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[] __initconst = {
 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[] __initconst = {
 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             cpu_mitigations_off())
 445                 return SPECTRE_V2_CMD_NONE;
 446
 447         ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg));
 448         if (ret < 0)
 449                 return SPECTRE_V2_CMD_AUTO;
 450
 451         for (i = 0; i < ARRAY_SIZE(mitigation_options); i++) {
 452                 if (!match_option(arg, ret, mitigation_options[i].option))
 453                         continue;
 454                 cmd = mitigation_options[i].cmd;
 455                 break;
 456         }
 457
 458         if (i >= ARRAY_SIZE(mitigation_options)) {
 459                 pr_err("unknown option (%s). Switching to AUTO select\n", arg);
 460                 return SPECTRE_V2_CMD_AUTO;
 461         }
 462
 463         if ((cmd == SPECTRE_V2_CMD_RETPOLINE ||
 464              cmd == SPECTRE_V2_CMD_RETPOLINE_AMD ||
 465              cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC) &&
 466             !IS_ENABLED(CONFIG_RETPOLINE)) {
 467                 pr_err("%s selected but not compiled in. Switching to AUTO select\n", mitigation_options[i].option);
 468                 return SPECTRE_V2_CMD_AUTO;
 469         }
 470
 471         if (cmd == SPECTRE_V2_CMD_RETPOLINE_AMD &&
 472             boot_cpu_data.x86_vendor != X86_VENDOR_HYGON &&
 473             boot_cpu_data.x86_vendor != X86_VENDOR_AMD) {
 474                 pr_err("retpoline,amd selected but CPU is not AMD. Switching to AUTO select\n");
 475                 return SPECTRE_V2_CMD_AUTO;
 476         }
 477
 478         spec_v2_print_cond(mitigation_options[i].option,
 479                            mitigation_options[i].secure);
 480         return cmd;
 481 }
 482
 483 static void __init spectre_v2_select_mitigation(void)
 484 {
 485         enum spectre_v2_mitigation_cmd cmd = spectre_v2_parse_cmdline();
 486         enum spectre_v2_mitigation mode = SPECTRE_V2_NONE;
 487
 488         /*
 489          * If the CPU is not affected and the command line mode is NONE or AUTO
 490          * then nothing to do.
 491          */
 492         if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2) &&
 493             (cmd == SPECTRE_V2_CMD_NONE || cmd == SPECTRE_V2_CMD_AUTO))
 494                 return;
 495
 496         switch (cmd) {
 497         case SPECTRE_V2_CMD_NONE:
 498                 return;
 499
 500         case SPECTRE_V2_CMD_FORCE:
 501         case SPECTRE_V2_CMD_AUTO:
 502                 if (boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) {
 503                         mode = SPECTRE_V2_IBRS_ENHANCED;
 504                         /* Force it so VMEXIT will restore correctly */
 505                         x86_spec_ctrl_base |= SPEC_CTRL_IBRS;
 506                         wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
 507                         goto specv2_set_mode;
 508                 }
 509                 if (IS_ENABLED(CONFIG_RETPOLINE))
 510                         goto retpoline_auto;
 511                 break;
 512         case SPECTRE_V2_CMD_RETPOLINE_AMD:
 513                 if (IS_ENABLED(CONFIG_RETPOLINE))
 514                         goto retpoline_amd;
 515                 break;
 516         case SPECTRE_V2_CMD_RETPOLINE_GENERIC:
 517                 if (IS_ENABLED(CONFIG_RETPOLINE))
 518                         goto retpoline_generic;
 519                 break;
 520         case SPECTRE_V2_CMD_RETPOLINE:
 521                 if (IS_ENABLED(CONFIG_RETPOLINE))
 522                         goto retpoline_auto;
 523                 break;
 524         }
 525         pr_err("Spectre mitigation: kernel not compiled with retpoline; no mitigation available!");
 526         return;
 527
 528 retpoline_auto:
 529         if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
 530             boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
 531         retpoline_amd:
 532                 if (!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) {
 533                         pr_err("Spectre mitigation: LFENCE not serializing, switching to generic retpoline\n");
 534                         goto retpoline_generic;
 535                 }
 536                 mode = SPECTRE_V2_RETPOLINE_AMD;
 537                 setup_force_cpu_cap(X86_FEATURE_RETPOLINE_AMD);
 538                 setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
 539         } else {
 540         retpoline_generic:
 541                 mode = SPECTRE_V2_RETPOLINE_GENERIC;
 542                 setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
 543         }
 544
 545 specv2_set_mode:
 546         spectre_v2_enabled = mode;
 547         pr_info("%s\n", spectre_v2_strings[mode]);
 548
 549         /*
 550          * If spectre v2 protection has been enabled, unconditionally fill
 551          * RSB during a context switch; this protects against two independent
 552          * issues:
 553          *
 554          *      - RSB underflow (and switch to BTB) on Skylake+
 555          *      - SpectreRSB variant of spectre v2 on X86_BUG_SPECTRE_V2 CPUs
 556          */
 557         setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
 558         pr_info("Spectre v2 / SpectreRSB mitigation: Filling RSB on context switch\n");
 559
 560         /*
 561          * Retpoline means the kernel is safe because it has no indirect
 562          * branches. Enhanced IBRS protects firmware too, so, enable restricted
 563          * speculation around firmware calls only when Enhanced IBRS isn't
 564          * supported.
 565          *
 566          * Use "mode" to check Enhanced IBRS instead of boot_cpu_has(), because
 567          * the user might select retpoline on the kernel command line and if
 568          * the CPU supports Enhanced IBRS, kernel might un-intentionally not
 569          * enable IBRS around firmware calls.
 570          */
 571         if (boot_cpu_has(X86_FEATURE_IBRS) && mode != SPECTRE_V2_IBRS_ENHANCED) {
 572                 setup_force_cpu_cap(X86_FEATURE_USE_IBRS_FW);
 573                 pr_info("Enabling Restricted Speculation for firmware calls\n");
 574         }
 575
 576         /* Set up IBPB and STIBP depending on the general spectre V2 command */
 577         spectre_v2_user_select_mitigation(cmd);
 578
 579         /* Enable STIBP if appropriate */
 580         arch_smt_update();
 581 }
 582
 583 static void update_stibp_msr(void * __unused)
 584 {
 585         wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
 586 }
 587
 588 /* Update x86_spec_ctrl_base in case SMT state changed. */
 589 static void update_stibp_strict(void)
 590 {
 591         u64 mask = x86_spec_ctrl_base & ~SPEC_CTRL_STIBP;
 592
 593         if (sched_smt_active())
 594                 mask |= SPEC_CTRL_STIBP;
 595
 596         if (mask == x86_spec_ctrl_base)
 597                 return;
 598
 599         pr_info("Update user space SMT mitigation: STIBP %s\n",
 600                 mask & SPEC_CTRL_STIBP ? "always-on" : "off");
 601         x86_spec_ctrl_base = mask;
 602         on_each_cpu(update_stibp_msr, NULL, 1);
 603 }
 604
 605 /* Update the static key controlling the evaluation of TIF_SPEC_IB */
 606 static void update_indir_branch_cond(void)
 607 {
 608         if (sched_smt_active())
 609                 static_branch_enable(&switch_to_cond_stibp);
 610         else
 611                 static_branch_disable(&switch_to_cond_stibp);
 612 }
 613
 614 void arch_smt_update(void)
 615 {
 616         /* Enhanced IBRS implies STIBP. No update required. */
 617         if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
 618                 return;
 619
 620         mutex_lock(&spec_ctrl_mutex);
 621
 622         switch (spectre_v2_user) {
 623         case SPECTRE_V2_USER_NONE:
 624                 break;
 625         case SPECTRE_V2_USER_STRICT:
 626         case SPECTRE_V2_USER_STRICT_PREFERRED:
 627                 update_stibp_strict();
 628                 break;
 629         case SPECTRE_V2_USER_PRCTL:
 630         case SPECTRE_V2_USER_SECCOMP:
 631                 update_indir_branch_cond();
 632                 break;
 633         }
 634
 635         mutex_unlock(&spec_ctrl_mutex);
 636 }
 637
 638 #undef pr_fmt
 639 #define pr_fmt(fmt)     "Speculative Store Bypass: " fmt
 640
 641 static enum ssb_mitigation ssb_mode __ro_after_init = SPEC_STORE_BYPASS_NONE;
 642
 643 /* The kernel command line selection */
 644 enum ssb_mitigation_cmd {
 645         SPEC_STORE_BYPASS_CMD_NONE,
 646         SPEC_STORE_BYPASS_CMD_AUTO,
 647         SPEC_STORE_BYPASS_CMD_ON,
 648         SPEC_STORE_BYPASS_CMD_PRCTL,
 649         SPEC_STORE_BYPASS_CMD_SECCOMP,
 650 };
 651
 652 static const char * const ssb_strings[] = {
 653         [SPEC_STORE_BYPASS_NONE]        = "Vulnerable",
 654         [SPEC_STORE_BYPASS_DISABLE]     = "Mitigation: Speculative Store Bypass disabled",
 655         [SPEC_STORE_BYPASS_PRCTL]       = "Mitigation: Speculative Store Bypass disabled via prctl",
 656         [SPEC_STORE_BYPASS_SECCOMP]     = "Mitigation: Speculative Store Bypass disabled via prctl and seccomp",
 657 };
 658
 659 static const struct {
 660         const char *option;
 661         enum ssb_mitigation_cmd cmd;
 662 } ssb_mitigation_options[]  __initconst = {
 663         { "auto",       SPEC_STORE_BYPASS_CMD_AUTO },    /* Platform decides */
 664         { "on",         SPEC_STORE_BYPASS_CMD_ON },      /* Disable Speculative Store Bypass */
 665         { "off",        SPEC_STORE_BYPASS_CMD_NONE },    /* Don't touch Speculative Store Bypass */
 666         { "prctl",      SPEC_STORE_BYPASS_CMD_PRCTL },   /* Disable Speculative Store Bypass via prctl */
 667         { "seccomp",    SPEC_STORE_BYPASS_CMD_SECCOMP }, /* Disable Speculative Store Bypass via prctl and seccomp */
 668 };
 669
 670 static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void)
 671 {
 672         enum ssb_mitigation_cmd cmd = SPEC_STORE_BYPASS_CMD_AUTO;
 673         char arg[20];
 674         int ret, i;
 675
 676         if (cmdline_find_option_bool(boot_command_line, "nospec_store_bypass_disable") ||
 677             cpu_mitigations_off()) {
 678                 return SPEC_STORE_BYPASS_CMD_NONE;
 679         } else {
 680                 ret = cmdline_find_option(boot_command_line, "spec_store_bypass_disable",
 681                                           arg, sizeof(arg));
 682                 if (ret < 0)
 683                         return SPEC_STORE_BYPASS_CMD_AUTO;
 684
 685                 for (i = 0; i < ARRAY_SIZE(ssb_mitigation_options); i++) {
 686                         if (!match_option(arg, ret, ssb_mitigation_options[i].option))
 687                                 continue;
 688
 689                         cmd = ssb_mitigation_options[i].cmd;
 690                         break;
 691                 }
 692
 693                 if (i >= ARRAY_SIZE(ssb_mitigation_options)) {
 694                         pr_err("unknown option (%s). Switching to AUTO select\n", arg);
 695                         return SPEC_STORE_BYPASS_CMD_AUTO;
 696                 }
 697         }
 698
 699         return cmd;
 700 }
 701
 702 static enum ssb_mitigation __init __ssb_select_mitigation(void)
 703 {
 704         enum ssb_mitigation mode = SPEC_STORE_BYPASS_NONE;
 705         enum ssb_mitigation_cmd cmd;
 706
 707         if (!boot_cpu_has(X86_FEATURE_SSBD))
 708                 return mode;
 709
 710         cmd = ssb_parse_cmdline();
 711         if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS) &&
 712             (cmd == SPEC_STORE_BYPASS_CMD_NONE ||
 713              cmd == SPEC_STORE_BYPASS_CMD_AUTO))
 714                 return mode;
 715
 716         switch (cmd) {
 717         case SPEC_STORE_BYPASS_CMD_AUTO:
 718         case SPEC_STORE_BYPASS_CMD_SECCOMP:
 719                 /*
 720                  * Choose prctl+seccomp as the default mode if seccomp is
 721                  * enabled.
 722                  */
 723                 if (IS_ENABLED(CONFIG_SECCOMP))
 724                         mode = SPEC_STORE_BYPASS_SECCOMP;
 725                 else
 726                         mode = SPEC_STORE_BYPASS_PRCTL;
 727                 break;
 728         case SPEC_STORE_BYPASS_CMD_ON:
 729                 mode = SPEC_STORE_BYPASS_DISABLE;
 730                 break;
 731         case SPEC_STORE_BYPASS_CMD_PRCTL:
 732                 mode = SPEC_STORE_BYPASS_PRCTL;
 733                 break;
 734         case SPEC_STORE_BYPASS_CMD_NONE:
 735                 break;
 736         }
 737
 738         /*
 739          * We have three CPU feature flags that are in play here:
 740          *  - X86_BUG_SPEC_STORE_BYPASS - CPU is susceptible.
 741          *  - X86_FEATURE_SSBD - CPU is able to turn off speculative store bypass
 742          *  - X86_FEATURE_SPEC_STORE_BYPASS_DISABLE - engage the mitigation
 743          */
 744         if (mode == SPEC_STORE_BYPASS_DISABLE) {
 745                 setup_force_cpu_cap(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE);
 746                 /*
 747                  * Intel uses the SPEC CTRL MSR Bit(2) for this, while AMD may
 748                  * use a completely different MSR and bit dependent on family.
 749                  */
 750                 if (!static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) &&
 751                     !static_cpu_has(X86_FEATURE_AMD_SSBD)) {
 752                         x86_amd_ssb_disable();
 753                 } else {
 754                         x86_spec_ctrl_base |= SPEC_CTRL_SSBD;
 755                         x86_spec_ctrl_mask |= SPEC_CTRL_SSBD;
 756                         wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
 757                 }
 758         }
 759
 760         return mode;
 761 }
 762
 763 static void ssb_select_mitigation(void)
 764 {
 765         ssb_mode = __ssb_select_mitigation();
 766
 767         if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
 768                 pr_info("%s\n", ssb_strings[ssb_mode]);
 769 }
 770
 771 #undef pr_fmt
 772 #define pr_fmt(fmt)     "Speculation prctl: " fmt
 773
 774 static void task_update_spec_tif(struct task_struct *tsk)
 775 {
 776         /* Force the update of the real TIF bits */
 777         set_tsk_thread_flag(tsk, TIF_SPEC_FORCE_UPDATE);
 778
 779         /*
 780          * Immediately update the speculation control MSRs for the current
 781          * task, but for a non-current task delay setting the CPU
 782          * mitigation until it is scheduled next.
 783          *
 784          * This can only happen for SECCOMP mitigation. For PRCTL it's
 785          * always the current task.
 786          */
 787         if (tsk == current)
 788                 speculation_ctrl_update_current();
 789 }
 790
 791 static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl)
 792 {
 793         if (ssb_mode != SPEC_STORE_BYPASS_PRCTL &&
 794             ssb_mode != SPEC_STORE_BYPASS_SECCOMP)
 795                 return -ENXIO;
 796
 797         switch (ctrl) {
 798         case PR_SPEC_ENABLE:
 799                 /* If speculation is force disabled, enable is not allowed */
 800                 if (task_spec_ssb_force_disable(task))
 801                         return -EPERM;
 802                 task_clear_spec_ssb_disable(task);
 803                 task_clear_spec_ssb_noexec(task);
 804                 task_update_spec_tif(task);
 805                 break;
 806         case PR_SPEC_DISABLE:
 807                 task_set_spec_ssb_disable(task);
 808                 task_clear_spec_ssb_noexec(task);
 809                 task_update_spec_tif(task);
 810                 break;
 811         case PR_SPEC_FORCE_DISABLE:
 812                 task_set_spec_ssb_disable(task);
 813                 task_set_spec_ssb_force_disable(task);
 814                 task_clear_spec_ssb_noexec(task);
 815                 task_update_spec_tif(task);
 816                 break;
 817         case PR_SPEC_DISABLE_NOEXEC:
 818                 if (task_spec_ssb_force_disable(task))
 819                         return -EPERM;
 820                 task_set_spec_ssb_disable(task);
 821                 task_set_spec_ssb_noexec(task);
 822                 task_update_spec_tif(task);
 823                 break;
 824         default:
 825                 return -ERANGE;
 826         }
 827         return 0;
 828 }
 829
 830 static int ib_prctl_set(struct task_struct *task, unsigned long ctrl)
 831 {
 832         switch (ctrl) {
 833         case PR_SPEC_ENABLE:
 834                 if (spectre_v2_user == SPECTRE_V2_USER_NONE)
 835                         return 0;
 836                 /*
 837                  * Indirect branch speculation is always disabled in strict
 838                  * mode.
 839                  */
 840                 if (spectre_v2_user == SPECTRE_V2_USER_STRICT ||
 841                     spectre_v2_user == SPECTRE_V2_USER_STRICT_PREFERRED)
 842                         return -EPERM;
 843                 task_clear_spec_ib_disable(task);
 844                 task_update_spec_tif(task);
 845                 break;
 846         case PR_SPEC_DISABLE:
 847         case PR_SPEC_FORCE_DISABLE:
 848                 /*
 849                  * Indirect branch speculation is always allowed when
 850                  * mitigation is force disabled.
 851                  */
 852                 if (spectre_v2_user == SPECTRE_V2_USER_NONE)
 853                         return -EPERM;
 854                 if (spectre_v2_user == SPECTRE_V2_USER_STRICT ||
 855                     spectre_v2_user == SPECTRE_V2_USER_STRICT_PREFERRED)
 856                         return 0;
 857                 task_set_spec_ib_disable(task);
 858                 if (ctrl == PR_SPEC_FORCE_DISABLE)
 859                         task_set_spec_ib_force_disable(task);
 860                 task_update_spec_tif(task);
 861                 break;
 862         default:
 863                 return -ERANGE;
 864         }
 865         return 0;
 866 }
 867
 868 int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which,
 869                              unsigned long ctrl)
 870 {
 871         switch (which) {
 872         case PR_SPEC_STORE_BYPASS:
 873                 return ssb_prctl_set(task, ctrl);
 874         case PR_SPEC_INDIRECT_BRANCH:
 875                 return ib_prctl_set(task, ctrl);
 876         default:
 877                 return -ENODEV;
 878         }
 879 }
 880
 881 #ifdef CONFIG_SECCOMP
 882 void arch_seccomp_spec_mitigate(struct task_struct *task)
 883 {
 884         if (ssb_mode == SPEC_STORE_BYPASS_SECCOMP)
 885                 ssb_prctl_set(task, PR_SPEC_FORCE_DISABLE);
 886         if (spectre_v2_user == SPECTRE_V2_USER_SECCOMP)
 887                 ib_prctl_set(task, PR_SPEC_FORCE_DISABLE);
 888 }
 889 #endif
 890
 891 static int ssb_prctl_get(struct task_struct *task)
 892 {
 893         switch (ssb_mode) {
 894         case SPEC_STORE_BYPASS_DISABLE:
 895                 return PR_SPEC_DISABLE;
 896         case SPEC_STORE_BYPASS_SECCOMP:
 897         case SPEC_STORE_BYPASS_PRCTL:
 898                 if (task_spec_ssb_force_disable(task))
 899                         return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE;
 900                 if (task_spec_ssb_noexec(task))
 901                         return PR_SPEC_PRCTL | PR_SPEC_DISABLE_NOEXEC;
 902                 if (task_spec_ssb_disable(task))
 903                         return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
 904                 return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
 905         default:
 906                 if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
 907                         return PR_SPEC_ENABLE;
 908                 return PR_SPEC_NOT_AFFECTED;
 909         }
 910 }
 911
 912 static int ib_prctl_get(struct task_struct *task)
 913 {
 914         if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
 915                 return PR_SPEC_NOT_AFFECTED;
 916
 917         switch (spectre_v2_user) {
 918         case SPECTRE_V2_USER_NONE:
 919                 return PR_SPEC_ENABLE;
 920         case SPECTRE_V2_USER_PRCTL:
 921         case SPECTRE_V2_USER_SECCOMP:
 922                 if (task_spec_ib_force_disable(task))
 923                         return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE;
 924                 if (task_spec_ib_disable(task))
 925                         return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
 926                 return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
 927         case SPECTRE_V2_USER_STRICT:
 928         case SPECTRE_V2_USER_STRICT_PREFERRED:
 929                 return PR_SPEC_DISABLE;
 930         default:
 931                 return PR_SPEC_NOT_AFFECTED;
 932         }
 933 }
 934
 935 int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
 936 {
 937         switch (which) {
 938         case PR_SPEC_STORE_BYPASS:
 939                 return ssb_prctl_get(task);
 940         case PR_SPEC_INDIRECT_BRANCH:
 941                 return ib_prctl_get(task);
 942         default:
 943                 return -ENODEV;
 944         }
 945 }
 946
 947 void x86_spec_ctrl_setup_ap(void)
 948 {
 949         if (boot_cpu_has(X86_FEATURE_MSR_SPEC_CTRL))
 950                 wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
 951
 952         if (ssb_mode == SPEC_STORE_BYPASS_DISABLE)
 953                 x86_amd_ssb_disable();
 954 }
 955
 956 #undef pr_fmt
 957 #define pr_fmt(fmt)     "L1TF: " fmt
 958
 959 /* Default mitigation for L1TF-affected CPUs */
 960 enum l1tf_mitigations l1tf_mitigation __ro_after_init = L1TF_MITIGATION_FLUSH;
 961 #if IS_ENABLED(CONFIG_KVM_INTEL)
 962 EXPORT_SYMBOL_GPL(l1tf_mitigation);
 963 #endif
 964 enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO;
 965 EXPORT_SYMBOL_GPL(l1tf_vmx_mitigation);
 966
 967 /*
 968  * These CPUs all support 44bits physical address space internally in the
 969  * cache but CPUID can report a smaller number of physical address bits.
 970  *
 971  * The L1TF mitigation uses the top most address bit for the inversion of
 972  * non present PTEs. When the installed memory reaches into the top most
 973  * address bit due to memory holes, which has been observed on machines
 974  * which report 36bits physical address bits and have 32G RAM installed,
 975  * then the mitigation range check in l1tf_select_mitigation() triggers.
 976  * This is a false positive because the mitigation is still possible due to
 977  * the fact that the cache uses 44bit internally. Use the cache bits
 978  * instead of the reported physical bits and adjust them on the affected
 979  * machines to 44bit if the reported bits are less than 44.
 980  */
 981 static void override_cache_bits(struct cpuinfo_x86 *c)
 982 {
 983         if (c->x86 != 6)
 984                 return;
 985
 986         switch (c->x86_model) {
 987         case INTEL_FAM6_NEHALEM:
 988         case INTEL_FAM6_WESTMERE:
 989         case INTEL_FAM6_SANDYBRIDGE:
 990         case INTEL_FAM6_IVYBRIDGE:
 991         case INTEL_FAM6_HASWELL_CORE:
 992         case INTEL_FAM6_HASWELL_ULT:
 993         case INTEL_FAM6_HASWELL_GT3E:
 994         case INTEL_FAM6_BROADWELL_CORE:
 995         case INTEL_FAM6_BROADWELL_GT3E:
 996         case INTEL_FAM6_SKYLAKE_MOBILE:
 997         case INTEL_FAM6_SKYLAKE_DESKTOP:
 998         case INTEL_FAM6_KABYLAKE_MOBILE:
 999         case INTEL_FAM6_KABYLAKE_DESKTOP:
1000                 if (c->x86_cache_bits < 44)
1001                         c->x86_cache_bits = 44;
1002                 break;
1003         }
1004 }
1005
1006 static void __init l1tf_select_mitigation(void)
1007 {
1008         u64 half_pa;
1009
1010         if (!boot_cpu_has_bug(X86_BUG_L1TF))
1011                 return;
1012
1013         if (cpu_mitigations_off())
1014                 l1tf_mitigation = L1TF_MITIGATION_OFF;
1015         else if (cpu_mitigations_auto_nosmt())
1016                 l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT;
1017
1018         override_cache_bits(&boot_cpu_data);
1019
1020         switch (l1tf_mitigation) {
1021         case L1TF_MITIGATION_OFF:
1022         case L1TF_MITIGATION_FLUSH_NOWARN:
1023         case L1TF_MITIGATION_FLUSH:
1024                 break;
1025         case L1TF_MITIGATION_FLUSH_NOSMT:
1026         case L1TF_MITIGATION_FULL:
1027                 cpu_smt_disable(false);
1028                 break;
1029         case L1TF_MITIGATION_FULL_FORCE:
1030                 cpu_smt_disable(true);
1031                 break;
1032         }
1033
1034 #if CONFIG_PGTABLE_LEVELS == 2
1035         pr_warn("Kernel not compiled for PAE. No mitigation for L1TF\n");
1036         return;
1037 #endif
1038
1039         half_pa = (u64)l1tf_pfn_limit() << PAGE_SHIFT;
1040         if (l1tf_mitigation != L1TF_MITIGATION_OFF &&
1041                         e820__mapped_any(half_pa, ULLONG_MAX - half_pa, E820_TYPE_RAM)) {
1042                 pr_warn("System has more than MAX_PA/2 memory. L1TF mitigation not effective.\n");
1043                 pr_info("You may make it effective by booting the kernel with mem=%llu parameter.\n",
1044                                 half_pa);
1045                 pr_info("However, doing so will make a part of your RAM unusable.\n");
1046                 pr_info("Reading https://www.kernel.org/doc/html/latest/admin-guide/l1tf.html might help you decide.\n");
1047                 return;
1048         }
1049
1050         setup_force_cpu_cap(X86_FEATURE_L1TF_PTEINV);
1051 }
1052
1053 static int __init l1tf_cmdline(char *str)
1054 {
1055         if (!boot_cpu_has_bug(X86_BUG_L1TF))
1056                 return 0;
1057
1058         if (!str)
1059                 return -EINVAL;
1060
1061         if (!strcmp(str, "off"))
1062                 l1tf_mitigation = L1TF_MITIGATION_OFF;
1063         else if (!strcmp(str, "flush,nowarn"))
1064                 l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOWARN;
1065         else if (!strcmp(str, "flush"))
1066                 l1tf_mitigation = L1TF_MITIGATION_FLUSH;
1067         else if (!strcmp(str, "flush,nosmt"))
1068                 l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT;
1069         else if (!strcmp(str, "full"))
1070                 l1tf_mitigation = L1TF_MITIGATION_FULL;
1071         else if (!strcmp(str, "full,force"))
1072                 l1tf_mitigation = L1TF_MITIGATION_FULL_FORCE;
1073
1074         return 0;
1075 }
1076 early_param("l1tf", l1tf_cmdline);
1077
1078 #undef pr_fmt
1079
1080 #ifdef CONFIG_SYSFS
1081
1082 #define L1TF_DEFAULT_MSG "Mitigation: PTE Inversion"
1083
1084 #if IS_ENABLED(CONFIG_KVM_INTEL)
1085 static const char * const l1tf_vmx_states[] = {
1086         [VMENTER_L1D_FLUSH_AUTO]                = "auto",
1087         [VMENTER_L1D_FLUSH_NEVER]               = "vulnerable",
1088         [VMENTER_L1D_FLUSH_COND]                = "conditional cache flushes",
1089         [VMENTER_L1D_FLUSH_ALWAYS]              = "cache flushes",
1090         [VMENTER_L1D_FLUSH_EPT_DISABLED]        = "EPT disabled",
1091         [VMENTER_L1D_FLUSH_NOT_REQUIRED]        = "flush not necessary"
1092 };
1093
1094 static ssize_t l1tf_show_state(char *buf)
1095 {
1096         if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_AUTO)
1097                 return sprintf(buf, "%s\n", L1TF_DEFAULT_MSG);
1098
1099         if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_EPT_DISABLED ||
1100             (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_NEVER &&
1101              sched_smt_active())) {
1102                 return sprintf(buf, "%s; VMX: %s\n", L1TF_DEFAULT_MSG,
1103                                l1tf_vmx_states[l1tf_vmx_mitigation]);
1104         }
1105
1106         return sprintf(buf, "%s; VMX: %s, SMT %s\n", L1TF_DEFAULT_MSG,
1107                        l1tf_vmx_states[l1tf_vmx_mitigation],
1108                        sched_smt_active() ? "vulnerable" : "disabled");
1109 }
1110 #else
1111 static ssize_t l1tf_show_state(char *buf)
1112 {
1113         return sprintf(buf, "%s\n", L1TF_DEFAULT_MSG);
1114 }
1115 #endif
1116
1117 static char *stibp_state(void)
1118 {
1119         if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
1120                 return "";
1121
1122         switch (spectre_v2_user) {
1123         case SPECTRE_V2_USER_NONE:
1124                 return ", STIBP: disabled";
1125         case SPECTRE_V2_USER_STRICT:
1126                 return ", STIBP: forced";
1127         case SPECTRE_V2_USER_STRICT_PREFERRED:
1128                 return ", STIBP: always-on";
1129         case SPECTRE_V2_USER_PRCTL:
1130         case SPECTRE_V2_USER_SECCOMP:
1131                 if (static_key_enabled(&switch_to_cond_stibp))
1132                         return ", STIBP: conditional";
1133         }
1134         return "";
1135 }
1136
1137 static char *ibpb_state(void)
1138 {
1139         if (boot_cpu_has(X86_FEATURE_IBPB)) {
1140                 if (static_key_enabled(&switch_mm_always_ibpb))
1141                         return ", IBPB: always-on";
1142                 if (static_key_enabled(&switch_mm_cond_ibpb))
1143                         return ", IBPB: conditional";
1144                 return ", IBPB: disabled";
1145         }
1146         return "";
1147 }
1148
1149 static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr,
1150                                char *buf, unsigned int bug)
1151 {
1152         if (!boot_cpu_has_bug(bug))
1153                 return sprintf(buf, "Not affected\n");
1154
1155         switch (bug) {
1156         case X86_BUG_CPU_MELTDOWN:
1157                 if (boot_cpu_has(X86_FEATURE_PTI))
1158                         return sprintf(buf, "Mitigation: PTI\n");
1159
1160                 if (hypervisor_is_type(X86_HYPER_XEN_PV))
1161                         return sprintf(buf, "Unknown (XEN PV detected, hypervisor mitigation required)\n");
1162
1163                 break;
1164
1165         case X86_BUG_SPECTRE_V1:
1166                 return sprintf(buf, "Mitigation: __user pointer sanitization\n");
1167
1168         case X86_BUG_SPECTRE_V2:
1169                 return sprintf(buf, "%s%s%s%s%s%s\n", spectre_v2_strings[spectre_v2_enabled],
1170                                ibpb_state(),
1171                                boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "",
1172                                stibp_state(),
1173                                boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB filling" : "",
1174                                spectre_v2_module_string());
1175
1176         case X86_BUG_SPEC_STORE_BYPASS:
1177                 return sprintf(buf, "%s\n", ssb_strings[ssb_mode]);
1178
1179         case X86_BUG_L1TF:
1180                 if (boot_cpu_has(X86_FEATURE_L1TF_PTEINV))
1181                         return l1tf_show_state(buf);
1182                 break;
1183         default:
1184                 break;
1185         }
1186
1187         return sprintf(buf, "Vulnerable\n");
1188 }
1189
1190 ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
1191 {
1192         return cpu_show_common(dev, attr, buf, X86_BUG_CPU_MELTDOWN);
1193 }
1194
1195 ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf)
1196 {
1197         return cpu_show_common(dev, attr, buf, X86_BUG_SPECTRE_V1);
1198 }
1199
1200 ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
1201 {
1202         return cpu_show_common(dev, attr, buf, X86_BUG_SPECTRE_V2);
1203 }
1204
1205 ssize_t cpu_show_spec_store_bypass(struct device *dev, struct device_attribute *attr, char *buf)
1206 {
1207         return cpu_show_common(dev, attr, buf, X86_BUG_SPEC_STORE_BYPASS);
1208 }
1209
1210 ssize_t cpu_show_l1tf(struct device *dev, struct device_attribute *attr, char *buf)
1211 {
1212         return cpu_show_common(dev, attr, buf, X86_BUG_L1TF);
1213 }
1214 #endif