CONFIG_CPU_UNRET_ENTRY)) {
 860                         retbleed_mitigation = RETBLEED_MITIGATION_UNRET;
 861                 } else {
 862                         pr_err("WARNING: kernel not compiled with CPU_UNRET_ENTRY.\n");
 863                         goto do_cmd_auto;
 864                 }
 865                 break;
 866
 867         case RETBLEED_CMD_IBPB:
 868                 if (!boot_cpu_has(X86_FEATURE_IBPB)) {
 869                         pr_err("WARNING: CPU does not support IBPB.\n");
 870                         goto do_cmd_auto;
 871                 } else if (IS_ENABLED(CONFIG_CPU_IBPB_ENTRY)) {
 872                         retbleed_mitigation = RETBLEED_MITIGATION_IBPB;
 873                 } else {
 874                         pr_err("WARNING: kernel not compiled with CPU_IBPB_ENTRY.\n");
 875                         goto do_cmd_auto;
 876                 }
 877                 break;
 878
 879 do_cmd_auto:
 880         case RETBLEED_CMD_AUTO:
 881         default:
 882                 if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
 883                     boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
 884                         if (IS_ENABLED(CONFIG_CPU_UNRET_ENTRY))
 885                                 retbleed_mitigation = RETBLEED_MITIGATION_UNRET;
 886                         else if (IS_ENABLED(CONFIG_CPU_IBPB_ENTRY) && boot_cpu_has(X86_FEATURE_IBPB))
 887                                 retbleed_mitigation = RETBLEED_MITIGATION_IBPB;
 888                 }
 889
 890                 /*
 891                  * The Intel mitigation (IBRS or eIBRS) was already selected in
 892                  * spectre_v2_select_mitigation().  'retbleed_mitigation' will
 893                  * be set accordingly below.
 894                  */
 895
 896                 break;
 897         }
 898
 899         switch (retbleed_mitigation) {
 900         case RETBLEED_MITIGATION_UNRET:
 901                 setup_force_cpu_cap(X86_FEATURE_RETHUNK);
 902                 setup_force_cpu_cap(X86_FEATURE_UNRET);
 903
 904                 if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
 905                     boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
 906                         pr_err(RETBLEED_UNTRAIN_MSG);
 907
 908                 mitigate_smt = true;
 909                 break;
 910
 911         case RETBLEED_MITIGATION_IBPB:
 912                 setup_force_cpu_cap(X86_FEATURE_ENTRY_IBPB);
 913                 mitigate_smt = true;
 914                 break;
 915
 916         default:
 917                 break;
 918         }
 919
 920         if (mitigate_smt && !boot_cpu_has(X86_FEATURE_STIBP) &&
 921             (retbleed_nosmt || cpu_mitigations_auto_nosmt()))
 922                 cpu_smt_disable(false);
 923
 924         /*
 925          * Let IBRS trump all on Intel without affecting the effects of the
 926          * retbleed= cmdline option.
 927          */
 928         if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) {
 929                 switch (spectre_v2_enabled) {
 930                 case SPECTRE_V2_IBRS:
 931                         retbleed_mitigation = RETBLEED_MITIGATION_IBRS;
 932                         break;
 933                 case SPECTRE_V2_EIBRS:
 934                 case SPECTRE_V2_EIBRS_RETPOLINE:
 935                 case SPECTRE_V2_EIBRS_LFENCE:
 936                         retbleed_mitigation = RETBLEED_MITIGATION_EIBRS;
 937                         break;
 938                 default:
 939                         pr_err(RETBLEED_INTEL_MSG);
 940                 }
 941         }
 942
 943         pr_info("%s\n", retbleed_strings[retbleed_mitigation]);
 944 }
 945
 946 #undef pr_fmt
 947 #define pr_fmt(fmt)     "Spectre V2 : " fmt
 948
 949 static enum spectre_v2_user_mitigation spectre_v2_user_stibp __ro_after_init =
 950         SPECTRE_V2_USER_NONE;
 951 static enum spectre_v2_user_mitigation spectre_v2_user_ibpb __ro_after_init =
 952         SPECTRE_V2_USER_NONE;
 953
 954 #ifdef CONFIG_RETPOLINE
 955 static bool spectre_v2_bad_module;
 956
 957 bool retpoline_module_ok(bool has_retpoline)
 958 {
 959         if (spectre_v2_enabled == SPECTRE_V2_NONE || has_retpoline)
 960                 return true;
 961
 962         pr_err("System may be vulnerable to spectre v2\n");
 963         spectre_v2_bad_module = true;
 964         return false;
 965 }
 966
 967 static inline const char *spectre_v2_module_string(void)
 968 {
 969         return spectre_v2_bad_module ? " - vulnerable module loaded" : "";
 970 }
 971 #else
 972 static inline const char *spectre_v2_module_string(void) { return ""; }
 973 #endif
 974
 975 #define SPECTRE_V2_LFENCE_MSG "WARNING: LFENCE mitigation is not recommended for this CPU, data leaks possible!\n"
 976 #define SPECTRE_V2_EIBRS_EBPF_MSG "WARNING: Unprivileged eBPF is enabled with eIBRS on, data leaks possible via Spectre v2 BHB attacks!\n"
 977 #define SPECTRE_V2_EIBRS_LFENCE_EBPF_SMT_MSG "WARNING: Unprivileged eBPF is enabled with eIBRS+LFENCE mitigation and SMT, data leaks possible via Spectre v2 BHB attacks!\n"
 978
 979 #ifdef CONFIG_BPF_SYSCALL
 980 void unpriv_ebpf_notify(int new_state)
 981 {
 982         if (new_state)
 983                 return;
 984
 985         /* Unprivileged eBPF is enabled */
 986
 987         switch (spectre_v2_enabled) {
 988         case SPECTRE_V2_EIBRS:
 989                 pr_err(SPECTRE_V2_EIBRS_EBPF_MSG);
 990                 break;
 991         case SPECTRE_V2_EIBRS_LFENCE:
 992                 if (sched_smt_active())
 993                         pr_err(SPECTRE_V2_EIBRS_LFENCE_EBPF_SMT_MSG);
 994                 break;
 995         default:
 996                 break;
 997         }
 998 }
 999 #endif
1000
1001 static inline bool match_option(const char *arg, int arglen, const char *opt)
1002 {
1003         int len = strlen(opt);
1004
1005         return len == arglen && !strncmp(arg, opt, len);
1006 }
1007
1008 /* The kernel command line selection for spectre v2 */
1009 enum spectre_v2_mitigation_cmd {
1010         SPECTRE_V2_CMD_NONE,
1011         SPECTRE_V2_CMD_AUTO,
1012         SPECTRE_V2_CMD_FORCE,
1013         SPECTRE_V2_CMD_RETPOLINE,
1014         SPECTRE_V2_CMD_RETPOLINE_GENERIC,
1015         SPECTRE_V2_CMD_RETPOLINE_LFENCE,
1016         SPECTRE_V2_CMD_EIBRS,
1017         SPECTRE_V2_CMD_EIBRS_RETPOLINE,
1018         SPECTRE_V2_CMD_EIBRS_LFENCE,
1019         SPECTRE_V2_CMD_IBRS,
1020 };
1021
1022 enum spectre_v2_user_cmd {
1023         SPECTRE_V2_USER_CMD_NONE,
1024         SPECTRE_V2_USER_CMD_AUTO,
1025         SPECTRE_V2_USER_CMD_FORCE,
1026         SPECTRE_V2_USER_CMD_PRCTL,
1027         SPECTRE_V2_USER_CMD_PRCTL_IBPB,
1028         SPECTRE_V2_USER_CMD_SECCOMP,
1029         SPECTRE_V2_USER_CMD_SECCOMP_IBPB,
1030 };
1031
1032 static const char * const spectre_v2_user_strings[] = {
1033         [SPECTRE_V2_USER_NONE]                  = "User space: Vulnerable",
1034         [SPECTRE_V2_USER_STRICT]                = "User space: Mitigation: STIBP protection",
1035         [SPECTRE_V2_USER_STRICT_PREFERRED]      = "User space: Mitigation: STIBP always-on protection",
1036         [SPECTRE_V2_USER_PRCTL]                 = "User space: Mitigation: STIBP via prctl",
1037         [SPECTRE_V2_USER_SECCOMP]               = "User space: Mitigation: STIBP via seccomp and prctl",
1038 };
1039
1040 static const struct {
1041         const char                      *option;
1042         enum spectre_v2_user_cmd        cmd;
1043         bool                            secure;
1044 } v2_user_options[] __initconst = {
1045         { "auto",               SPECTRE_V2_USER_CMD_AUTO,               false },
1046         { "off",                SPECTRE_V2_USER_CMD_NONE,               false },
1047         { "on",                 SPECTRE_V2_USER_CMD_FORCE,              true  },
1048         { "prctl",              SPECTRE_V2_USER_CMD_PRCTL,              false },
1049         { "prctl,ibpb",         SPECTRE_V2_USER_CMD_PRCTL_IBPB,         false },
1050         { "seccomp",            SPECTRE_V2_USER_CMD_SECCOMP,            false },
1051         { "seccomp,ibpb",       SPECTRE_V2_USER_CMD_SECCOMP_IBPB,       false },
1052 };
1053
1054 static void __init spec_v2_user_print_cond(const char *reason, bool secure)
1055 {
1056         if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2) != secure)
1057                 pr_info("spectre_v2_user=%s forced on command line.\n", reason);
1058 }
1059
1060 static __ro_after_init enum spectre_v2_mitigation_cmd spectre_v2_cmd;
1061
1062 static enum spectre_v2_user_cmd __init
1063 spectre_v2_parse_user_cmdline(void)
1064 {
1065         char arg[20];
1066         int ret, i;
1067
1068         switch (spectre_v2_cmd) {
1069         case SPECTRE_V2_CMD_NONE:
1070                 return SPECTRE_V2_USER_CMD_NONE;
1071         case SPECTRE_V2_CMD_FORCE:
1072                 return SPECTRE_V2_USER_CMD_FORCE;
1073         default:
1074                 break;
1075         }
1076
1077         ret = cmdline_find_option(boot_command_line, "spectre_v2_user",
1078                                   arg, sizeof(arg));
1079         if (ret < 0)
1080                 return SPECTRE_V2_USER_CMD_AUTO;
1081
1082         for (i = 0; i < ARRAY_SIZE(v2_user_options); i++) {
1083                 if (match_option(arg, ret, v2_user_options[i].option)) {
1084                         spec_v2_user_print_cond(v2_user_options[i].option,
1085                                                 v2_user_options[i].secure);
1086                         return v2_user_options[i].cmd;
1087                 }
1088         }
1089
1090         pr_err("Unknown user space protection option (%s). Switching to AUTO select\n", arg);
1091         return SPECTRE_V2_USER_CMD_AUTO;
1092 }
1093
1094 static inline bool spectre_v2_in_ibrs_mode(enum spectre_v2_mitigation mode)
1095 {
1096         return mode == SPECTRE_V2_IBRS ||
1097                mode == SPECTRE_V2_EIBRS ||
1098                mode == SPECTRE_V2_EIBRS_RETPOLINE ||
1099                mode == SPECTRE_V2_EIBRS_LFENCE;
1100 }
1101
1102 static void __init
1103 spectre_v2_user_select_mitigation(void)
1104 {
1105         enum spectre_v2_user_mitigation mode = SPECTRE_V2_USER_NONE;
1106         bool smt_possible = IS_ENABLED(CONFIG_SMP);
1107         enum spectre_v2_user_cmd cmd;
1108
1109         if (!boot_cpu_has(X86_FEATURE_IBPB) && !boot_cpu_has(X86_FEATURE_STIBP))
1110                 return;
1111
1112         if (cpu_smt_control == CPU_SMT_FORCE_DISABLED ||
1113             cpu_smt_control == CPU_SMT_NOT_SUPPORTED)
1114                 smt_possible = false;
1115
1116         cmd = spectre_v2_parse_user_cmdline();
1117         switch (cmd) {
1118         case SPECTRE_V2_USER_CMD_NONE:
1119                 goto set_mode;
1120         case SPECTRE_V2_USER_CMD_FORCE:
1121                 mode = SPECTRE_V2_USER_STRICT;
1122                 break;
1123         case SPECTRE_V2_USER_CMD_AUTO:
1124         case SPECTRE_V2_USER_CMD_PRCTL:
1125         case SPECTRE_V2_USER_CMD_PRCTL_IBPB:
1126                 mode = SPECTRE_V2_USER_PRCTL;
1127                 break;
1128         case SPECTRE_V2_USER_CMD_SECCOMP:
1129         case SPECTRE_V2_USER_CMD_SECCOMP_IBPB:
1130                 if (IS_ENABLED(CONFIG_SECCOMP))
1131                         mode = SPECTRE_V2_USER_SECCOMP;
1132                 else
1133                         mode = SPECTRE_V2_USER_PRCTL;
1134                 break;
1135         }
1136
1137         /* Initialize Indirect Branch Prediction Barrier */
1138         if (boot_cpu_has(X86_FEATURE_IBPB)) {
1139                 setup_force_cpu_cap(X86_FEATURE_USE_IBPB);
1140
1141                 spectre_v2_user_ibpb = mode;
1142                 switch (cmd) {
1143                 case SPECTRE_V2_USER_CMD_FORCE:
1144                 case SPECTRE_V2_USER_CMD_PRCTL_IBPB:
1145                 case SPECTRE_V2_USER_CMD_SECCOMP_IBPB:
1146                         static_branch_enable(&switch_mm_always_ibpb);
1147                         spectre_v2_user_ibpb = SPECTRE_V2_USER_STRICT;
1148                         break;
1149                 case SPECTRE_V2_USER_CMD_PRCTL:
1150                 case SPECTRE_V2_USER_CMD_AUTO:
1151                 case SPECTRE_V2_USER_CMD_SECCOMP:
1152                         static_branch_enable(&switch_mm_cond_ibpb);
1153                         break;
1154                 default:
1155                         break;
1156                 }
1157
1158                 pr_info("mitigation: Enabling %s Indirect Branch Prediction Barrier\n",
1159                         static_key_enabled(&switch_mm_always_ibpb) ?
1160                         "always-on" : "conditional");
1161         }
1162
1163         /*
1164          * If no STIBP, IBRS or enhanced IBRS is enabled, or SMT impossible,
1165          * STIBP is not required.
1166          */
1167         if (!boot_cpu_has(X86_FEATURE_STIBP) ||
1168             !smt_possible ||
1169             spectre_v2_in_ibrs_mode(spectre_v2_enabled))
1170                 return;
1171
1172         /*
1173          * At this point, an STIBP mode other than "off" has been set.
1174          * If STIBP support is not being forced, check if STIBP always-on
1175          * is preferred.
1176          */
1177         if (mode != SPECTRE_V2_USER_STRICT &&
1178             boot_cpu_has(X86_FEATURE_AMD_STIBP_ALWAYS_ON))
1179                 mode = SPECTRE_V2_USER_STRICT_PREFERRED;
1180
1181         if (retbleed_mitigation == RETBLEED_MITIGATION_UNRET) {
1182                 if (mode != SPECTRE_V2_USER_STRICT &&
1183                     mode != SPECTRE_V2_USER_STRICT_PREFERRED)
1184                         pr_info("Selecting STIBP always-on mode to complement retbleed mitigation'\n");
1185                 mode = SPECTRE_V2_USER_STRICT_PREFERRED;
1186         }
1187
1188         spectre_v2_user_stibp = mode;
1189
1190 set_mode:
1191         pr_info("%s\n", spectre_v2_user_strings[mode]);
1192 }
1193
1194 static const char * const spectre_v2_strings[] = {
1195         [SPECTRE_V2_NONE]                       = "Vulnerable",
1196         [SPECTRE_V2_RETPOLINE]                  = "Mitigation: Retpolines",
1197         [SPECTRE_V2_LFENCE]                     = "Mitigation: LFENCE",
1198         [SPECTRE_V2_EIBRS]                      = "Mitigation: Enhanced IBRS",
1199         [SPECTRE_V2_EIBRS_LFENCE]               = "Mitigation: Enhanced IBRS + LFENCE",
1200         [SPECTRE_V2_EIBRS_RETPOLINE]            = "Mitigation: Enhanced IBRS + Retpolines",
1201         [SPECTRE_V2_IBRS]                       = "Mitigation: IBRS",
1202 };
1203
1204 static const struct {
1205         const char *option;
1206         enum spectre_v2_mitigation_cmd cmd;
1207         bool secure;
1208 } mitigation_options[] __initconst = {
1209         { "off",                SPECTRE_V2_CMD_NONE,              false },
1210         { "on",                 SPECTRE_V2_CMD_FORCE,             true  },
1211         { "retpoline",          SPECTRE_V2_CMD_RETPOLINE,         false },
1212         { "retpoline,amd",      SPECTRE_V2_CMD_RETPOLINE_LFENCE,  false },
1213         { "retpoline,lfence",   SPECTRE_V2_CMD_RETPOLINE_LFENCE,  false },
1214         { "retpoline,generic",  SPECTRE_V2_CMD_RETPOLINE_GENERIC, false },
1215         { "eibrs",              SPECTRE_V2_CMD_EIBRS,             false },
1216         { "eibrs,lfence",       SPECTRE_V2_CMD_EIBRS_LFENCE,      false },
1217         { "eibrs,retpoline",    SPECTRE_V2_CMD_EIBRS_RETPOLINE,   false },
1218         { "auto",               SPECTRE_V2_CMD_AUTO,              false },
1219         { "ibrs",               SPECTRE_V2_CMD_IBRS,              false },
1220 };
1221
1222 static void __init spec_v2_print_cond(const char *reason, bool secure)
1223 {
1224         if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2) != secure)
1225                 pr_info("%s selected on command line.\n", reason);
1226 }
1227
1228 static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
1229 {
1230         enum spectre_v2_mitigation_cmd cmd = SPECTRE_V2_CMD_AUTO;
1231         char arg[20];
1232         int ret, i;
1233
1234         if (cmdline_find_option_bool(boot_command_line, "nospectre_v2") ||
1235             cpu_mitigations_off())
1236                 return SPECTRE_V2_CMD_NONE;
1237
1238         ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg));
1239         if (ret < 0)
1240                 return SPECTRE_V2_CMD_AUTO;
1241
1242         for (i = 0; i < ARRAY_SIZE(mitigation_options); i++) {
1243                 if (!match_option(arg, ret, mitigation_options[i].option))
1244                         continue;
1245                 cmd = mitigation_options[i].cmd;
1246                 break;
1247         }
1248
1249         if (i >= ARRAY_SIZE(mitigation_options)) {
1250                 pr_err("unknown option (%s). Switching to AUTO select\n", arg);
1251                 return SPECTRE_V2_CMD_AUTO;
1252         }
1253
1254         if ((cmd == SPECTRE_V2_CMD_RETPOLINE ||
1255              cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE ||
1256              cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC ||
1257              cmd == SPECTRE_V2_CMD_EIBRS_LFENCE ||
1258              cmd == SPECTRE_V2_CMD_EIBRS_RETPOLINE) &&
1259             !IS_ENABLED(CONFIG_RETPOLINE)) {
1260                 pr_err("%s selected but not compiled in. Switching to AUTO select\n",
1261                        mitigation_options[i].option);
1262                 return SPECTRE_V2_CMD_AUTO;
1263         }
1264
1265         if ((cmd == SPECTRE_V2_CMD_EIBRS ||
1266              cmd == SPECTRE_V2_CMD_EIBRS_LFENCE ||
1267              cmd == SPECTRE_V2_CMD_EIBRS_RETPOLINE) &&
1268             !boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) {
1269                 pr_err("%s selected but CPU doesn't have eIBRS. Switching to AUTO select\n",
1270                        mitigation_options[i].option);
1271                 return SPECTRE_V2_CMD_AUTO;
1272         }
1273
1274         if ((cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE ||
1275              cmd == SPECTRE_V2_CMD_EIBRS_LFENCE) &&
1276             !boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) {
1277                 pr_err("%s selected, but CPU doesn't have a serializing LFENCE. Switching to AUTO select\n",
1278                        mitigation_options[i].option);
1279                 return SPECTRE_V2_CMD_AUTO;
1280         }
1281
1282         if (cmd == SPECTRE_V2_CMD_IBRS && !IS_ENABLED(CONFIG_CPU_IBRS_ENTRY)) {
1283                 pr_err("%s selected but not compiled in. Switching to AUTO select\n",
1284                        mitigation_options[i].option);
1285                 return SPECTRE_V2_CMD_AUTO;
1286         }
1287
1288         if (cmd == SPECTRE_V2_CMD_IBRS && boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) {
1289                 pr_err("%s selected but not Intel CPU. Switching to AUTO select\n",
1290                        mitigation_options[i].option);
1291                 return SPECTRE_V2_CMD_AUTO;
1292         }
1293
1294         if (cmd == SPECTRE_V2_CMD_IBRS && !boot_cpu_has(X86_FEATURE_IBRS)) {
1295                 pr_err("%s selected but CPU doesn't have IBRS. Switching to AUTO select\n",
1296                        mitigation_options[i].option);
1297                 return SPECTRE_V2_CMD_AUTO;
1298         }
1299
1300         if (cmd == SPECTRE_V2_CMD_IBRS && boot_cpu_has(X86_FEATURE_XENPV)) {
1301                 pr_err("%s selected but running as XenPV guest. Switching to AUTO select\n",
1302                        mitigation_options[i].option);
1303                 return SPECTRE_V2_CMD_AUTO;
1304         }
1305
1306         spec_v2_print_cond(mitigation_options[i].option,
1307                            mitigation_options[i].secure);
1308         return cmd;
1309 }
1310
1311 static enum spectre_v2_mitigation __init spectre_v2_select_retpoline(void)
1312 {
1313         if (!IS_ENABLED(CONFIG_RETPOLINE)) {
1314                 pr_err("Kernel not compiled with retpoline; no mitigation available!");
1315                 return SPECTRE_V2_NONE;
1316         }
1317
1318         return SPECTRE_V2_RETPOLINE;
1319 }
1320
1321 /* Disable in-kernel use of non-RSB RET predictors */
1322 static void __init spec_ctrl_disable_kernel_rrsba(void)
1323 {
1324         u64 ia32_cap;
1325
1326         if (!boot_cpu_has(X86_FEATURE_RRSBA_CTRL))
1327                 return;
1328
1329         ia32_cap = x86_read_arch_cap_msr();
1330
1331         if (ia32_cap & ARCH_CAP_RRSBA) {
1332                 x86_spec_ctrl_base |= SPEC_CTRL_RRSBA_DIS_S;
1333                 write_spec_ctrl_current(x86_spec_ctrl_base, true);
1334         }
1335 }
1336
1337 static void __init spectre_v2_select_mitigation(void)
1338 {
1339         enum spectre_v2_mitigation_cmd cmd = spectre_v2_parse_cmdline();
1340         enum spectre_v2_mitigation mode = SPECTRE_V2_NONE;
1341
1342         /*
1343          * If the CPU is not affected and the command line mode is NONE or AUTO
1344          * then nothing to do.
1345          */
1346         if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2) &&
1347             (cmd == SPECTRE_V2_CMD_NONE || cmd == SPECTRE_V2_CMD_AUTO))
1348                 return;
1349
1350         switch (cmd) {
1351         case SPECTRE_V2_CMD_NONE:
1352                 return;
1353
1354         case SPECTRE_V2_CMD_FORCE:
1355         case SPECTRE_V2_CMD_AUTO:
1356                 if (boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) {
1357                         mode = SPECTRE_V2_EIBRS;
1358                         break;
1359                 }
1360
1361                 if (IS_ENABLED(CONFIG_CPU_IBRS_ENTRY) &&
1362                     boot_cpu_has_bug(X86_BUG_RETBLEED) &&
1363                     retbleed_cmd != RETBLEED_CMD_OFF &&
1364                     boot_cpu_has(X86_FEATURE_IBRS) &&
1365                     boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) {
1366                         mode = SPECTRE_V2_IBRS;
1367                         break;
1368                 }
1369
1370                 mode = spectre_v2_select_retpoline();
1371                 break;
1372
1373         case SPECTRE_V2_CMD_RETPOLINE_LFENCE:
1374                 pr_err(SPECTRE_V2_LFENCE_MSG);
1375                 mode = SPECTRE_V2_LFENCE;
1376                 break;
1377
1378         case SPECTRE_V2_CMD_RETPOLINE_GENERIC:
1379                 mode = SPECTRE_V2_RETPOLINE;
1380                 break;
1381
1382         case SPECTRE_V2_CMD_RETPOLINE:
1383                 mode = spectre_v2_select_retpoline();
1384                 break;
1385
1386         case SPECTRE_V2_CMD_IBRS:
1387                 mode = SPECTRE_V2_IBRS;
1388                 break;
1389
1390         case SPECTRE_V2_CMD_EIBRS:
1391                 mode = SPECTRE_V2_EIBRS;
1392                 break;
1393
1394         case SPECTRE_V2_CMD_EIBRS_LFENCE:
1395                 mode = SPECTRE_V2_EIBRS_LFENCE;
1396                 break;
1397
1398         case SPECTRE_V2_CMD_EIBRS_RETPOLINE:
1399                 mode = SPECTRE_V2_EIBRS_RETPOLINE;
1400                 break;
1401         }
1402
1403         if (mode == SPECTRE_V2_EIBRS && unprivileged_ebpf_enabled())
1404                 pr_err(SPECTRE_V2_EIBRS_EBPF_MSG);
1405
1406         if (spectre_v2_in_ibrs_mode(mode)) {
1407                 x86_spec_ctrl_base |= SPEC_CTRL_IBRS;
1408                 write_spec_ctrl_current(x86_spec_ctrl_base, true);
1409         }
1410
1411         switch (mode) {
1412         case SPECTRE_V2_NONE:
1413         case SPECTRE_V2_EIBRS:
1414                 break;
1415
1416         case SPECTRE_V2_IBRS:
1417                 setup_force_cpu_cap(X86_FEATURE_KERNEL_IBRS);
1418                 break;
1419
1420         case SPECTRE_V2_LFENCE:
1421         case SPECTRE_V2_EIBRS_LFENCE:
1422                 setup_force_cpu_cap(X86_FEATURE_RETPOLINE_LFENCE);
1423                 fallthrough;
1424
1425         case SPECTRE_V2_RETPOLINE:
1426         case SPECTRE_V2_EIBRS_RETPOLINE:
1427                 setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
1428                 break;
1429         }
1430
1431         /*
1432          * Disable alternate RSB predictions in kernel when indirect CALLs and
1433          * JMPs gets protection against BHI and Intramode-BTI, but RET
1434          * prediction from a non-RSB predictor is still a risk.
1435          */
1436         if (mode == SPECTRE_V2_EIBRS_LFENCE ||
1437             mode == SPECTRE_V2_EIBRS_RETPOLINE ||
1438             mode == SPECTRE_V2_RETPOLINE)
1439                 spec_ctrl_disable_kernel_rrsba();
1440
1441         spectre_v2_enabled = mode;
1442         pr_info("%s\n", spectre_v2_strings[mode]);
1443
1444         /*
1445          * If Spectre v2 protection has been enabled, fill the RSB during a
1446          * context switch.  In general there are two types of RSB attacks
1447          * across context switches, for which the CALLs/RETs may be unbalanced.
1448          *
1449          * 1) RSB underflow
1450          *
1451          *    Some Intel parts have "bottomless RSB".  When the RSB is empty,
1452          *    speculated return targets may come from the branch predictor,
1453          *    which could have a user-poisoned BTB or BHB entry.
1454          *
1455          *    AMD has it even worse: *all* returns are speculated from the BTB,
1456          *    regardless of the state of the RSB.
1457          *
1458          *    When IBRS or eIBRS is enabled, the "user -> kernel" attack
1459          *    scenario is mitigated by the IBRS branch prediction isolation
1460          *    properties, so the RSB buffer filling wouldn't be necessary to
1461          *    protect against this type of attack.
1462          *
1463          *    The "user -> user" attack scenario is mitigated by RSB filling.
1464          *
1465          * 2) Poisoned RSB entry
1466          *
1467          *    If the 'next' in-kernel return stack is shorter than 'prev',
1468          *    'next' could be tricked into speculating with a user-poisoned RSB
1469          *    entry.
1470          *
1471          *    The "user -> kernel" attack scenario is mitigated by SMEP and
1472          *    eIBRS.
1473          *
1474          *    The "user -> user" scenario, also known as SpectreBHB, requires
1475          *    RSB clearing.
1476          *
1477          * So to mitigate all cases, unconditionally fill RSB on context
1478          * switches.
1479          *
1480          * FIXME: Is this pointless for retbleed-affected AMD?
1481          */
1482         setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
1483         pr_info("Spectre v2 / SpectreRSB mitigation: Filling RSB on context switch\n");
1484
1485         /*
1486          * Similar to context switches, there are two types of RSB attacks
1487          * after vmexit:
1488          *
1489          * 1) RSB underflow
1490          *
1491          * 2) Poisoned RSB entry
1492          *
1493          * When retpoline is enabled, both are mitigated by filling/clearing
1494          * the RSB.
1495          *
1496          * When IBRS is enabled, while #1 would be mitigated by the IBRS branch
1497          * prediction isolation protections, RSB still needs to be cleared
1498          * because of #2.  Note that SMEP provides no protection here, unlike
1499          * user-space-poisoned RSB entries.
1500          *
1501          * eIBRS, on the other hand, has RSB-poisoning protections, so it
1502          * doesn't need RSB clearing after vmexit.
1503          */
1504         if (boot_cpu_has(X86_FEATURE_RETPOLINE) ||
1505             boot_cpu_has(X86_FEATURE_KERNEL_IBRS))
1506                 setup_force_cpu_cap(X86_FEATURE_RSB_VMEXIT);
1507
1508         /*
1509          * Retpoline protects the kernel, but doesn't protect firmware.  IBRS
1510          * and Enhanced IBRS protect firmware too, so enable IBRS around
1511          * firmware calls only when IBRS / Enhanced IBRS aren't otherwise
1512          * enabled.
1513          *
1514          * Use "mode" to check Enhanced IBRS instead of boot_cpu_has(), because
1515          * the user might select retpoline on the kernel command line and if
1516          * the CPU supports Enhanced IBRS, kernel might un-intentionally not
1517          * enable IBRS around firmware calls.
1518          */
1519         if (boot_cpu_has(X86_FEATURE_IBRS) && !spectre_v2_in_ibrs_mode(mode)) {
1520                 setup_force_cpu_cap(X86_FEATURE_USE_IBRS_FW);
1521                 pr_info("Enabling Restricted Speculation for firmware calls\n");
1522         }
1523
1524         /* Set up IBPB and STIBP depending on the general spectre V2 command */
1525         spectre_v2_cmd = cmd;
1526 }
1527
1528 static void update_stibp_msr(void * __unused)
1529 {
1530         u64 val = spec_ctrl_current() | (x86_spec_ctrl_base & SPEC_CTRL_STIBP);
1531         write_spec_ctrl_current(val, true);
1532 }
1533
1534 /* Update x86_spec_ctrl_base in case SMT state changed. */
1535 static void update_stibp_strict(void)
1536 {
1537         u64 mask = x86_spec_ctrl_base & ~SPEC_CTRL_STIBP;
1538
1539         if (sched_smt_active())
1540                 mask |= SPEC_CTRL_STIBP;
1541
1542         if (mask == x86_spec_ctrl_base)
1543                 return;
1544
1545         pr_info("Update user space SMT mitigation: STIBP %s\n",
1546                 mask & SPEC_CTRL_STIBP ? "always-on" : "off");
1547         x86_spec_ctrl_base = mask;
1548         on_each_cpu(update_stibp_msr, NULL, 1);
1549 }
1550
1551 /* Update the static key controlling the evaluation of TIF_SPEC_IB */
1552 static void update_indir_branch_cond(void)
1553 {
1554         if (sched_smt_active())
1555                 static_branch_enable(&switch_to_cond_stibp);
1556         else
1557                 static_branch_disable(&switch_to_cond_stibp);
1558 }
1559
1560 #undef pr_fmt
1561 #define pr_fmt(fmt) fmt
1562
1563 /* Update the static key controlling the MDS CPU buffer clear in idle */
1564 static void update_mds_branch_idle(void)
1565 {
1566         u64 ia32_cap = x86_read_arch_cap_msr();
1567
1568         /*
1569          * Enable the idle clearing if SMT is active on CPUs which are
1570          * affected only by MSBDS and not any other MDS variant.
1571          *
1572          * The other variants cannot be mitigated when SMT is enabled, so
1573          * clearing the buffers on idle just to prevent the Store Buffer
1574          * repartitioning leak would be a window dressing exercise.
1575          */
1576         if (!boot_cpu_has_bug(X86_BUG_MSBDS_ONLY))
1577                 return;
1578
1579         if (sched_smt_active()) {
1580                 static_branch_enable(&mds_idle_clear);
1581         } else if (mmio_mitigation == MMIO_MITIGATION_OFF ||
1582                    (ia32_cap & ARCH_CAP_FBSDP_NO)) {
1583                 static_branch_disable(&mds_idle_clear);
1584         }
1585 }
1586
1587 #define MDS_MSG_SMT "MDS CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html for more details.\n"
1588 #define TAA_MSG_SMT "TAA CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html for more details.\n"
1589 #define MMIO_MSG_SMT "MMIO Stale Data CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/processor_mmio_stale_data.html for more details.\n"
1590
1591 void cpu_bugs_smt_update(void)
1592 {
1593         mutex_lock(&spec_ctrl_mutex);
1594
1595         if (sched_smt_active() && unprivileged_ebpf_enabled() &&
1596             spectre_v2_enabled == SPECTRE_V2_EIBRS_LFENCE)
1597                 pr_warn_once(SPECTRE_V2_EIBRS_LFENCE_EBPF_SMT_MSG);
1598
1599         switch (spectre_v2_user_stibp) {
1600         case SPECTRE_V2_USER_NONE:
1601                 break;
1602         case SPECTRE_V2_USER_STRICT:
1603         case SPECTRE_V2_USER_STRICT_PREFERRED:
1604                 update_stibp_strict();
1605                 break;
1606         case SPECTRE_V2_USER_PRCTL:
1607         case SPECTRE_V2_USER_SECCOMP:
1608                 update_indir_branch_cond();
1609                 break;
1610         }
1611
1612         switch (mds_mitigation) {
1613         case MDS_MITIGATION_FULL:
1614         case MDS_MITIGATION_VMWERV:
1615                 if (sched_smt_active() && !boot_cpu_has(X86_BUG_MSBDS_ONLY))
1616                         pr_warn_once(MDS_MSG_SMT);
1617                 update_mds_branch_idle();
1618                 break;
1619         case MDS_MITIGATION_OFF:
1620                 break;
1621         }
1622
1623         switch (taa_mitigation) {
1624         case TAA_MITIGATION_VERW:
1625         case TAA_MITIGATION_UCODE_NEEDED:
1626                 if (sched_smt_active())
1627                         pr_warn_once(TAA_MSG_SMT);
1628                 break;
1629         case TAA_MITIGATION_TSX_DISABLED:
1630         case TAA_MITIGATION_OFF:
1631                 break;
1632         }
1633
1634         switch (mmio_mitigation) {
1635         case MMIO_MITIGATION_VERW:
1636         case MMIO_MITIGATION_UCODE_NEEDED:
1637                 if (sched_smt_active())
1638                         pr_warn_once(MMIO_MSG_SMT);
1639                 break;
1640         case MMIO_MITIGATION_OFF:
1641                 break;
1642         }
1643
1644         mutex_unlock(&spec_ctrl_mutex);
1645 }
1646
1647 #undef pr_fmt
1648 #define pr_fmt(fmt)     "Speculative Store Bypass: " fmt
1649
1650 static enum ssb_mitigation ssb_mode __ro_after_init = SPEC_STORE_BYPASS_NONE;
1651
1652 /* The kernel command line selection */
1653 enum ssb_mitigation_cmd {
1654         SPEC_STORE_BYPASS_CMD_NONE,
1655         SPEC_STORE_BYPASS_CMD_AUTO,
1656         SPEC_STORE_BYPASS_CMD_ON,
1657         SPEC_STORE_BYPASS_CMD_PRCTL,
1658         SPEC_STORE_BYPASS_CMD_SECCOMP,
1659 };
1660
1661 static const char * const ssb_strings[] = {
1662         [SPEC_STORE_BYPASS_NONE]        = "Vulnerable",
1663         [SPEC_STORE_BYPASS_DISABLE]     = "Mitigation: Speculative Store Bypass disabled",
1664         [SPEC_STORE_BYPASS_PRCTL]       = "Mitigation: Speculative Store Bypass disabled via prctl",
1665         [SPEC_STORE_BYPASS_SECCOMP]     = "Mitigation: Speculative Store Bypass disabled via prctl and seccomp",
1666 };
1667
1668 static const struct {
1669         const char *option;
1670         enum ssb_mitigation_cmd cmd;
1671 } ssb_mitigation_options[]  __initconst = {
1672         { "auto",       SPEC_STORE_BYPASS_CMD_AUTO },    /* Platform decides */
1673         { "on",         SPEC_STORE_BYPASS_CMD_ON },      /* Disable Speculative Store Bypass */
1674         { "off",        SPEC_STORE_BYPASS_CMD_NONE },    /* Don't touch Speculative Store Bypass */
1675         { "prctl",      SPEC_STORE_BYPASS_CMD_PRCTL },   /* Disable Speculative Store Bypass via prctl */
1676         { "seccomp",    SPEC_STORE_BYPASS_CMD_SECCOMP }, /* Disable Speculative Store Bypass via prctl and seccomp */
1677 };
1678
1679 static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void)
1680 {
1681         enum ssb_mitigation_cmd cmd = SPEC_STORE_BYPASS_CMD_AUTO;
1682         char arg[20];
1683         int ret, i;
1684
1685         if (cmdline_find_option_bool(boot_command_line, "nospec_store_bypass_disable") ||
1686             cpu_mitigations_off()) {
1687                 return SPEC_STORE_BYPASS_CMD_NONE;
1688         } else {
1689                 ret = cmdline_find_option(boot_command_line, "spec_store_bypass_disable",
1690                                           arg, sizeof(arg));
1691                 if (ret < 0)
1692                         return SPEC_STORE_BYPASS_CMD_AUTO;
1693
1694                 for (i = 0; i < ARRAY_SIZE(ssb_mitigation_options); i++) {
1695                         if (!match_option(arg, ret, ssb_mitigation_options[i].option))
1696                                 continue;
1697
1698                         cmd = ssb_mitigation_options[i].cmd;
1699                         break;
1700                 }
1701
1702                 if (i >= ARRAY_SIZE(ssb_mitigation_options)) {
1703                         pr_err("unknown option (%s). Switching to AUTO select\n", arg);
1704                         return SPEC_STORE_BYPASS_CMD_AUTO;
1705                 }
1706         }
1707
1708         return cmd;
1709 }
1710
1711 static enum ssb_mitigation __init __ssb_select_mitigation(void)
1712 {
1713         enum ssb_mitigation mode = SPEC_STORE_BYPASS_NONE;
1714         enum ssb_mitigation_cmd cmd;
1715
1716         if (!boot_cpu_has(X86_FEATURE_SSBD))
1717                 return mode;
1718
1719         cmd = ssb_parse_cmdline();
1720         if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS) &&
1721             (cmd == SPEC_STORE_BYPASS_CMD_NONE ||
1722              cmd == SPEC_STORE_BYPASS_CMD_AUTO))
1723                 return mode;
1724
1725         switch (cmd) {
1726         case SPEC_STORE_BYPASS_CMD_SECCOMP:
1727                 /*
1728                  * Choose prctl+seccomp as the default mode if seccomp is
1729                  * enabled.
1730                  */
1731                 if (IS_ENABLED(CONFIG_SECCOMP))
1732                         mode = SPEC_STORE_BYPASS_SECCOMP;
1733                 else
1734                         mode = SPEC_STORE_BYPASS_PRCTL;
1735                 break;
1736         case SPEC_STORE_BYPASS_CMD_ON:
1737                 mode = SPEC_STORE_BYPASS_DISABLE;
1738                 break;
1739         case SPEC_STORE_BYPASS_CMD_AUTO:
1740         case SPEC_STORE_BYPASS_CMD_PRCTL:
1741                 mode = SPEC_STORE_BYPASS_PRCTL;
1742                 break;
1743         case SPEC_STORE_BYPASS_CMD_NONE:
1744                 break;
1745         }
1746
1747         /*
1748          * We have three CPU feature flags that are in play here:
1749          *  - X86_BUG_SPEC_STORE_BYPASS - CPU is susceptible.
1750          *  - X86_FEATURE_SSBD - CPU is able to turn off speculative store bypass
1751          *  - X86_FEATURE_SPEC_STORE_BYPASS_DISABLE - engage the mitigation
1752          */
1753         if (mode == SPEC_STORE_BYPASS_DISABLE) {
1754                 setup_force_cpu_cap(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE);
1755                 /*
1756                  * Intel uses the SPEC CTRL MSR Bit(2) for this, while AMD may
1757                  * use a completely different MSR and bit dependent on family.
1758                  */
1759                 if (!static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) &&
1760                     !static_cpu_has(X86_FEATURE_AMD_SSBD)) {
1761                         x86_amd_ssb_disable();
1762                 } else {
1763                         x86_spec_ctrl_base |= SPEC_CTRL_SSBD;
1764                         write_spec_ctrl_current(x86_spec_ctrl_base, true);
1765                 }
1766         }
1767
1768         return mode;
1769 }
1770
1771 static void ssb_select_mitigation(void)
1772 {
1773         ssb_mode = __ssb_select_mitigation();
1774
1775         if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
1776                 pr_info("%s\n", ssb_strings[ssb_mode]);
1777 }
1778
1779 #undef pr_fmt
1780 #define pr_fmt(fmt)     "Speculation prctl: " fmt
1781
1782 static void task_update_spec_tif(struct task_struct *tsk)
1783 {
1784         /* Force the update of the real TIF bits */
1785         set_tsk_thread_flag(tsk, TIF_SPEC_FORCE_UPDATE);
1786
1787         /*
1788          * Immediately update the speculation control MSRs for the current
1789          * task, but for a non-current task delay setting the CPU
1790          * mitigation until it is scheduled next.
1791          *
1792          * This can only happen for SECCOMP mitigation. For PRCTL it's
1793          * always the current task.
1794          */
1795         if (tsk == current)
1796                 speculation_ctrl_update_current();
1797 }
1798
1799 static int l1d_flush_prctl_set(struct task_struct *task, unsigned long ctrl)
1800 {
1801
1802         if (!static_branch_unlikely(&switch_mm_cond_l1d_flush))
1803                 return -EPERM;
1804
1805         switch (ctrl) {
1806         case PR_SPEC_ENABLE:
1807                 set_ti_thread_flag(&task->thread_info, TIF_SPEC_L1D_FLUSH);
1808                 return 0;
1809         case PR_SPEC_DISABLE:
1810                 clear_ti_thread_flag(&task->thread_info, TIF_SPEC_L1D_FLUSH);
1811                 return 0;
1812         default:
1813                 return -ERANGE;
1814         }
1815 }
1816
1817 static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl)
1818 {
1819         if (ssb_mode != SPEC_STORE_BYPASS_PRCTL &&
1820             ssb_mode != SPEC_STORE_BYPASS_SECCOMP)
1821                 return -ENXIO;
1822
1823         switch (ctrl) {
1824         case PR_SPEC_ENABLE:
1825                 /* If speculation is force disabled, enable is not allowed */
1826                 if (task_spec_ssb_force_disable(task))
1827                         return -EPERM;
1828                 task_clear_spec_ssb_disable(task);
1829                 task_clear_spec_ssb_noexec(task);
1830                 task_update_spec_tif(task);
1831                 break;
1832         case PR_SPEC_DISABLE:
1833                 task_set_spec_ssb_disable(task);
1834                 task_clear_spec_ssb_noexec(task);
1835                 task_update_spec_tif(task);
1836                 break;
1837         case PR_SPEC_FORCE_DISABLE:
1838                 task_set_spec_ssb_disable(task);
1839                 task_set_spec_ssb_force_disable(task);
1840                 task_clear_spec_ssb_noexec(task);
1841                 task_update_spec_tif(task);
1842                 break;
1843         case PR_SPEC_DISABLE_NOEXEC:
1844                 if (task_spec_ssb_force_disable(task))
1845                         return -EPERM;
1846                 task_set_spec_ssb_disable(task);
1847                 task_set_spec_ssb_noexec(task);
1848                 task_update_spec_tif(task);
1849                 break;
1850         default:
1851                 return -ERANGE;
1852         }
1853         return 0;
1854 }
1855
1856 static bool is_spec_ib_user_controlled(void)
1857 {
1858         return spectre_v2_user_ibpb == SPECTRE_V2_USER_PRCTL ||
1859                 spectre_v2_user_ibpb == SPECTRE_V2_USER_SECCOMP ||
1860                 spectre_v2_user_stibp == SPECTRE_V2_USER_PRCTL ||
1861                 spectre_v2_user_stibp == SPECTRE_V2_USER_SECCOMP;
1862 }
1863
1864 static int ib_prctl_set(struct task_struct *task, unsigned long ctrl)
1865 {
1866         switch (ctrl) {
1867         case PR_SPEC_ENABLE:
1868                 if (spectre_v2_user_ibpb == SPECTRE_V2_USER_NONE &&
1869                     spectre_v2_user_stibp == SPECTRE_V2_USER_NONE)
1870                         return 0;
1871
1872                 /*
1873                  * With strict mode for both IBPB and STIBP, the instruction
1874                  * code paths avoid checking this task flag and instead,
1875                  * unconditionally run the instruction. However, STIBP and IBPB
1876                  * are independent and either can be set to conditionally
1877                  * enabled regardless of the mode of the other.
1878                  *
1879                  * If either is set to conditional, allow the task flag to be
1880                  * updated, unless it was force-disabled by a previous prctl
1881                  * call. Currently, this is possible on an AMD CPU which has the
1882                  * feature X86_FEATURE_AMD_STIBP_ALWAYS_ON. In this case, if the
1883                  * kernel is booted with 'spectre_v2_user=seccomp', then
1884                  * spectre_v2_user_ibpb == SPECTRE_V2_USER_SECCOMP and
1885                  * spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED.
1886                  */
1887                 if (!is_spec_ib_user_controlled() ||
1888                     task_spec_ib_force_disable(task))
1889                         return -EPERM;
1890
1891                 task_clear_spec_ib_disable(task);
1892                 task_update_spec_tif(task);
1893                 break;
1894         case PR_SPEC_DISABLE:
1895         case PR_SPEC_FORCE_DISABLE:
1896                 /*
1897                  * Indirect branch speculation is always allowed when
1898                  * mitigation is force disabled.
1899                  */
1900                 if (spectre_v2_user_ibpb == SPECTRE_V2_USER_NONE &&
1901                     spectre_v2_user_stibp == SPECTRE_V2_USER_NONE)
1902                         return -EPERM;
1903
1904                 if (!is_spec_ib_user_controlled())
1905                         return 0;
1906
1907                 task_set_spec_ib_disable(task);
1908                 if (ctrl == PR_SPEC_FORCE_DISABLE)
1909                         task_set_spec_ib_force_disable(task);
1910                 task_update_spec_tif(task);
1911                 break;
1912         default:
1913                 return -ERANGE;
1914         }
1915         return 0;
1916 }
1917
1918 int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which,
1919                              unsigned long ctrl)
1920 {
1921         switch (which) {
1922         case PR_SPEC_STORE_BYPASS:
1923                 return ssb_prctl_set(task, ctrl);
1924         case PR_SPEC_INDIRECT_BRANCH:
1925                 return ib_prctl_set(task, ctrl);
1926         case PR_SPEC_L1D_FLUSH:
1927                 return l1d_flush_prctl_set(task, ctrl);
1928         default:
1929                 return -ENODEV;
1930         }
1931 }
1932
1933 #ifdef CONFIG_SECCOMP
1934 void arch_seccomp_spec_mitigate(struct task_struct *task)
1935 {
1936         if (ssb_mode == SPEC_STORE_BYPASS_SECCOMP)
1937                 ssb_prctl_set(task, PR_SPEC_FORCE_DISABLE);
1938         if (spectre_v2_user_ibpb == SPECTRE_V2_USER_SECCOMP ||
1939             spectre_v2_user_stibp == SPECTRE_V2_USER_SECCOMP)
1940                 ib_prctl_set(task, PR_SPEC_FORCE_DISABLE);
1941 }
1942 #endif
1943
1944 static int l1d_flush_prctl_get(struct task_struct *task)
1945 {
1946         if (!static_branch_unlikely(&switch_mm_cond_l1d_flush))
1947                 return PR_SPEC_FORCE_DISABLE;
1948
1949         if (test_ti_thread_flag(&task->thread_info, TIF_SPEC_L1D_FLUSH))
1950                 return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
1951         else
1952                 return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
1953 }
1954
1955 static int ssb_prctl_get(struct task_struct *task)
1956 {
1957         switch (ssb_mode) {
1958         case SPEC_STORE_BYPASS_DISABLE:
1959                 return PR_SPEC_DISABLE;
1960         case SPEC_STORE_BYPASS_SECCOMP:
1961         case SPEC_STORE_BYPASS_PRCTL:
1962                 if (task_spec_ssb_force_disable(task))
1963                         return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE;
1964                 if (task_spec_ssb_noexec(task))
1965                         return PR_SPEC_PRCTL | PR_SPEC_DISABLE_NOEXEC;
1966                 if (task_spec_ssb_disable(task))
1967                         return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
1968                 return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
1969         default:
1970                 if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
1971                         return PR_SPEC_ENABLE;
1972                 return PR_SPEC_NOT_AFFECTED;
1973         }
1974 }
1975
1976 static int ib_prctl_get(struct task_struct *task)
1977 {
1978         if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
1979                 return PR_SPEC_NOT_AFFECTED;
1980
1981         if (spectre_v2_user_ibpb == SPECTRE_V2_USER_NONE &&
1982             spectre_v2_user_stibp == SPECTRE_V2_USER_NONE)
1983                 return PR_SPEC_ENABLE;
1984         else if (is_spec_ib_user_controlled()) {
1985                 if (task_spec_ib_force_disable(task))
1986                         return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE;
1987                 if (task_spec_ib_disable(task))
1988                         return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
1989                 return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
1990         } else if (spectre_v2_user_ibpb == SPECTRE_V2_USER_STRICT ||
1991             spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT ||
1992             spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED)
1993                 return PR_SPEC_DISABLE;
1994         else
1995                 return PR_SPEC_NOT_AFFECTED;
1996 }
1997
1998 int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
1999 {
2000         switch (which) {
2001         case PR_SPEC_STORE_BYPASS:
2002                 return ssb_prctl_get(task);
2003         case PR_SPEC_INDIRECT_BRANCH:
2004                 return ib_prctl_get(task);
2005         case PR_SPEC_L1D_FLUSH:
2006                 return l1d_flush_prctl_get(task);
2007         default:
2008                 return -ENODEV;
2009         }
2010 }
2011
2012 void x86_spec_ctrl_setup_ap(void)
2013 {
2014         if (boot_cpu_has(X86_FEATURE_MSR_SPEC_CTRL))
2015                 write_spec_ctrl_current(x86_spec_ctrl_base, true);
2016
2017         if (ssb_mode == SPEC_STORE_BYPASS_DISABLE)
2018                 x86_amd_ssb_disable();
2019 }
2020
2021 bool itlb_multihit_kvm_mitigation;
2022 EXPORT_SYMBOL_GPL(itlb_multihit_kvm_mitigation);
2023
2024 #undef pr_fmt
2025 #define pr_fmt(fmt)     "L1TF: " fmt
2026
2027 /* Default mitigation for L1TF-affected CPUs */
2028 enum l1tf_mitigations l1tf_mitigation __ro_after_init = L1TF_MITIGATION_FLUSH;
2029 #if IS_ENABLED(CONFIG_KVM_INTEL)
2030 EXPORT_SYMBOL_GPL(l1tf_mitigation);
2031 #endif
2032 enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO;
2033 EXPORT_SYMBOL_GPL(l1tf_vmx_mitigation);
2034
2035 /*
2036  * These CPUs all support 44bits physical address space internally in the
2037  * cache but CPUID can report a smaller number of physical address bits.
2038  *
2039  * The L1TF mitigation uses the top most address bit for the inversion of
2040  * non present PTEs. When the installed memory reaches into the top most
2041  * address bit due to memory holes, which has been observed on machines
2042  * which report 36bits physical address bits and have 32G RAM installed,
2043  * then the mitigation range check in l1tf_select_mitigation() triggers.
2044  * This is a false positive because the mitigation is still possible due to
2045  * the fact that the cache uses 44bit internally. Use the cache bits
2046  * instead of the reported physical bits and adjust them on the affected
2047  * machines to 44bit if the reported bits are less than 44.
2048  */
2049 static void override_cache_bits(struct cpuinfo_x86 *c)
2050 {
2051         if (c->x86 != 6)
2052                 return;
2053
2054         switch (c->x86_model) {
2055         case INTEL_FAM6_NEHALEM:
2056         case INTEL_FAM6_WESTMERE:
2057         case INTEL_FAM6_SANDYBRIDGE:
2058         case INTEL_FAM6_IVYBRIDGE:
2059         case INTEL_FAM6_HASWELL:
2060         case INTEL_FAM6_HASWELL_L:
2061         case INTEL_FAM6_HASWELL_G:
2062         case INTEL_FAM6_BROADWELL:
2063         case INTEL_FAM6_BROADWELL_G:
2064         case INTEL_FAM6_SKYLAKE_L:
2065         case INTEL_FAM6_SKYLAKE:
2066         case INTEL_FAM6_KABYLAKE_L:
2067         case INTEL_FAM6_KABYLAKE:
2068                 if (c->x86_cache_bits < 44)
2069                         c->x86_cache_bits = 44;
2070                 break;
2071         }
2072 }
2073
2074 static void __init l1tf_select_mitigation(void)
2075 {
2076         u64 half_pa;
2077
2078         if (!boot_cpu_has_bug(X86_BUG_L1TF))
2079                 return;
2080
2081         if (cpu_mitigations_off())
2082                 l1tf_mitigation = L1TF_MITIGATION_OFF;
2083         else if (cpu_mitigations_auto_nosmt())
2084                 l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT;
2085
2086         override_cache_bits(&boot_cpu_data);
2087
2088         switch (l1tf_mitigation) {
2089         case L1TF_MITIGATION_OFF:
2090         case L1TF_MITIGATION_FLUSH_NOWARN:
2091         case L1TF_MITIGATION_FLUSH:
2092                 break;
2093         case L1TF_MITIGATION_FLUSH_NOSMT:
2094         case L1TF_MITIGATION_FULL:
2095                 cpu_smt_disable(false);
2096                 break;
2097         case L1TF_MITIGATION_FULL_FORCE:
2098                 cpu_smt_disable(true);
2099                 break;
2100         }
2101
2102 #if CONFIG_PGTABLE_LEVELS == 2
2103         pr_warn("Kernel not compiled for PAE. No mitigation for L1TF\n");
2104         return;
2105 #endif
2106
2107         half_pa = (u64)l1tf_pfn_limit() << PAGE_SHIFT;
2108         if (l1tf_mitigation != L1TF_MITIGATION_OFF &&
2109                         e820__mapped_any(half_pa, ULLONG_MAX - half_pa, E820_TYPE_RAM)) {
2110                 pr_warn("System has more than MAX_PA/2 memory. L1TF mitigation not effective.\n");
2111                 pr_info("You may make it effective by booting the kernel with mem=%llu parameter.\n",
2112                                 half_pa);
2113                 pr_info("However, doing so will make a part of your RAM unusable.\n");
2114                 pr_info("Reading https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html might help you decide.\n");
2115                 return;
2116         }
2117
2118         setup_force_cpu_cap(X86_FEATURE_L1TF_PTEINV);
2119 }
2120
2121 static int __init l1tf_cmdline(char *str)
2122 {
2123         if (!boot_cpu_has_bug(X86_BUG_L1TF))
2124                 return 0;
2125
2126         if (!str)
2127                 return -EINVAL;
2128
2129         if (!strcmp(str, "off"))
2130                 l1tf_mitigation = L1TF_MITIGATION_OFF;
2131         else if (!strcmp(str, "flush,nowarn"))
2132                 l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOWARN;
2133         else if (!strcmp(str, "flush"))
2134                 l1tf_mitigation = L1TF_MITIGATION_FLUSH;
2135         else if (!strcmp(str, "flush,nosmt"))
2136                 l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT;
2137         else if (!strcmp(str, "full"))
2138                 l1tf_mitigation = L1TF_MITIGATION_FULL;
2139         else if (!strcmp(str, "full,force"))
2140                 l1tf_mitigation = L1TF_MITIGATION_FULL_FORCE;
2141
2142         return 0;
2143 }
2144 early_param("l1tf", l1tf_cmdline);
2145
2146 #undef pr_fmt
2147 #define pr_fmt(fmt) fmt
2148
2149 #ifdef CONFIG_SYSFS
2150
2151 #define L1TF_DEFAULT_MSG "Mitigation: PTE Inversion"
2152
2153 #if IS_ENABLED(CONFIG_KVM_INTEL)
2154 static const char * const l1tf_vmx_states[] = {
2155         [VMENTER_L1D_FLUSH_AUTO]                = "auto",
2156         [VMENTER_L1D_FLUSH_NEVER]               = "vulnerable",
2157         [VMENTER_L1D_FLUSH_COND]                = "conditional cache flushes",
2158         [VMENTER_L1D_FLUSH_ALWAYS]              = "cache flushes",
2159         [VMENTER_L1D_FLUSH_EPT_DISABLED]        = "EPT disabled",
2160         [VMENTER_L1D_FLUSH_NOT_REQUIRED]        = "flush not necessary"
2161 };
2162
2163 static ssize_t l1tf_show_state(char *buf)
2164 {
2165         if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_AUTO)
2166                 return sprintf(buf, "%s\n", L1TF_DEFAULT_MSG);
2167
2168         if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_EPT_DISABLED ||
2169             (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_NEVER &&
2170              sched_smt_active())) {
2171                 return sprintf(buf, "%s; VMX: %s\n", L1TF_DEFAULT_MSG,
2172                                l1tf_vmx_states[l1tf_vmx_mitigation]);
2173         }
2174
2175         return sprintf(buf, "%s; VMX: %s, SMT %s\n", L1TF_DEFAULT_MSG,
2176                        l1tf_vmx_states[l1tf_vmx_mitigation],
2177                        sched_smt_active() ? "vulnerable" : "disabled");
2178 }
2179
2180 static ssize_t itlb_multihit_show_state(char *buf)
2181 {
2182         if (!boot_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) ||
2183             !boot_cpu_has(X86_FEATURE_VMX))
2184                 return sprintf(buf, "KVM: Mitigation: VMX unsupported\n");
2185         else if (!(cr4_read_shadow() & X86_CR4_VMXE))
2186                 return sprintf(buf, "KVM: Mitigation: VMX disabled\n");
2187         else if (itlb_multihit_kvm_mitigation)
2188                 return sprintf(buf, "KVM: Mitigation: Split huge pages\n");
2189         else
2190                 return sprintf(buf, "KVM: Vulnerable\n");
2191 }
2192 #else
2193 static ssize_t l1tf_show_state(char *buf)
2194 {
2195         return sprintf(buf, "%s\n", L1TF_DEFAULT_MSG);
2196 }
2197
2198 static ssize_t itlb_multihit_show_state(char *buf)
2199 {
2200         return sprintf(buf, "Processor vulnerable\n");
2201 }
2202 #endif
2203
2204 static ssize_t mds_show_state(char *buf)
2205 {
2206         if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
2207                 return sprintf(buf, "%s; SMT Host state unknown\n",
2208                                mds_strings[mds_mitigation]);
2209         }
2210
2211         if (boot_cpu_has(X86_BUG_MSBDS_ONLY)) {
2212                 return sprintf(buf, "%s; SMT %s\n", mds_strings[mds_mitigation],
2213                                (mds_mitigation == MDS_MITIGATION_OFF ? "vulnerable" :
2214                                 sched_smt_active() ? "mitigated" : "disabled"));
2215         }
2216
2217         return sprintf(buf, "%s; SMT %s\n", mds_strings[mds_mitigation],
2218                        sched_smt_active() ? "vulnerable" : "disabled");
2219 }
2220
2221 static ssize_t tsx_async_abort_show_state(char *buf)
2222 {
2223         if ((taa_mitigation == TAA_MITIGATION_TSX_DISABLED) ||
2224             (taa_mitigation == TAA_MITIGATION_OFF))
2225                 return sprintf(buf, "%s\n", taa_strings[taa_mitigation]);
2226
2227         if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
2228                 return sprintf(buf, "%s; SMT Host state unknown\n",
2229                                taa_strings[taa_mitigation]);
2230         }
2231
2232         return sprintf(buf, "%s; SMT %s\n", taa_strings[taa_mitigation],
2233                        sched_smt_active() ? "vulnerable" : "disabled");
2234 }
2235
2236 static ssize_t mmio_stale_data_show_state(char *buf)
2237 {
2238         if (mmio_mitigation == MMIO_MITIGATION_OFF)
2239                 return sysfs_emit(buf, "%s\n", mmio_strings[mmio_mitigation]);
2240
2241         if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
2242                 return sysfs_emit(buf, "%s; SMT Host state unknown\n",
2243                                   mmio_strings[mmio_mitigation]);
2244         }
2245
2246         return sysfs_emit(buf, "%s; SMT %s\n", mmio_strings[mmio_mitigation],
2247                           sched_smt_active() ? "vulnerable" : "disabled");
2248 }
2249
2250 static char *stibp_state(void)
2251 {
2252         if (spectre_v2_in_ibrs_mode(spectre_v2_enabled))
2253                 return "";
2254
2255         switch (spectre_v2_user_stibp) {
2256         case SPECTRE_V2_USER_NONE:
2257                 return ", STIBP: disabled";
2258         case SPECTRE_V2_USER_STRICT:
2259                 return ", STIBP: forced";
2260         case SPECTRE_V2_USER_STRICT_PREFERRED:
2261                 return ", STIBP: always-on";
2262         case SPECTRE_V2_USER_PRCTL:
2263         case SPECTRE_V2_USER_SECCOMP:
2264                 if (static_key_enabled(&switch_to_cond_stibp))
2265                         return ", STIBP: conditional";
2266         }
2267         return "";
2268 }
2269
2270 static char *ibpb_state(void)
2271 {
2272         if (boot_cpu_has(X86_FEATURE_IBPB)) {
2273                 if (static_key_enabled(&switch_mm_always_ibpb))
2274                         return ", IBPB: always-on";
2275                 if (static_key_enabled(&switch_mm_cond_ibpb))
2276                         return ", IBPB: conditional";
2277                 return ", IBPB: disabled";
2278         }
2279         return "";
2280 }
2281
2282 static ssize_t spectre_v2_show_state(char *buf)
2283 {
2284         if (spectre_v2_enabled == SPECTRE_V2_LFENCE)
2285                 return sprintf(buf, "Vulnerable: LFENCE\n");
2286
2287         if (spectre_v2_enabled == SPECTRE_V2_EIBRS && unprivileged_ebpf_enabled())
2288                 return sprintf(buf, "Vulnerable: eIBRS with unprivileged eBPF\n");
2289
2290         if (sched_smt_active() && unprivileged_ebpf_enabled() &&
2291             spectre_v2_enabled == SPECTRE_V2_EIBRS_LFENCE)
2292                 return sprintf(buf, "Vulnerable: eIBRS+LFENCE with unprivileged eBPF and SMT\n");
2293
2294         return sprintf(buf, "%s%s%s%s%s%s\n",
2295                        spectre_v2_strings[spectre_v2_enabled],
2296                        ibpb_state(),
2297                        boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "",
2298                        stibp_state(),
2299                        boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB filling" : "",
2300                        spectre_v2_module_string());
2301 }
2302
2303 static ssize_t srbds_show_state(char *buf)
2304 {
2305         return sprintf(buf, "%s\n", srbds_strings[srbds_mitigation]);
2306 }
2307
2308 static ssize_t retbleed_show_state(char *buf)
2309 {
2310         if (retbleed_mitigation == RETBLEED_MITIGATION_UNRET) {
2311             if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
2312                 boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
2313                     return sprintf(buf, "Vulnerable: untrained return thunk on non-Zen uarch\n");
2314
2315             return sprintf(buf, "%s; SMT %s\n",
2316                            retbleed_strings[retbleed_mitigation],
2317                            !sched_smt_active() ? "disabled" :
2318                            spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT ||
2319                            spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED ?
2320                            "enabled with STIBP protection" : "vulnerable");
2321         }
2322
2323         return sprintf(buf, "%s\n", retbleed_strings[retbleed_mitigation]);
2324 }
2325
2326 static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr,
2327                                char *buf, unsigned int bug)
2328 {
2329         if (!boot_cpu_has_bug(bug))
2330                 return sprintf(buf, "Not affected\n");
2331
2332         switch (bug) {
2333         case X86_BUG_CPU_MELTDOWN:
2334                 if (boot_cpu_has(X86_FEATURE_PTI))
2335                         return sprintf(buf, "Mitigation: PTI\n");
2336
2337                 if (hypervisor_is_type(X86_HYPER_XEN_PV))
2338                         return sprintf(buf, "Unknown (XEN PV detected, hypervisor mitigation required)\n");
2339
2340                 break;
2341
2342         case X86_BUG_SPECTRE_V1:
2343                 return sprintf(buf, "%s\n", spectre_v1_strings[spectre_v1_mitigation]);
2344
2345         case X86_BUG_SPECTRE_V2:
2346                 return spectre_v2_show_state(buf);
2347
2348         case X86_BUG_SPEC_STORE_BYPASS:
2349                 return sprintf(buf, "%s\n", ssb_strings[ssb_mode]);
2350
2351         case X86_BUG_L1TF:
2352                 if (boot_cpu_has(X86_FEATURE_L1TF_PTEINV))
2353                         return l1tf_show_state(buf);
2354                 break;
2355
2356         case X86_BUG_MDS:
2357                 return mds_show_state(buf);
2358
2359         case X86_BUG_TAA:
2360                 return tsx_async_abort_show_state(buf);
2361
2362         case X86_BUG_ITLB_MULTIHIT:
2363                 return itlb_multihit_show_state(buf);
2364
2365         case X86_BUG_SRBDS:
2366                 return srbds_show_state(buf);
2367
2368         case X86_BUG_MMIO_STALE_DATA:
2369                 return mmio_stale_data_show_state(buf);
2370
2371         case X86_BUG_RETBLEED:
2372                 return retbleed_show_state(buf);
2373
2374         default:
2375                 break;
2376         }
2377
2378         return sprintf(buf, "Vulnerable\n");
2379 }
2380
2381 ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
2382 {
2383         return cpu_show_common(dev, attr, buf, X86_BUG_CPU_MELTDOWN);
2384 }
2385
2386 ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf)
2387 {
2388         return cpu_show_common(dev, attr, buf, X86_BUG_SPECTRE_V1);
2389 }
2390
2391 ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
2392 {
2393         return cpu_show_common(dev, attr, buf, X86_BUG_SPECTRE_V2);
2394 }
2395
2396 ssize_t cpu_show_spec_store_bypass(struct device *dev, struct device_attribute *attr, char *buf)
2397 {
2398         return cpu_show_common(dev, attr, buf, X86_BUG_SPEC_STORE_BYPASS);
2399 }
2400
2401 ssize_t cpu_show_l1tf(struct device *dev, struct device_attribute *attr, char *buf)
2402 {
2403         return cpu_show_common(dev, attr, buf, X86_BUG_L1TF);
2404 }
2405
2406 ssize_t cpu_show_mds(struct device *dev, struct device_attribute *attr, char *buf)
2407 {
2408         return cpu_show_common(dev, attr, buf, X86_BUG_MDS);
2409 }
2410
2411 ssize_t cpu_show_tsx_async_abort(struct device *dev, struct device_attribute *attr, char *buf)
2412 {
2413         return cpu_show_common(dev, attr, buf, X86_BUG_TAA);
2414 }
2415
2416 ssize_t cpu_show_itlb_multihit(struct device *dev, struct device_attribute *attr, char *buf)
2417 {
2418         return cpu_show_common(dev, attr, buf, X86_BUG_ITLB_MULTIHIT);
2419 }
2420
2421 ssize_t cpu_show_srbds(struct device *dev, struct device_attribute *attr, char *buf)
2422 {
2423         return cpu_show_common(dev, attr, buf, X86_BUG_SRBDS);
2424 }
2425
2426 ssize_t cpu_show_mmio_stale_data(struct device *dev, struct device_attribute *attr, char *buf)
2427 {
2428         return cpu_show_common(dev, attr, buf, X86_BUG_MMIO_STALE_DATA);
2429 }
2430
2431 ssize_t cpu_show_retbleed(struct device *dev, struct device_attribute *attr, char *buf)
2432 {
2433         return cpu_show_common(dev, attr, buf, X86_BUG_RETBLEED);
2434 }
2435 #endif