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
  19 #include <asm/spec-ctrl.h>
  20 #include <asm/cmdline.h>
  21 #include <asm/bugs.h>
  22 #include <asm/processor.h>
  23 #include <asm/processor-flags.h>
  24 #include <asm/fpu/internal.h>
  25 #include <asm/msr.h>
  26 #include <asm/vmx.h>
  27 #include <asm/paravirt.h>
  28 #include <asm/alternative.h>
  29 #include <asm/pgtable.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
  35 #include "cpu.h"
  36
  37 static void __init spectre_v2_select_mitigation(void);
  38 static void __init ssb_select_mitigation(void);
  39 static void __init l1tf_select_mitigation(void);
  40
  41 /* The base value of the SPEC_CTRL MSR that always has to be preserved. */
  42 u64 x86_spec_ctrl_base;
  43 EXPORT_SYMBOL_GPL(x86_spec_ctrl_base);
  44 static DEFINE_MUTEX(spec_ctrl_mutex);
  45
  46 /*
  47  * The vendor and possibly platform specific bits which can be modified in
  48  * x86_spec_ctrl_base.
  49  */
  50 static u64 __ro_after_init x86_spec_ctrl_mask = SPEC_CTRL_IBRS;
  51
  52 /*
  53  * AMD specific MSR info for Speculative Store Bypass control.
  54  * x86_amd_ls_cfg_ssbd_mask is initialized in identify_boot_cpu().
  55  */
  56 u64 __ro_after_init x86_amd_ls_cfg_base;
  57 u64 __ro_after_init x86_amd_ls_cfg_ssbd_mask;
  58
  59 /* Control conditional STIBP in switch_to() */
  60 DEFINE_STATIC_KEY_FALSE(switch_to_cond_stibp);
  61 /* Control conditional IBPB in switch_mm() */
  62 DEFINE_STATIC_KEY_FALSE(switch_mm_cond_ibpb);
  63 /* Control unconditional IBPB in switch_mm() */
  64 DEFINE_STATIC_KEY_FALSE(switch_mm_always_ibpb);
  65
  66 void __init check_bugs(void)
  67 {
  68         identify_boot_cpu();
  69
  70         /*
  71          * identify_boot_cpu() initialized SMT support information, let the
  72          * core code know.
  73          */
  74         cpu_smt_check_topology();
  75
  76         if (!IS_ENABLED(CONFIG_SMP)) {
  77                 pr_info("CPU: ");
  78                 print_cpu_info(&boot_cpu_data);
  79         }
  80
  81         /*
  82          * Read the SPEC_CTRL MSR to account for reserved bits which may
  83          * have unknown values. AMD64_LS_CFG MSR is cached in the early AMD
  84          * init code as it is not enumerated and depends on the family.
  85          */
  86         if (boot_cpu_has(X86_FEATURE_MSR_SPEC_CTRL))
  87                 rdmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
  88
  89         /* Allow STIBP in MSR_SPEC_CTRL if supported */
  90         if (boot_cpu_has(X86_FEATURE_STIBP))
  91                 x86_spec_ctrl_mask |= SPEC_CTRL_STIBP;
  92
  93         /* Select the proper spectre mitigation before patching alternatives */
  94         spectre_v2_select_mitigation();
  95
  96         /*
  97          * Select proper mitigation for any exposure to the Speculative Store
  98          * Bypass vulnerability.
  99          */
 100         ssb_select_mitigation();
 101
 102         l1tf_select_mitigation();
 103
 104 #ifdef CONFIG_X86_32
 105         /*
 106          * Check whether we are able to run this kernel safely on SMP.
 107          *
 108          * - i386 is no longer supported.
 109          * - In order to run on anything without a TSC, we need to be
 110          *   compiled for a i486.
 111          */
 112         if (boot_cpu_data.x86 < 4)
 113                 panic("Kernel requires i486+ for 'invlpg' and other features");
 114
 115         init_utsname()->machine[1] =
 116                 '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
 117         alternative_instructions();
 118
 119         fpu__init_check_bugs();
 120 #else /* CONFIG_X86_64 */
 121         alternative_instructions();
 122
 123         /*
 124          * Make sure the first 2MB area is not mapped by huge pages
 125          * There are typically fixed size MTRRs in there and overlapping
 126          * MTRRs into large pages causes slow downs.
 127          *
 128          * Right now we don't do that with gbpages because there seems
 129          * very little benefit for that case.
 130          */
 131         if (!direct_gbpages)
 132                 set_memory_4k((unsigned long)__va(0), 1);
 133 #endif
 134 }
 135
 136 void
 137 x86_virt_spec_ctrl(u64 guest_spec_ctrl, u64 guest_virt_spec_ctrl, bool setguest)
 138 {
 139         u64 msrval, guestval, hostval = x86_spec_ctrl_base;
 140         struct thread_info *ti = current_thread_info();
 141
 142         /* Is MSR_SPEC_CTRL implemented ? */
 143         if (static_cpu_has(X86_FEATURE_MSR_SPEC_CTRL)) {
 144                 /*
 145                  * Restrict guest_spec_ctrl to supported values. Clear the
 146                  * modifiable bits in the host base value and or the
 147                  * modifiable bits from the guest value.
 148                  */
 149                 guestval = hostval & ~x86_spec_ctrl_mask;
 150                 guestval |= guest_spec_ctrl & x86_spec_ctrl_mask;
 151
 152                 /* SSBD controlled in MSR_SPEC_CTRL */
 153                 if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) ||
 154                     static_cpu_has(X86_FEATURE_AMD_SSBD))
 155                         hostval |= ssbd_tif_to_spec_ctrl(ti->flags);
 156
 157                 /* Conditional STIBP enabled? */
 158                 if (static_branch_unlikely(&switch_to_cond_stibp))
 159                         hostval |= stibp_tif_to_spec_ctrl(ti->flags);
 160
 161                 if (hostval != guestval) {
 162                         msrval = setguest ? guestval : hostval;
 163                         wrmsrl(MSR_IA32_SPEC_CTRL, msrval);
 164                 }
 165         }
 166
 167         /*
 168          * If SSBD is not handled in MSR_SPEC_CTRL on AMD, update
 169          * MSR_AMD64_L2_CFG or MSR_VIRT_SPEC_CTRL if supported.
 170          */
 171         if (!static_cpu_has(X86_FEATURE_LS_CFG_SSBD) &&
 172             !static_cpu_has(X86_FEATURE_VIRT_SSBD))
 173                 return;
 174
 175         /*
 176          * If the host has SSBD mitigation enabled, force it in the host's
 177          * virtual MSR value. If its not permanently enabled, evaluate
 178          * current's TIF_SSBD thread flag.
 179          */
 180         if (static_cpu_has(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE))
 181                 hostval = SPEC_CTRL_SSBD;
 182         else
 183                 hostval = ssbd_tif_to_spec_ctrl(ti->flags);
 184
 185         /* Sanitize the guest value */
 186         guestval = guest_virt_spec_ctrl & SPEC_CTRL_SSBD;
 187
 188         if (hostval != guestval) {
 189                 unsigned long tif;
 190
 191                 tif = setguest ? ssbd_spec_ctrl_to_tif(guestval) :
 192                                  ssbd_spec_ctrl_to_tif(hostval);
 193
 194                 speculation_ctrl_update(tif);
 195         }
 196 }
 197 EXPORT_SYMBOL_GPL(x86_virt_spec_ctrl);
 198
 199 static void x86_amd_ssb_disable(void)
 200 {
 201         u64 msrval = x86_amd_ls_cfg_base | x86_amd_ls_cfg_ssbd_mask;
 202
 203         if (boot_cpu_has(X86_FEATURE_VIRT_SSBD))
 204                 wrmsrl(MSR_AMD64_VIRT_SPEC_CTRL, SPEC_CTRL_SSBD);
 205         else if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD))
 206                 wrmsrl(MSR_AMD64_LS_CFG, msrval);
 207 }
 208
 209 #undef pr_fmt
 210 #define pr_fmt(fmt)     "Spectre V2 : " fmt
 211
 212 static enum spectre_v2_mitigation spectre_v2_enabled __ro_after_init =
 213         SPECTRE_V2_NONE;
 214
 215 static enum spectre_v2_user_mitigation spectre_v2_user __ro_after_init =
 216         SPECTRE_V2_USER_NONE;
 217
 218 #ifdef CONFIG_RETPOLINE
 219 static bool spectre_v2_bad_module;
 220
 221 bool retpoline_module_ok(bool has_retpoline)
 222 {
 223         if (spectre_v2_enabled == SPECTRE_V2_NONE || has_retpoline)
 224                 return true;
 225
 226         pr_err("System may be vulnerable to spectre v2\n");
 227         spectre_v2_bad_module = true;
 228         return false;
 229 }
 230
 231 static inline const char *spectre_v2_module_string(void)
 232 {
 233         return spectre_v2_bad_module ? " - vulnerable module loaded" : "";
 234 }
 235 #else
 236 static inline const char *spectre_v2_module_string(void) { return ""; }
 237 #endif
 238
 239 static inline bool match_option(const char *arg, int arglen, const char *opt)
 240 {
 241         int len = strlen(opt);
 242
 243         return len == arglen && !strncmp(arg, opt, len);
 244 }
 245
 246 /* The kernel command line selection for spectre v2 */
 247 enum spectre_v2_mitigation_cmd {
 248         SPECTRE_V2_CMD_NONE,
 249         SPECTRE_V2_CMD_AUTO,
 250         SPECTRE_V2_CMD_FORCE,
 251         SPECTRE_V2_CMD_RETPOLINE,
 252         SPECTRE_V2_CMD_RETPOLINE_GENERIC,
 253         SPECTRE_V2_CMD_RETPOLINE_AMD,
 254 };
 255
 256 enum spectre_v2_user_cmd {
 257         SPECTRE_V2_USER_CMD_NONE,
 258         SPECTRE_V2_USER_CMD_AUTO,
 259         SPECTRE_V2_USER_CMD_FORCE,
 260         SPECTRE_V2_USER_CMD_PRCTL,
 261         SPECTRE_V2_USER_CMD_PRCTL_IBPB,
 262         SPECTRE_V2_USER_CMD_SECCOMP,
 263         SPECTRE_V2_USER_CMD_SECCOMP_IBPB,
 264 };
 265
 266 static const char * const spectre_v2_user_strings[] = {
 267         [SPECTRE_V2_USER_NONE]                  = "User space: Vulnerable",
 268         [SPECTRE_V2_USER_STRICT]                = "User space: Mitigation: STIBP protection",
 269         [SPECTRE_V2_USER_STRICT_PREFERRED]      = "User space: Mitigation: STIBP always-on protection",
 270         [SPECTRE_V2_USER_PRCTL]                 = "User space: Mitigation: STIBP via prctl",
 271         [SPECTRE_V2_USER_SECCOMP]               = "User space: Mitigation: STIBP via seccomp and prctl",
 272 };
 273
 274 static const struct {
 275         const char                      *option;
 276         enum spectre_v2_user_cmd        cmd;
 277         bool                            secure;
 278 } v2_user_options[] __initdata = {
 279         { "auto",               SPECTRE_V2_USER_CMD_AUTO,               false },
 280         { "off",                SPECTRE_V2_USER_CMD_NONE,               false },
 281         { "on",                 SPECTRE_V2_USER_CMD_FORCE,              true  },
 282         { "prctl",              SPECTRE_V2_USER_CMD_PRCTL,              false },
 283         { "prctl,ibpb",         SPECTRE_V2_USER_CMD_PRCTL_IBPB,         false },
 284         { "seccomp",            SPECTRE_V2_USER_CMD_SECCOMP,            false },
 285         { "seccomp,ibpb",       SPECTRE_V2_USER_CMD_SECCOMP_IBPB,       false },
 286 };
 287
 288 static void __init spec_v2_user_print_cond(const char *reason, bool secure)
 289 {
 290         if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2) != secure)
 291                 pr_info("spectre_v2_user=%s forced on command line.\n", reason);
 292 }
 293
 294 static enum spectre_v2_user_cmd __init
 295 spectre_v2_parse_user_cmdline(enum spectre_v2_mitigation_cmd v2_cmd)
 296 {
 297         char arg[20];
 298         int ret, i;
 299
 300         switch (v2_cmd) {
 301         case SPECTRE_V2_CMD_NONE:
 302                 return SPECTRE_V2_USER_CMD_NONE;
 303         case SPECTRE_V2_CMD_FORCE:
 304                 return SPECTRE_V2_USER_CMD_FORCE;
 305         default:
 306                 break;
 307         }
 308
 309         ret = cmdline_find_option(boot_command_line, "spectre_v2_user",
 310                                   arg, sizeof(arg));
 311         if (ret < 0)
 312                 return SPECTRE_V2_USER_CMD_AUTO;
 313
 314         for (i = 0; i < ARRAY_SIZE(v2_user_options); i++) {
 315                 if (match_option(arg, ret, v2_user_options[i].option)) {
 316                         spec_v2_user_print_cond(v2_user_options[i].option,
 317                                                 v2_user_options[i].secure);
 318                         return v2_user_options[i].cmd;
 319                 }
 320         }
 321
 322         pr_err("Unknown user space protection option (%s). Switching to AUTO select\n", arg);
 323         return SPECTRE_V2_USER_CMD_AUTO;
 324 }
 325
 326 static void __init
 327 spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd)
 328 {
 329         enum spectre_v2_user_mitigation mode = SPECTRE_V2_USER_NONE;
 330         bool smt_possible = IS_ENABLED(CONFIG_SMP);
 331         enum spectre_v2_user_cmd cmd;
 332
 333         if (!boot_cpu_has(X86_FEATURE_IBPB) && !boot_cpu_has(X86_FEATURE_STIBP))
 334                 return;
 335
 336         if (cpu_smt_control == CPU_SMT_FORCE_DISABLED ||
 337             cpu_smt_control == CPU_SMT_NOT_SUPPORTED)
 338                 smt_possible = false;
 339
 340         cmd = spectre_v2_parse_user_cmdline(v2_cmd);
 341         switch (cmd) {
 342         case SPECTRE_V2_USER_CMD_NONE:
 343                 goto set_mode;
 344         case SPECTRE_V2_USER_CMD_FORCE:
 345                 mode = SPECTRE_V2_USER_STRICT;
 346                 break;
 347         case SPECTRE_V2_USER_CMD_PRCTL:
 348         case SPECTRE_V2_USER_CMD_PRCTL_IBPB:
 349                 mode = SPECTRE_V2_USER_PRCTL;
 350                 break;
 351         case SPECTRE_V2_USER_CMD_AUTO:
 352         case SPECTRE_V2_USER_CMD_SECCOMP:
 353         case SPECTRE_V2_USER_CMD_SECCOMP_IBPB:
 354                 if (IS_ENABLED(CONFIG_SECCOMP))
 355                         mode = SPECTRE_V2_USER_SECCOMP;
 356                 else
 357                         mode = SPECTRE_V2_USER_PRCTL;
 358                 break;
 359         }
 360
 361         /*
 362          * At this point, an STIBP mode other than "off" has been set.
 363          * If STIBP support is not being forced, check if STIBP always-on
 364          * is preferred.
 365          */
 366         if (mode != SPECTRE_V2_USER_STRICT &&
 367             boot_cpu_has(X86_FEATURE_AMD_STIBP_ALWAYS_ON))
 368                 mode = SPECTRE_V2_USER_STRICT_PREFERRED;
 369
 370         /* Initialize Indirect Branch Prediction Barrier */
 371         if (boot_cpu_has(X86_FEATURE_IBPB)) {
 372                 setup_force_cpu_cap(X86_FEATURE_USE_IBPB);
 373
 374                 switch (cmd) {
 375                 case SPECTRE_V2_USER_CMD_FORCE:
 376                 case SPECTRE_V2_USER_CMD_PRCTL_IBPB:
 377                 case SPECTRE_V2_USER_CMD_SECCOMP_IBPB:
 378                         static_branch_enable(&switch_mm_always_ibpb);
 379                         break;
 380                 case SPECTRE_V2_USER_CMD_PRCTL:
 381                 case SPECTRE_V2_USER_CMD_AUTO:
 382                 case SPECTRE_V2_USER_CMD_SECCOMP:
 383                         static_branch_enable(&switch_mm_cond_ibpb);
 384                         break;
 385                 default:
 386                         break;
 387                 }
 388
 389                 pr_info("mitigation: Enabling %s Indirect Branch Prediction Barrier\n",
 390                         static_key_enabled(&switch_mm_always_ibpb) ?
 391                         "always-on" : "conditional");
 392         }
 393
 394         /* If enhanced IBRS is enabled no STIBP required */
 395         if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
 396                 return;
 397
 398         /*
 399          * If SMT is not possible or STIBP is not available clear the STIBP
 400          * mode.
 401          */
 402         if (!smt_possible || !boot_cpu_has(X86_FEATURE_STIBP))
 403                 mode = SPECTRE_V2_USER_NONE;
 404 set_mode:
 405         spectre_v2_user = mode;
 406         /* Only print the STIBP mode when SMT possible */
 407         if (smt_possible)
 408                 pr_info("%s\n", spectre_v2_user_strings[mode]);
 409 }
 410
 411 static const char * const spectre_v2_strings[] = {
 412         [SPECTRE_V2_NONE]                       = "Vulnerable",
 413         [SPECTRE_V2_RETPOLINE_GENERIC]          = "Mitigation: Full generic retpoline",
 414         [SPECTRE_V2_RETPOLINE_AMD]              = "Mitigation: Full AMD retpoline",
 415         [SPECTRE_V2_IBRS_ENHANCED]              = "Mitigation: Enhanced IBRS",
 416 };
 417
 418 static const struct {
 419         const char *option;
 420         enum spectre_v2_mitigation_cmd cmd;
 421         bool secure;
 422 } mitigation_options[] __initdata = {
 423         { "off",                SPECTRE_V2_CMD_NONE,              false },
 424         { "on",                 SPECTRE_V2_CMD_FORCE,             true  },
 425         { "retpoline",          SPECTRE_V2_CMD_RETPOLINE,         false },
 426         { "retpoline,amd",      SPECTRE_V2_CMD_RETPOLINE_AMD,     false },
 427         { "retpoline,generic",  SPECTRE_V2_CMD_RETPOLINE_GENERIC, false },
 428         { "auto",               SPECTRE_V2_CMD_AUTO,              false },
 429 };
 430
 431 static void __init spec_v2_print_cond(const char *reason, bool secure)
 432 {
 433         if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2) != secure)
 434                 pr_info("%s selected on command line.\n", reason);
 435 }
 436
 437 static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
 438 {
 439         enum spectre_v2_mitigation_cmd cmd = SPECTRE_V2_CMD_AUTO;
 440         char arg[20];
 441         int ret, i;
 442
 443         if (cmdline_find_option_bool(boot_command_line, "nospectre_v2"))
 444                 return SPECTRE_V2_CMD_NONE;
 445
 446         ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg));
 447         if (ret < 0)
 448                 return SPECTRE_V2_CMD_AUTO;
 449
 450         for (i = 0; i < ARRAY_SIZE(mitigation_options); i++) {
 451                 if (!match_option(arg, ret, mitigation_options[i].option))
 452                         continue;
 453                 cmd = mitigation_options[i].cmd;
 454                 break;
 455         }
 456
 457         if (i >= ARRAY_SIZE(mitigation_options)) {
 458                 pr_err("unknown option (%s). Switching to AUTO select\n", arg);
 459                 return SPECTRE_V2_CMD_AUTO;
 460         }
 461
 462         if ((cmd == SPECTRE_V2_CMD_RETPOLINE ||
 463              cmd == SPECTRE_V2_CMD_RETPOLINE_AMD ||
 464              cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC) &&
 465             !IS_ENABLED(CONFIG_RETPOLINE)) {
 466                 pr_err("%s selected but not compiled in. Switching to AUTO select\n", mitigation_options[i].option);
 467                 return SPECTRE_V2_CMD_AUTO;
 468         }
 469
 470         if (cmd == SPECTRE_V2_CMD_RETPOLINE_AMD &&
 471             boot_cpu_data.x86_vendor != X86_VENDOR_HYGON &&
 472             boot_cpu_data.x86_vendor != X86_VENDOR_AMD) {
 473                 pr_err("retpoline,amd selected but CPU is not AMD. Switching to AUTO select\n");
 474                 return SPECTRE_V2_CMD_AUTO;
 475         }
 476
 477         spec_v2_print_cond(mitigation_options[i].option,
 478                            mitigation_options[i].secure);
 479         return cmd;
 480 }
 481
 482 static void __init spectre_v2_select_mitigation(void)
 483 {
 484         enum spectre_v2_mitigation_cmd cmd = spectre_v2_parse_cmdline();
 485         enum spectre_v2_mitigation mode = SPECTRE_V2_NONE;
 486
 487         /*
 488          * If the CPU is not affected and the command line mode is NONE or AUTO
 489          * then nothing to do.
 490          */
 491         if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2) &&
 492             (cmd == SPECTRE_V2_CMD_NONE || cmd == SPECTRE_V2_CMD_AUTO))
 493                 return;
 494
 495         switch (cmd) {
 496         case SPECTRE_V2_CMD_NONE:
 497                 return;
 498
 499         case SPECTRE_V2_CMD_FORCE:
 500         case SPECTRE_V2_CMD_AUTO:
 501                 if (boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) {
 502                         mode = SPECTRE_V2_IBRS_ENHANCED;
 503                         /* Force it so VMEXIT will restore correctly */
 504                         x86_spec_ctrl_base |= SPEC_CTRL_IBRS;
 505                         wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
 506                         goto specv2_set_mode;
 507                 }
 508                 if (IS_ENABLED(CONFIG_RETPOLINE))
 509                         goto retpoline_auto;
 510                 break;
 511         case SPECTRE_V2_CMD_RETPOLINE_AMD:
 512                 if (IS_ENABLED(CONFIG_RETPOLINE))
 513                         goto retpoline_amd;
 514                 break;
 515         case SPECTRE_V2_CMD_RETPOLINE_GENERIC:
 516                 if (IS_ENABLED(CONFIG_RETPOLINE))
 517                         goto retpoline_generic;
 518                 break;
 519         case SPECTRE_V2_CMD_RETPOLINE:
 520                 if (IS_ENABLED(CONFIG_RETPOLINE))
 521                         goto retpoline_auto;
 522                 break;
 523         }
 524         pr_err("Spectre mitigation: kernel not compiled with retpoline; no mitigation available!");
 525         return;
 526
 527 retpoline_auto:
 528         if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
 529             boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
 530         retpoline_amd:
 531                 if (!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) {
 532                         pr_err("Spectre mitigation: LFENCE not serializing, switching to generic retpoline\n");
 533                         goto retpoline_generic;
 534                 }
 535                 mode = SPECTRE_V2_RETPOLINE_AMD;
 536                 setup_force_cpu_cap(X86_FEATURE_RETPOLINE_AMD);
 537                 setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
 538         } else {
 539         retpoline_generic:
 540                 mode = SPECTRE_V2_RETPOLINE_GENERIC;
 541                 setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
 542         }
 543
 544 specv2_set_mode:
 545         spectre_v2_enabled = mode;
 546         pr_info("%s\n", spectre_v2_strings[mode]);
 547
 548         /*
 549          * If spectre v2 protection has been enabled, unconditionally fill
 550          * RSB during a context switch; this protects against two independent
 551          * issues:
 552          *
 553          *      - RSB underflow (and switch to BTB) on Skylake+
 554          *      - SpectreRSB variant of spectre v2 on X86_BUG_SPECTRE_V2 CPUs
 555          */
 556         setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
 557         pr_info("Spectre v2 / SpectreRSB mitigation: Filling RSB on context switch\n");
 558
 559         /*
 560          * Retpoline means the kernel is safe because it has no indirect
 561          * branches. Enhanced IBRS protects firmware too, so, enable restricted
 562          * speculation around firmware calls only when Enhanced IBRS isn't
 563          * supported.
 564          *
 565          * Use "mode" to check Enhanced IBRS instead of boot_cpu_has(), because
 566          * the user might select retpoline on the kernel command line and if
 567          * the CPU supports Enhanced IBRS, kernel might un-intentionally not
 568          * enable IBRS around firmware calls.
 569          */
 570         if (boot_cpu_has(X86_FEATURE_IBRS) && mode != SPECTRE_V2_IBRS_ENHANCED) {
 571                 setup_force_cpu_cap(X86_FEATURE_USE_IBRS_FW);
 572                 pr_info("Enabling Restricted Speculation for firmware calls\n");
 573         }
 574
 575         /* Set up IBPB and STIBP depending on the general spectre V2 command */
 576         spectre_v2_user_select_mitigation(cmd);
 577
 578         /* Enable STIBP if appropriate */
 579         arch_smt_update();
 580 }
 581
 582 static void update_stibp_msr(void * __unused)
 583 {
 584         wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
 585 }
 586
 587 /* Update x86_spec_ctrl_base in case SMT state changed. */
 588 static void update_stibp_strict(void)
 589 {
 590         u64 mask = x86_spec_ctrl_base & ~SPEC_CTRL_STIBP;
 591
 592         if (sched_smt_active())
 593                 mask |= SPEC_CTRL_STIBP;
 594
 595         if (mask == x86_spec_ctrl_base)
 596                 return;
 597
 598         pr_info("Update user space SMT mitigation: STIBP %s\n",
 599                 mask & SPEC_CTRL_STIBP ? "always-on" : "off");
 600         x86_spec_ctrl_base = mask;
 601         on_each_cpu(update_stibp_msr, NULL, 1);
 602 }
 603
 604 /* Update the static key controlling the evaluation of TIF_SPEC_IB */
 605 static void update_indir_branch_cond(void)
 606 {
 607         if (sched_smt_active())
 608                 static_branch_enable(&switch_to_cond_stibp);
 609         else
 610                 static_branch_disable(&switch_to_cond_stibp);
 611 }
 612
 613 void arch_smt_update(void)
 614 {
 615         /* Enhanced IBRS implies STIBP. No update required. */
 616         if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
 617                 return;
 618
 619         mutex_lock(&spec_ctrl_mutex);
 620
 621         switch (spectre_v2_user) {
 622         case SPECTRE_V2_USER_NONE:
 623                 break;
 624         case SPECTRE_V2_USER_STRICT:
 625         case SPECTRE_V2_USER_STRICT_PREFERRED:
 626                 update_stibp_strict();
 627                 break;
 628         case SPECTRE_V2_USER_PRCTL:
 629         case SPECTRE_V2_USER_SECCOMP:
 630                 update_indir_branch_cond();
 631                 break;
 632         }
 633
 634         mutex_unlock(&spec_ctrl_mutex);
 635 }
 636
 637 #undef pr_fmt
 638 #define pr_fmt(fmt)     "Speculative Store Bypass: " fmt
 639
 640 static enum ssb_mitigation ssb_mode __ro_after_init = SPEC_STORE_BYPASS_NONE;
 641
 642 /* The kernel command line selection */
 643 enum ssb_mitigation_cmd {
 644         SPEC_STORE_BYPASS_CMD_NONE,
 645         SPEC_STORE_BYPASS_CMD_AUTO,
 646         SPEC_STORE_BYPASS_CMD_ON,
 647         SPEC_STORE_BYPASS_CMD_PRCTL,
 648         SPEC_STORE_BYPASS_CMD_SECCOMP,
 649 };
 650
 651 static const char * const ssb_strings[] = {
 652         [SPEC_STORE_BYPASS_NONE]        = "Vulnerable",
 653         [SPEC_STORE_BYPASS_DISABLE]     = "Mitigation: Speculative Store Bypass disabled",
 654         [SPEC_STORE_BYPASS_PRCTL]       = "Mitigation: Speculative Store Bypass disabled via prctl",
 655         [SPEC_STORE_BYPASS_SECCOMP]     = "Mitigation: Speculative Store Bypass disabled via prctl and seccomp",
 656 };
 657
 658 static const struct {
 659         const char *option;
 660         enum ssb_mitigation_cmd cmd;
 661 } ssb_mitigation_options[]  __initdata = {
 662         { "auto",       SPEC_STORE_BYPASS_CMD_AUTO },    /* Platform decides */
 663         { "on",         SPEC_STORE_BYPASS_CMD_ON },      /* Disable Speculative Store Bypass */
 664         { "off",        SPEC_STORE_BYPASS_CMD_NONE },    /* Don't touch Speculative Store Bypass */
 665         { "prctl",      SPEC_STORE_BYPASS_CMD_PRCTL },   /* Disable Speculative Store Bypass via prctl */
 666         { "seccomp",    SPEC_STORE_BYPASS_CMD_SECCOMP }, /* Disable Speculative Store Bypass via prctl and seccomp */
 667 };
 668
 669 static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void)
 670 {
 671         enum ssb_mitigation_cmd cmd = SPEC_STORE_BYPASS_CMD_AUTO;
 672         char arg[20];
 673         int ret, i;
 674
 675         if (cmdline_find_option_bool(boot_command_line, "nospec_store_bypass_disable")) {
 676                 return SPEC_STORE_BYPASS_CMD_NONE;
 677         } else {
 678                 ret = cmdline_find_option(boot_command_line, "spec_store_bypass_disable",
 679                                           arg, sizeof(arg));
 680                 if (ret < 0)
 681                         return SPEC_STORE_BYPASS_CMD_AUTO;
 682
 683                 for (i = 0; i < ARRAY_SIZE(ssb_mitigation_options); i++) {
 684                         if (!match_option(arg, ret, ssb_mitigation_options[i].option))
 685                                 continue;
 686
 687                         cmd = ssb_mitigation_options[i].cmd;
 688                         break;
 689                 }
 690
 691                 if (i >= ARRAY_SIZE(ssb_mitigation_options)) {
 692                         pr_err("unknown option (%s). Switching to AUTO select\n", arg);
 693                         return SPEC_STORE_BYPASS_CMD_AUTO;
 694                 }
 695         }
 696
 697         return cmd;
 698 }
 699
 700 static enum ssb_mitigation __init __ssb_select_mitigation(void)
 701 {
 702         enum ssb_mitigation mode = SPEC_STORE_BYPASS_NONE;
 703         enum ssb_mitigation_cmd cmd;
 704
 705         if (!boot_cpu_has(X86_FEATURE_SSBD))
 706                 return mode;
 707
 708         cmd = ssb_parse_cmdline();
 709         if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS) &&
 710             (cmd == SPEC_STORE_BYPASS_CMD_NONE ||
 711              cmd == SPEC_STORE_BYPASS_CMD_AUTO))
 712                 return mode;
 713
 714         switch (cmd) {
 715         case SPEC_STORE_BYPASS_CMD_AUTO:
 716         case SPEC_STORE_BYPASS_CMD_SECCOMP:
 717                 /*
 718                  * Choose prctl+seccomp as the default mode if seccomp is
 719                  * enabled.
 720                  */
 721                 if (IS_ENABLED(CONFIG_SECCOMP))
 722                         mode = SPEC_STORE_BYPASS_SECCOMP;
 723                 else
 724                         mode = SPEC_STORE_BYPASS_PRCTL;
 725                 break;
 726         case SPEC_STORE_BYPASS_CMD_ON:
 727                 mode = SPEC_STORE_BYPASS_DISABLE;
 728                 break;
 729         case SPEC_STORE_BYPASS_CMD_PRCTL:
 730                 mode = SPEC_STORE_BYPASS_PRCTL;
 731                 break;
 732         case SPEC_STORE_BYPASS_CMD_NONE:
 733                 break;
 734         }
 735
 736         /*
 737          * We have three CPU feature flags that are in play here:
 738          *  - X86_BUG_SPEC_STORE_BYPASS - CPU is susceptible.
 739          *  - X86_FEATURE_SSBD - CPU is able to turn off speculative store bypass
 740          *  - X86_FEATURE_SPEC_STORE_BYPASS_DISABLE - engage the mitigation
 741          */
 742         if (mode == SPEC_STORE_BYPASS_DISABLE) {
 743                 setup_force_cpu_cap(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE);
 744                 /*
 745                  * Intel uses the SPEC CTRL MSR Bit(2) for this, while AMD may
 746                  * use a completely different MSR and bit dependent on family.
 747                  */
 748                 if (!static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) &&
 749                     !static_cpu_has(X86_FEATURE_AMD_SSBD)) {
 750                         x86_amd_ssb_disable();
 751                 } else {
 752                         x86_spec_ctrl_base |= SPEC_CTRL_SSBD;
 753                         x86_spec_ctrl_mask |= SPEC_CTRL_SSBD;
 754                         wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
 755                 }
 756         }
 757
 758         return mode;
 759 }
 760
 761 static void ssb_select_mitigation(void)
 762 {
 763         ssb_mode = __ssb_select_mitigation();
 764
 765         if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
 766                 pr_info("%s\n", ssb_strings[ssb_mode]);
 767 }
 768
 769 #undef pr_fmt
 770 #define pr_fmt(fmt)     "Speculation prctl: " fmt
 771
 772 static void task_update_spec_tif(struct task_struct *tsk)
 773 {
 774         /* Force the update of the real TIF bits */
 775         set_tsk_thread_flag(tsk, TIF_SPEC_FORCE_UPDATE);
 776
 777         /*
 778          * Immediately update the speculation control MSRs for the current
 779          * task, but for a non-current task delay setting the CPU
 780          * mitigation until it is scheduled next.
 781          *
 782          * This can only happen for SECCOMP mitigation. For PRCTL it's
 783          * always the current task.
 784          */
 785         if (tsk == current)
 786                 speculation_ctrl_update_current();
 787 }
 788
 789 static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl)
 790 {
 791         if (ssb_mode != SPEC_STORE_BYPASS_PRCTL &&
 792             ssb_mode != SPEC_STORE_BYPASS_SECCOMP)
 793                 return -ENXIO;
 794
 795         switch (ctrl) {
 796         case PR_SPEC_ENABLE:
 797                 /* If speculation is force disabled, enable is not allowed */
 798                 if (task_spec_ssb_force_disable(task))
 799                         return -EPERM;
 800                 task_clear_spec_ssb_disable(task);
 801                 task_clear_spec_ssb_noexec(task);
 802                 task_update_spec_tif(task);
 803                 break;
 804         case PR_SPEC_DISABLE:
 805                 task_set_spec_ssb_disable(task);
 806                 task_clear_spec_ssb_noexec(task);
 807                 task_update_spec_tif(task);
 808                 break;
 809         case PR_SPEC_FORCE_DISABLE:
 810                 task_set_spec_ssb_disable(task);
 811                 task_set_spec_ssb_force_disable(task);
 812                 task_clear_spec_ssb_noexec(task);
 813                 task_update_spec_tif(task);
 814                 break;
 815         case PR_SPEC_DISABLE_NOEXEC:
 816                 if (task_spec_ssb_force_disable(task))
 817                         return -EPERM;
 818                 task_set_spec_ssb_disable(task);
 819                 task_set_spec_ssb_noexec(task);
 820                 task_update_spec_tif(task);
 821                 break;
 822         default:
 823                 return -ERANGE;
 824         }
 825         return 0;
 826 }
 827
 828 static int ib_prctl_set(struct task_struct *task, unsigned long ctrl)
 829 {
 830         switch (ctrl) {
 831         case PR_SPEC_ENABLE:
 832                 if (spectre_v2_user == SPECTRE_V2_USER_NONE)
 833                         return 0;
 834                 /*
 835                  * Indirect branch speculation is always disabled in strict
 836                  * mode.
 837                  */
 838                 if (spectre_v2_user == SPECTRE_V2_USER_STRICT ||
 839                     spectre_v2_user == SPECTRE_V2_USER_STRICT_PREFERRED)
 840                         return -EPERM;
 841                 task_clear_spec_ib_disable(task);
 842                 task_update_spec_tif(task);
 843                 break;
 844         case PR_SPEC_DISABLE:
 845         case PR_SPEC_FORCE_DISABLE:
 846                 /*
 847                  * Indirect branch speculation is always allowed when
 848                  * mitigation is force disabled.
 849                  */
 850                 if (spectre_v2_user == SPECTRE_V2_USER_NONE)
 851                         return -EPERM;
 852                 if (spectre_v2_user == SPECTRE_V2_USER_STRICT ||
 853                     spectre_v2_user == SPECTRE_V2_USER_STRICT_PREFERRED)
 854                         return 0;
 855                 task_set_spec_ib_disable(task);
 856                 if (ctrl == PR_SPEC_FORCE_DISABLE)
 857                         task_set_spec_ib_force_disable(task);
 858                 task_update_spec_tif(task);
 859                 break;
 860         default:
 861                 return -ERANGE;
 862         }
 863         return 0;
 864 }
 865
 866 int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which,
 867                              unsigned long ctrl)
 868 {
 869         switch (which) {
 870         case PR_SPEC_STORE_BYPASS:
 871                 return ssb_prctl_set(task, ctrl);
 872         case PR_SPEC_INDIRECT_BRANCH:
 873                 return ib_prctl_set(task, ctrl);
 874         default:
 875                 return -ENODEV;
 876         }
 877 }
 878
 879 #ifdef CONFIG_SECCOMP
 880 void arch_seccomp_spec_mitigate(struct task_struct *task)
 881 {
 882         if (ssb_mode == SPEC_STORE_BYPASS_SECCOMP)
 883                 ssb_prctl_set(task, PR_SPEC_FORCE_DISABLE);
 884         if (spectre_v2_user == SPECTRE_V2_USER_SECCOMP)
 885                 ib_prctl_set(task, PR_SPEC_FORCE_DISABLE);
 886 }
 887 #endif
 888
 889 static int ssb_prctl_get(struct task_struct *task)
 890 {
 891         switch (ssb_mode) {
 892         case SPEC_STORE_BYPASS_DISABLE:
 893                 return PR_SPEC_DISABLE;
 894         case SPEC_STORE_BYPASS_SECCOMP:
 895         case SPEC_STORE_BYPASS_PRCTL:
 896                 if (task_spec_ssb_force_disable(task))
 897                         return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE;
 898                 if (task_spec_ssb_noexec(task))
 899                         return PR_SPEC_PRCTL | PR_SPEC_DISABLE_NOEXEC;
 900                 if (task_spec_ssb_disable(task))
 901                         return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
 902                 return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
 903         default:
 904                 if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
 905                         return PR_SPEC_ENABLE;
 906                 return PR_SPEC_NOT_AFFECTED;
 907         }
 908 }
 909
 910 static int ib_prctl_get(struct task_struct *task)
 911 {
 912         if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
 913                 return PR_SPEC_NOT_AFFECTED;
 914
 915         switch (spectre_v2_user) {
 916         case SPECTRE_V2_USER_NONE:
 917                 return PR_SPEC_ENABLE;
 918         case SPECTRE_V2_USER_PRCTL:
 919         case SPECTRE_V2_USER_SECCOMP:
 920                 if (task_spec_ib_force_disable(task))
 921                         return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE;
 922                 if (task_spec_ib_disable(task))
 923                         return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
 924                 return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
 925         case SPECTRE_V2_USER_STRICT:
 926         case SPECTRE_V2_USER_STRICT_PREFERRED:
 927                 return PR_SPEC_DISABLE;
 928         default:
 929                 return PR_SPEC_NOT_AFFECTED;
 930         }
 931 }
 932
 933 int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
 934 {
 935         switch (which) {
 936         case PR_SPEC_STORE_BYPASS:
 937                 return ssb_prctl_get(task);
 938         case PR_SPEC_INDIRECT_BRANCH:
 939                 return ib_prctl_get(task);
 940         default:
 941                 return -ENODEV;
 942         }
 943 }
 944
 945 void x86_spec_ctrl_setup_ap(void)
 946 {
 947         if (boot_cpu_has(X86_FEATURE_MSR_SPEC_CTRL))
 948                 wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
 949
 950         if (ssb_mode == SPEC_STORE_BYPASS_DISABLE)
 951                 x86_amd_ssb_disable();
 952 }
 953
 954 #undef pr_fmt
 955 #define pr_fmt(fmt)     "L1TF: " fmt
 956
 957 /* Default mitigation for L1TF-affected CPUs */
 958 enum l1tf_mitigations l1tf_mitigation __ro_after_init = L1TF_MITIGATION_FLUSH;
 959 #if IS_ENABLED(CONFIG_KVM_INTEL)
 960 EXPORT_SYMBOL_GPL(l1tf_mitigation);
 961 #endif
 962 enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO;
 963 EXPORT_SYMBOL_GPL(l1tf_vmx_mitigation);
 964
 965 /*
 966  * These CPUs all support 44bits physical address space internally in the
 967  * cache but CPUID can report a smaller number of physical address bits.
 968  *
 969  * The L1TF mitigation uses the top most address bit for the inversion of
 970  * non present PTEs. When the installed memory reaches into the top most
 971  * address bit due to memory holes, which has been observed on machines
 972  * which report 36bits physical address bits and have 32G RAM installed,
 973  * then the mitigation range check in l1tf_select_mitigation() triggers.
 974  * This is a false positive because the mitigation is still possible due to
 975  * the fact that the cache uses 44bit internally. Use the cache bits
 976  * instead of the reported physical bits and adjust them on the affected
 977  * machines to 44bit if the reported bits are less than 44.
 978  */
 979 static void override_cache_bits(struct cpuinfo_x86 *c)
 980 {
 981         if (c->x86 != 6)
 982                 return;
 983
 984         switch (c->x86_model) {
 985         case INTEL_FAM6_NEHALEM:
 986         case INTEL_FAM6_WESTMERE:
 987         case INTEL_FAM6_SANDYBRIDGE:
 988         case INTEL_FAM6_IVYBRIDGE:
 989         case INTEL_FAM6_HASWELL_CORE:
 990         case INTEL_FAM6_HASWELL_ULT:
 991         case INTEL_FAM6_HASWELL_GT3E:
 992         case INTEL_FAM6_BROADWELL_CORE:
 993         case INTEL_FAM6_BROADWELL_GT3E:
 994         case INTEL_FAM6_SKYLAKE_MOBILE:
 995         case INTEL_FAM6_SKYLAKE_DESKTOP:
 996         case INTEL_FAM6_KABYLAKE_MOBILE:
 997         case INTEL_FAM6_KABYLAKE_DESKTOP:
 998                 if (c->x86_cache_bits < 44)
 999                         c->x86_cache_bits = 44;
1000                 break;
1001         }
1002 }
1003
1004 static void __init l1tf_select_mitigation(void)
1005 {
1006         u64 half_pa;
1007
1008         if (!boot_cpu_has_bug(X86_BUG_L1TF))
1009                 return;
1010
1011         override_cache_bits(&boot_cpu_data);
1012
1013         switch (l1tf_mitigation) {
1014         case L1TF_MITIGATION_OFF:
1015         case L1TF_MITIGATION_FLUSH_NOWARN:
1016         case L1TF_MITIGATION_FLUSH:
1017                 break;
1018         case L1TF_MITIGATION_FLUSH_NOSMT:
1019         case L1TF_MITIGATION_FULL:
1020                 cpu_smt_disable(false);
1021                 break;
1022         case L1TF_MITIGATION_FULL_FORCE:
1023                 cpu_smt_disable(true);
1024                 break;
1025         }
1026
1027 #if CONFIG_PGTABLE_LEVELS == 2
1028         pr_warn("Kernel not compiled for PAE. No mitigation for L1TF\n");
1029         return;
1030 #endif
1031
1032         half_pa = (u64)l1tf_pfn_limit() << PAGE_SHIFT;
1033         if (l1tf_mitigation != L1TF_MITIGATION_OFF &&
1034                         e820__mapped_any(half_pa, ULLONG_MAX - half_pa, E820_TYPE_RAM)) {
1035                 pr_warn("System has more than MAX_PA/2 memory. L1TF mitigation not effective.\n");
1036                 pr_info("You may make it effective by booting the kernel with mem=%llu parameter.\n",
1037                                 half_pa);
1038                 pr_info("However, doing so will make a part of your RAM unusable.\n");
1039                 pr_info("Reading https://www.kernel.org/doc/html/latest/admin-guide/l1tf.html might help you decide.\n");
1040                 return;
1041         }
1042
1043         setup_force_cpu_cap(X86_FEATURE_L1TF_PTEINV);
1044 }
1045
1046 static int __init l1tf_cmdline(char *str)
1047 {
1048         if (!boot_cpu_has_bug(X86_BUG_L1TF))
1049                 return 0;
1050
1051         if (!str)
1052                 return -EINVAL;
1053
1054         if (!strcmp(str, "off"))
1055                 l1tf_mitigation = L1TF_MITIGATION_OFF;
1056         else if (!strcmp(str, "flush,nowarn"))
1057                 l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOWARN;
1058         else if (!strcmp(str, "flush"))
1059                 l1tf_mitigation = L1TF_MITIGATION_FLUSH;
1060         else if (!strcmp(str, "flush,nosmt"))
1061                 l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT;
1062         else if (!strcmp(str, "full"))
1063                 l1tf_mitigation = L1TF_MITIGATION_FULL;
1064         else if (!strcmp(str, "full,force"))
1065                 l1tf_mitigation = L1TF_MITIGATION_FULL_FORCE;
1066
1067         return 0;
1068 }
1069 early_param("l1tf", l1tf_cmdline);
1070
1071 #undef pr_fmt
1072
1073 #ifdef CONFIG_SYSFS
1074
1075 #define L1TF_DEFAULT_MSG "Mitigation: PTE Inversion"
1076
1077 #if IS_ENABLED(CONFIG_KVM_INTEL)
1078 static const char * const l1tf_vmx_states[] = {
1079         [VMENTER_L1D_FLUSH_AUTO]                = "auto",
1080         [VMENTER_L1D_FLUSH_NEVER]               = "vulnerable",
1081         [VMENTER_L1D_FLUSH_COND]                = "conditional cache flushes",
1082         [VMENTER_L1D_FLUSH_ALWAYS]              = "cache flushes",
1083         [VMENTER_L1D_FLUSH_EPT_DISABLED]        = "EPT disabled",
1084         [VMENTER_L1D_FLUSH_NOT_REQUIRED]        = "flush not necessary"
1085 };
1086
1087 static ssize_t l1tf_show_state(char *buf)
1088 {
1089         if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_AUTO)
1090                 return sprintf(buf, "%s\n", L1TF_DEFAULT_MSG);
1091
1092         if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_EPT_DISABLED ||
1093             (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_NEVER &&
1094              sched_smt_active())) {
1095                 return sprintf(buf, "%s; VMX: %s\n", L1TF_DEFAULT_MSG,
1096                                l1tf_vmx_states[l1tf_vmx_mitigation]);
1097         }
1098
1099         return sprintf(buf, "%s; VMX: %s, SMT %s\n", L1TF_DEFAULT_MSG,
1100                        l1tf_vmx_states[l1tf_vmx_mitigation],
1101                        sched_smt_active() ? "vulnerable" : "disabled");
1102 }
1103 #else
1104 static ssize_t l1tf_show_state(char *buf)
1105 {
1106         return sprintf(buf, "%s\n", L1TF_DEFAULT_MSG);
1107 }
1108 #endif
1109
1110 static char *stibp_state(void)
1111 {
1112         if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
1113                 return "";
1114
1115         switch (spectre_v2_user) {
1116         case SPECTRE_V2_USER_NONE:
1117                 return ", STIBP: disabled";
1118         case SPECTRE_V2_USER_STRICT:
1119                 return ", STIBP: forced";
1120         case SPECTRE_V2_USER_STRICT_PREFERRED:
1121                 return ", STIBP: always-on";
1122         case SPECTRE_V2_USER_PRCTL:
1123         case SPECTRE_V2_USER_SECCOMP:
1124                 if (static_key_enabled(&switch_to_cond_stibp))
1125                         return ", STIBP: conditional";
1126         }
1127         return "";
1128 }
1129
1130 static char *ibpb_state(void)
1131 {
1132         if (boot_cpu_has(X86_FEATURE_IBPB)) {
1133                 if (static_key_enabled(&switch_mm_always_ibpb))
1134                         return ", IBPB: always-on";
1135                 if (static_key_enabled(&switch_mm_cond_ibpb))
1136                         return ", IBPB: conditional";
1137                 return ", IBPB: disabled";
1138         }
1139         return "";
1140 }
1141
1142 static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr,
1143                                char *buf, unsigned int bug)
1144 {
1145         if (!boot_cpu_has_bug(bug))
1146                 return sprintf(buf, "Not affected\n");
1147
1148         switch (bug) {
1149         case X86_BUG_CPU_MELTDOWN:
1150                 if (boot_cpu_has(X86_FEATURE_PTI))
1151                         return sprintf(buf, "Mitigation: PTI\n");
1152
1153                 if (hypervisor_is_type(X86_HYPER_XEN_PV))
1154                         return sprintf(buf, "Unknown (XEN PV detected, hypervisor mitigation required)\n");
1155
1156                 break;
1157
1158         case X86_BUG_SPECTRE_V1:
1159                 return sprintf(buf, "Mitigation: __user pointer sanitization\n");
1160
1161         case X86_BUG_SPECTRE_V2:
1162                 return sprintf(buf, "%s%s%s%s%s%s\n", spectre_v2_strings[spectre_v2_enabled],
1163                                ibpb_state(),
1164                                boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "",
1165                                stibp_state(),
1166                                boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB filling" : "",
1167                                spectre_v2_module_string());
1168
1169         case X86_BUG_SPEC_STORE_BYPASS:
1170                 return sprintf(buf, "%s\n", ssb_strings[ssb_mode]);
1171
1172         case X86_BUG_L1TF:
1173                 if (boot_cpu_has(X86_FEATURE_L1TF_PTEINV))
1174                         return l1tf_show_state(buf);
1175                 break;
1176         default:
1177                 break;
1178         }
1179
1180         return sprintf(buf, "Vulnerable\n");
1181 }
1182
1183 ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
1184 {
1185         return cpu_show_common(dev, attr, buf, X86_BUG_CPU_MELTDOWN);
1186 }
1187
1188 ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf)
1189 {
1190         return cpu_show_common(dev, attr, buf, X86_BUG_SPECTRE_V1);
1191 }
1192
1193 ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
1194 {
1195         return cpu_show_common(dev, attr, buf, X86_BUG_SPECTRE_V2);
1196 }
1197
1198 ssize_t cpu_show_spec_store_bypass(struct device *dev, struct device_attribute *attr, char *buf)
1199 {
1200         return cpu_show_common(dev, attr, buf, X86_BUG_SPEC_STORE_BYPASS);
1201 }
1202
1203 ssize_t cpu_show_l1tf(struct device *dev, struct device_attribute *attr, char *buf)
1204 {
1205         return cpu_show_common(dev, attr, buf, X86_BUG_L1TF);
1206 }
1207 #endif