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
  20 #include <asm/spec-ctrl.h>
  21 #include <asm/cmdline.h>
  22 #include <asm/bugs.h>
  23 #include <asm/processor.h>
  24 #include <asm/processor-flags.h>
  25 #include <asm/fpu/internal.h>
  26 #include <asm/msr.h>
  27 #include <asm/vmx.h>
  28 #include <asm/paravirt.h>
  29 #include <asm/alternative.h>
  30 #include <asm/set_memory.h>
  31 #include <asm/intel-family.h>
  32 #include <asm/e820/api.h>
  33 #include <asm/hypervisor.h>
  34 #include <asm/tlbflush.h>
  35
  36 #include "cpu.h"
  37
  38 static void __init spectre_v1_select_mitigation(void);
  39 static void __init spectre_v2_select_mitigation(void);
  40 static void __init ssb_select_mitigation(void);
  41 static void __init l1tf_select_mitigation(void);
  42 static void __init mds_select_mitigation(void);
  43 static void __init mds_print_mitigation(void);
  44 static void __init taa_select_mitigation(void);
  45 static void __init srbds_select_mitigation(void);
  46 static void __init l1d_flush_select_mitigation(void);
  47
  48 /* The base value of the SPEC_CTRL MSR that always has to be preserved. */
  49 u64 x86_spec_ctrl_base;
  50 EXPORT_SYMBOL_GPL(x86_spec_ctrl_base);
  51 static DEFINE_MUTEX(spec_ctrl_mutex);
  52
  53 /*
  54  * The vendor and possibly platform specific bits which can be modified in
  55  * x86_spec_ctrl_base.
  56  */
  57 static u64 __ro_after_init x86_spec_ctrl_mask = SPEC_CTRL_IBRS;
  58
  59 /*
  60  * AMD specific MSR info for Speculative Store Bypass control.
  61  * x86_amd_ls_cfg_ssbd_mask is initialized in identify_boot_cpu().
  62  */
  63 u64 __ro_after_init x86_amd_ls_cfg_base;
  64 u64 __ro_after_init x86_amd_ls_cfg_ssbd_mask;
  65
  66 /* Control conditional STIBP in switch_to() */
  67 DEFINE_STATIC_KEY_FALSE(switch_to_cond_stibp);
  68 /* Control conditional IBPB in switch_mm() */
  69 DEFINE_STATIC_KEY_FALSE(switch_mm_cond_ibpb);
  70 /* Control unconditional IBPB in switch_mm() */
  71 DEFINE_STATIC_KEY_FALSE(switch_mm_always_ibpb);
  72
  73 /* Control MDS CPU buffer clear before returning to user space */
  74 DEFINE_STATIC_KEY_FALSE(mds_user_clear);
  75 EXPORT_SYMBOL_GPL(mds_user_clear);
  76 /* Control MDS CPU buffer clear before idling (halt, mwait) */
  77 DEFINE_STATIC_KEY_FALSE(mds_idle_clear);
  78 EXPORT_SYMBOL_GPL(mds_idle_clear);
  79
  80 /*
  81  * Controls whether l1d flush based mitigations are enabled,
  82  * based on hw features and admin setting via boot parameter
  83  * defaults to false
  84  */
  85 DEFINE_STATIC_KEY_FALSE(switch_mm_cond_l1d_flush);
  86
  87 void __init check_bugs(void)
  88 {
  89         identify_boot_cpu();
  90
  91         /*
  92          * identify_boot_cpu() initialized SMT support information, let the
  93          * core code know.
  94          */
  95         cpu_smt_check_topology();
  96
  97         if (!IS_ENABLED(CONFIG_SMP)) {
  98                 pr_info("CPU: ");
  99                 print_cpu_info(&boot_cpu_data);
 100         }
 101
 102         /*
 103          * Read the SPEC_CTRL MSR to account for reserved bits which may
 104          * have unknown values. AMD64_LS_CFG MSR is cached in the early AMD
 105          * init code as it is not enumerated and depends on the family.
 106          */
 107         if (boot_cpu_has(X86_FEATURE_MSR_SPEC_CTRL))
 108                 rdmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
 109
 110         /* Allow STIBP in MSR_SPEC_CTRL if supported */
 111         if (boot_cpu_has(X86_FEATURE_STIBP))
 112                 x86_spec_ctrl_mask |= SPEC_CTRL_STIBP;
 113
 114         /* Select the proper CPU mitigations before patching alternatives: */
 115         spectre_v1_select_mitigation();
 116         spectre_v2_select_mitigation();
 117         ssb_select_mitigation();
 118         l1tf_select_mitigation();
 119         mds_select_mitigation();
 120         taa_select_mitigation();
 121         srbds_select_mitigation();
 122         l1d_flush_select_mitigation();
 123
 124         /*
 125          * As MDS and TAA mitigations are inter-related, print MDS
 126          * mitigation until after TAA mitigation selection is done.
 127          */
 128         mds_print_mitigation();
 129
 130         arch_smt_update();
 131
 132 #ifdef CONFIG_X86_32
 133         /*
 134          * Check whether we are able to run this kernel safely on SMP.
 135          *
 136          * - i386 is no longer supported.
 137          * - In order to run on anything without a TSC, we need to be
 138          *   compiled for a i486.
 139          */
 140         if (boot_cpu_data.x86 < 4)
 141                 panic("Kernel requires i486+ for 'invlpg' and other features");
 142
 143         init_utsname()->machine[1] =
 144                 '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
 145         alternative_instructions();
 146
 147         fpu__init_check_bugs();
 148 #else /* CONFIG_X86_64 */
 149         alternative_instructions();
 150
 151         /*
 152          * Make sure the first 2MB area is not mapped by huge pages
 153          * There are typically fixed size MTRRs in there and overlapping
 154          * MTRRs into large pages causes slow downs.
 155          *
 156          * Right now we don't do that with gbpages because there seems
 157          * very little benefit for that case.
 158          */
 159         if (!direct_gbpages)
 160                 set_memory_4k((unsigned long)__va(0), 1);
 161 #endif
 162 }
 163
 164 void
 165 x86_virt_spec_ctrl(u64 guest_spec_ctrl, u64 guest_virt_spec_ctrl, bool setguest)
 166 {
 167         u64 msrval, guestval, hostval = x86_spec_ctrl_base;
 168         struct thread_info *ti = current_thread_info();
 169
 170         /* Is MSR_SPEC_CTRL implemented ? */
 171         if (static_cpu_has(X86_FEATURE_MSR_SPEC_CTRL)) {
 172                 /*
 173                  * Restrict guest_spec_ctrl to supported values. Clear the
 174                  * modifiable bits in the host base value and or the
 175                  * modifiable bits from the guest value.
 176                  */
 177                 guestval = hostval & ~x86_spec_ctrl_mask;
 178                 guestval |= guest_spec_ctrl & x86_spec_ctrl_mask;
 179
 180                 /* SSBD controlled in MSR_SPEC_CTRL */
 181                 if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) ||
 182                     static_cpu_has(X86_FEATURE_AMD_SSBD))
 183                         hostval |= ssbd_tif_to_spec_ctrl(ti->flags);
 184
 185                 /* Conditional STIBP enabled? */
 186                 if (static_branch_unlikely(&switch_to_cond_stibp))
 187                         hostval |= stibp_tif_to_spec_ctrl(ti->flags);
 188
 189                 if (hostval != guestval) {
 190                         msrval = setguest ? guestval : hostval;
 191                         wrmsrl(MSR_IA32_SPEC_CTRL, msrval);
 192                 }
 193         }
 194
 195         /*
 196          * If SSBD is not handled in MSR_SPEC_CTRL on AMD, update
 197          * MSR_AMD64_L2_CFG or MSR_VIRT_SPEC_CTRL if supported.
 198          */
 199         if (!static_cpu_has(X86_FEATURE_LS_CFG_SSBD) &&
 200             !static_cpu_has(X86_FEATURE_VIRT_SSBD))
 201                 return;
 202
 203         /*
 204          * If the host has SSBD mitigation enabled, force it in the host's
 205          * virtual MSR value. If its not permanently enabled, evaluate
 206          * current's TIF_SSBD thread flag.
 207          */
 208         if (static_cpu_has(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE))
 209                 hostval = SPEC_CTRL_SSBD;
 210         else
 211                 hostval = ssbd_tif_to_spec_ctrl(ti->flags);
 212
 213         /* Sanitize the guest value */
 214         guestval = guest_virt_spec_ctrl & SPEC_CTRL_SSBD;
 215
 216         if (hostval != guestval) {
 217                 unsigned long tif;
 218
 219                 tif = setguest ? ssbd_spec_ctrl_to_tif(guestval) :
 220                                  ssbd_spec_ctrl_to_tif(hostval);
 221
 222                 speculation_ctrl_update(tif);
 223         }
 224 }
 225 EXPORT_SYMBOL_GPL(x86_virt_spec_ctrl);
 226
 227 static void x86_amd_ssb_disable(void)
 228 {
 229         u64 msrval = x86_amd_ls_cfg_base | x86_amd_ls_cfg_ssbd_mask;
 230
 231         if (boot_cpu_has(X86_FEATURE_VIRT_SSBD))
 232                 wrmsrl(MSR_AMD64_VIRT_SPEC_CTRL, SPEC_CTRL_SSBD);
 233         else if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD))
 234                 wrmsrl(MSR_AMD64_LS_CFG, msrval);
 235 }
 236
 237 #undef pr_fmt
 238 #define pr_fmt(fmt)     "MDS: " fmt
 239
 240 /* Default mitigation for MDS-affected CPUs */
 241 static enum mds_mitigations mds_mitigation __ro_after_init = MDS_MITIGATION_FULL;
 242 static bool mds_nosmt __ro_after_init = false;
 243
 244 static const char * const mds_strings[] = {
 245         [MDS_MITIGATION_OFF]    = "Vulnerable",
 246         [MDS_MITIGATION_FULL]   = "Mitigation: Clear CPU buffers",
 247         [MDS_MITIGATION_VMWERV] = "Vulnerable: Clear CPU buffers attempted, no microcode",
 248 };
 249
 250 static void __init mds_select_mitigation(void)
 251 {
 252         if (!boot_cpu_has_bug(X86_BUG_MDS) || cpu_mitigations_off()) {
 253                 mds_mitigation = MDS_MITIGATION_OFF;
 254                 return;
 255         }
 256
 257         if (mds_mitigation == MDS_MITIGATION_FULL) {
 258                 if (!boot_cpu_has(X86_FEATURE_MD_CLEAR))
 259                         mds_mitigation = MDS_MITIGATION_VMWERV;
 260
 261                 static_branch_enable(&mds_user_clear);
 262
 263                 if (!boot_cpu_has(X86_BUG_MSBDS_ONLY) &&
 264                     (mds_nosmt || cpu_mitigations_auto_nosmt()))
 265                         cpu_smt_disable(false);
 266         }
 267 }
 268
 269 static void __init mds_print_mitigation(void)
 270 {
 271         if (!boot_cpu_has_bug(X86_BUG_MDS) || cpu_mitigations_off())
 272                 return;
 273
 274         pr_info("%s\n", mds_strings[mds_mitigation]);
 275 }
 276
 277 static int __init mds_cmdline(char *str)
 278 {
 279         if (!boot_cpu_has_bug(X86_BUG_MDS))
 280                 return 0;
 281
 282         if (!str)
 283                 return -EINVAL;
 284
 285         if (!strcmp(str, "off"))
 286                 mds_mitigation = MDS_MITIGATION_OFF;
 287         else if (!strcmp(str, "full"))
 288                 mds_mitigation = MDS_MITIGATION_FULL;
 289         else if (!strcmp(str, "full,nosmt")) {
 290                 mds_mitigation = MDS_MITIGATION_FULL;
 291                 mds_nosmt = true;
 292         }
 293
 294         return 0;
 295 }
 296 early_param("mds", mds_cmdline);
 297
 298 #undef pr_fmt
 299 #define pr_fmt(fmt)     "TAA: " fmt
 300
 301 enum taa_mitigations {
 302         TAA_MITIGATION_OFF,
 303         TAA_MITIGATION_UCODE_NEEDED,
 304         TAA_MITIGATION_VERW,
 305         TAA_MITIGATION_TSX_DISABLED,
 306 };
 307
 308 /* Default mitigation for TAA-affected CPUs */
 309 static enum taa_mitigations taa_mitigation __ro_after_init = TAA_MITIGATION_VERW;
 310 static bool taa_nosmt __ro_after_init;
 311
 312 static const char * const taa_strings[] = {
 313         [TAA_MITIGATION_OFF]            = "Vulnerable",
 314         [TAA_MITIGATION_UCODE_NEEDED]   = "Vulnerable: Clear CPU buffers attempted, no microcode",
 315         [TAA_MITIGATION_VERW]           = "Mitigation: Clear CPU buffers",
 316         [TAA_MITIGATION_TSX_DISABLED]   = "Mitigation: TSX disabled",
 317 };
 318
 319 static void __init taa_select_mitigation(void)
 320 {
 321         u64 ia32_cap;
 322
 323         if (!boot_cpu_has_bug(X86_BUG_TAA)) {
 324                 taa_mitigation = TAA_MITIGATION_OFF;
 325                 return;
 326         }
 327
 328         /* TSX previously disabled by tsx=off */
 329         if (!boot_cpu_has(X86_FEATURE_RTM)) {
 330                 taa_mitigation = TAA_MITIGATION_TSX_DISABLED;
 331                 goto out;
 332         }
 333
 334         if (cpu_mitigations_off()) {
 335                 taa_mitigation = TAA_MITIGATION_OFF;
 336                 return;
 337         }
 338
 339         /*
 340          * TAA mitigation via VERW is turned off if both
 341          * tsx_async_abort=off and mds=off are specified.
 342          */
 343         if (taa_mitigation == TAA_MITIGATION_OFF &&
 344             mds_mitigation == MDS_MITIGATION_OFF)
 345                 goto out;
 346
 347         if (boot_cpu_has(X86_FEATURE_MD_CLEAR))
 348                 taa_mitigation = TAA_MITIGATION_VERW;
 349         else
 350                 taa_mitigation = TAA_MITIGATION_UCODE_NEEDED;
 351
 352         /*
 353          * VERW doesn't clear the CPU buffers when MD_CLEAR=1 and MDS_NO=1.
 354          * A microcode update fixes this behavior to clear CPU buffers. It also
 355          * adds support for MSR_IA32_TSX_CTRL which is enumerated by the
 356          * ARCH_CAP_TSX_CTRL_MSR bit.
 357          *
 358          * On MDS_NO=1 CPUs if ARCH_CAP_TSX_CTRL_MSR is not set, microcode
 359          * update is required.
 360          */
 361         ia32_cap = x86_read_arch_cap_msr();
 362         if ( (ia32_cap & ARCH_CAP_MDS_NO) &&
 363             !(ia32_cap & ARCH_CAP_TSX_CTRL_MSR))
 364                 taa_mitigation = TAA_MITIGATION_UCODE_NEEDED;
 365
 366         /*
 367          * TSX is enabled, select alternate mitigation for TAA which is
 368          * the same as MDS. Enable MDS static branch to clear CPU buffers.
 369          *
 370          * For guests that can't determine whether the correct microcode is
 371          * present on host, enable the mitigation for UCODE_NEEDED as well.
 372          */
 373         static_branch_enable(&mds_user_clear);
 374
 375         if (taa_nosmt || cpu_mitigations_auto_nosmt())
 376                 cpu_smt_disable(false);
 377
 378         /*
 379          * Update MDS mitigation, if necessary, as the mds_user_clear is
 380          * now enabled for TAA mitigation.
 381          */
 382         if (mds_mitigation == MDS_MITIGATION_OFF &&
 383             boot_cpu_has_bug(X86_BUG_MDS)) {
 384                 mds_mitigation = MDS_MITIGATION_FULL;
 385                 mds_select_mitigation();
 386         }
 387 out:
 388         pr_info("%s\n", taa_strings[taa_mitigation]);
 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)     "SRBDS: " fmt
 414
 415 enum srbds_mitigations {
 416         SRBDS_MITIGATION_OFF,
 417         SRBDS_MITIGATION_UCODE_NEEDED,
 418         SRBDS_MITIGATION_FULL,
 419         SRBDS_MITIGATION_TSX_OFF,
 420         SRBDS_MITIGATION_HYPERVISOR,
 421 };
 422
 423 static enum srbds_mitigations srbds_mitigation __ro_after_init = SRBDS_MITIGATION_FULL;
 424
 425 static const char * const srbds_strings[] = {
 426         [SRBDS_MITIGATION_OFF]          = "Vulnerable",
 427         [SRBDS_MITIGATION_UCODE_NEEDED] = "Vulnerable: No microcode",
 428         [SRBDS_MITIGATION_FULL]         = "Mitigation: Microcode",
 429         [SRBDS_MITIGATION_TSX_OFF]      = "Mitigation: TSX disabled",
 430         [SRBDS_MITIGATION_HYPERVISOR]   = "Unknown: Dependent on hypervisor status",
 431 };
 432
 433 static bool srbds_off;
 434
 435 void update_srbds_msr(void)
 436 {
 437         u64 mcu_ctrl;
 438
 439         if (!boot_cpu_has_bug(X86_BUG_SRBDS))
 440                 return;
 441
 442         if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
 443                 return;
 444
 445         if (srbds_mitigation == SRBDS_MITIGATION_UCODE_NEEDED)
 446                 return;
 447
 448         rdmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl);
 449
 450         switch (srbds_mitigation) {
 451         case SRBDS_MITIGATION_OFF:
 452         case SRBDS_MITIGATION_TSX_OFF:
 453                 mcu_ctrl |= RNGDS_MITG_DIS;
 454                 break;
 455         case SRBDS_MITIGATION_FULL:
 456                 mcu_ctrl &= ~RNGDS_MITG_DIS;
 457                 break;
 458         default:
 459                 break;
 460         }
 461
 462         wrmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl);
 463 }
 464
 465 static void __init srbds_select_mitigation(void)
 466 {
 467         u64 ia32_cap;
 468
 469         if (!boot_cpu_has_bug(X86_BUG_SRBDS))
 470                 return;
 471
 472         /*
 473          * Check to see if this is one of the MDS_NO systems supporting
 474          * TSX that are only exposed to SRBDS when TSX is enabled.
 475          */
 476         ia32_cap = x86_read_arch_cap_msr();
 477         if ((ia32_cap & ARCH_CAP_MDS_NO) && !boot_cpu_has(X86_FEATURE_RTM))
 478                 srbds_mitigation = SRBDS_MITIGATION_TSX_OFF;
 479         else if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
 480                 srbds_mitigation = SRBDS_MITIGATION_HYPERVISOR;
 481         else if (!boot_cpu_has(X86_FEATURE_SRBDS_CTRL))
 482                 srbds_mitigation = SRBDS_MITIGATION_UCODE_NEEDED;
 483         else if (cpu_mitigations_off() || srbds_off)
 484                 srbds_mitigation = SRBDS_MITIGATION_OFF;
 485
 486         update_srbds_msr();
 487         pr_info("%s\n", srbds_strings[srbds_mitigation]);
 488 }
 489
 490 static int __init srbds_parse_cmdline(char *str)
 491 {
 492         if (!str)
 493                 return -EINVAL;
 494
 495         if (!boot_cpu_has_bug(X86_BUG_SRBDS))
 496                 return 0;
 497
 498         srbds_off = !strcmp(str, "off");
 499         return 0;
 500 }
 501 early_param("srbds", srbds_parse_cmdline);
 502
 503 #undef pr_fmt
 504 #define pr_fmt(fmt)     "L1D Flush : " fmt
 505
 506 enum l1d_flush_mitigations {
 507         L1D_FLUSH_OFF = 0,
 508         L1D_FLUSH_ON,
 509 };
 510
 511 static enum l1d_flush_mitigations l1d_flush_mitigation __initdata = L1D_FLUSH_OFF;
 512
 513 static void __init l1d_flush_select_mitigation(void)
 514 {
 515         if (!l1d_flush_mitigation || !boot_cpu_has(X86_FEATURE_FLUSH_L1D))
 516                 return;
 517
 518         static_branch_enable(&switch_mm_cond_l1d_flush);
 519         pr_info("Conditional flush on switch_mm() enabled\n");
 520 }
 521
 522 static int __init l1d_flush_parse_cmdline(char *str)
 523 {
 524         if (!strcmp(str, "on"))
 525                 l1d_flush_mitigation = L1D_FLUSH_ON;
 526
 527         return 0;
 528 }
 529 early_param("l1d_flush", l1d_flush_parse_cmdline);
 530
 531 #undef pr_fmt
 532 #define pr_fmt(fmt)     "Spectre V1 : " fmt
 533
 534 enum spectre_v1_mitigation {
 535         SPECTRE_V1_MITIGATION_NONE,
 536         SPECTRE_V1_MITIGATION_AUTO,
 537 };
 538
 539 static enum spectre_v1_mitigation spectre_v1_mitigation __ro_after_init =
 540         SPECTRE_V1_MITIGATION_AUTO;
 541
 542 static const char * const spectre_v1_strings[] = {
 543         [SPECTRE_V1_MITIGATION_NONE] = "Vulnerable: __user pointer sanitization and usercopy barriers only; no swapgs barriers",
 544         [SPECTRE_V1_MITIGATION_AUTO] = "Mitigation: usercopy/swapgs barriers and __user pointer sanitization",
 545 };
 546
 547 /*
 548  * Does SMAP provide full mitigation against speculative kernel access to
 549  * userspace?
 550  */
 551 static bool smap_works_speculatively(void)
 552 {
 553         if (!boot_cpu_has(X86_FEATURE_SMAP))
 554                 return false;
 555
 556         /*
 557          * On CPUs which are vulnerable to Meltdown, SMAP does not
 558          * prevent speculative access to user data in the L1 cache.
 559          * Consider SMAP to be non-functional as a mitigation on these
 560          * CPUs.
 561          */
 562         if (boot_cpu_has(X86_BUG_CPU_MELTDOWN))
 563                 return false;
 564
 565         return true;
 566 }
 567
 568 static void __init spectre_v1_select_mitigation(void)
 569 {
 570         if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V1) || cpu_mitigations_off()) {
 571                 spectre_v1_mitigation = SPECTRE_V1_MITIGATION_NONE;
 572                 return;
 573         }
 574
 575         if (spectre_v1_mitigation == SPECTRE_V1_MITIGATION_AUTO) {
 576                 /*
 577                  * With Spectre v1, a user can speculatively control either
 578                  * path of a conditional swapgs with a user-controlled GS
 579                  * value.  The mitigation is to add lfences to both code paths.
 580                  *
 581                  * If FSGSBASE is enabled, the user can put a kernel address in
 582                  * GS, in which case SMAP provides no protection.
 583                  *
 584                  * If FSGSBASE is disabled, the user can only put a user space
 585                  * address in GS.  That makes an attack harder, but still
 586                  * possible if there's no SMAP protection.
 587                  */
 588                 if (boot_cpu_has(X86_FEATURE_FSGSBASE) ||
 589                     !smap_works_speculatively()) {
 590                         /*
 591                          * Mitigation can be provided from SWAPGS itself or
 592                          * PTI as the CR3 write in the Meltdown mitigation
 593                          * is serializing.
 594                          *
 595                          * If neither is there, mitigate with an LFENCE to
 596                          * stop speculation through swapgs.
 597                          */
 598                         if (boot_cpu_has_bug(X86_BUG_SWAPGS) &&
 599                             !boot_cpu_has(X86_FEATURE_PTI))
 600                                 setup_force_cpu_cap(X86_FEATURE_FENCE_SWAPGS_USER);
 601
 602                         /*
 603                          * Enable lfences in the kernel entry (non-swapgs)
 604                          * paths, to prevent user entry from speculatively
 605                          * skipping swapgs.
 606                          */
 607                         setup_force_cpu_cap(X86_FEATURE_FENCE_SWAPGS_KERNEL);
 608                 }
 609         }
 610
 611         pr_info("%s\n", spectre_v1_strings[spectre_v1_mitigation]);
 612 }
 613
 614 static int __init nospectre_v1_cmdline(char *str)
 615 {
 616         spectre_v1_mitigation = SPECTRE_V1_MITIGATION_NONE;
 617         return 0;
 618 }
 619 early_param("nospectre_v1", nospectre_v1_cmdline);
 620
 621 #undef pr_fmt
 622 #define pr_fmt(fmt)     "Spectre V2 : " fmt
 623
 624 static enum spectre_v2_mitigation spectre_v2_enabled __ro_after_init =
 625         SPECTRE_V2_NONE;
 626
 627 static enum spectre_v2_user_mitigation spectre_v2_user_stibp __ro_after_init =
 628         SPECTRE_V2_USER_NONE;
 629 static enum spectre_v2_user_mitigation spectre_v2_user_ibpb __ro_after_init =
 630         SPECTRE_V2_USER_NONE;
 631
 632 #ifdef CONFIG_RETPOLINE
 633 static bool spectre_v2_bad_module;
 634
 635 bool retpoline_module_ok(bool has_retpoline)
 636 {
 637         if (spectre_v2_enabled == SPECTRE_V2_NONE || has_retpoline)
 638                 return true;
 639
 640         pr_err("System may be vulnerable to spectre v2\n");
 641         spectre_v2_bad_module = true;
 642         return false;
 643 }
 644
 645 static inline const char *spectre_v2_module_string(void)
 646 {
 647         return spectre_v2_bad_module ? " - vulnerable module loaded" : "";
 648 }
 649 #else
 650 static inline const char *spectre_v2_module_string(void) { return ""; }
 651 #endif
 652
 653 static inline bool match_option(const char *arg, int arglen, const char *opt)
 654 {
 655         int len = strlen(opt);
 656
 657         return len == arglen && !strncmp(arg, opt, len);
 658 }
 659
 660 /* The kernel command line selection for spectre v2 */
 661 enum spectre_v2_mitigation_cmd {
 662         SPECTRE_V2_CMD_NONE,
 663         SPECTRE_V2_CMD_AUTO,
 664         SPECTRE_V2_CMD_FORCE,
 665         SPECTRE_V2_CMD_RETPOLINE,
 666         SPECTRE_V2_CMD_RETPOLINE_GENERIC,
 667         SPECTRE_V2_CMD_RETPOLINE_AMD,
 668 };
 669
 670 enum spectre_v2_user_cmd {
 671         SPECTRE_V2_USER_CMD_NONE,
 672         SPECTRE_V2_USER_CMD_AUTO,
 673         SPECTRE_V2_USER_CMD_FORCE,
 674         SPECTRE_V2_USER_CMD_PRCTL,
 675         SPECTRE_V2_USER_CMD_PRCTL_IBPB,
 676         SPECTRE_V2_USER_CMD_SECCOMP,
 677         SPECTRE_V2_USER_CMD_SECCOMP_IBPB,
 678 };
 679
 680 static const char * const spectre_v2_user_strings[] = {
 681         [SPECTRE_V2_USER_NONE]                  = "User space: Vulnerable",
 682         [SPECTRE_V2_USER_STRICT]                = "User space: Mitigation: STIBP protection",
 683         [SPECTRE_V2_USER_STRICT_PREFERRED]      = "User space: Mitigation: STIBP always-on protection",
 684         [SPECTRE_V2_USER_PRCTL]                 = "User space: Mitigation: STIBP via prctl",
 685         [SPECTRE_V2_USER_SECCOMP]               = "User space: Mitigation: STIBP via seccomp and prctl",
 686 };
 687
 688 static const struct {
 689         const char                      *option;
 690         enum spectre_v2_user_cmd        cmd;
 691         bool                            secure;
 692 } v2_user_options[] __initconst = {
 693         { "auto",               SPECTRE_V2_USER_CMD_AUTO,               false },
 694         { "off",                SPECTRE_V2_USER_CMD_NONE,               false },
 695         { "on",                 SPECTRE_V2_USER_CMD_FORCE,              true  },
 696         { "prctl",              SPECTRE_V2_USER_CMD_PRCTL,              false },
 697         { "prctl,ibpb",         SPECTRE_V2_USER_CMD_PRCTL_IBPB,         false },
 698         { "seccomp",            SPECTRE_V2_USER_CMD_SECCOMP,            false },
 699         { "seccomp,ibpb",       SPECTRE_V2_USER_CMD_SECCOMP_IBPB,       false },
 700 };
 701
 702 static void __init spec_v2_user_print_cond(const char *reason, bool secure)
 703 {
 704         if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2) != secure)
 705                 pr_info("spectre_v2_user=%s forced on command line.\n", reason);
 706 }
 707
 708 static enum spectre_v2_user_cmd __init
 709 spectre_v2_parse_user_cmdline(enum spectre_v2_mitigation_cmd v2_cmd)
 710 {
 711         char arg[20];
 712         int ret, i;
 713
 714         switch (v2_cmd) {
 715         case SPECTRE_V2_CMD_NONE:
 716                 return SPECTRE_V2_USER_CMD_NONE;
 717         case SPECTRE_V2_CMD_FORCE:
 718                 return SPECTRE_V2_USER_CMD_FORCE;
 719         default:
 720                 break;
 721         }
 722
 723         ret = cmdline_find_option(boot_command_line, "spectre_v2_user",
 724                                   arg, sizeof(arg));
 725         if (ret < 0)
 726                 return SPECTRE_V2_USER_CMD_AUTO;
 727
 728         for (i = 0; i < ARRAY_SIZE(v2_user_options); i++) {
 729                 if (match_option(arg, ret, v2_user_options[i].option)) {
 730                         spec_v2_user_print_cond(v2_user_options[i].option,
 731                                                 v2_user_options[i].secure);
 732                         return v2_user_options[i].cmd;
 733                 }
 734         }
 735
 736         pr_err("Unknown user space protection option (%s). Switching to AUTO select\n", arg);
 737         return SPECTRE_V2_USER_CMD_AUTO;
 738 }
 739
 740 static void __init
 741 spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd)
 742 {
 743         enum spectre_v2_user_mitigation mode = SPECTRE_V2_USER_NONE;
 744         bool smt_possible = IS_ENABLED(CONFIG_SMP);
 745         enum spectre_v2_user_cmd cmd;
 746
 747         if (!boot_cpu_has(X86_FEATURE_IBPB) && !boot_cpu_has(X86_FEATURE_STIBP))
 748                 return;
 749
 750         if (cpu_smt_control == CPU_SMT_FORCE_DISABLED ||
 751             cpu_smt_control == CPU_SMT_NOT_SUPPORTED)
 752                 smt_possible = false;
 753
 754         cmd = spectre_v2_parse_user_cmdline(v2_cmd);
 755         switch (cmd) {
 756         case SPECTRE_V2_USER_CMD_NONE:
 757                 goto set_mode;
 758         case SPECTRE_V2_USER_CMD_FORCE:
 759                 mode = SPECTRE_V2_USER_STRICT;
 760                 break;
 761         case SPECTRE_V2_USER_CMD_PRCTL:
 762         case SPECTRE_V2_USER_CMD_PRCTL_IBPB:
 763                 mode = SPECTRE_V2_USER_PRCTL;
 764                 break;
 765         case SPECTRE_V2_USER_CMD_AUTO:
 766         case SPECTRE_V2_USER_CMD_SECCOMP:
 767         case SPECTRE_V2_USER_CMD_SECCOMP_IBPB:
 768                 if (IS_ENABLED(CONFIG_SECCOMP))
 769                         mode = SPECTRE_V2_USER_SECCOMP;
 770                 else
 771                         mode = SPECTRE_V2_USER_PRCTL;
 772                 break;
 773         }
 774
 775         /* Initialize Indirect Branch Prediction Barrier */
 776         if (boot_cpu_has(X86_FEATURE_IBPB)) {
 777                 setup_force_cpu_cap(X86_FEATURE_USE_IBPB);
 778
 779                 spectre_v2_user_ibpb = mode;
 780                 switch (cmd) {
 781                 case SPECTRE_V2_USER_CMD_FORCE:
 782                 case SPECTRE_V2_USER_CMD_PRCTL_IBPB:
 783                 case SPECTRE_V2_USER_CMD_SECCOMP_IBPB:
 784                         static_branch_enable(&switch_mm_always_ibpb);
 785                         spectre_v2_user_ibpb = SPECTRE_V2_USER_STRICT;
 786                         break;
 787                 case SPECTRE_V2_USER_CMD_PRCTL:
 788                 case SPECTRE_V2_USER_CMD_AUTO:
 789                 case SPECTRE_V2_USER_CMD_SECCOMP:
 790                         static_branch_enable(&switch_mm_cond_ibpb);
 791                         break;
 792                 default:
 793                         break;
 794                 }
 795
 796                 pr_info("mitigation: Enabling %s Indirect Branch Prediction Barrier\n",
 797                         static_key_enabled(&switch_mm_always_ibpb) ?
 798                         "always-on" : "conditional");
 799         }
 800
 801         /*
 802          * If no STIBP, enhanced IBRS is enabled or SMT impossible, STIBP is not
 803          * required.
 804          */
 805         if (!boot_cpu_has(X86_FEATURE_STIBP) ||
 806             !smt_possible ||
 807             spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
 808                 return;
 809
 810         /*
 811          * At this point, an STIBP mode other than "off" has been set.
 812          * If STIBP support is not being forced, check if STIBP always-on
 813          * is preferred.
 814          */
 815         if (mode != SPECTRE_V2_USER_STRICT &&
 816             boot_cpu_has(X86_FEATURE_AMD_STIBP_ALWAYS_ON))
 817                 mode = SPECTRE_V2_USER_STRICT_PREFERRED;
 818
 819         spectre_v2_user_stibp = mode;
 820
 821 set_mode:
 822         pr_info("%s\n", spectre_v2_user_strings[mode]);
 823 }
 824
 825 static const char * const spectre_v2_strings[] = {
 826         [SPECTRE_V2_NONE]                       = "Vulnerable",
 827         [SPECTRE_V2_RETPOLINE_GENERIC]          = "Mitigation: Full generic retpoline",
 828         [SPECTRE_V2_RETPOLINE_AMD]              = "Mitigation: Full AMD retpoline",
 829         [SPECTRE_V2_IBRS_ENHANCED]              = "Mitigation: Enhanced IBRS",
 830 };
 831
 832 static const struct {
 833         const char *option;
 834         enum spectre_v2_mitigation_cmd cmd;
 835         bool secure;
 836 } mitigation_options[] __initconst = {
 837         { "off",                SPECTRE_V2_CMD_NONE,              false },
 838         { "on",                 SPECTRE_V2_CMD_FORCE,             true  },
 839         { "retpoline",          SPECTRE_V2_CMD_RETPOLINE,         false },
 840         { "retpoline,amd",      SPECTRE_V2_CMD_RETPOLINE_AMD,     false },
 841         { "retpoline,generic",  SPECTRE_V2_CMD_RETPOLINE_GENERIC, false },
 842         { "auto",               SPECTRE_V2_CMD_AUTO,              false },
 843 };
 844
 845 static void __init spec_v2_print_cond(const char *reason, bool secure)
 846 {
 847         if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2) != secure)
 848                 pr_info("%s selected on command line.\n", reason);
 849 }
 850
 851 static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
 852 {
 853         enum spectre_v2_mitigation_cmd cmd = SPECTRE_V2_CMD_AUTO;
 854         char arg[20];
 855         int ret, i;
 856
 857         if (cmdline_find_option_bool(boot_command_line, "nospectre_v2") ||
 858             cpu_mitigations_off())
 859                 return SPECTRE_V2_CMD_NONE;
 860
 861         ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg));
 862         if (ret < 0)
 863                 return SPECTRE_V2_CMD_AUTO;
 864
 865         for (i = 0; i < ARRAY_SIZE(mitigation_options); i++) {
 866                 if (!match_option(arg, ret, mitigation_options[i].option))
 867                         continue;
 868                 cmd = mitigation_options[i].cmd;
 869                 break;
 870         }
 871
 872         if (i >= ARRAY_SIZE(mitigation_options)) {
 873                 pr_err("unknown option (%s). Switching to AUTO select\n", arg);
 874                 return SPECTRE_V2_CMD_AUTO;
 875         }
 876
 877         if ((cmd == SPECTRE_V2_CMD_RETPOLINE ||
 878              cmd == SPECTRE_V2_CMD_RETPOLINE_AMD ||
 879              cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC) &&
 880             !IS_ENABLED(CONFIG_RETPOLINE)) {
 881                 pr_err("%s selected but not compiled in. Switching to AUTO select\n", mitigation_options[i].option);
 882                 return SPECTRE_V2_CMD_AUTO;
 883         }
 884
 885         if (cmd == SPECTRE_V2_CMD_RETPOLINE_AMD &&
 886             boot_cpu_data.x86_vendor != X86_VENDOR_HYGON &&
 887             boot_cpu_data.x86_vendor != X86_VENDOR_AMD) {
 888                 pr_err("retpoline,amd selected but CPU is not AMD. Switching to AUTO select\n");
 889                 return SPECTRE_V2_CMD_AUTO;
 890         }
 891
 892         spec_v2_print_cond(mitigation_options[i].option,
 893                            mitigation_options[i].secure);
 894         return cmd;
 895 }
 896
 897 static void __init spectre_v2_select_mitigation(void)
 898 {
 899         enum spectre_v2_mitigation_cmd cmd = spectre_v2_parse_cmdline();
 900         enum spectre_v2_mitigation mode = SPECTRE_V2_NONE;
 901
 902         /*
 903          * If the CPU is not affected and the command line mode is NONE or AUTO
 904          * then nothing to do.
 905          */
 906         if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2) &&
 907             (cmd == SPECTRE_V2_CMD_NONE || cmd == SPECTRE_V2_CMD_AUTO))
 908                 return;
 909
 910         switch (cmd) {
 911         case SPECTRE_V2_CMD_NONE:
 912                 return;
 913
 914         case SPECTRE_V2_CMD_FORCE:
 915         case SPECTRE_V2_CMD_AUTO:
 916                 if (boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) {
 917                         mode = SPECTRE_V2_IBRS_ENHANCED;
 918                         /* Force it so VMEXIT will restore correctly */
 919                         x86_spec_ctrl_base |= SPEC_CTRL_IBRS;
 920                         wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
 921                         goto specv2_set_mode;
 922                 }
 923                 if (IS_ENABLED(CONFIG_RETPOLINE))
 924                         goto retpoline_auto;
 925                 break;
 926         case SPECTRE_V2_CMD_RETPOLINE_AMD:
 927                 if (IS_ENABLED(CONFIG_RETPOLINE))
 928                         goto retpoline_amd;
 929                 break;
 930         case SPECTRE_V2_CMD_RETPOLINE_GENERIC:
 931                 if (IS_ENABLED(CONFIG_RETPOLINE))
 932                         goto retpoline_generic;
 933                 break;
 934         case SPECTRE_V2_CMD_RETPOLINE:
 935                 if (IS_ENABLED(CONFIG_RETPOLINE))
 936                         goto retpoline_auto;
 937                 break;
 938         }
 939         pr_err("Spectre mitigation: kernel not compiled with retpoline; no mitigation available!");
 940         return;
 941
 942 retpoline_auto:
 943         if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
 944             boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
 945         retpoline_amd:
 946                 if (!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) {
 947                         pr_err("Spectre mitigation: LFENCE not serializing, switching to generic retpoline\n");
 948                         goto retpoline_generic;
 949                 }
 950                 mode = SPECTRE_V2_RETPOLINE_AMD;
 951                 setup_force_cpu_cap(X86_FEATURE_RETPOLINE_AMD);
 952                 setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
 953         } else {
 954         retpoline_generic:
 955                 mode = SPECTRE_V2_RETPOLINE_GENERIC;
 956                 setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
 957         }
 958
 959 specv2_set_mode:
 960         spectre_v2_enabled = mode;
 961         pr_info("%s\n", spectre_v2_strings[mode]);
 962
 963         /*
 964          * If spectre v2 protection has been enabled, unconditionally fill
 965          * RSB during a context switch; this protects against two independent
 966          * issues:
 967          *
 968          *      - RSB underflow (and switch to BTB) on Skylake+
 969          *      - SpectreRSB variant of spectre v2 on X86_BUG_SPECTRE_V2 CPUs
 970          */
 971         setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
 972         pr_info("Spectre v2 / SpectreRSB mitigation: Filling RSB on context switch\n");
 973
 974         /*
 975          * Retpoline means the kernel is safe because it has no indirect
 976          * branches. Enhanced IBRS protects firmware too, so, enable restricted
 977          * speculation around firmware calls only when Enhanced IBRS isn't
 978          * supported.
 979          *
 980          * Use "mode" to check Enhanced IBRS instead of boot_cpu_has(), because
 981          * the user might select retpoline on the kernel command line and if
 982          * the CPU supports Enhanced IBRS, kernel might un-intentionally not
 983          * enable IBRS around firmware calls.
 984          */
 985         if (boot_cpu_has(X86_FEATURE_IBRS) && mode != SPECTRE_V2_IBRS_ENHANCED) {
 986                 setup_force_cpu_cap(X86_FEATURE_USE_IBRS_FW);
 987                 pr_info("Enabling Restricted Speculation for firmware calls\n");
 988         }
 989
 990         /* Set up IBPB and STIBP depending on the general spectre V2 command */
 991         spectre_v2_user_select_mitigation(cmd);
 992 }
 993
 994 static void update_stibp_msr(void * __unused)
 995 {
 996         wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
 997 }
 998
 999 /* Update x86_spec_ctrl_base in case SMT state changed. */
1000 static void update_stibp_strict(void)
1001 {
1002         u64 mask = x86_spec_ctrl_base & ~SPEC_CTRL_STIBP;
1003
1004         if (sched_smt_active())
1005                 mask |= SPEC_CTRL_STIBP;
1006
1007         if (mask == x86_spec_ctrl_base)
1008                 return;
1009
1010         pr_info("Update user space SMT mitigation: STIBP %s\n",
1011                 mask & SPEC_CTRL_STIBP ? "always-on" : "off");
1012         x86_spec_ctrl_base = mask;
1013         on_each_cpu(update_stibp_msr, NULL, 1);
1014 }
1015
1016 /* Update the static key controlling the evaluation of TIF_SPEC_IB */
1017 static void update_indir_branch_cond(void)
1018 {
1019         if (sched_smt_active())
1020                 static_branch_enable(&switch_to_cond_stibp);
1021         else
1022                 static_branch_disable(&switch_to_cond_stibp);
1023 }
1024
1025 #undef pr_fmt
1026 #define pr_fmt(fmt) fmt
1027
1028 /* Update the static key controlling the MDS CPU buffer clear in idle */
1029 static void update_mds_branch_idle(void)
1030 {
1031         /*
1032          * Enable the idle clearing if SMT is active on CPUs which are
1033          * affected only by MSBDS and not any other MDS variant.
1034          *
1035          * The other variants cannot be mitigated when SMT is enabled, so
1036          * clearing the buffers on idle just to prevent the Store Buffer
1037          * repartitioning leak would be a window dressing exercise.
1038          */
1039         if (!boot_cpu_has_bug(X86_BUG_MSBDS_ONLY))
1040                 return;
1041
1042         if (sched_smt_active())
1043                 static_branch_enable(&mds_idle_clear);
1044         else
1045                 static_branch_disable(&mds_idle_clear);
1046 }
1047
1048 #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"
1049 #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"
1050
1051 void cpu_bugs_smt_update(void)
1052 {
1053         mutex_lock(&spec_ctrl_mutex);
1054
1055         switch (spectre_v2_user_stibp) {
1056         case SPECTRE_V2_USER_NONE:
1057                 break;
1058         case SPECTRE_V2_USER_STRICT:
1059         case SPECTRE_V2_USER_STRICT_PREFERRED:
1060                 update_stibp_strict();
1061                 break;
1062         case SPECTRE_V2_USER_PRCTL:
1063         case SPECTRE_V2_USER_SECCOMP:
1064                 update_indir_branch_cond();
1065                 break;
1066         }
1067
1068         switch (mds_mitigation) {
1069         case MDS_MITIGATION_FULL:
1070         case MDS_MITIGATION_VMWERV:
1071                 if (sched_smt_active() && !boot_cpu_has(X86_BUG_MSBDS_ONLY))
1072                         pr_warn_once(MDS_MSG_SMT);
1073                 update_mds_branch_idle();
1074                 break;
1075         case MDS_MITIGATION_OFF:
1076                 break;
1077         }
1078
1079         switch (taa_mitigation) {
1080         case TAA_MITIGATION_VERW:
1081         case TAA_MITIGATION_UCODE_NEEDED:
1082                 if (sched_smt_active())
1083                         pr_warn_once(TAA_MSG_SMT);
1084                 break;
1085         case TAA_MITIGATION_TSX_DISABLED:
1086         case TAA_MITIGATION_OFF:
1087                 break;
1088         }
1089
1090         mutex_unlock(&spec_ctrl_mutex);
1091 }
1092
1093 #undef pr_fmt
1094 #define pr_fmt(fmt)     "Speculative Store Bypass: " fmt
1095
1096 static enum ssb_mitigation ssb_mode __ro_after_init = SPEC_STORE_BYPASS_NONE;
1097
1098 /* The kernel command line selection */
1099 enum ssb_mitigation_cmd {
1100         SPEC_STORE_BYPASS_CMD_NONE,
1101         SPEC_STORE_BYPASS_CMD_AUTO,
1102         SPEC_STORE_BYPASS_CMD_ON,
1103         SPEC_STORE_BYPASS_CMD_PRCTL,
1104         SPEC_STORE_BYPASS_CMD_SECCOMP,
1105 };
1106
1107 static const char * const ssb_strings[] = {
1108         [SPEC_STORE_BYPASS_NONE]        = "Vulnerable",
1109         [SPEC_STORE_BYPASS_DISABLE]     = "Mitigation: Speculative Store Bypass disabled",
1110         [SPEC_STORE_BYPASS_PRCTL]       = "Mitigation: Speculative Store Bypass disabled via prctl",
1111         [SPEC_STORE_BYPASS_SECCOMP]     = "Mitigation: Speculative Store Bypass disabled via prctl and seccomp",
1112 };
1113
1114 static const struct {
1115         const char *option;
1116         enum ssb_mitigation_cmd cmd;
1117 } ssb_mitigation_options[]  __initconst = {
1118         { "auto",       SPEC_STORE_BYPASS_CMD_AUTO },    /* Platform decides */
1119         { "on",         SPEC_STORE_BYPASS_CMD_ON },      /* Disable Speculative Store Bypass */
1120         { "off",        SPEC_STORE_BYPASS_CMD_NONE },    /* Don't touch Speculative Store Bypass */
1121         { "prctl",      SPEC_STORE_BYPASS_CMD_PRCTL },   /* Disable Speculative Store Bypass via prctl */
1122         { "seccomp",    SPEC_STORE_BYPASS_CMD_SECCOMP }, /* Disable Speculative Store Bypass via prctl and seccomp */
1123 };
1124
1125 static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void)
1126 {
1127         enum ssb_mitigation_cmd cmd = SPEC_STORE_BYPASS_CMD_AUTO;
1128         char arg[20];
1129         int ret, i;
1130
1131         if (cmdline_find_option_bool(boot_command_line, "nospec_store_bypass_disable") ||
1132             cpu_mitigations_off()) {
1133                 return SPEC_STORE_BYPASS_CMD_NONE;
1134         } else {
1135                 ret = cmdline_find_option(boot_command_line, "spec_store_bypass_disable",
1136                                           arg, sizeof(arg));
1137                 if (ret < 0)
1138                         return SPEC_STORE_BYPASS_CMD_AUTO;
1139
1140                 for (i = 0; i < ARRAY_SIZE(ssb_mitigation_options); i++) {
1141                         if (!match_option(arg, ret, ssb_mitigation_options[i].option))
1142                                 continue;
1143
1144                         cmd = ssb_mitigation_options[i].cmd;
1145                         break;
1146                 }
1147
1148                 if (i >= ARRAY_SIZE(ssb_mitigation_options)) {
1149                         pr_err("unknown option (%s). Switching to AUTO select\n", arg);
1150                         return SPEC_STORE_BYPASS_CMD_AUTO;
1151                 }
1152         }
1153
1154         return cmd;
1155 }
1156
1157 static enum ssb_mitigation __init __ssb_select_mitigation(void)
1158 {
1159         enum ssb_mitigation mode = SPEC_STORE_BYPASS_NONE;
1160         enum ssb_mitigation_cmd cmd;
1161
1162         if (!boot_cpu_has(X86_FEATURE_SSBD))
1163                 return mode;
1164
1165         cmd = ssb_parse_cmdline();
1166         if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS) &&
1167             (cmd == SPEC_STORE_BYPASS_CMD_NONE ||
1168              cmd == SPEC_STORE_BYPASS_CMD_AUTO))
1169                 return mode;
1170
1171         switch (cmd) {
1172         case SPEC_STORE_BYPASS_CMD_AUTO:
1173         case SPEC_STORE_BYPASS_CMD_SECCOMP:
1174                 /*
1175                  * Choose prctl+seccomp as the default mode if seccomp is
1176                  * enabled.
1177                  */
1178                 if (IS_ENABLED(CONFIG_SECCOMP))
1179                         mode = SPEC_STORE_BYPASS_SECCOMP;
1180                 else
1181                         mode = SPEC_STORE_BYPASS_PRCTL;
1182                 break;
1183         case SPEC_STORE_BYPASS_CMD_ON:
1184                 mode = SPEC_STORE_BYPASS_DISABLE;
1185                 break;
1186         case SPEC_STORE_BYPASS_CMD_PRCTL:
1187                 mode = SPEC_STORE_BYPASS_PRCTL;
1188                 break;
1189         case SPEC_STORE_BYPASS_CMD_NONE:
1190                 break;
1191         }
1192
1193         /*
1194          * If SSBD is controlled by the SPEC_CTRL MSR, then set the proper
1195          * bit in the mask to allow guests to use the mitigation even in the
1196          * case where the host does not enable it.
1197          */
1198         if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) ||
1199             static_cpu_has(X86_FEATURE_AMD_SSBD)) {
1200                 x86_spec_ctrl_mask |= SPEC_CTRL_SSBD;
1201         }
1202
1203         /*
1204          * We have three CPU feature flags that are in play here:
1205          *  - X86_BUG_SPEC_STORE_BYPASS - CPU is susceptible.
1206          *  - X86_FEATURE_SSBD - CPU is able to turn off speculative store bypass
1207          *  - X86_FEATURE_SPEC_STORE_BYPASS_DISABLE - engage the mitigation
1208          */
1209         if (mode == SPEC_STORE_BYPASS_DISABLE) {
1210                 setup_force_cpu_cap(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE);
1211                 /*
1212                  * Intel uses the SPEC CTRL MSR Bit(2) for this, while AMD may
1213                  * use a completely different MSR and bit dependent on family.
1214                  */
1215                 if (!static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) &&
1216                     !static_cpu_has(X86_FEATURE_AMD_SSBD)) {
1217                         x86_amd_ssb_disable();
1218                 } else {
1219                         x86_spec_ctrl_base |= SPEC_CTRL_SSBD;
1220                         wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
1221                 }
1222         }
1223
1224         return mode;
1225 }
1226
1227 static void ssb_select_mitigation(void)
1228 {
1229         ssb_mode = __ssb_select_mitigation();
1230
1231         if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
1232                 pr_info("%s\n", ssb_strings[ssb_mode]);
1233 }
1234
1235 #undef pr_fmt
1236 #define pr_fmt(fmt)     "Speculation prctl: " fmt
1237
1238 static void task_update_spec_tif(struct task_struct *tsk)
1239 {
1240         /* Force the update of the real TIF bits */
1241         set_tsk_thread_flag(tsk, TIF_SPEC_FORCE_UPDATE);
1242
1243         /*
1244          * Immediately update the speculation control MSRs for the current
1245          * task, but for a non-current task delay setting the CPU
1246          * mitigation until it is scheduled next.
1247          *
1248          * This can only happen for SECCOMP mitigation. For PRCTL it's
1249          * always the current task.
1250          */
1251         if (tsk == current)
1252                 speculation_ctrl_update_current();
1253 }
1254
1255 static int l1d_flush_prctl_set(struct task_struct *task, unsigned long ctrl)
1256 {
1257
1258         if (!static_branch_unlikely(&switch_mm_cond_l1d_flush))
1259                 return -EPERM;
1260
1261         switch (ctrl) {
1262         case PR_SPEC_ENABLE:
1263                 set_ti_thread_flag(&task->thread_info, TIF_SPEC_L1D_FLUSH);
1264                 return 0;
1265         case PR_SPEC_DISABLE:
1266                 clear_ti_thread_flag(&task->thread_info, TIF_SPEC_L1D_FLUSH);
1267                 return 0;
1268         default:
1269                 return -ERANGE;
1270         }
1271 }
1272
1273 static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl)
1274 {
1275         if (ssb_mode != SPEC_STORE_BYPASS_PRCTL &&
1276             ssb_mode != SPEC_STORE_BYPASS_SECCOMP)
1277                 return -ENXIO;
1278
1279         switch (ctrl) {
1280         case PR_SPEC_ENABLE:
1281                 /* If speculation is force disabled, enable is not allowed */
1282                 if (task_spec_ssb_force_disable(task))
1283                         return -EPERM;
1284                 task_clear_spec_ssb_disable(task);
1285                 task_clear_spec_ssb_noexec(task);
1286                 task_update_spec_tif(task);
1287                 break;
1288         case PR_SPEC_DISABLE:
1289                 task_set_spec_ssb_disable(task);
1290                 task_clear_spec_ssb_noexec(task);
1291                 task_update_spec_tif(task);
1292                 break;
1293         case PR_SPEC_FORCE_DISABLE:
1294                 task_set_spec_ssb_disable(task);
1295                 task_set_spec_ssb_force_disable(task);
1296                 task_clear_spec_ssb_noexec(task);
1297                 task_update_spec_tif(task);
1298                 break;
1299         case PR_SPEC_DISABLE_NOEXEC:
1300                 if (task_spec_ssb_force_disable(task))
1301                         return -EPERM;
1302                 task_set_spec_ssb_disable(task);
1303                 task_set_spec_ssb_noexec(task);
1304                 task_update_spec_tif(task);
1305                 break;
1306         default:
1307                 return -ERANGE;
1308         }
1309         return 0;
1310 }
1311
1312 static bool is_spec_ib_user_controlled(void)
1313 {
1314         return spectre_v2_user_ibpb == SPECTRE_V2_USER_PRCTL ||
1315                 spectre_v2_user_ibpb == SPECTRE_V2_USER_SECCOMP ||
1316                 spectre_v2_user_stibp == SPECTRE_V2_USER_PRCTL ||
1317                 spectre_v2_user_stibp == SPECTRE_V2_USER_SECCOMP;
1318 }
1319
1320 static int ib_prctl_set(struct task_struct *task, unsigned long ctrl)
1321 {
1322         switch (ctrl) {
1323         case PR_SPEC_ENABLE:
1324                 if (spectre_v2_user_ibpb == SPECTRE_V2_USER_NONE &&
1325                     spectre_v2_user_stibp == SPECTRE_V2_USER_NONE)
1326                         return 0;
1327
1328                 /*
1329                  * With strict mode for both IBPB and STIBP, the instruction
1330                  * code paths avoid checking this task flag and instead,
1331                  * unconditionally run the instruction. However, STIBP and IBPB
1332                  * are independent and either can be set to conditionally
1333                  * enabled regardless of the mode of the other.
1334                  *
1335                  * If either is set to conditional, allow the task flag to be
1336                  * updated, unless it was force-disabled by a previous prctl
1337                  * call. Currently, this is possible on an AMD CPU which has the
1338                  * feature X86_FEATURE_AMD_STIBP_ALWAYS_ON. In this case, if the
1339                  * kernel is booted with 'spectre_v2_user=seccomp', then
1340                  * spectre_v2_user_ibpb == SPECTRE_V2_USER_SECCOMP and
1341                  * spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED.
1342                  */
1343                 if (!is_spec_ib_user_controlled() ||
1344                     task_spec_ib_force_disable(task))
1345                         return -EPERM;
1346
1347                 task_clear_spec_ib_disable(task);
1348                 task_update_spec_tif(task);
1349                 break;
1350         case PR_SPEC_DISABLE:
1351         case PR_SPEC_FORCE_DISABLE:
1352                 /*
1353                  * Indirect branch speculation is always allowed when
1354                  * mitigation is force disabled.
1355                  */
1356                 if (spectre_v2_user_ibpb == SPECTRE_V2_USER_NONE &&
1357                     spectre_v2_user_stibp == SPECTRE_V2_USER_NONE)
1358                         return -EPERM;
1359
1360                 if (!is_spec_ib_user_controlled())
1361                         return 0;
1362
1363                 task_set_spec_ib_disable(task);
1364                 if (ctrl == PR_SPEC_FORCE_DISABLE)
1365                         task_set_spec_ib_force_disable(task);
1366                 task_update_spec_tif(task);
1367                 break;
1368         default:
1369                 return -ERANGE;
1370         }
1371         return 0;
1372 }
1373
1374 int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which,
1375                              unsigned long ctrl)
1376 {
1377         switch (which) {
1378         case PR_SPEC_STORE_BYPASS:
1379                 return ssb_prctl_set(task, ctrl);
1380         case PR_SPEC_INDIRECT_BRANCH:
1381                 return ib_prctl_set(task, ctrl);
1382         case PR_SPEC_L1D_FLUSH:
1383                 return l1d_flush_prctl_set(task, ctrl);
1384         default:
1385                 return -ENODEV;
1386         }
1387 }
1388
1389 #ifdef CONFIG_SECCOMP
1390 void arch_seccomp_spec_mitigate(struct task_struct *task)
1391 {
1392         if (ssb_mode == SPEC_STORE_BYPASS_SECCOMP)
1393                 ssb_prctl_set(task, PR_SPEC_FORCE_DISABLE);
1394         if (spectre_v2_user_ibpb == SPECTRE_V2_USER_SECCOMP ||
1395             spectre_v2_user_stibp == SPECTRE_V2_USER_SECCOMP)
1396                 ib_prctl_set(task, PR_SPEC_FORCE_DISABLE);
1397 }
1398 #endif
1399
1400 static int l1d_flush_prctl_get(struct task_struct *task)
1401 {
1402         if (!static_branch_unlikely(&switch_mm_cond_l1d_flush))
1403                 return PR_SPEC_FORCE_DISABLE;
1404
1405         if (test_ti_thread_flag(&task->thread_info, TIF_SPEC_L1D_FLUSH))
1406                 return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
1407         else
1408                 return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
1409 }
1410
1411 static int ssb_prctl_get(struct task_struct *task)
1412 {
1413         switch (ssb_mode) {
1414         case SPEC_STORE_BYPASS_DISABLE:
1415                 return PR_SPEC_DISABLE;
1416         case SPEC_STORE_BYPASS_SECCOMP:
1417         case SPEC_STORE_BYPASS_PRCTL:
1418                 if (task_spec_ssb_force_disable(task))
1419                         return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE;
1420                 if (task_spec_ssb_noexec(task))
1421                         return PR_SPEC_PRCTL | PR_SPEC_DISABLE_NOEXEC;
1422                 if (task_spec_ssb_disable(task))
1423                         return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
1424                 return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
1425         default:
1426                 if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
1427                         return PR_SPEC_ENABLE;
1428                 return PR_SPEC_NOT_AFFECTED;
1429         }
1430 }
1431
1432 static int ib_prctl_get(struct task_struct *task)
1433 {
1434         if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
1435                 return PR_SPEC_NOT_AFFECTED;
1436
1437         if (spectre_v2_user_ibpb == SPECTRE_V2_USER_NONE &&
1438             spectre_v2_user_stibp == SPECTRE_V2_USER_NONE)
1439                 return PR_SPEC_ENABLE;
1440         else if (is_spec_ib_user_controlled()) {
1441                 if (task_spec_ib_force_disable(task))
1442                         return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE;
1443                 if (task_spec_ib_disable(task))
1444                         return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
1445                 return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
1446         } else if (spectre_v2_user_ibpb == SPECTRE_V2_USER_STRICT ||
1447             spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT ||
1448             spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED)
1449                 return PR_SPEC_DISABLE;
1450         else
1451                 return PR_SPEC_NOT_AFFECTED;
1452 }
1453
1454 int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
1455 {
1456         switch (which) {
1457         case PR_SPEC_STORE_BYPASS:
1458                 return ssb_prctl_get(task);
1459         case PR_SPEC_INDIRECT_BRANCH:
1460                 return ib_prctl_get(task);
1461         case PR_SPEC_L1D_FLUSH:
1462                 return l1d_flush_prctl_get(task);
1463         default:
1464                 return -ENODEV;
1465         }
1466 }
1467
1468 void x86_spec_ctrl_setup_ap(void)
1469 {
1470         if (boot_cpu_has(X86_FEATURE_MSR_SPEC_CTRL))
1471                 wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
1472
1473         if (ssb_mode == SPEC_STORE_BYPASS_DISABLE)
1474                 x86_amd_ssb_disable();
1475 }
1476
1477 bool itlb_multihit_kvm_mitigation;
1478 EXPORT_SYMBOL_GPL(itlb_multihit_kvm_mitigation);
1479
1480 #undef pr_fmt
1481 #define pr_fmt(fmt)     "L1TF: " fmt
1482
1483 /* Default mitigation for L1TF-affected CPUs */
1484 enum l1tf_mitigations l1tf_mitigation __ro_after_init = L1TF_MITIGATION_FLUSH;
1485 #if IS_ENABLED(CONFIG_KVM_INTEL)
1486 EXPORT_SYMBOL_GPL(l1tf_mitigation);
1487 #endif
1488 enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO;
1489 EXPORT_SYMBOL_GPL(l1tf_vmx_mitigation);
1490
1491 /*
1492  * These CPUs all support 44bits physical address space internally in the
1493  * cache but CPUID can report a smaller number of physical address bits.
1494  *
1495  * The L1TF mitigation uses the top most address bit for the inversion of
1496  * non present PTEs. When the installed memory reaches into the top most
1497  * address bit due to memory holes, which has been observed on machines
1498  * which report 36bits physical address bits and have 32G RAM installed,
1499  * then the mitigation range check in l1tf_select_mitigation() triggers.
1500  * This is a false positive because the mitigation is still possible due to
1501  * the fact that the cache uses 44bit internally. Use the cache bits
1502  * instead of the reported physical bits and adjust them on the affected
1503  * machines to 44bit if the reported bits are less than 44.
1504  */
1505 static void override_cache_bits(struct cpuinfo_x86 *c)
1506 {
1507         if (c->x86 != 6)
1508                 return;
1509
1510         switch (c->x86_model) {
1511         case INTEL_FAM6_NEHALEM:
1512         case INTEL_FAM6_WESTMERE:
1513         case INTEL_FAM6_SANDYBRIDGE:
1514         case INTEL_FAM6_IVYBRIDGE:
1515         case INTEL_FAM6_HASWELL:
1516         case INTEL_FAM6_HASWELL_L:
1517         case INTEL_FAM6_HASWELL_G:
1518         case INTEL_FAM6_BROADWELL:
1519         case INTEL_FAM6_BROADWELL_G:
1520         case INTEL_FAM6_SKYLAKE_L:
1521         case INTEL_FAM6_SKYLAKE:
1522         case INTEL_FAM6_KABYLAKE_L:
1523         case INTEL_FAM6_KABYLAKE:
1524                 if (c->x86_cache_bits < 44)
1525                         c->x86_cache_bits = 44;
1526                 break;
1527         }
1528 }
1529
1530 static void __init l1tf_select_mitigation(void)
1531 {
1532         u64 half_pa;
1533
1534         if (!boot_cpu_has_bug(X86_BUG_L1TF))
1535                 return;
1536
1537         if (cpu_mitigations_off())
1538                 l1tf_mitigation = L1TF_MITIGATION_OFF;
1539         else if (cpu_mitigations_auto_nosmt())
1540                 l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT;
1541
1542         override_cache_bits(&boot_cpu_data);
1543
1544         switch (l1tf_mitigation) {
1545         case L1TF_MITIGATION_OFF:
1546         case L1TF_MITIGATION_FLUSH_NOWARN:
1547         case L1TF_MITIGATION_FLUSH:
1548                 break;
1549         case L1TF_MITIGATION_FLUSH_NOSMT:
1550         case L1TF_MITIGATION_FULL:
1551                 cpu_smt_disable(false);
1552                 break;
1553         case L1TF_MITIGATION_FULL_FORCE:
1554                 cpu_smt_disable(true);
1555                 break;
1556         }
1557
1558 #if CONFIG_PGTABLE_LEVELS == 2
1559         pr_warn("Kernel not compiled for PAE. No mitigation for L1TF\n");
1560         return;
1561 #endif
1562
1563         half_pa = (u64)l1tf_pfn_limit() << PAGE_SHIFT;
1564         if (l1tf_mitigation != L1TF_MITIGATION_OFF &&
1565                         e820__mapped_any(half_pa, ULLONG_MAX - half_pa, E820_TYPE_RAM)) {
1566                 pr_warn("System has more than MAX_PA/2 memory. L1TF mitigation not effective.\n");
1567                 pr_info("You may make it effective by booting the kernel with mem=%llu parameter.\n",
1568                                 half_pa);
1569                 pr_info("However, doing so will make a part of your RAM unusable.\n");
1570                 pr_info("Reading https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html might help you decide.\n");
1571                 return;
1572         }
1573
1574         setup_force_cpu_cap(X86_FEATURE_L1TF_PTEINV);
1575 }
1576
1577 static int __init l1tf_cmdline(char *str)
1578 {
1579         if (!boot_cpu_has_bug(X86_BUG_L1TF))
1580                 return 0;
1581
1582         if (!str)
1583                 return -EINVAL;
1584
1585         if (!strcmp(str, "off"))
1586                 l1tf_mitigation = L1TF_MITIGATION_OFF;
1587         else if (!strcmp(str, "flush,nowarn"))
1588                 l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOWARN;
1589         else if (!strcmp(str, "flush"))
1590                 l1tf_mitigation = L1TF_MITIGATION_FLUSH;
1591         else if (!strcmp(str, "flush,nosmt"))
1592                 l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT;
1593         else if (!strcmp(str, "full"))
1594                 l1tf_mitigation = L1TF_MITIGATION_FULL;
1595         else if (!strcmp(str, "full,force"))
1596                 l1tf_mitigation = L1TF_MITIGATION_FULL_FORCE;
1597
1598         return 0;
1599 }
1600 early_param("l1tf", l1tf_cmdline);
1601
1602 #undef pr_fmt
1603 #define pr_fmt(fmt) fmt
1604
1605 #ifdef CONFIG_SYSFS
1606
1607 #define L1TF_DEFAULT_MSG "Mitigation: PTE Inversion"
1608
1609 #if IS_ENABLED(CONFIG_KVM_INTEL)
1610 static const char * const l1tf_vmx_states[] = {
1611         [VMENTER_L1D_FLUSH_AUTO]                = "auto",
1612         [VMENTER_L1D_FLUSH_NEVER]               = "vulnerable",
1613         [VMENTER_L1D_FLUSH_COND]                = "conditional cache flushes",
1614         [VMENTER_L1D_FLUSH_ALWAYS]              = "cache flushes",
1615         [VMENTER_L1D_FLUSH_EPT_DISABLED]        = "EPT disabled",
1616         [VMENTER_L1D_FLUSH_NOT_REQUIRED]        = "flush not necessary"
1617 };
1618
1619 static ssize_t l1tf_show_state(char *buf)
1620 {
1621         if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_AUTO)
1622                 return sprintf(buf, "%s\n", L1TF_DEFAULT_MSG);
1623
1624         if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_EPT_DISABLED ||
1625             (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_NEVER &&
1626              sched_smt_active())) {
1627                 return sprintf(buf, "%s; VMX: %s\n", L1TF_DEFAULT_MSG,
1628                                l1tf_vmx_states[l1tf_vmx_mitigation]);
1629         }
1630
1631         return sprintf(buf, "%s; VMX: %s, SMT %s\n", L1TF_DEFAULT_MSG,
1632                        l1tf_vmx_states[l1tf_vmx_mitigation],
1633                        sched_smt_active() ? "vulnerable" : "disabled");
1634 }
1635
1636 static ssize_t itlb_multihit_show_state(char *buf)
1637 {
1638         if (!boot_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) ||
1639             !boot_cpu_has(X86_FEATURE_VMX))
1640                 return sprintf(buf, "KVM: Mitigation: VMX unsupported\n");
1641         else if (!(cr4_read_shadow() & X86_CR4_VMXE))
1642                 return sprintf(buf, "KVM: Mitigation: VMX disabled\n");
1643         else if (itlb_multihit_kvm_mitigation)
1644                 return sprintf(buf, "KVM: Mitigation: Split huge pages\n");
1645         else
1646                 return sprintf(buf, "KVM: Vulnerable\n");
1647 }
1648 #else
1649 static ssize_t l1tf_show_state(char *buf)
1650 {
1651         return sprintf(buf, "%s\n", L1TF_DEFAULT_MSG);
1652 }
1653
1654 static ssize_t itlb_multihit_show_state(char *buf)
1655 {
1656         return sprintf(buf, "Processor vulnerable\n");
1657 }
1658 #endif
1659
1660 static ssize_t mds_show_state(char *buf)
1661 {
1662         if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
1663                 return sprintf(buf, "%s; SMT Host state unknown\n",
1664                                mds_strings[mds_mitigation]);
1665         }
1666
1667         if (boot_cpu_has(X86_BUG_MSBDS_ONLY)) {
1668                 return sprintf(buf, "%s; SMT %s\n", mds_strings[mds_mitigation],
1669                                (mds_mitigation == MDS_MITIGATION_OFF ? "vulnerable" :
1670                                 sched_smt_active() ? "mitigated" : "disabled"));
1671         }
1672
1673         return sprintf(buf, "%s; SMT %s\n", mds_strings[mds_mitigation],
1674                        sched_smt_active() ? "vulnerable" : "disabled");
1675 }
1676
1677 static ssize_t tsx_async_abort_show_state(char *buf)
1678 {
1679         if ((taa_mitigation == TAA_MITIGATION_TSX_DISABLED) ||
1680             (taa_mitigation == TAA_MITIGATION_OFF))
1681                 return sprintf(buf, "%s\n", taa_strings[taa_mitigation]);
1682
1683         if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
1684                 return sprintf(buf, "%s; SMT Host state unknown\n",
1685                                taa_strings[taa_mitigation]);
1686         }
1687
1688         return sprintf(buf, "%s; SMT %s\n", taa_strings[taa_mitigation],
1689                        sched_smt_active() ? "vulnerable" : "disabled");
1690 }
1691
1692 static char *stibp_state(void)
1693 {
1694         if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
1695                 return "";
1696
1697         switch (spectre_v2_user_stibp) {
1698         case SPECTRE_V2_USER_NONE:
1699                 return ", STIBP: disabled";
1700         case SPECTRE_V2_USER_STRICT:
1701                 return ", STIBP: forced";
1702         case SPECTRE_V2_USER_STRICT_PREFERRED:
1703                 return ", STIBP: always-on";
1704         case SPECTRE_V2_USER_PRCTL:
1705         case SPECTRE_V2_USER_SECCOMP:
1706                 if (static_key_enabled(&switch_to_cond_stibp))
1707                         return ", STIBP: conditional";
1708         }
1709         return "";
1710 }
1711
1712 static char *ibpb_state(void)
1713 {
1714         if (boot_cpu_has(X86_FEATURE_IBPB)) {
1715                 if (static_key_enabled(&switch_mm_always_ibpb))
1716                         return ", IBPB: always-on";
1717                 if (static_key_enabled(&switch_mm_cond_ibpb))
1718                         return ", IBPB: conditional";
1719                 return ", IBPB: disabled";
1720         }
1721         return "";
1722 }
1723
1724 static ssize_t srbds_show_state(char *buf)
1725 {
1726         return sprintf(buf, "%s\n", srbds_strings[srbds_mitigation]);
1727 }
1728
1729 static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr,
1730                                char *buf, unsigned int bug)
1731 {
1732         if (!boot_cpu_has_bug(bug))
1733                 return sprintf(buf, "Not affected\n");
1734
1735         switch (bug) {
1736         case X86_BUG_CPU_MELTDOWN:
1737                 if (boot_cpu_has(X86_FEATURE_PTI))
1738                         return sprintf(buf, "Mitigation: PTI\n");
1739
1740                 if (hypervisor_is_type(X86_HYPER_XEN_PV))
1741                         return sprintf(buf, "Unknown (XEN PV detected, hypervisor mitigation required)\n");
1742
1743                 break;
1744
1745         case X86_BUG_SPECTRE_V1:
1746                 return sprintf(buf, "%s\n", spectre_v1_strings[spectre_v1_mitigation]);
1747
1748         case X86_BUG_SPECTRE_V2:
1749                 return sprintf(buf, "%s%s%s%s%s%s\n", spectre_v2_strings[spectre_v2_enabled],
1750                                ibpb_state(),
1751                                boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "",
1752                                stibp_state(),
1753                                boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB filling" : "",
1754                                spectre_v2_module_string());
1755
1756         case X86_BUG_SPEC_STORE_BYPASS:
1757                 return sprintf(buf, "%s\n", ssb_strings[ssb_mode]);
1758
1759         case X86_BUG_L1TF:
1760                 if (boot_cpu_has(X86_FEATURE_L1TF_PTEINV))
1761                         return l1tf_show_state(buf);
1762                 break;
1763
1764         case X86_BUG_MDS:
1765                 return mds_show_state(buf);
1766
1767         case X86_BUG_TAA:
1768                 return tsx_async_abort_show_state(buf);
1769
1770         case X86_BUG_ITLB_MULTIHIT:
1771                 return itlb_multihit_show_state(buf);
1772
1773         case X86_BUG_SRBDS:
1774                 return srbds_show_state(buf);
1775
1776         default:
1777                 break;
1778         }
1779
1780         return sprintf(buf, "Vulnerable\n");
1781 }
1782
1783 ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
1784 {
1785         return cpu_show_common(dev, attr, buf, X86_BUG_CPU_MELTDOWN);
1786 }
1787
1788 ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf)
1789 {
1790         return cpu_show_common(dev, attr, buf, X86_BUG_SPECTRE_V1);
1791 }
1792
1793 ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
1794 {
1795         return cpu_show_common(dev, attr, buf, X86_BUG_SPECTRE_V2);
1796 }
1797
1798 ssize_t cpu_show_spec_store_bypass(struct device *dev, struct device_attribute *attr, char *buf)
1799 {
1800         return cpu_show_common(dev, attr, buf, X86_BUG_SPEC_STORE_BYPASS);
1801 }
1802
1803 ssize_t cpu_show_l1tf(struct device *dev, struct device_attribute *attr, char *buf)
1804 {
1805         return cpu_show_common(dev, attr, buf, X86_BUG_L1TF);
1806 }
1807
1808 ssize_t cpu_show_mds(struct device *dev, struct device_attribute *attr, char *buf)
1809 {
1810         return cpu_show_common(dev, attr, buf, X86_BUG_MDS);
1811 }
1812
1813 ssize_t cpu_show_tsx_async_abort(struct device *dev, struct device_attribute *attr, char *buf)
1814 {
1815         return cpu_show_common(dev, attr, buf, X86_BUG_TAA);
1816 }
1817
1818 ssize_t cpu_show_itlb_multihit(struct device *dev, struct device_attribute *attr, char *buf)
1819 {
1820         return cpu_show_common(dev, attr, buf, X86_BUG_ITLB_MULTIHIT);
1821 }
1822
1823 ssize_t cpu_show_srbds(struct device *dev, struct device_attribute *attr, char *buf)
1824 {
1825         return cpu_show_common(dev, attr, buf, X86_BUG_SRBDS);
1826 }
1827 #endif