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  *        <[email protected]>
   8  *      - Channing Corn (tests & fixes),
   9  *      - Andrew D. Balsa (code cleanup).
  10  */
  11 #include <linux/init.h>
  12 #include <linux/cpu.h>
  13 #include <linux/module.h>
  14 #include <linux/nospec.h>
  15 #include <linux/prctl.h>
  16 #include <linux/sched/smt.h>
  17 #include <linux/pgtable.h>
  18 #include <linux/bpf.h>
  19
  20 #include <asm/spec-ctrl.h>
  21 #include <asm/cmdline.h>
  22 #include <asm/bugs.h>
  23 #include <asm/processor.h>
  24 #include <asm/processor-flags.h>
  25 #include <asm/fpu/api.h>
  26 #include <asm/msr.h>
  27 #include <asm/vmx.h>
  28 #include <asm/paravirt.h>
  29 #include <asm/intel-family.h>
  30 #include <asm/e820/api.h>
  31 #include <asm/hypervisor.h>
  32 #include <asm/tlbflush.h>
  33 #include <asm/cpu.h>
  34
  35 #include "cpu.h"
  36
  37 static void __init spectre_v1_select_mitigation(void);
  38 static void __init spectre_v2_select_mitigation(void);
  39 static void __init retbleed_select_mitigation(void);
  40 static void __init spectre_v2_user_select_mitigation(void);
  41 static void __init ssb_select_mitigation(void);
  42 static void __init l1tf_select_mitigation(void);
  43 static void __init mds_select_mitigation(void);
  44 static void __init md_clear_update_mitigation(void);
  45 static void __init md_clear_select_mitigation(void);
  46 static void __init taa_select_mitigation(void);
  47 static void __init mmio_select_mitigation(void);
  48 static void __init srbds_select_mitigation(void);
  49 static void __init l1d_flush_select_mitigation(void);
  50 static void __init srso_select_mitigation(void);
  51 static void __init gds_select_mitigation(void);
  52
  53 /* The base value of the SPEC_CTRL MSR without task-specific bits set */
  54 u64 x86_spec_ctrl_base;
  55 EXPORT_SYMBOL_GPL(x86_spec_ctrl_base);
  56
  57 /* The current value of the SPEC_CTRL MSR with task-specific bits set */
  58 DEFINE_PER_CPU(u64, x86_spec_ctrl_current);
  59 EXPORT_SYMBOL_GPL(x86_spec_ctrl_current);
  60
  61 u64 x86_pred_cmd __ro_after_init = PRED_CMD_IBPB;
  62 EXPORT_SYMBOL_GPL(x86_pred_cmd);
  63
  64 static DEFINE_MUTEX(spec_ctrl_mutex);
  65
  66 void (*x86_return_thunk)(void) __ro_after_init = __x86_return_thunk;
  67
  68 /* Update SPEC_CTRL MSR and its cached copy unconditionally */
  69 static void update_spec_ctrl(u64 val)
  70 {
  71         this_cpu_write(x86_spec_ctrl_current, val);
  72         wrmsrl(MSR_IA32_SPEC_CTRL, val);
  73 }
  74
  75 /*
  76  * Keep track of the SPEC_CTRL MSR value for the current task, which may differ
  77  * from x86_spec_ctrl_base due to STIBP/SSB in __speculation_ctrl_update().
  78  */
  79 void update_spec_ctrl_cond(u64 val)
  80 {
  81         if (this_cpu_read(x86_spec_ctrl_current) == val)
  82                 return;
  83
  84         this_cpu_write(x86_spec_ctrl_current, val);
  85
  86         /*
  87          * When KERNEL_IBRS this MSR is written on return-to-user, unless
  88          * forced the update can be delayed until that time.
  89          */
  90         if (!cpu_feature_enabled(X86_FEATURE_KERNEL_IBRS))
  91                 wrmsrl(MSR_IA32_SPEC_CTRL, val);
  92 }
  93
  94 noinstr u64 spec_ctrl_current(void)
  95 {
  96         return this_cpu_read(x86_spec_ctrl_current);
  97 }
  98 EXPORT_SYMBOL_GPL(spec_ctrl_current);
  99
 100 /*
 101  * AMD specific MSR info for Speculative Store Bypass control.
 102  * x86_amd_ls_cfg_ssbd_mask is initialized in identify_boot_cpu().
 103  */
 104 u64 __ro_after_init x86_amd_ls_cfg_base;
 105 u64 __ro_after_init x86_amd_ls_cfg_ssbd_mask;
 106
 107 /* Control conditional STIBP in switch_to() */
 108 DEFINE_STATIC_KEY_FALSE(switch_to_cond_stibp);
 109 /* Control conditional IBPB in switch_mm() */
 110 DEFINE_STATIC_KEY_FALSE(switch_mm_cond_ibpb);
 111 /* Control unconditional IBPB in switch_mm() */
 112 DEFINE_STATIC_KEY_FALSE(switch_mm_always_ibpb);
 113
 114 /* Control MDS CPU buffer clear before returning to user space */
 115 DEFINE_STATIC_KEY_FALSE(mds_user_clear);
 116 EXPORT_SYMBOL_GPL(mds_user_clear);
 117 /* Control MDS CPU buffer clear before idling (halt, mwait) */
 118 DEFINE_STATIC_KEY_FALSE(mds_idle_clear);
 119 EXPORT_SYMBOL_GPL(mds_idle_clear);
 120
 121 /*
 122  * Controls whether l1d flush based mitigations are enabled,
 123  * based on hw features and admin setting via boot parameter
 124  * defaults to false
 125  */
 126 DEFINE_STATIC_KEY_FALSE(switch_mm_cond_l1d_flush);
 127
 128 /* Controls CPU Fill buffer clear before KVM guest MMIO accesses */
 129 DEFINE_STATIC_KEY_FALSE(mmio_stale_data_clear);
 130 EXPORT_SYMBOL_GPL(mmio_stale_data_clear);
 131
 132 void __init cpu_select_mitigations(void)
 133 {
 134         /*
 135          * Read the SPEC_CTRL MSR to account for reserved bits which may
 136          * have unknown values. AMD64_LS_CFG MSR is cached in the early AMD
 137          * init code as it is not enumerated and depends on the family.
 138          */
 139         if (cpu_feature_enabled(X86_FEATURE_MSR_SPEC_CTRL)) {
 140                 rdmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
 141
 142                 /*
 143                  * Previously running kernel (kexec), may have some controls
 144                  * turned ON. Clear them and let the mitigations setup below
 145                  * rediscover them based on configuration.
 146                  */
 147                 x86_spec_ctrl_base &= ~SPEC_CTRL_MITIGATIONS_MASK;
 148         }
 149
 150         /* Select the proper CPU mitigations before patching alternatives: */
 151         spectre_v1_select_mitigation();
 152         spectre_v2_select_mitigation();
 153         /*
 154          * retbleed_select_mitigation() relies on the state set by
 155          * spectre_v2_select_mitigation(); specifically it wants to know about
 156          * spectre_v2=ibrs.
 157          */
 158         retbleed_select_mitigation();
 159         /*
 160          * spectre_v2_user_select_mitigation() relies on the state set by
 161          * retbleed_select_mitigation(); specifically the STIBP selection is
 162          * forced for UNRET or IBPB.
 163          */
 164         spectre_v2_user_select_mitigation();
 165         ssb_select_mitigation();
 166         l1tf_select_mitigation();
 167         md_clear_select_mitigation();
 168         srbds_select_mitigation();
 169         l1d_flush_select_mitigation();
 170
 171         /*
 172          * srso_select_mitigation() depends and must run after
 173          * retbleed_select_mitigation().
 174          */
 175         srso_select_mitigation();
 176         gds_select_mitigation();
 177 }
 178
 179 /*
 180  * NOTE: This function is *only* called for SVM, since Intel uses
 181  * MSR_IA32_SPEC_CTRL for SSBD.
 182  */
 183 void
 184 x86_virt_spec_ctrl(u64 guest_virt_spec_ctrl, bool setguest)
 185 {
 186         u64 guestval, hostval;
 187         struct thread_info *ti = current_thread_info();
 188
 189         /*
 190          * If SSBD is not handled in MSR_SPEC_CTRL on AMD, update
 191          * MSR_AMD64_L2_CFG or MSR_VIRT_SPEC_CTRL if supported.
 192          */
 193         if (!static_cpu_has(X86_FEATURE_LS_CFG_SSBD) &&
 194             !static_cpu_has(X86_FEATURE_VIRT_SSBD))
 195                 return;
 196
 197         /*
 198          * If the host has SSBD mitigation enabled, force it in the host's
 199          * virtual MSR value. If its not permanently enabled, evaluate
 200          * current's TIF_SSBD thread flag.
 201          */
 202         if (static_cpu_has(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE))
 203                 hostval = SPEC_CTRL_SSBD;
 204         else
 205                 hostval = ssbd_tif_to_spec_ctrl(ti->flags);
 206
 207         /* Sanitize the guest value */
 208         guestval = guest_virt_spec_ctrl & SPEC_CTRL_SSBD;
 209
 210         if (hostval != guestval) {
 211                 unsigned long tif;
 212
 213                 tif = setguest ? ssbd_spec_ctrl_to_tif(guestval) :
 214                                  ssbd_spec_ctrl_to_tif(hostval);
 215
 216                 speculation_ctrl_update(tif);
 217         }
 218 }
 219 EXPORT_SYMBOL_GPL(x86_virt_spec_ctrl);
 220
 221 static void x86_amd_ssb_disable(void)
 222 {
 223         u64 msrval = x86_amd_ls_cfg_base | x86_amd_ls_cfg_ssbd_mask;
 224
 225         if (boot_cpu_has(X86_FEATURE_VIRT_SSBD))
 226                 wrmsrl(MSR_AMD64_VIRT_SPEC_CTRL, SPEC_CTRL_SSBD);
 227         else if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD))
 228                 wrmsrl(MSR_AMD64_LS_CFG, msrval);
 229 }
 230
 231 #undef pr_fmt
 232 #define pr_fmt(fmt)     "MDS: " fmt
 233
 234 /* Default mitigation for MDS-affected CPUs */
 235 static enum mds_mitigations mds_mitigation __ro_after_init = MDS_MITIGATION_FULL;
 236 static bool mds_nosmt __ro_after_init = false;
 237
 238 static const char * const mds_strings[] = {
 239         [MDS_MITIGATION_OFF]    = "Vulnerable",
 240         [MDS_MITIGATION_FULL]   = "Mitigation: Clear CPU buffers",
 241         [MDS_MITIGATION_VMWERV] = "Vulnerable: Clear CPU buffers attempted, no microcode",
 242 };
 243
 244 static void __init mds_select_mitigation(void)
 245 {
 246         if (!boot_cpu_has_bug(X86_BUG_MDS) || cpu_mitigations_off()) {
 247                 mds_mitigation = MDS_MITIGATION_OFF;
 248                 return;
 249         }
 250
 251         if (mds_mitigation == MDS_MITIGATION_FULL) {
 252                 if (!boot_cpu_has(X86_FEATURE_MD_CLEAR))
 253                         mds_mitigation = MDS_MITIGATION_VMWERV;
 254
 255                 static_branch_enable(&mds_user_clear);
 256
 257                 if (!boot_cpu_has(X86_BUG_MSBDS_ONLY) &&
 258                     (mds_nosmt || cpu_mitigations_auto_nosmt()))
 259                         cpu_smt_disable(false);
 260         }
 261 }
 262
 263 static int __init mds_cmdline(char *str)
 264 {
 265         if (!boot_cpu_has_bug(X86_BUG_MDS))
 266                 return 0;
 267
 268         if (!str)
 269                 return -EINVAL;
 270
 271         if (!strcmp(str, "off"))
 272                 mds_mitigation = MDS_MITIGATION_OFF;
 273         else if (!strcmp(str, "full"))
 274                 mds_mitigation = MDS_MITIGATION_FULL;
 275         else if (!strcmp(str, "full,nosmt")) {
 276                 mds_mitigation = MDS_MITIGATION_FULL;
 277                 mds_nosmt = true;
 278         }
 279
 280         return 0;
 281 }
 282 early_param("mds", mds_cmdline);
 283
 284 #undef pr_fmt
 285 #define pr_fmt(fmt)     "TAA: " fmt
 286
 287 enum taa_mitigations {
 288         TAA_MITIGATION_OFF,
 289         TAA_MITIGATION_UCODE_NEEDED,
 290         TAA_MITIGATION_VERW,
 291         TAA_MITIGATION_TSX_DISABLED,
 292 };
 293
 294 /* Default mitigation for TAA-affected CPUs */
 295 static enum taa_mitigations taa_mitigation __ro_after_init = TAA_MITIGATION_VERW;
 296 static bool taa_nosmt __ro_after_init;
 297
 298 static const char * const taa_strings[] = {
 299         [TAA_MITIGATION_OFF]            = "Vulnerable",
 300         [TAA_MITIGATION_UCODE_NEEDED]   = "Vulnerable: Clear CPU buffers attempted, no microcode",
 301         [TAA_MITIGATION_VERW]           = "Mitigation: Clear CPU buffers",
 302         [TAA_MITIGATION_TSX_DISABLED]   = "Mitigation: TSX disabled",
 303 };
 304
 305 static void __init taa_select_mitigation(void)
 306 {
 307         u64 ia32_cap;
 308
 309         if (!boot_cpu_has_bug(X86_BUG_TAA)) {
 310                 taa_mitigation = TAA_MITIGATION_OFF;
 311                 return;
 312         }
 313
 314         /* TSX previously disabled by tsx=off */
 315         if (!boot_cpu_has(X86_FEATURE_RTM)) {
 316                 taa_mitigation = TAA_MITIGATION_TSX_DISABLED;
 317                 return;
 318         }
 319
 320         if (cpu_mitigations_off()) {
 321                 taa_mitigation = TAA_MITIGATION_OFF;
 322                 return;
 323         }
 324
 325         /*
 326          * TAA mitigation via VERW is turned off if both
 327          * tsx_async_abort=off and mds=off are specified.
 328          */
 329         if (taa_mitigation == TAA_MITIGATION_OFF &&
 330             mds_mitigation == MDS_MITIGATION_OFF)
 331                 return;
 332
 333         if (boot_cpu_has(X86_FEATURE_MD_CLEAR))
 334                 taa_mitigation = TAA_MITIGATION_VERW;
 335         else
 336                 taa_mitigation = TAA_MITIGATION_UCODE_NEEDED;
 337
 338         /*
 339          * VERW doesn't clear the CPU buffers when MD_CLEAR=1 and MDS_NO=1.
 340          * A microcode update fixes this behavior to clear CPU buffers. It also
 341          * adds support for MSR_IA32_TSX_CTRL which is enumerated by the
 342          * ARCH_CAP_TSX_CTRL_MSR bit.
 343          *
 344          * On MDS_NO=1 CPUs if ARCH_CAP_TSX_CTRL_MSR is not set, microcode
 345          * update is required.
 346          */
 347         ia32_cap = x86_read_arch_cap_msr();
 348         if ( (ia32_cap & ARCH_CAP_MDS_NO) &&
 349             !(ia32_cap & ARCH_CAP_TSX_CTRL_MSR))
 350                 taa_mitigation = TAA_MITIGATION_UCODE_NEEDED;
 351
 352         /*
 353          * TSX is enabled, select alternate mitigation for TAA which is
 354          * the same as MDS. Enable MDS static branch to clear CPU buffers.
 355          *
 356          * For guests that can't determine whether the correct microcode is
 357          * present on host, enable the mitigation for UCODE_NEEDED as well.
 358          */
 359         static_branch_enable(&mds_user_clear);
 360
 361         if (taa_nosmt || cpu_mitigations_auto_nosmt())
 362                 cpu_smt_disable(false);
 363 }
 364
 365 static int __init tsx_async_abort_parse_cmdline(char *str)
 366 {
 367         if (!boot_cpu_has_bug(X86_BUG_TAA))
 368                 return 0;
 369
 370         if (!str)
 371                 return -EINVAL;
 372
 373         if (!strcmp(str, "off")) {
 374                 taa_mitigation = TAA_MITIGATION_OFF;
 375         } else if (!strcmp(str, "full")) {
 376                 taa_mitigation = TAA_MITIGATION_VERW;
 377         } else if (!strcmp(str, "full,nosmt")) {
 378                 taa_mitigation = TAA_MITIGATION_VERW;
 379                 taa_nosmt = true;
 380         }
 381
 382         return 0;
 383 }
 384 early_param("tsx_async_abort", tsx_async_abort_parse_cmdline);
 385
 386 #undef pr_fmt
 387 #define pr_fmt(fmt)     "MMIO Stale Data: " fmt
 388
 389 enum mmio_mitigations {
 390         MMIO_MITIGATION_OFF,
 391         MMIO_MITIGATION_UCODE_NEEDED,
 392         MMIO_MITIGATION_VERW,
 393 };
 394
 395 /* Default mitigation for Processor MMIO Stale Data vulnerabilities */
 396 static enum mmio_mitigations mmio_mitigation __ro_after_init = MMIO_MITIGATION_VERW;
 397 static bool mmio_nosmt __ro_after_init = false;
 398
 399 static const char * const mmio_strings[] = {
 400         [MMIO_MITIGATION_OFF]           = "Vulnerable",
 401         [MMIO_MITIGATION_UCODE_NEEDED]  = "Vulnerable: Clear CPU buffers attempted, no microcode",
 402         [MMIO_MITIGATION_VERW]          = "Mitigation: Clear CPU buffers",
 403 };
 404
 405 static void __init mmio_select_mitigation(void)
 406 {
 407         u64 ia32_cap;
 408
 409         if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA) ||
 410              boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN) ||
 411              cpu_mitigations_off()) {
 412                 mmio_mitigation = MMIO_MITIGATION_OFF;
 413                 return;
 414         }
 415
 416         if (mmio_mitigation == MMIO_MITIGATION_OFF)
 417                 return;
 418
 419         ia32_cap = x86_read_arch_cap_msr();
 420
 421         /*
 422          * Enable CPU buffer clear mitigation for host and VMM, if also affected
 423          * by MDS or TAA. Otherwise, enable mitigation for VMM only.
 424          */
 425         if (boot_cpu_has_bug(X86_BUG_MDS) || (boot_cpu_has_bug(X86_BUG_TAA) &&
 426                                               boot_cpu_has(X86_FEATURE_RTM)))
 427                 static_branch_enable(&mds_user_clear);
 428         else
 429                 static_branch_enable(&mmio_stale_data_clear);
 430
 431         /*
 432          * If Processor-MMIO-Stale-Data bug is present and Fill Buffer data can
 433          * be propagated to uncore buffers, clearing the Fill buffers on idle
 434          * is required irrespective of SMT state.
 435          */
 436         if (!(ia32_cap & ARCH_CAP_FBSDP_NO))
 437                 static_branch_enable(&mds_idle_clear);
 438
 439         /*
 440          * Check if the system has the right microcode.
 441          *
 442          * CPU Fill buffer clear mitigation is enumerated by either an explicit
 443          * FB_CLEAR or by the presence of both MD_CLEAR and L1D_FLUSH on MDS
 444          * affected systems.
 445          */
 446         if ((ia32_cap & ARCH_CAP_FB_CLEAR) ||
 447             (boot_cpu_has(X86_FEATURE_MD_CLEAR) &&
 448              boot_cpu_has(X86_FEATURE_FLUSH_L1D) &&
 449              !(ia32_cap & ARCH_CAP_MDS_NO)))
 450                 mmio_mitigation = MMIO_MITIGATION_VERW;
 451         else
 452                 mmio_mitigation = MMIO_MITIGATION_UCODE_NEEDED;
 453
 454         if (mmio_nosmt || cpu_mitigations_auto_nosmt())
 455                 cpu_smt_disable(false);
 456 }
 457
 458 static int __init mmio_stale_data_parse_cmdline(char *str)
 459 {
 460         if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA))
 461                 return 0;
 462
 463         if (!str)
 464                 return -EINVAL;
 465
 466         if (!strcmp(str, "off")) {
 467                 mmio_mitigation = MMIO_MITIGATION_OFF;
 468         } else if (!strcmp(str, "full")) {
 469                 mmio_mitigation = MMIO_MITIGATION_VERW;
 470         } else if (!strcmp(str, "full,nosmt")) {
 471                 mmio_mitigation = MMIO_MITIGATION_VERW;
 472                 mmio_nosmt = true;
 473         }
 474
 475         return 0;
 476 }
 477 early_param("mmio_stale_data", mmio_stale_data_parse_cmdline);
 478
 479 #undef pr_fmt
 480 #define pr_fmt(fmt)     "" fmt
 481
 482 static void __init md_clear_update_mitigation(void)
 483 {
 484         if (cpu_mitigations_off())
 485                 return;
 486
 487         if (!static_key_enabled(&mds_user_clear))
 488                 goto out;
 489
 490         /*
 491          * mds_user_clear is now enabled. Update MDS, TAA and MMIO Stale Data
 492          * mitigation, if necessary.
 493          */
 494         if (mds_mitigation == MDS_MITIGATION_OFF &&
 495             boot_cpu_has_bug(X86_BUG_MDS)) {
 496                 mds_mitigation = MDS_MITIGATION_FULL;
 497                 mds_select_mitigation();
 498         }
 499         if (taa_mitigation == TAA_MITIGATION_OFF &&
 500             boot_cpu_has_bug(X86_BUG_TAA)) {
 501                 taa_mitigation = TAA_MITIGATION_VERW;
 502                 taa_select_mitigation();
 503         }
 504         if (mmio_mitigation == MMIO_MITIGATION_OFF &&
 505             boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA)) {
 506                 mmio_mitigation = MMIO_MITIGATION_VERW;
 507                 mmio_select_mitigation();
 508         }
 509 out:
 510         if (boot_cpu_has_bug(X86_BUG_MDS))
 511                 pr_info("MDS: %s\n", mds_strings[mds_mitigation]);
 512         if (boot_cpu_has_bug(X86_BUG_TAA))
 513                 pr_info("TAA: %s\n", taa_strings[taa_mitigation]);
 514         if (boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA))
 515                 pr_info("MMIO Stale Data: %s\n", mmio_strings[mmio_mitigation]);
 516         else if (boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN))
 517                 pr_info("MMIO Stale Data: Unknown: No mitigations\n");
 518 }
 519
 520 static void __init md_clear_select_mitigation(void)
 521 {
 522         mds_select_mitigation();
 523         taa_select_mitigation();
 524         mmio_select_mitigation();
 525
 526         /*
 527          * As MDS, TAA and MMIO Stale Data mitigations are inter-related, update
 528          * and print their mitigation after MDS, TAA and MMIO Stale Data
 529          * mitigation selection is done.
 530          */
 531         md_clear_update_mitigation();
 532 }
 533
 534 #undef pr_fmt
 535 #define pr_fmt(fmt)     "SRBDS: " fmt
 536
 537 enum srbds_mitigations {
 538         SRBDS_MITIGATION_OFF,
 539         SRBDS_MITIGATION_UCODE_NEEDED,
 540         SRBDS_MITIGATION_FULL,
 541         SRBDS_MITIGATION_TSX_OFF,
 542         SRBDS_MITIGATION_HYPERVISOR,
 543 };
 544
 545 static enum srbds_mitigations srbds_mitigation __ro_after_init = SRBDS_MITIGATION_FULL;
 546
 547 static const char * const srbds_strings[] = {
 548         [SRBDS_MITIGATION_OFF]          = "Vulnerable",
 549         [SRBDS_MITIGATION_UCODE_NEEDED] = "Vulnerable: No microcode",
 550         [SRBDS_MITIGATION_FULL]         = "Mitigation: Microcode",
 551         [SRBDS_MITIGATION_TSX_OFF]      = "Mitigation: TSX disabled",
 552         [SRBDS_MITIGATION_HYPERVISOR]   = "Unknown: Dependent on hypervisor status",
 553 };
 554
 555 static bool srbds_off;
 556
 557 void update_srbds_msr(void)
 558 {
 559         u64 mcu_ctrl;
 560
 561         if (!boot_cpu_has_bug(X86_BUG_SRBDS))
 562                 return;
 563
 564         if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
 565                 return;
 566
 567         if (srbds_mitigation == SRBDS_MITIGATION_UCODE_NEEDED)
 568                 return;
 569
 570         /*
 571          * A MDS_NO CPU for which SRBDS mitigation is not needed due to TSX
 572          * being disabled and it hasn't received the SRBDS MSR microcode.
 573          */
 574         if (!boot_cpu_has(X86_FEATURE_SRBDS_CTRL))
 575                 return;
 576
 577         rdmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl);
 578
 579         switch (srbds_mitigation) {
 580         case SRBDS_MITIGATION_OFF:
 581         case SRBDS_MITIGATION_TSX_OFF:
 582                 mcu_ctrl |= RNGDS_MITG_DIS;
 583                 break;
 584         case SRBDS_MITIGATION_FULL:
 585                 mcu_ctrl &= ~RNGDS_MITG_DIS;
 586                 break;
 587         default:
 588                 break;
 589         }
 590
 591         wrmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl);
 592 }
 593
 594 static void __init srbds_select_mitigation(void)
 595 {
 596         u64 ia32_cap;
 597
 598         if (!boot_cpu_has_bug(X86_BUG_SRBDS))
 599                 return;
 600
 601         /*
 602          * Check to see if this is one of the MDS_NO systems supporting TSX that
 603          * are only exposed to SRBDS when TSX is enabled or when CPU is affected
 604          * by Processor MMIO Stale Data vulnerability.
 605          */
 606         ia32_cap = x86_read_arch_cap_msr();
 607         if ((ia32_cap & ARCH_CAP_MDS_NO) && !boot_cpu_has(X86_FEATURE_RTM) &&
 608             !boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA))
 609                 srbds_mitigation = SRBDS_MITIGATION_TSX_OFF;
 610         else if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
 611                 srbds_mitigation = SRBDS_MITIGATION_HYPERVISOR;
 612         else if (!boot_cpu_has(X86_FEATURE_SRBDS_CTRL))
 613                 srbds_mitigation = SRBDS_MITIGATION_UCODE_NEEDED;
 614         else if (cpu_mitigations_off() || srbds_off)
 615                 srbds_mitigation = SRBDS_MITIGATION_OFF;
 616
 617         update_srbds_msr();
 618         pr_info("%s\n", srbds_strings[srbds_mitigation]);
 619 }
 620
 621 static int __init srbds_parse_cmdline(char *str)
 622 {
 623         if (!str)
 624                 return -EINVAL;
 625
 626         if (!boot_cpu_has_bug(X86_BUG_SRBDS))
 627                 return 0;
 628
 629         srbds_off = !strcmp(str, "off");
 630         return 0;
 631 }
 632 early_param("srbds", srbds_parse_cmdline);
 633
 634 #undef pr_fmt
 635 #define pr_fmt(fmt)     "L1D Flush : " fmt
 636
 637 enum l1d_flush_mitigations {
 638         L1D_FLUSH_OFF = 0,
 639         L1D_FLUSH_ON,
 640 };
 641
 642 static enum l1d_flush_mitigations l1d_flush_mitigation __initdata = L1D_FLUSH_OFF;
 643
 644 static void __init l1d_flush_select_mitigation(void)
 645 {
 646         if (!l1d_flush_mitigation || !boot_cpu_has(X86_FEATURE_FLUSH_L1D))
 647                 return;
 648
 649         static_branch_enable(&switch_mm_cond_l1d_flush);
 650         pr_info("Conditional flush on switch_mm() enabled\n");
 651 }
 652
 653 static int __init l1d_flush_parse_cmdline(char *str)
 654 {
 655         if (!strcmp(str, "on"))
 656                 l1d_flush_mitigation = L1D_FLUSH_ON;
 657
 658         return 0;
 659 }
 660 early_param("l1d_flush", l1d_flush_parse_cmdline);
 661
 662 #undef pr_fmt
 663 #define pr_fmt(fmt)     "GDS: " fmt
 664
 665 enum gds_mitigations {
 666         GDS_MITIGATION_OFF,
 667         GDS_MITIGATION_UCODE_NEEDED,
 668         GDS_MITIGATION_FORCE,
 669         GDS_MITIGATION_FULL,
 670         GDS_MITIGATION_FULL_LOCKED,
 671         GDS_MITIGATION_HYPERVISOR,
 672 };
 673
 674 #if IS_ENABLED(CONFIG_GDS_FORCE_MITIGATION)
 675 static enum gds_mitigations gds_mitigation __ro_after_init = GDS_MITIGATION_FORCE;
 676 #else
 677 static enum gds_mitigations gds_mitigation __ro_after_init = GDS_MITIGATION_FULL;
 678 #endif
 679
 680 static const char * const gds_strings[] = {
 681         [GDS_MITIGATION_OFF]            = "Vulnerable",
 682         [GDS_MITIGATION_UCODE_NEEDED]   = "Vulnerable: No microcode",
 683         [GDS_MITIGATION_FORCE]          = "Mitigation: AVX disabled, no microcode",
 684         [GDS_MITIGATION_FULL]           = "Mitigation: Microcode",
 685         [GDS_MITIGATION_FULL_LOCKED]    = "Mitigation: Microcode (locked)",
 686         [GDS_MITIGATION_HYPERVISOR]     = "Unknown: Dependent on hypervisor status",
 687 };
 688
 689 bool gds_ucode_mitigated(void)
 690 {
 691         return (gds_mitigation == GDS_MITIGATION_FULL ||
 692                 gds_mitigation == GDS_MITIGATION_FULL_LOCKED);
 693 }
 694 EXPORT_SYMBOL_GPL(gds_ucode_mitigated);
 695
 696 void update_gds_msr(void)
 697 {
 698         u64 mcu_ctrl_after;
 699         u64 mcu_ctrl;
 700
 701         switch (gds_mitigation) {
 702         case GDS_MITIGATION_OFF:
 703                 rdmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl);
 704                 mcu_ctrl |= GDS_MITG_DIS;
 705                 break;
 706         case GDS_MITIGATION_FULL_LOCKED:
 707                 /*
 708                  * The LOCKED state comes from the boot CPU. APs might not have
 709                  * the same state. Make sure the mitigation is enabled on all
 710                  * CPUs.
 711                  */
 712         case GDS_MITIGATION_FULL:
 713                 rdmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl);
 714                 mcu_ctrl &= ~GDS_MITG_DIS;
 715                 break;
 716         case GDS_MITIGATION_FORCE:
 717         case GDS_MITIGATION_UCODE_NEEDED:
 718         case GDS_MITIGATION_HYPERVISOR:
 719                 return;
 720         }
 721
 722         wrmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl);
 723
 724         /*
 725          * Check to make sure that the WRMSR value was not ignored. Writes to
 726          * GDS_MITG_DIS will be ignored if this processor is locked but the boot
 727          * processor was not.
 728          */
 729         rdmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl_after);
 730         WARN_ON_ONCE(mcu_ctrl != mcu_ctrl_after);
 731 }
 732
 733 static void __init gds_select_mitigation(void)
 734 {
 735         u64 mcu_ctrl;
 736
 737         if (!boot_cpu_has_bug(X86_BUG_GDS))
 738                 return;
 739
 740         if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
 741                 gds_mitigation = GDS_MITIGATION_HYPERVISOR;
 742                 goto out;
 743         }
 744
 745         if (cpu_mitigations_off())
 746                 gds_mitigation = GDS_MITIGATION_OFF;
 747         /* Will verify below that mitigation _can_ be disabled */
 748
 749         /* No microcode */
 750         if (!(x86_read_arch_cap_msr() & ARCH_CAP_GDS_CTRL)) {
 751                 if (gds_mitigation == GDS_MITIGATION_FORCE) {
 752                         /*
 753                          * This only needs to be done on the boot CPU so do it
 754                          * here rather than in update_gds_msr()
 755                          */
 756                         setup_clear_cpu_cap(X86_FEATURE_AVX);
 757                         pr_warn("Microcode update needed! Disabling AVX as mitigation.\n");
 758                 } else {
 759                         gds_mitigation = GDS_MITIGATION_UCODE_NEEDED;
 760                 }
 761                 goto out;
 762         }
 763
 764         /* Microcode has mitigation, use it */
 765         if (gds_mitigation == GDS_MITIGATION_FORCE)
 766                 gds_mitigation = GDS_MITIGATION_FULL;
 767
 768         rdmsrl(MSR_IA32_MCU_OPT_CTRL, mcu_ctrl);
 769         if (mcu_ctrl & GDS_MITG_LOCKED) {
 770                 if (gds_mitigation == GDS_MITIGATION_OFF)
 771                         pr_warn("Mitigation locked. Disable failed.\n");
 772
 773                 /*
 774                  * The mitigation is selected from the boot CPU. All other CPUs
 775                  * _should_ have the same state. If the boot CPU isn't locked
 776                  * but others are then update_gds_msr() will WARN() of the state
 777                  * mismatch. If the boot CPU is locked update_gds_msr() will
 778                  * ensure the other CPUs have the mitigation enabled.
 779                  */
 780                 gds_mitigation = GDS_MITIGATION_FULL_LOCKED;
 781         }
 782
 783         update_gds_msr();
 784 out:
 785         pr_info("%s\n", gds_strings[gds_mitigation]);
 786 }
 787
 788 static int __init gds_parse_cmdline(char *str)
 789 {
 790         if (!str)
 791                 return -EINVAL;
 792
 793         if (!boot_cpu_has_bug(X86_BUG_GDS))
 794                 return 0;
 795
 796         if (!strcmp(str, "off"))
 797                 gds_mitigation = GDS_MITIGATION_OFF;
 798         else if (!strcmp(str, "force"))
 799                 gds_mitigation = GDS_MITIGATION_FORCE;
 800
 801         return 0;
 802 }
 803 early_param("gather_data_sampling", gds_parse_cmdline);
 804
 805 #undef pr_fmt
 806 #define pr_fmt(fmt)     "Spectre V1 : " fmt
 807
 808 enum spectre_v1_mitigation {
 809         SPECTRE_V1_MITIGATION_NONE,
 810         SPECTRE_V1_MITIGATION_AUTO,
 811 };
 812
 813 static enum spectre_v1_mitigation spectre_v1_mitigation __ro_after_init =
 814         SPECTRE_V1_MITIGATION_AUTO;
 815
 816 static const char * const spectre_v1_strings[] = {
 817         [SPECTRE_V1_MITIGATION_NONE] = "Vulnerable: __user pointer sanitization and usercopy barriers only; no swapgs barriers",
 818         [SPECTRE_V1_MITIGATION_AUTO] = "Mitigation: usercopy/swapgs barriers and __user pointer sanitization",
 819 };
 820
 821 /*
 822  * Does SMAP provide full mitigation against speculative kernel access to
 823  * userspace?
 824  */
 825 static bool smap_works_speculatively(void)
 826 {
 827         if (!boot_cpu_has(X86_FEATURE_SMAP))
 828                 return false;
 829
 830         /*
 831          * On CPUs which are vulnerable to Meltdown, SMAP does not
 832          * prevent speculative access to user data in the L1 cache.
 833          * Consider SMAP to be non-functional as a mitigation on these
 834          * CPUs.
 835          */
 836         if (boot_cpu_has(X86_BUG_CPU_MELTDOWN))
 837                 return false;
 838
 839         return true;
 840 }
 841
 842 static void __init spectre_v1_select_mitigation(void)
 843 {
 844         if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V1) || cpu_mitigations_off()) {
 845                 spectre_v1_mitigation = SPECTRE_V1_MITIGATION_NONE;
 846                 return;
 847         }
 848
 849         if (spectre_v1_mitigation == SPECTRE_V1_MITIGATION_AUTO) {
 850                 /*
 851                  * With Spectre v1, a user can speculatively control either
 852                  * path of a conditional swapgs with a user-controlled GS
 853                  * value.  The mitigation is to add lfences to both code paths.
 854                  *
 855                  * If FSGSBASE is enabled, the user can put a kernel address in
 856                  * GS, in which case SMAP provides no protection.
 857                  *
 858                  * If FSGSBASE is disabled, the user can only put a user space
 859                  * address in GS.  That makes an attack harder, but still
 860                  * possible if there's no SMAP protection.
 861                  */
 862                 if (boot_cpu_has(X86_FEATURE_FSGSBASE) ||
 863                     !smap_works_speculatively()) {
 864                         /*
 865                          * Mitigation can be provided from SWAPGS itself or
 866                          * PTI as the CR3 write in the Meltdown mitigation
 867                          * is serializing.
 868                          *
 869                          * If neither is there, mitigate with an LFENCE to
 870                          * stop speculation through swapgs.
 871                          */
 872                         if (boot_cpu_has_bug(X86_BUG_SWAPGS) &&
 873                             !boot_cpu_has(X86_FEATURE_PTI))
 874                                 setup_force_cpu_cap(X86_FEATURE_FENCE_SWAPGS_USER);
 875
 876                         /*
 877                          * Enable lfences in the kernel entry (non-swapgs)
 878                          * paths, to prevent user entry from speculatively
 879                          * skipping swapgs.
 880                          */
 881                         setup_force_cpu_cap(X86_FEATURE_FENCE_SWAPGS_KERNEL);
 882                 }
 883         }
 884
 885         pr_info("%s\n", spectre_v1_strings[spectre_v1_mitigation]);
 886 }
 887
 888 static int __init nospectre_v1_cmdline(char *str)
 889 {
 890         spectre_v1_mitigation = SPECTRE_V1_MITIGATION_NONE;
 891         return 0;
 892 }
 893 early_param("nospectre_v1", nospectre_v1_cmdline);
 894
 895 enum spectre_v2_mitigation spectre_v2_enabled __ro_after_init = SPECTRE_V2_NONE;
 896
 897 #undef pr_fmt
 898 #define pr_fmt(fmt)     "RETBleed: " fmt
 899
 900 enum retbleed_mitigation {
 901         RETBLEED_MITIGATION_NONE,
 902         RETBLEED_MITIGATION_UNRET,
 903         RETBLEED_MITIGATION_IBPB,
 904         RETBLEED_MITIGATION_IBRS,
 905         RETBLEED_MITIGATION_EIBRS,
 906         RETBLEED_MITIGATION_STUFF,
 907 };
 908
 909 enum retbleed_mitigation_cmd {
 910         RETBLEED_CMD_OFF,
 911         RETBLEED_CMD_AUTO,
 912         RETBLEED_CMD_UNRET,
 913         RETBLEED_CMD_IBPB,
 914         RETBLEED_CMD_STUFF,
 915 };
 916
 917 static const char * const retbleed_strings[] = {
 918         [RETBLEED_MITIGATION_NONE]      = "Vulnerable",
 919         [RETBLEED_MITIGATION_UNRET]     = "Mitigation: untrained return thunk",
 920         [RETBLEED_MITIGATION_IBPB]      = "Mitigation: IBPB",
 921         [RETBLEED_MITIGATION_IBRS]      = "Mitigation: IBRS",
 922         [RETBLEED_MITIGATION_EIBRS]     = "Mitigation: Enhanced IBRS",
 923         [RETBLEED_MITIGATION_STUFF]     = "Mitigation: Stuffing",
 924 };
 925
 926 static enum retbleed_mitigation retbleed_mitigation __ro_after_init =
 927         RETBLEED_MITIGATION_NONE;
 928 static enum retbleed_mitigation_cmd retbleed_cmd __ro_after_init =
 929         RETBLEED_CMD_AUTO;
 930
 931 static int __ro_after_init retbleed_nosmt = false;
 932
 933 static int __init retbleed_parse_cmdline(char *str)
 934 {
 935         if (!str)
 936                 return -EINVAL;
 937
 938         while (str) {
 939                 char *next = strchr(str, ',');
 940                 if (next) {
 941                         *next = 0;
 942                         next++;
 943                 }
 944
 945                 if (!strcmp(str, "off")) {
 946                         retbleed_cmd = RETBLEED_CMD_OFF;
 947                 } else if (!strcmp(str, "auto")) {
 948                         retbleed_cmd = RETBLEED_CMD_AUTO;
 949                 } else if (!strcmp(str, "unret")) {
 950                         retbleed_cmd = RETBLEED_CMD_UNRET;
 951                 } else if (!strcmp(str, "ibpb")) {
 952                         retbleed_cmd = RETBLEED_CMD_IBPB;
 953                 } else if (!strcmp(str, "stuff")) {
 954                         retbleed_cmd = RETBLEED_CMD_STUFF;
 955                 } else if (!strcmp(str, "nosmt")) {
 956                         retbleed_nosmt = true;
 957                 } else if (!strcmp(str, "force")) {
 958                         setup_force_cpu_bug(X86_BUG_RETBLEED);
 959                 } else {
 960                         pr_err("Ignoring unknown retbleed option (%s).", str);
 961                 }
 962
 963                 str = next;
 964         }
 965
 966         return 0;
 967 }
 968 early_param("retbleed", retbleed_parse_cmdline);
 969
 970 #define RETBLEED_UNTRAIN_MSG "WARNING: BTB untrained return thunk mitigation is only effective on AMD/Hygon!\n"
 971 #define RETBLEED_INTEL_MSG "WARNING: Spectre v2 mitigation leaves CPU vulnerable to RETBleed attacks, data leaks possible!\n"
 972
 973 static void __init retbleed_select_mitigation(void)
 974 {
 975         bool mitigate_smt = false;
 976
 977         if (!boot_cpu_has_bug(X86_BUG_RETBLEED) || cpu_mitigations_off())
 978                 return;
 979
 980         switch (retbleed_cmd) {
 981         case RETBLEED_CMD_OFF:
 982                 return;
 983
 984         case RETBLEED_CMD_UNRET:
 985                 if (IS_ENABLED(CONFIG_CPU_UNRET_ENTRY)) {
 986                         retbleed_mitigation = RETBLEED_MITIGATION_UNRET;
 987                 } else {
 988                         pr_err("WARNING: kernel not compiled with CPU_UNRET_ENTRY.\n");
 989                         goto do_cmd_auto;
 990                 }
 991                 break;
 992
 993         case RETBLEED_CMD_IBPB:
 994                 if (!boot_cpu_has(X86_FEATURE_IBPB)) {
 995                         pr_err("WARNING: CPU does not support IBPB.\n");
 996                         goto do_cmd_auto;
 997                 } else if (IS_ENABLED(CONFIG_CPU_IBPB_ENTRY)) {
 998                         retbleed_mitigation = RETBLEED_MITIGATION_IBPB;
 999                 } else {
1000                         pr_err("WARNING: kernel not compiled with CPU_IBPB_ENTRY.\n");
1001                         goto do_cmd_auto;
1002                 }
1003                 break;
1004
1005         case RETBLEED_CMD_STUFF:
1006                 if (IS_ENABLED(CONFIG_CALL_DEPTH_TRACKING) &&
1007                     spectre_v2_enabled == SPECTRE_V2_RETPOLINE) {
1008                         retbleed_mitigation = RETBLEED_MITIGATION_STUFF;
1009
1010                 } else {
1011                         if (IS_ENABLED(CONFIG_CALL_DEPTH_TRACKING))
1012                                 pr_err("WARNING: retbleed=stuff depends on spectre_v2=retpoline\n");
1013                         else
1014                                 pr_err("WARNING: kernel not compiled with CALL_DEPTH_TRACKING.\n");
1015
1016                         goto do_cmd_auto;
1017                 }
1018                 break;
1019
1020 do_cmd_auto:
1021         case RETBLEED_CMD_AUTO:
1022                 if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
1023                     boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
1024                         if (IS_ENABLED(CONFIG_CPU_UNRET_ENTRY))
1025                                 retbleed_mitigation = RETBLEED_MITIGATION_UNRET;
1026                         else if (IS_ENABLED(CONFIG_CPU_IBPB_ENTRY) && boot_cpu_has(X86_FEATURE_IBPB))
1027                                 retbleed_mitigation = RETBLEED_MITIGATION_IBPB;
1028                 }
1029
1030                 /*
1031                  * The Intel mitigation (IBRS or eIBRS) was already selected in
1032                  * spectre_v2_select_mitigation().  'retbleed_mitigation' will
1033                  * be set accordingly below.
1034                  */
1035
1036                 break;
1037         }
1038
1039         switch (retbleed_mitigation) {
1040         case RETBLEED_MITIGATION_UNRET:
1041                 setup_force_cpu_cap(X86_FEATURE_RETHUNK);
1042                 setup_force_cpu_cap(X86_FEATURE_UNRET);
1043
1044                 x86_return_thunk = retbleed_return_thunk;
1045
1046                 if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
1047                     boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
1048                         pr_err(RETBLEED_UNTRAIN_MSG);
1049
1050                 mitigate_smt = true;
1051                 break;
1052
1053         case RETBLEED_MITIGATION_IBPB:
1054                 setup_force_cpu_cap(X86_FEATURE_ENTRY_IBPB);
1055                 setup_force_cpu_cap(X86_FEATURE_IBPB_ON_VMEXIT);
1056                 mitigate_smt = true;
1057                 break;
1058
1059         case RETBLEED_MITIGATION_STUFF:
1060                 setup_force_cpu_cap(X86_FEATURE_RETHUNK);
1061                 setup_force_cpu_cap(X86_FEATURE_CALL_DEPTH);
1062
1063                 x86_return_thunk = call_depth_return_thunk;
1064                 break;
1065
1066         default:
1067                 break;
1068         }
1069
1070         if (mitigate_smt && !boot_cpu_has(X86_FEATURE_STIBP) &&
1071             (retbleed_nosmt || cpu_mitigations_auto_nosmt()))
1072                 cpu_smt_disable(false);
1073
1074         /*
1075          * Let IBRS trump all on Intel without affecting the effects of the
1076          * retbleed= cmdline option except for call depth based stuffing
1077          */
1078         if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) {
1079                 switch (spectre_v2_enabled) {
1080                 case SPECTRE_V2_IBRS:
1081                         retbleed_mitigation = RETBLEED_MITIGATION_IBRS;
1082                         break;
1083                 case SPECTRE_V2_EIBRS:
1084                 case SPECTRE_V2_EIBRS_RETPOLINE:
1085                 case SPECTRE_V2_EIBRS_LFENCE:
1086                         retbleed_mitigation = RETBLEED_MITIGATION_EIBRS;
1087                         break;
1088                 default:
1089                         if (retbleed_mitigation != RETBLEED_MITIGATION_STUFF)
1090                                 pr_err(RETBLEED_INTEL_MSG);
1091                 }
1092         }
1093
1094         pr_info("%s\n", retbleed_strings[retbleed_mitigation]);
1095 }
1096
1097 #undef pr_fmt
1098 #define pr_fmt(fmt)     "Spectre V2 : " fmt
1099
1100 static enum spectre_v2_user_mitigation spectre_v2_user_stibp __ro_after_init =
1101         SPECTRE_V2_USER_NONE;
1102 static enum spectre_v2_user_mitigation spectre_v2_user_ibpb __ro_after_init =
1103         SPECTRE_V2_USER_NONE;
1104
1105 #ifdef CONFIG_RETPOLINE
1106 static bool spectre_v2_bad_module;
1107
1108 bool retpoline_module_ok(bool has_retpoline)
1109 {
1110         if (spectre_v2_enabled == SPECTRE_V2_NONE || has_retpoline)
1111                 return true;
1112
1113         pr_err("System may be vulnerable to spectre v2\n");
1114         spectre_v2_bad_module = true;
1115         return false;
1116 }
1117
1118 static inline const char *spectre_v2_module_string(void)
1119 {
1120         return spectre_v2_bad_module ? " - vulnerable module loaded" : "";
1121 }
1122 #else
1123 static inline const char *spectre_v2_module_string(void) { return ""; }
1124 #endif
1125
1126 #define SPECTRE_V2_LFENCE_MSG "WARNING: LFENCE mitigation is not recommended for this CPU, data leaks possible!\n"
1127 #define SPECTRE_V2_EIBRS_EBPF_MSG "WARNING: Unprivileged eBPF is enabled with eIBRS on, data leaks possible via Spectre v2 BHB attacks!\n"
1128 #define SPECTRE_V2_EIBRS_LFENCE_EBPF_SMT_MSG "WARNING: Unprivileged eBPF is enabled with eIBRS+LFENCE mitigation and SMT, data leaks possible via Spectre v2 BHB attacks!\n"
1129 #define SPECTRE_V2_IBRS_PERF_MSG "WARNING: IBRS mitigation selected on Enhanced IBRS CPU, this may cause unnecessary performance loss\n"
1130
1131 #ifdef CONFIG_BPF_SYSCALL
1132 void unpriv_ebpf_notify(int new_state)
1133 {
1134         if (new_state)
1135                 return;
1136
1137         /* Unprivileged eBPF is enabled */
1138
1139         switch (spectre_v2_enabled) {
1140         case SPECTRE_V2_EIBRS:
1141                 pr_err(SPECTRE_V2_EIBRS_EBPF_MSG);
1142                 break;
1143         case SPECTRE_V2_EIBRS_LFENCE:
1144                 if (sched_smt_active())
1145                         pr_err(SPECTRE_V2_EIBRS_LFENCE_EBPF_SMT_MSG);
1146                 break;
1147         default:
1148                 break;
1149         }
1150 }
1151 #endif
1152
1153 static inline bool match_option(const char *arg, int arglen, const char *opt)
1154 {
1155         int len = strlen(opt);
1156
1157         return len == arglen && !strncmp(arg, opt, len);
1158 }
1159
1160 /* The kernel command line selection for spectre v2 */
1161 enum spectre_v2_mitigation_cmd {
1162         SPECTRE_V2_CMD_NONE,
1163         SPECTRE_V2_CMD_AUTO,
1164         SPECTRE_V2_CMD_FORCE,
1165         SPECTRE_V2_CMD_RETPOLINE,
1166         SPECTRE_V2_CMD_RETPOLINE_GENERIC,
1167         SPECTRE_V2_CMD_RETPOLINE_LFENCE,
1168         SPECTRE_V2_CMD_EIBRS,
1169         SPECTRE_V2_CMD_EIBRS_RETPOLINE,
1170         SPECTRE_V2_CMD_EIBRS_LFENCE,
1171         SPECTRE_V2_CMD_IBRS,
1172 };
1173
1174 enum spectre_v2_user_cmd {
1175         SPECTRE_V2_USER_CMD_NONE,
1176         SPECTRE_V2_USER_CMD_AUTO,
1177         SPECTRE_V2_USER_CMD_FORCE,
1178         SPECTRE_V2_USER_CMD_PRCTL,
1179         SPECTRE_V2_USER_CMD_PRCTL_IBPB,
1180         SPECTRE_V2_USER_CMD_SECCOMP,
1181         SPECTRE_V2_USER_CMD_SECCOMP_IBPB,
1182 };
1183
1184 static const char * const spectre_v2_user_strings[] = {
1185         [SPECTRE_V2_USER_NONE]                  = "User space: Vulnerable",
1186         [SPECTRE_V2_USER_STRICT]                = "User space: Mitigation: STIBP protection",
1187         [SPECTRE_V2_USER_STRICT_PREFERRED]      = "User space: Mitigation: STIBP always-on protection",
1188         [SPECTRE_V2_USER_PRCTL]                 = "User space: Mitigation: STIBP via prctl",
1189         [SPECTRE_V2_USER_SECCOMP]               = "User space: Mitigation: STIBP via seccomp and prctl",
1190 };
1191
1192 static const struct {
1193         const char                      *option;
1194         enum spectre_v2_user_cmd        cmd;
1195         bool                            secure;
1196 } v2_user_options[] __initconst = {
1197         { "auto",               SPECTRE_V2_USER_CMD_AUTO,               false },
1198         { "off",                SPECTRE_V2_USER_CMD_NONE,               false },
1199         { "on",                 SPECTRE_V2_USER_CMD_FORCE,              true  },
1200         { "prctl",              SPECTRE_V2_USER_CMD_PRCTL,              false },
1201         { "prctl,ibpb",         SPECTRE_V2_USER_CMD_PRCTL_IBPB,         false },
1202         { "seccomp",            SPECTRE_V2_USER_CMD_SECCOMP,            false },
1203         { "seccomp,ibpb",       SPECTRE_V2_USER_CMD_SECCOMP_IBPB,       false },
1204 };
1205
1206 static void __init spec_v2_user_print_cond(const char *reason, bool secure)
1207 {
1208         if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2) != secure)
1209                 pr_info("spectre_v2_user=%s forced on command line.\n", reason);
1210 }
1211
1212 static __ro_after_init enum spectre_v2_mitigation_cmd spectre_v2_cmd;
1213
1214 static enum spectre_v2_user_cmd __init
1215 spectre_v2_parse_user_cmdline(void)
1216 {
1217         char arg[20];
1218         int ret, i;
1219
1220         switch (spectre_v2_cmd) {
1221         case SPECTRE_V2_CMD_NONE:
1222                 return SPECTRE_V2_USER_CMD_NONE;
1223         case SPECTRE_V2_CMD_FORCE:
1224                 return SPECTRE_V2_USER_CMD_FORCE;
1225         default:
1226                 break;
1227         }
1228
1229         ret = cmdline_find_option(boot_command_line, "spectre_v2_user",
1230                                   arg, sizeof(arg));
1231         if (ret < 0)
1232                 return SPECTRE_V2_USER_CMD_AUTO;
1233
1234         for (i = 0; i < ARRAY_SIZE(v2_user_options); i++) {
1235                 if (match_option(arg, ret, v2_user_options[i].option)) {
1236                         spec_v2_user_print_cond(v2_user_options[i].option,
1237                                                 v2_user_options[i].secure);
1238                         return v2_user_options[i].cmd;
1239                 }
1240         }
1241
1242         pr_err("Unknown user space protection option (%s). Switching to AUTO select\n", arg);
1243         return SPECTRE_V2_USER_CMD_AUTO;
1244 }
1245
1246 static inline bool spectre_v2_in_ibrs_mode(enum spectre_v2_mitigation mode)
1247 {
1248         return spectre_v2_in_eibrs_mode(mode) || mode == SPECTRE_V2_IBRS;
1249 }
1250
1251 static void __init
1252 spectre_v2_user_select_mitigation(void)
1253 {
1254         enum spectre_v2_user_mitigation mode = SPECTRE_V2_USER_NONE;
1255         bool smt_possible = IS_ENABLED(CONFIG_SMP);
1256         enum spectre_v2_user_cmd cmd;
1257
1258         if (!boot_cpu_has(X86_FEATURE_IBPB) && !boot_cpu_has(X86_FEATURE_STIBP))
1259                 return;
1260
1261         if (cpu_smt_control == CPU_SMT_FORCE_DISABLED ||
1262             cpu_smt_control == CPU_SMT_NOT_SUPPORTED)
1263                 smt_possible = false;
1264
1265         cmd = spectre_v2_parse_user_cmdline();
1266         switch (cmd) {
1267         case SPECTRE_V2_USER_CMD_NONE:
1268                 goto set_mode;
1269         case SPECTRE_V2_USER_CMD_FORCE:
1270                 mode = SPECTRE_V2_USER_STRICT;
1271                 break;
1272         case SPECTRE_V2_USER_CMD_AUTO:
1273         case SPECTRE_V2_USER_CMD_PRCTL:
1274         case SPECTRE_V2_USER_CMD_PRCTL_IBPB:
1275                 mode = SPECTRE_V2_USER_PRCTL;
1276                 break;
1277         case SPECTRE_V2_USER_CMD_SECCOMP:
1278         case SPECTRE_V2_USER_CMD_SECCOMP_IBPB:
1279                 if (IS_ENABLED(CONFIG_SECCOMP))
1280                         mode = SPECTRE_V2_USER_SECCOMP;
1281                 else
1282                         mode = SPECTRE_V2_USER_PRCTL;
1283                 break;
1284         }
1285
1286         /* Initialize Indirect Branch Prediction Barrier */
1287         if (boot_cpu_has(X86_FEATURE_IBPB)) {
1288                 setup_force_cpu_cap(X86_FEATURE_USE_IBPB);
1289
1290                 spectre_v2_user_ibpb = mode;
1291                 switch (cmd) {
1292                 case SPECTRE_V2_USER_CMD_NONE:
1293                         break;
1294                 case SPECTRE_V2_USER_CMD_FORCE:
1295                 case SPECTRE_V2_USER_CMD_PRCTL_IBPB:
1296                 case SPECTRE_V2_USER_CMD_SECCOMP_IBPB:
1297                         static_branch_enable(&switch_mm_always_ibpb);
1298                         spectre_v2_user_ibpb = SPECTRE_V2_USER_STRICT;
1299                         break;
1300                 case SPECTRE_V2_USER_CMD_PRCTL:
1301                 case SPECTRE_V2_USER_CMD_AUTO:
1302                 case SPECTRE_V2_USER_CMD_SECCOMP:
1303                         static_branch_enable(&switch_mm_cond_ibpb);
1304                         break;
1305                 }
1306
1307                 pr_info("mitigation: Enabling %s Indirect Branch Prediction Barrier\n",
1308                         static_key_enabled(&switch_mm_always_ibpb) ?
1309                         "always-on" : "conditional");
1310         }
1311
1312         /*
1313          * If no STIBP, Intel enhanced IBRS is enabled, or SMT impossible, STIBP
1314          * is not required.
1315          *
1316          * Intel's Enhanced IBRS also protects against cross-thread branch target
1317          * injection in user-mode as the IBRS bit remains always set which
1318          * implicitly enables cross-thread protections.  However, in legacy IBRS
1319          * mode, the IBRS bit is set only on kernel entry and cleared on return
1320          * to userspace.  AMD Automatic IBRS also does not protect userspace.
1321          * These modes therefore disable the implicit cross-thread protection,
1322          * so allow for STIBP to be selected in those cases.
1323          */
1324         if (!boot_cpu_has(X86_FEATURE_STIBP) ||
1325             !smt_possible ||
1326             (spectre_v2_in_eibrs_mode(spectre_v2_enabled) &&
1327              !boot_cpu_has(X86_FEATURE_AUTOIBRS)))
1328                 return;
1329
1330         /*
1331          * At this point, an STIBP mode other than "off" has been set.
1332          * If STIBP support is not being forced, check if STIBP always-on
1333          * is preferred.
1334          */
1335         if (mode != SPECTRE_V2_USER_STRICT &&
1336             boot_cpu_has(X86_FEATURE_AMD_STIBP_ALWAYS_ON))
1337                 mode = SPECTRE_V2_USER_STRICT_PREFERRED;
1338
1339         if (retbleed_mitigation == RETBLEED_MITIGATION_UNRET ||
1340             retbleed_mitigation == RETBLEED_MITIGATION_IBPB) {
1341                 if (mode != SPECTRE_V2_USER_STRICT &&
1342                     mode != SPECTRE_V2_USER_STRICT_PREFERRED)
1343                         pr_info("Selecting STIBP always-on mode to complement retbleed mitigation\n");
1344                 mode = SPECTRE_V2_USER_STRICT_PREFERRED;
1345         }
1346
1347         spectre_v2_user_stibp = mode;
1348
1349 set_mode:
1350         pr_info("%s\n", spectre_v2_user_strings[mode]);
1351 }
1352
1353 static const char * const spectre_v2_strings[] = {
1354         [SPECTRE_V2_NONE]                       = "Vulnerable",
1355         [SPECTRE_V2_RETPOLINE]                  = "Mitigation: Retpolines",
1356         [SPECTRE_V2_LFENCE]                     = "Mitigation: LFENCE",
1357         [SPECTRE_V2_EIBRS]                      = "Mitigation: Enhanced / Automatic IBRS",
1358         [SPECTRE_V2_EIBRS_LFENCE]               = "Mitigation: Enhanced / Automatic IBRS + LFENCE",
1359         [SPECTRE_V2_EIBRS_RETPOLINE]            = "Mitigation: Enhanced / Automatic IBRS + Retpolines",
1360         [SPECTRE_V2_IBRS]                       = "Mitigation: IBRS",
1361 };
1362
1363 static const struct {
1364         const char *option;
1365         enum spectre_v2_mitigation_cmd cmd;
1366         bool secure;
1367 } mitigation_options[] __initconst = {
1368         { "off",                SPECTRE_V2_CMD_NONE,              false },
1369         { "on",                 SPECTRE_V2_CMD_FORCE,             true  },
1370         { "retpoline",          SPECTRE_V2_CMD_RETPOLINE,         false },
1371         { "retpoline,amd",      SPECTRE_V2_CMD_RETPOLINE_LFENCE,  false },
1372         { "retpoline,lfence",   SPECTRE_V2_CMD_RETPOLINE_LFENCE,  false },
1373         { "retpoline,generic",  SPECTRE_V2_CMD_RETPOLINE_GENERIC, false },
1374         { "eibrs",              SPECTRE_V2_CMD_EIBRS,             false },
1375         { "eibrs,lfence",       SPECTRE_V2_CMD_EIBRS_LFENCE,      false },
1376         { "eibrs,retpoline",    SPECTRE_V2_CMD_EIBRS_RETPOLINE,   false },
1377         { "auto",               SPECTRE_V2_CMD_AUTO,              false },
1378         { "ibrs",               SPECTRE_V2_CMD_IBRS,              false },
1379 };
1380
1381 static void __init spec_v2_print_cond(const char *reason, bool secure)
1382 {
1383         if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2) != secure)
1384                 pr_info("%s selected on command line.\n", reason);
1385 }
1386
1387 static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
1388 {
1389         enum spectre_v2_mitigation_cmd cmd = SPECTRE_V2_CMD_AUTO;
1390         char arg[20];
1391         int ret, i;
1392
1393         if (cmdline_find_option_bool(boot_command_line, "nospectre_v2") ||
1394             cpu_mitigations_off())
1395                 return SPECTRE_V2_CMD_NONE;
1396
1397         ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg));
1398         if (ret < 0)
1399                 return SPECTRE_V2_CMD_AUTO;
1400
1401         for (i = 0; i < ARRAY_SIZE(mitigation_options); i++) {
1402                 if (!match_option(arg, ret, mitigation_options[i].option))
1403                         continue;
1404                 cmd = mitigation_options[i].cmd;
1405                 break;
1406         }
1407
1408         if (i >= ARRAY_SIZE(mitigation_options)) {
1409                 pr_err("unknown option (%s). Switching to AUTO select\n", arg);
1410                 return SPECTRE_V2_CMD_AUTO;
1411         }
1412
1413         if ((cmd == SPECTRE_V2_CMD_RETPOLINE ||
1414              cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE ||
1415              cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC ||
1416              cmd == SPECTRE_V2_CMD_EIBRS_LFENCE ||
1417              cmd == SPECTRE_V2_CMD_EIBRS_RETPOLINE) &&
1418             !IS_ENABLED(CONFIG_RETPOLINE)) {
1419                 pr_err("%s selected but not compiled in. Switching to AUTO select\n",
1420                        mitigation_options[i].option);
1421                 return SPECTRE_V2_CMD_AUTO;
1422         }
1423
1424         if ((cmd == SPECTRE_V2_CMD_EIBRS ||
1425              cmd == SPECTRE_V2_CMD_EIBRS_LFENCE ||
1426              cmd == SPECTRE_V2_CMD_EIBRS_RETPOLINE) &&
1427             !boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) {
1428                 pr_err("%s selected but CPU doesn't have Enhanced or Automatic IBRS. Switching to AUTO select\n",
1429                        mitigation_options[i].option);
1430                 return SPECTRE_V2_CMD_AUTO;
1431         }
1432
1433         if ((cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE ||
1434              cmd == SPECTRE_V2_CMD_EIBRS_LFENCE) &&
1435             !boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) {
1436                 pr_err("%s selected, but CPU doesn't have a serializing LFENCE. Switching to AUTO select\n",
1437                        mitigation_options[i].option);
1438                 return SPECTRE_V2_CMD_AUTO;
1439         }
1440
1441         if (cmd == SPECTRE_V2_CMD_IBRS && !IS_ENABLED(CONFIG_CPU_IBRS_ENTRY)) {
1442                 pr_err("%s selected but not compiled in. Switching to AUTO select\n",
1443                        mitigation_options[i].option);
1444                 return SPECTRE_V2_CMD_AUTO;
1445         }
1446
1447         if (cmd == SPECTRE_V2_CMD_IBRS && boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) {
1448                 pr_err("%s selected but not Intel CPU. Switching to AUTO select\n",
1449                        mitigation_options[i].option);
1450                 return SPECTRE_V2_CMD_AUTO;
1451         }
1452
1453         if (cmd == SPECTRE_V2_CMD_IBRS && !boot_cpu_has(X86_FEATURE_IBRS)) {
1454                 pr_err("%s selected but CPU doesn't have IBRS. Switching to AUTO select\n",
1455                        mitigation_options[i].option);
1456                 return SPECTRE_V2_CMD_AUTO;
1457         }
1458
1459         if (cmd == SPECTRE_V2_CMD_IBRS && cpu_feature_enabled(X86_FEATURE_XENPV)) {
1460                 pr_err("%s selected but running as XenPV guest. Switching to AUTO select\n",
1461                        mitigation_options[i].option);
1462                 return SPECTRE_V2_CMD_AUTO;
1463         }
1464
1465         spec_v2_print_cond(mitigation_options[i].option,
1466                            mitigation_options[i].secure);
1467         return cmd;
1468 }
1469
1470 static enum spectre_v2_mitigation __init spectre_v2_select_retpoline(void)
1471 {
1472         if (!IS_ENABLED(CONFIG_RETPOLINE)) {
1473                 pr_err("Kernel not compiled with retpoline; no mitigation available!");
1474                 return SPECTRE_V2_NONE;
1475         }
1476
1477         return SPECTRE_V2_RETPOLINE;
1478 }
1479
1480 /* Disable in-kernel use of non-RSB RET predictors */
1481 static void __init spec_ctrl_disable_kernel_rrsba(void)
1482 {
1483         u64 ia32_cap;
1484
1485         if (!boot_cpu_has(X86_FEATURE_RRSBA_CTRL))
1486                 return;
1487
1488         ia32_cap = x86_read_arch_cap_msr();
1489
1490         if (ia32_cap & ARCH_CAP_RRSBA) {
1491                 x86_spec_ctrl_base |= SPEC_CTRL_RRSBA_DIS_S;
1492                 update_spec_ctrl(x86_spec_ctrl_base);
1493         }
1494 }
1495
1496 static void __init spectre_v2_determine_rsb_fill_type_at_vmexit(enum spectre_v2_mitigation mode)
1497 {
1498         /*
1499          * Similar to context switches, there are two types of RSB attacks
1500          * after VM exit:
1501          *
1502          * 1) RSB underflow
1503          *
1504          * 2) Poisoned RSB entry
1505          *
1506          * When retpoline is enabled, both are mitigated by filling/clearing
1507          * the RSB.
1508          *
1509          * When IBRS is enabled, while #1 would be mitigated by the IBRS branch
1510          * prediction isolation protections, RSB still needs to be cleared
1511          * because of #2.  Note that SMEP provides no protection here, unlike
1512          * user-space-poisoned RSB entries.
1513          *
1514          * eIBRS should protect against RSB poisoning, but if the EIBRS_PBRSB
1515          * bug is present then a LITE version of RSB protection is required,
1516          * just a single call needs to retire before a RET is executed.
1517          */
1518         switch (mode) {
1519         case SPECTRE_V2_NONE:
1520                 return;
1521
1522         case SPECTRE_V2_EIBRS_LFENCE:
1523         case SPECTRE_V2_EIBRS:
1524                 if (boot_cpu_has_bug(X86_BUG_EIBRS_PBRSB)) {
1525                         setup_force_cpu_cap(X86_FEATURE_RSB_VMEXIT_LITE);
1526                         pr_info("Spectre v2 / PBRSB-eIBRS: Retire a single CALL on VMEXIT\n");
1527                 }
1528                 return;
1529
1530         case SPECTRE_V2_EIBRS_RETPOLINE:
1531         case SPECTRE_V2_RETPOLINE:
1532         case SPECTRE_V2_LFENCE:
1533         case SPECTRE_V2_IBRS:
1534                 setup_force_cpu_cap(X86_FEATURE_RSB_VMEXIT);
1535                 pr_info("Spectre v2 / SpectreRSB : Filling RSB on VMEXIT\n");
1536                 return;
1537         }
1538
1539         pr_warn_once("Unknown Spectre v2 mode, disabling RSB mitigation at VM exit");
1540         dump_stack();
1541 }
1542
1543 static void __init spectre_v2_select_mitigation(void)
1544 {
1545         enum spectre_v2_mitigation_cmd cmd = spectre_v2_parse_cmdline();
1546         enum spectre_v2_mitigation mode = SPECTRE_V2_NONE;
1547
1548         /*
1549          * If the CPU is not affected and the command line mode is NONE or AUTO
1550          * then nothing to do.
1551          */
1552         if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2) &&
1553             (cmd == SPECTRE_V2_CMD_NONE || cmd == SPECTRE_V2_CMD_AUTO))
1554                 return;
1555
1556         switch (cmd) {
1557         case SPECTRE_V2_CMD_NONE:
1558                 return;
1559
1560         case SPECTRE_V2_CMD_FORCE:
1561         case SPECTRE_V2_CMD_AUTO:
1562                 if (boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) {
1563                         mode = SPECTRE_V2_EIBRS;
1564                         break;
1565                 }
1566
1567                 if (IS_ENABLED(CONFIG_CPU_IBRS_ENTRY) &&
1568                     boot_cpu_has_bug(X86_BUG_RETBLEED) &&
1569                     retbleed_cmd != RETBLEED_CMD_OFF &&
1570                     retbleed_cmd != RETBLEED_CMD_STUFF &&
1571                     boot_cpu_has(X86_FEATURE_IBRS) &&
1572                     boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) {
1573                         mode = SPECTRE_V2_IBRS;
1574                         break;
1575                 }
1576
1577                 mode = spectre_v2_select_retpoline();
1578                 break;
1579
1580         case SPECTRE_V2_CMD_RETPOLINE_LFENCE:
1581                 pr_err(SPECTRE_V2_LFENCE_MSG);
1582                 mode = SPECTRE_V2_LFENCE;
1583                 break;
1584
1585         case SPECTRE_V2_CMD_RETPOLINE_GENERIC:
1586                 mode = SPECTRE_V2_RETPOLINE;
1587                 break;
1588
1589         case SPECTRE_V2_CMD_RETPOLINE:
1590                 mode = spectre_v2_select_retpoline();
1591                 break;
1592
1593         case SPECTRE_V2_CMD_IBRS:
1594                 mode = SPECTRE_V2_IBRS;
1595                 break;
1596
1597         case SPECTRE_V2_CMD_EIBRS:
1598                 mode = SPECTRE_V2_EIBRS;
1599                 break;
1600
1601         case SPECTRE_V2_CMD_EIBRS_LFENCE:
1602                 mode = SPECTRE_V2_EIBRS_LFENCE;
1603                 break;
1604
1605         case SPECTRE_V2_CMD_EIBRS_RETPOLINE:
1606                 mode = SPECTRE_V2_EIBRS_RETPOLINE;
1607                 break;
1608         }
1609
1610         if (mode == SPECTRE_V2_EIBRS && unprivileged_ebpf_enabled())
1611                 pr_err(SPECTRE_V2_EIBRS_EBPF_MSG);
1612
1613         if (spectre_v2_in_ibrs_mode(mode)) {
1614                 if (boot_cpu_has(X86_FEATURE_AUTOIBRS)) {
1615                         msr_set_bit(MSR_EFER, _EFER_AUTOIBRS);
1616                 } else {
1617                         x86_spec_ctrl_base |= SPEC_CTRL_IBRS;
1618                         update_spec_ctrl(x86_spec_ctrl_base);
1619                 }
1620         }
1621
1622         switch (mode) {
1623         case SPECTRE_V2_NONE:
1624         case SPECTRE_V2_EIBRS:
1625                 break;
1626
1627         case SPECTRE_V2_IBRS:
1628                 setup_force_cpu_cap(X86_FEATURE_KERNEL_IBRS);
1629                 if (boot_cpu_has(X86_FEATURE_IBRS_ENHANCED))
1630                         pr_warn(SPECTRE_V2_IBRS_PERF_MSG);
1631                 break;
1632
1633         case SPECTRE_V2_LFENCE:
1634         case SPECTRE_V2_EIBRS_LFENCE:
1635                 setup_force_cpu_cap(X86_FEATURE_RETPOLINE_LFENCE);
1636                 fallthrough;
1637
1638         case SPECTRE_V2_RETPOLINE:
1639         case SPECTRE_V2_EIBRS_RETPOLINE:
1640                 setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
1641                 break;
1642         }
1643
1644         /*
1645          * Disable alternate RSB predictions in kernel when indirect CALLs and
1646          * JMPs gets protection against BHI and Intramode-BTI, but RET
1647          * prediction from a non-RSB predictor is still a risk.
1648          */
1649         if (mode == SPECTRE_V2_EIBRS_LFENCE ||
1650             mode == SPECTRE_V2_EIBRS_RETPOLINE ||
1651             mode == SPECTRE_V2_RETPOLINE)
1652                 spec_ctrl_disable_kernel_rrsba();
1653
1654         spectre_v2_enabled = mode;
1655         pr_info("%s\n", spectre_v2_strings[mode]);
1656
1657         /*
1658          * If Spectre v2 protection has been enabled, fill the RSB during a
1659          * context switch.  In general there are two types of RSB attacks
1660          * across context switches, for which the CALLs/RETs may be unbalanced.
1661          *
1662          * 1) RSB underflow
1663          *
1664          *    Some Intel parts have "bottomless RSB".  When the RSB is empty,
1665          *    speculated return targets may come from the branch predictor,
1666          *    which could have a user-poisoned BTB or BHB entry.
1667          *
1668          *    AMD has it even worse: *all* returns are speculated from the BTB,
1669          *    regardless of the state of the RSB.
1670          *
1671          *    When IBRS or eIBRS is enabled, the "user -> kernel" attack
1672          *    scenario is mitigated by the IBRS branch prediction isolation
1673          *    properties, so the RSB buffer filling wouldn't be necessary to
1674          *    protect against this type of attack.
1675          *
1676          *    The "user -> user" attack scenario is mitigated by RSB filling.
1677          *
1678          * 2) Poisoned RSB entry
1679          *
1680          *    If the 'next' in-kernel return stack is shorter than 'prev',
1681          *    'next' could be tricked into speculating with a user-poisoned RSB
1682          *    entry.
1683          *
1684          *    The "user -> kernel" attack scenario is mitigated by SMEP and
1685          *    eIBRS.
1686          *
1687          *    The "user -> user" scenario, also known as SpectreBHB, requires
1688          *    RSB clearing.
1689          *
1690          * So to mitigate all cases, unconditionally fill RSB on context
1691          * switches.
1692          *
1693          * FIXME: Is this pointless for retbleed-affected AMD?
1694          */
1695         setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
1696         pr_info("Spectre v2 / SpectreRSB mitigation: Filling RSB on context switch\n");
1697
1698         spectre_v2_determine_rsb_fill_type_at_vmexit(mode);
1699
1700         /*
1701          * Retpoline protects the kernel, but doesn't protect firmware.  IBRS
1702          * and Enhanced IBRS protect firmware too, so enable IBRS around
1703          * firmware calls only when IBRS / Enhanced / Automatic IBRS aren't
1704          * otherwise enabled.
1705          *
1706          * Use "mode" to check Enhanced IBRS instead of boot_cpu_has(), because
1707          * the user might select retpoline on the kernel command line and if
1708          * the CPU supports Enhanced IBRS, kernel might un-intentionally not
1709          * enable IBRS around firmware calls.
1710          */
1711         if (boot_cpu_has_bug(X86_BUG_RETBLEED) &&
1712             boot_cpu_has(X86_FEATURE_IBPB) &&
1713             (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
1714              boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)) {
1715
1716                 if (retbleed_cmd != RETBLEED_CMD_IBPB) {
1717                         setup_force_cpu_cap(X86_FEATURE_USE_IBPB_FW);
1718                         pr_info("Enabling Speculation Barrier for firmware calls\n");
1719                 }
1720
1721         } else if (boot_cpu_has(X86_FEATURE_IBRS) && !spectre_v2_in_ibrs_mode(mode)) {
1722                 setup_force_cpu_cap(X86_FEATURE_USE_IBRS_FW);
1723                 pr_info("Enabling Restricted Speculation for firmware calls\n");
1724         }
1725
1726         /* Set up IBPB and STIBP depending on the general spectre V2 command */
1727         spectre_v2_cmd = cmd;
1728 }
1729
1730 static void update_stibp_msr(void * __unused)
1731 {
1732         u64 val = spec_ctrl_current() | (x86_spec_ctrl_base & SPEC_CTRL_STIBP);
1733         update_spec_ctrl(val);
1734 }
1735
1736 /* Update x86_spec_ctrl_base in case SMT state changed. */
1737 static void update_stibp_strict(void)
1738 {
1739         u64 mask = x86_spec_ctrl_base & ~SPEC_CTRL_STIBP;
1740
1741         if (sched_smt_active())
1742                 mask |= SPEC_CTRL_STIBP;
1743
1744         if (mask == x86_spec_ctrl_base)
1745                 return;
1746
1747         pr_info("Update user space SMT mitigation: STIBP %s\n",
1748                 mask & SPEC_CTRL_STIBP ? "always-on" : "off");
1749         x86_spec_ctrl_base = mask;
1750         on_each_cpu(update_stibp_msr, NULL, 1);
1751 }
1752
1753 /* Update the static key controlling the evaluation of TIF_SPEC_IB */
1754 static void update_indir_branch_cond(void)
1755 {
1756         if (sched_smt_active())
1757                 static_branch_enable(&switch_to_cond_stibp);
1758         else
1759                 static_branch_disable(&switch_to_cond_stibp);
1760 }
1761
1762 #undef pr_fmt
1763 #define pr_fmt(fmt) fmt
1764
1765 /* Update the static key controlling the MDS CPU buffer clear in idle */
1766 static void update_mds_branch_idle(void)
1767 {
1768         u64 ia32_cap = x86_read_arch_cap_msr();
1769
1770         /*
1771          * Enable the idle clearing if SMT is active on CPUs which are
1772          * affected only by MSBDS and not any other MDS variant.
1773          *
1774          * The other variants cannot be mitigated when SMT is enabled, so
1775          * clearing the buffers on idle just to prevent the Store Buffer
1776          * repartitioning leak would be a window dressing exercise.
1777          */
1778         if (!boot_cpu_has_bug(X86_BUG_MSBDS_ONLY))
1779                 return;
1780
1781         if (sched_smt_active()) {
1782                 static_branch_enable(&mds_idle_clear);
1783         } else if (mmio_mitigation == MMIO_MITIGATION_OFF ||
1784                    (ia32_cap & ARCH_CAP_FBSDP_NO)) {
1785                 static_branch_disable(&mds_idle_clear);
1786         }
1787 }
1788
1789 #define MDS_MSG_SMT "MDS CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html for more details.\n"
1790 #define TAA_MSG_SMT "TAA CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html for more details.\n"
1791 #define MMIO_MSG_SMT "MMIO Stale Data CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/processor_mmio_stale_data.html for more details.\n"
1792
1793 void cpu_bugs_smt_update(void)
1794 {
1795         mutex_lock(&spec_ctrl_mutex);
1796
1797         if (sched_smt_active() && unprivileged_ebpf_enabled() &&
1798             spectre_v2_enabled == SPECTRE_V2_EIBRS_LFENCE)
1799                 pr_warn_once(SPECTRE_V2_EIBRS_LFENCE_EBPF_SMT_MSG);
1800
1801         switch (spectre_v2_user_stibp) {
1802         case SPECTRE_V2_USER_NONE:
1803                 break;
1804         case SPECTRE_V2_USER_STRICT:
1805         case SPECTRE_V2_USER_STRICT_PREFERRED:
1806                 update_stibp_strict();
1807                 break;
1808         case SPECTRE_V2_USER_PRCTL:
1809         case SPECTRE_V2_USER_SECCOMP:
1810                 update_indir_branch_cond();
1811                 break;
1812         }
1813
1814         switch (mds_mitigation) {
1815         case MDS_MITIGATION_FULL:
1816         case MDS_MITIGATION_VMWERV:
1817                 if (sched_smt_active() && !boot_cpu_has(X86_BUG_MSBDS_ONLY))
1818                         pr_warn_once(MDS_MSG_SMT);
1819                 update_mds_branch_idle();
1820                 break;
1821         case MDS_MITIGATION_OFF:
1822                 break;
1823         }
1824
1825         switch (taa_mitigation) {
1826         case TAA_MITIGATION_VERW:
1827         case TAA_MITIGATION_UCODE_NEEDED:
1828                 if (sched_smt_active())
1829                         pr_warn_once(TAA_MSG_SMT);
1830                 break;
1831         case TAA_MITIGATION_TSX_DISABLED:
1832         case TAA_MITIGATION_OFF:
1833                 break;
1834         }
1835
1836         switch (mmio_mitigation) {
1837         case MMIO_MITIGATION_VERW:
1838         case MMIO_MITIGATION_UCODE_NEEDED:
1839                 if (sched_smt_active())
1840                         pr_warn_once(MMIO_MSG_SMT);
1841                 break;
1842         case MMIO_MITIGATION_OFF:
1843                 break;
1844         }
1845
1846         mutex_unlock(&spec_ctrl_mutex);
1847 }
1848
1849 #undef pr_fmt
1850 #define pr_fmt(fmt)     "Speculative Store Bypass: " fmt
1851
1852 static enum ssb_mitigation ssb_mode __ro_after_init = SPEC_STORE_BYPASS_NONE;
1853
1854 /* The kernel command line selection */
1855 enum ssb_mitigation_cmd {
1856         SPEC_STORE_BYPASS_CMD_NONE,
1857         SPEC_STORE_BYPASS_CMD_AUTO,
1858         SPEC_STORE_BYPASS_CMD_ON,
1859         SPEC_STORE_BYPASS_CMD_PRCTL,
1860         SPEC_STORE_BYPASS_CMD_SECCOMP,
1861 };
1862
1863 static const char * const ssb_strings[] = {
1864         [SPEC_STORE_BYPASS_NONE]        = "Vulnerable",
1865         [SPEC_STORE_BYPASS_DISABLE]     = "Mitigation: Speculative Store Bypass disabled",
1866         [SPEC_STORE_BYPASS_PRCTL]       = "Mitigation: Speculative Store Bypass disabled via prctl",
1867         [SPEC_STORE_BYPASS_SECCOMP]     = "Mitigation: Speculative Store Bypass disabled via prctl and seccomp",
1868 };
1869
1870 static const struct {
1871         const char *option;
1872         enum ssb_mitigation_cmd cmd;
1873 } ssb_mitigation_options[]  __initconst = {
1874         { "auto",       SPEC_STORE_BYPASS_CMD_AUTO },    /* Platform decides */
1875         { "on",         SPEC_STORE_BYPASS_CMD_ON },      /* Disable Speculative Store Bypass */
1876         { "off",        SPEC_STORE_BYPASS_CMD_NONE },    /* Don't touch Speculative Store Bypass */
1877         { "prctl",      SPEC_STORE_BYPASS_CMD_PRCTL },   /* Disable Speculative Store Bypass via prctl */
1878         { "seccomp",    SPEC_STORE_BYPASS_CMD_SECCOMP }, /* Disable Speculative Store Bypass via prctl and seccomp */
1879 };
1880
1881 static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void)
1882 {
1883         enum ssb_mitigation_cmd cmd = SPEC_STORE_BYPASS_CMD_AUTO;
1884         char arg[20];
1885         int ret, i;
1886
1887         if (cmdline_find_option_bool(boot_command_line, "nospec_store_bypass_disable") ||
1888             cpu_mitigations_off()) {
1889                 return SPEC_STORE_BYPASS_CMD_NONE;
1890         } else {
1891                 ret = cmdline_find_option(boot_command_line, "spec_store_bypass_disable",
1892                                           arg, sizeof(arg));
1893                 if (ret < 0)
1894                         return SPEC_STORE_BYPASS_CMD_AUTO;
1895
1896                 for (i = 0; i < ARRAY_SIZE(ssb_mitigation_options); i++) {
1897                         if (!match_option(arg, ret, ssb_mitigation_options[i].option))
1898                                 continue;
1899
1900                         cmd = ssb_mitigation_options[i].cmd;
1901                         break;
1902                 }
1903
1904                 if (i >= ARRAY_SIZE(ssb_mitigation_options)) {
1905                         pr_err("unknown option (%s). Switching to AUTO select\n", arg);
1906                         return SPEC_STORE_BYPASS_CMD_AUTO;
1907                 }
1908         }
1909
1910         return cmd;
1911 }
1912
1913 static enum ssb_mitigation __init __ssb_select_mitigation(void)
1914 {
1915         enum ssb_mitigation mode = SPEC_STORE_BYPASS_NONE;
1916         enum ssb_mitigation_cmd cmd;
1917
1918         if (!boot_cpu_has(X86_FEATURE_SSBD))
1919                 return mode;
1920
1921         cmd = ssb_parse_cmdline();
1922         if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS) &&
1923             (cmd == SPEC_STORE_BYPASS_CMD_NONE ||
1924              cmd == SPEC_STORE_BYPASS_CMD_AUTO))
1925                 return mode;
1926
1927         switch (cmd) {
1928         case SPEC_STORE_BYPASS_CMD_SECCOMP:
1929                 /*
1930                  * Choose prctl+seccomp as the default mode if seccomp is
1931                  * enabled.
1932                  */
1933                 if (IS_ENABLED(CONFIG_SECCOMP))
1934                         mode = SPEC_STORE_BYPASS_SECCOMP;
1935                 else
1936                         mode = SPEC_STORE_BYPASS_PRCTL;
1937                 break;
1938         case SPEC_STORE_BYPASS_CMD_ON:
1939                 mode = SPEC_STORE_BYPASS_DISABLE;
1940                 break;
1941         case SPEC_STORE_BYPASS_CMD_AUTO:
1942         case SPEC_STORE_BYPASS_CMD_PRCTL:
1943                 mode = SPEC_STORE_BYPASS_PRCTL;
1944                 break;
1945         case SPEC_STORE_BYPASS_CMD_NONE:
1946                 break;
1947         }
1948
1949         /*
1950          * We have three CPU feature flags that are in play here:
1951          *  - X86_BUG_SPEC_STORE_BYPASS - CPU is susceptible.
1952          *  - X86_FEATURE_SSBD - CPU is able to turn off speculative store bypass
1953          *  - X86_FEATURE_SPEC_STORE_BYPASS_DISABLE - engage the mitigation
1954          */
1955         if (mode == SPEC_STORE_BYPASS_DISABLE) {
1956                 setup_force_cpu_cap(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE);
1957                 /*
1958                  * Intel uses the SPEC CTRL MSR Bit(2) for this, while AMD may
1959                  * use a completely different MSR and bit dependent on family.
1960                  */
1961                 if (!static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) &&
1962                     !static_cpu_has(X86_FEATURE_AMD_SSBD)) {
1963                         x86_amd_ssb_disable();
1964                 } else {
1965                         x86_spec_ctrl_base |= SPEC_CTRL_SSBD;
1966                         update_spec_ctrl(x86_spec_ctrl_base);
1967                 }
1968         }
1969
1970         return mode;
1971 }
1972
1973 static void ssb_select_mitigation(void)
1974 {
1975         ssb_mode = __ssb_select_mitigation();
1976
1977         if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
1978                 pr_info("%s\n", ssb_strings[ssb_mode]);
1979 }
1980
1981 #undef pr_fmt
1982 #define pr_fmt(fmt)     "Speculation prctl: " fmt
1983
1984 static void task_update_spec_tif(struct task_struct *tsk)
1985 {
1986         /* Force the update of the real TIF bits */
1987         set_tsk_thread_flag(tsk, TIF_SPEC_FORCE_UPDATE);
1988
1989         /*
1990          * Immediately update the speculation control MSRs for the current
1991          * task, but for a non-current task delay setting the CPU
1992          * mitigation until it is scheduled next.
1993          *
1994          * This can only happen for SECCOMP mitigation. For PRCTL it's
1995          * always the current task.
1996          */
1997         if (tsk == current)
1998                 speculation_ctrl_update_current();
1999 }
2000
2001 static int l1d_flush_prctl_set(struct task_struct *task, unsigned long ctrl)
2002 {
2003
2004         if (!static_branch_unlikely(&switch_mm_cond_l1d_flush))
2005                 return -EPERM;
2006
2007         switch (ctrl) {
2008         case PR_SPEC_ENABLE:
2009                 set_ti_thread_flag(&task->thread_info, TIF_SPEC_L1D_FLUSH);
2010                 return 0;
2011         case PR_SPEC_DISABLE:
2012                 clear_ti_thread_flag(&task->thread_info, TIF_SPEC_L1D_FLUSH);
2013                 return 0;
2014         default:
2015                 return -ERANGE;
2016         }
2017 }
2018
2019 static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl)
2020 {
2021         if (ssb_mode != SPEC_STORE_BYPASS_PRCTL &&
2022             ssb_mode != SPEC_STORE_BYPASS_SECCOMP)
2023                 return -ENXIO;
2024
2025         switch (ctrl) {
2026         case PR_SPEC_ENABLE:
2027                 /* If speculation is force disabled, enable is not allowed */
2028                 if (task_spec_ssb_force_disable(task))
2029                         return -EPERM;
2030                 task_clear_spec_ssb_disable(task);
2031                 task_clear_spec_ssb_noexec(task);
2032                 task_update_spec_tif(task);
2033                 break;
2034         case PR_SPEC_DISABLE:
2035                 task_set_spec_ssb_disable(task);
2036                 task_clear_spec_ssb_noexec(task);
2037                 task_update_spec_tif(task);
2038                 break;
2039         case PR_SPEC_FORCE_DISABLE:
2040                 task_set_spec_ssb_disable(task);
2041                 task_set_spec_ssb_force_disable(task);
2042                 task_clear_spec_ssb_noexec(task);
2043                 task_update_spec_tif(task);
2044                 break;
2045         case PR_SPEC_DISABLE_NOEXEC:
2046                 if (task_spec_ssb_force_disable(task))
2047                         return -EPERM;
2048                 task_set_spec_ssb_disable(task);
2049                 task_set_spec_ssb_noexec(task);
2050                 task_update_spec_tif(task);
2051                 break;
2052         default:
2053                 return -ERANGE;
2054         }
2055         return 0;
2056 }
2057
2058 static bool is_spec_ib_user_controlled(void)
2059 {
2060         return spectre_v2_user_ibpb == SPECTRE_V2_USER_PRCTL ||
2061                 spectre_v2_user_ibpb == SPECTRE_V2_USER_SECCOMP ||
2062                 spectre_v2_user_stibp == SPECTRE_V2_USER_PRCTL ||
2063                 spectre_v2_user_stibp == SPECTRE_V2_USER_SECCOMP;
2064 }
2065
2066 static int ib_prctl_set(struct task_struct *task, unsigned long ctrl)
2067 {
2068         switch (ctrl) {
2069         case PR_SPEC_ENABLE:
2070                 if (spectre_v2_user_ibpb == SPECTRE_V2_USER_NONE &&
2071                     spectre_v2_user_stibp == SPECTRE_V2_USER_NONE)
2072                         return 0;
2073
2074                 /*
2075                  * With strict mode for both IBPB and STIBP, the instruction
2076                  * code paths avoid checking this task flag and instead,
2077                  * unconditionally run the instruction. However, STIBP and IBPB
2078                  * are independent and either can be set to conditionally
2079                  * enabled regardless of the mode of the other.
2080                  *
2081                  * If either is set to conditional, allow the task flag to be
2082                  * updated, unless it was force-disabled by a previous prctl
2083                  * call. Currently, this is possible on an AMD CPU which has the
2084                  * feature X86_FEATURE_AMD_STIBP_ALWAYS_ON. In this case, if the
2085                  * kernel is booted with 'spectre_v2_user=seccomp', then
2086                  * spectre_v2_user_ibpb == SPECTRE_V2_USER_SECCOMP and
2087                  * spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED.
2088                  */
2089                 if (!is_spec_ib_user_controlled() ||
2090                     task_spec_ib_force_disable(task))
2091                         return -EPERM;
2092
2093                 task_clear_spec_ib_disable(task);
2094                 task_update_spec_tif(task);
2095                 break;
2096         case PR_SPEC_DISABLE:
2097         case PR_SPEC_FORCE_DISABLE:
2098                 /*
2099                  * Indirect branch speculation is always allowed when
2100                  * mitigation is force disabled.
2101                  */
2102                 if (spectre_v2_user_ibpb == SPECTRE_V2_USER_NONE &&
2103                     spectre_v2_user_stibp == SPECTRE_V2_USER_NONE)
2104                         return -EPERM;
2105
2106                 if (!is_spec_ib_user_controlled())
2107                         return 0;
2108
2109                 task_set_spec_ib_disable(task);
2110                 if (ctrl == PR_SPEC_FORCE_DISABLE)
2111                         task_set_spec_ib_force_disable(task);
2112                 task_update_spec_tif(task);
2113                 if (task == current)
2114                         indirect_branch_prediction_barrier();
2115                 break;
2116         default:
2117                 return -ERANGE;
2118         }
2119         return 0;
2120 }
2121
2122 int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which,
2123                              unsigned long ctrl)
2124 {
2125         switch (which) {
2126         case PR_SPEC_STORE_BYPASS:
2127                 return ssb_prctl_set(task, ctrl);
2128         case PR_SPEC_INDIRECT_BRANCH:
2129                 return ib_prctl_set(task, ctrl);
2130         case PR_SPEC_L1D_FLUSH:
2131                 return l1d_flush_prctl_set(task, ctrl);
2132         default:
2133                 return -ENODEV;
2134         }
2135 }
2136
2137 #ifdef CONFIG_SECCOMP
2138 void arch_seccomp_spec_mitigate(struct task_struct *task)
2139 {
2140         if (ssb_mode == SPEC_STORE_BYPASS_SECCOMP)
2141                 ssb_prctl_set(task, PR_SPEC_FORCE_DISABLE);
2142         if (spectre_v2_user_ibpb == SPECTRE_V2_USER_SECCOMP ||
2143             spectre_v2_user_stibp == SPECTRE_V2_USER_SECCOMP)
2144                 ib_prctl_set(task, PR_SPEC_FORCE_DISABLE);
2145 }
2146 #endif
2147
2148 static int l1d_flush_prctl_get(struct task_struct *task)
2149 {
2150         if (!static_branch_unlikely(&switch_mm_cond_l1d_flush))
2151                 return PR_SPEC_FORCE_DISABLE;
2152
2153         if (test_ti_thread_flag(&task->thread_info, TIF_SPEC_L1D_FLUSH))
2154                 return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
2155         else
2156                 return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
2157 }
2158
2159 static int ssb_prctl_get(struct task_struct *task)
2160 {
2161         switch (ssb_mode) {
2162         case SPEC_STORE_BYPASS_NONE:
2163                 if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
2164                         return PR_SPEC_ENABLE;
2165                 return PR_SPEC_NOT_AFFECTED;
2166         case SPEC_STORE_BYPASS_DISABLE:
2167                 return PR_SPEC_DISABLE;
2168         case SPEC_STORE_BYPASS_SECCOMP:
2169         case SPEC_STORE_BYPASS_PRCTL:
2170                 if (task_spec_ssb_force_disable(task))
2171                         return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE;
2172                 if (task_spec_ssb_noexec(task))
2173                         return PR_SPEC_PRCTL | PR_SPEC_DISABLE_NOEXEC;
2174                 if (task_spec_ssb_disable(task))
2175                         return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
2176                 return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
2177         }
2178         BUG();
2179 }
2180
2181 static int ib_prctl_get(struct task_struct *task)
2182 {
2183         if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
2184                 return PR_SPEC_NOT_AFFECTED;
2185
2186         if (spectre_v2_user_ibpb == SPECTRE_V2_USER_NONE &&
2187             spectre_v2_user_stibp == SPECTRE_V2_USER_NONE)
2188                 return PR_SPEC_ENABLE;
2189         else if (is_spec_ib_user_controlled()) {
2190                 if (task_spec_ib_force_disable(task))
2191                         return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE;
2192                 if (task_spec_ib_disable(task))
2193                         return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
2194                 return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
2195         } else if (spectre_v2_user_ibpb == SPECTRE_V2_USER_STRICT ||
2196             spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT ||
2197             spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED)
2198                 return PR_SPEC_DISABLE;
2199         else
2200                 return PR_SPEC_NOT_AFFECTED;
2201 }
2202
2203 int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
2204 {
2205         switch (which) {
2206         case PR_SPEC_STORE_BYPASS:
2207                 return ssb_prctl_get(task);
2208         case PR_SPEC_INDIRECT_BRANCH:
2209                 return ib_prctl_get(task);
2210         case PR_SPEC_L1D_FLUSH:
2211                 return l1d_flush_prctl_get(task);
2212         default:
2213                 return -ENODEV;
2214         }
2215 }
2216
2217 void x86_spec_ctrl_setup_ap(void)
2218 {
2219         if (boot_cpu_has(X86_FEATURE_MSR_SPEC_CTRL))
2220                 update_spec_ctrl(x86_spec_ctrl_base);
2221
2222         if (ssb_mode == SPEC_STORE_BYPASS_DISABLE)
2223                 x86_amd_ssb_disable();
2224 }
2225
2226 bool itlb_multihit_kvm_mitigation;
2227 EXPORT_SYMBOL_GPL(itlb_multihit_kvm_mitigation);
2228
2229 #undef pr_fmt
2230 #define pr_fmt(fmt)     "L1TF: " fmt
2231
2232 /* Default mitigation for L1TF-affected CPUs */
2233 enum l1tf_mitigations l1tf_mitigation __ro_after_init = L1TF_MITIGATION_FLUSH;
2234 #if IS_ENABLED(CONFIG_KVM_INTEL)
2235 EXPORT_SYMBOL_GPL(l1tf_mitigation);
2236 #endif
2237 enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO;
2238 EXPORT_SYMBOL_GPL(l1tf_vmx_mitigation);
2239
2240 /*
2241  * These CPUs all support 44bits physical address space internally in the
2242  * cache but CPUID can report a smaller number of physical address bits.
2243  *
2244  * The L1TF mitigation uses the top most address bit for the inversion of
2245  * non present PTEs. When the installed memory reaches into the top most
2246  * address bit due to memory holes, which has been observed on machines
2247  * which report 36bits physical address bits and have 32G RAM installed,
2248  * then the mitigation range check in l1tf_select_mitigation() triggers.
2249  * This is a false positive because the mitigation is still possible due to
2250  * the fact that the cache uses 44bit internally. Use the cache bits
2251  * instead of the reported physical bits and adjust them on the affected
2252  * machines to 44bit if the reported bits are less than 44.
2253  */
2254 static void override_cache_bits(struct cpuinfo_x86 *c)
2255 {
2256         if (c->x86 != 6)
2257                 return;
2258
2259         switch (c->x86_model) {
2260         case INTEL_FAM6_NEHALEM:
2261         case INTEL_FAM6_WESTMERE:
2262         case INTEL_FAM6_SANDYBRIDGE:
2263         case INTEL_FAM6_IVYBRIDGE:
2264         case INTEL_FAM6_HASWELL:
2265         case INTEL_FAM6_HASWELL_L:
2266         case INTEL_FAM6_HASWELL_G:
2267         case INTEL_FAM6_BROADWELL:
2268         case INTEL_FAM6_BROADWELL_G:
2269         case INTEL_FAM6_SKYLAKE_L:
2270         case INTEL_FAM6_SKYLAKE:
2271         case INTEL_FAM6_KABYLAKE_L:
2272         case INTEL_FAM6_KABYLAKE:
2273                 if (c->x86_cache_bits < 44)
2274                         c->x86_cache_bits = 44;
2275                 break;
2276         }
2277 }
2278
2279 static void __init l1tf_select_mitigation(void)
2280 {
2281         u64 half_pa;
2282
2283         if (!boot_cpu_has_bug(X86_BUG_L1TF))
2284                 return;
2285
2286         if (cpu_mitigations_off())
2287                 l1tf_mitigation = L1TF_MITIGATION_OFF;
2288         else if (cpu_mitigations_auto_nosmt())
2289                 l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT;
2290
2291         override_cache_bits(&boot_cpu_data);
2292
2293         switch (l1tf_mitigation) {
2294         case L1TF_MITIGATION_OFF:
2295         case L1TF_MITIGATION_FLUSH_NOWARN:
2296         case L1TF_MITIGATION_FLUSH:
2297                 break;
2298         case L1TF_MITIGATION_FLUSH_NOSMT:
2299         case L1TF_MITIGATION_FULL:
2300                 cpu_smt_disable(false);
2301                 break;
2302         case L1TF_MITIGATION_FULL_FORCE:
2303                 cpu_smt_disable(true);
2304                 break;
2305         }
2306
2307 #if CONFIG_PGTABLE_LEVELS == 2
2308         pr_warn("Kernel not compiled for PAE. No mitigation for L1TF\n");
2309         return;
2310 #endif
2311
2312         half_pa = (u64)l1tf_pfn_limit() << PAGE_SHIFT;
2313         if (l1tf_mitigation != L1TF_MITIGATION_OFF &&
2314                         e820__mapped_any(half_pa, ULLONG_MAX - half_pa, E820_TYPE_RAM)) {
2315                 pr_warn("System has more than MAX_PA/2 memory. L1TF mitigation not effective.\n");
2316                 pr_info("You may make it effective by booting the kernel with mem=%llu parameter.\n",
2317                                 half_pa);
2318                 pr_info("However, doing so will make a part of your RAM unusable.\n");
2319                 pr_info("Reading https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html might help you decide.\n");
2320                 return;
2321         }
2322
2323         setup_force_cpu_cap(X86_FEATURE_L1TF_PTEINV);
2324 }
2325
2326 static int __init l1tf_cmdline(char *str)
2327 {
2328         if (!boot_cpu_has_bug(X86_BUG_L1TF))
2329                 return 0;
2330
2331         if (!str)
2332                 return -EINVAL;
2333
2334         if (!strcmp(str, "off"))
2335                 l1tf_mitigation = L1TF_MITIGATION_OFF;
2336         else if (!strcmp(str, "flush,nowarn"))
2337                 l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOWARN;
2338         else if (!strcmp(str, "flush"))
2339                 l1tf_mitigation = L1TF_MITIGATION_FLUSH;
2340         else if (!strcmp(str, "flush,nosmt"))
2341                 l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT;
2342         else if (!strcmp(str, "full"))
2343                 l1tf_mitigation = L1TF_MITIGATION_FULL;
2344         else if (!strcmp(str, "full,force"))
2345                 l1tf_mitigation = L1TF_MITIGATION_FULL_FORCE;
2346
2347         return 0;
2348 }
2349 early_param("l1tf", l1tf_cmdline);
2350
2351 #undef pr_fmt
2352 #define pr_fmt(fmt)     "Speculative Return Stack Overflow: " fmt
2353
2354 enum srso_mitigation {
2355         SRSO_MITIGATION_NONE,
2356         SRSO_MITIGATION_UCODE_NEEDED,
2357         SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED,
2358         SRSO_MITIGATION_MICROCODE,
2359         SRSO_MITIGATION_SAFE_RET,
2360         SRSO_MITIGATION_IBPB,
2361         SRSO_MITIGATION_IBPB_ON_VMEXIT,
2362 };
2363
2364 enum srso_mitigation_cmd {
2365         SRSO_CMD_OFF,
2366         SRSO_CMD_MICROCODE,
2367         SRSO_CMD_SAFE_RET,
2368         SRSO_CMD_IBPB,
2369         SRSO_CMD_IBPB_ON_VMEXIT,
2370 };
2371
2372 static const char * const srso_strings[] = {
2373         [SRSO_MITIGATION_NONE]                  = "Vulnerable",
2374         [SRSO_MITIGATION_UCODE_NEEDED]          = "Vulnerable: No microcode",
2375         [SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED] = "Vulnerable: Safe RET, no microcode",
2376         [SRSO_MITIGATION_MICROCODE]             = "Vulnerable: Microcode, no safe RET",
2377         [SRSO_MITIGATION_SAFE_RET]              = "Mitigation: Safe RET",
2378         [SRSO_MITIGATION_IBPB]                  = "Mitigation: IBPB",
2379         [SRSO_MITIGATION_IBPB_ON_VMEXIT]        = "Mitigation: IBPB on VMEXIT only"
2380 };
2381
2382 static enum srso_mitigation srso_mitigation __ro_after_init = SRSO_MITIGATION_NONE;
2383 static enum srso_mitigation_cmd srso_cmd __ro_after_init = SRSO_CMD_SAFE_RET;
2384
2385 static int __init srso_parse_cmdline(char *str)
2386 {
2387         if (!str)
2388                 return -EINVAL;
2389
2390         if (!strcmp(str, "off"))
2391                 srso_cmd = SRSO_CMD_OFF;
2392         else if (!strcmp(str, "microcode"))
2393                 srso_cmd = SRSO_CMD_MICROCODE;
2394         else if (!strcmp(str, "safe-ret"))
2395                 srso_cmd = SRSO_CMD_SAFE_RET;
2396         else if (!strcmp(str, "ibpb"))
2397                 srso_cmd = SRSO_CMD_IBPB;
2398         else if (!strcmp(str, "ibpb-vmexit"))
2399                 srso_cmd = SRSO_CMD_IBPB_ON_VMEXIT;
2400         else
2401                 pr_err("Ignoring unknown SRSO option (%s).", str);
2402
2403         return 0;
2404 }
2405 early_param("spec_rstack_overflow", srso_parse_cmdline);
2406
2407 #define SRSO_NOTICE "WARNING: See https://kernel.org/doc/html/latest/admin-guide/hw-vuln/srso.html for mitigation options."
2408
2409 static void __init srso_select_mitigation(void)
2410 {
2411         bool has_microcode = boot_cpu_has(X86_FEATURE_IBPB_BRTYPE);
2412
2413         if (cpu_mitigations_off())
2414                 return;
2415
2416         if (!boot_cpu_has_bug(X86_BUG_SRSO)) {
2417                 if (boot_cpu_has(X86_FEATURE_SBPB))
2418                         x86_pred_cmd = PRED_CMD_SBPB;
2419                 return;
2420         }
2421
2422         if (has_microcode) {
2423                 /*
2424                  * Zen1/2 with SMT off aren't vulnerable after the right
2425                  * IBPB microcode has been applied.
2426                  *
2427                  * Zen1/2 don't have SBPB, no need to try to enable it here.
2428                  */
2429                 if (boot_cpu_data.x86 < 0x19 && !cpu_smt_possible()) {
2430                         setup_force_cpu_cap(X86_FEATURE_SRSO_NO);
2431                         return;
2432                 }
2433
2434                 if (retbleed_mitigation == RETBLEED_MITIGATION_IBPB) {
2435                         srso_mitigation = SRSO_MITIGATION_IBPB;
2436                         goto out;
2437                 }
2438         } else {
2439                 pr_warn("IBPB-extending microcode not applied!\n");
2440                 pr_warn(SRSO_NOTICE);
2441
2442                 /* may be overwritten by SRSO_CMD_SAFE_RET below */
2443                 srso_mitigation = SRSO_MITIGATION_UCODE_NEEDED;
2444         }
2445
2446         switch (srso_cmd) {
2447         case SRSO_CMD_OFF:
2448                 if (boot_cpu_has(X86_FEATURE_SBPB))
2449                         x86_pred_cmd = PRED_CMD_SBPB;
2450                 return;
2451
2452         case SRSO_CMD_MICROCODE:
2453                 if (has_microcode) {
2454                         srso_mitigation = SRSO_MITIGATION_MICROCODE;
2455                         pr_warn(SRSO_NOTICE);
2456                 }
2457                 break;
2458
2459         case SRSO_CMD_SAFE_RET:
2460                 if (IS_ENABLED(CONFIG_CPU_SRSO)) {
2461                         /*
2462                          * Enable the return thunk for generated code
2463                          * like ftrace, static_call, etc.
2464                          */
2465                         setup_force_cpu_cap(X86_FEATURE_RETHUNK);
2466                         setup_force_cpu_cap(X86_FEATURE_UNRET);
2467
2468                         if (boot_cpu_data.x86 == 0x19) {
2469                                 setup_force_cpu_cap(X86_FEATURE_SRSO_ALIAS);
2470                                 x86_return_thunk = srso_alias_return_thunk;
2471                         } else {
2472                                 setup_force_cpu_cap(X86_FEATURE_SRSO);
2473                                 x86_return_thunk = srso_return_thunk;
2474                         }
2475                         if (has_microcode)
2476                                 srso_mitigation = SRSO_MITIGATION_SAFE_RET;
2477                         else
2478                                 srso_mitigation = SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED;
2479                 } else {
2480                         pr_err("WARNING: kernel not compiled with CPU_SRSO.\n");
2481                 }
2482                 break;
2483
2484         case SRSO_CMD_IBPB:
2485                 if (IS_ENABLED(CONFIG_CPU_IBPB_ENTRY)) {
2486                         if (has_microcode) {
2487                                 setup_force_cpu_cap(X86_FEATURE_ENTRY_IBPB);
2488                                 srso_mitigation = SRSO_MITIGATION_IBPB;
2489                         }
2490                 } else {
2491                         pr_err("WARNING: kernel not compiled with CPU_IBPB_ENTRY.\n");
2492                 }
2493                 break;
2494
2495         case SRSO_CMD_IBPB_ON_VMEXIT:
2496                 if (IS_ENABLED(CONFIG_CPU_SRSO)) {
2497                         if (!boot_cpu_has(X86_FEATURE_ENTRY_IBPB) && has_microcode) {
2498                                 setup_force_cpu_cap(X86_FEATURE_IBPB_ON_VMEXIT);
2499                                 srso_mitigation = SRSO_MITIGATION_IBPB_ON_VMEXIT;
2500                         }
2501                 } else {
2502                         pr_err("WARNING: kernel not compiled with CPU_SRSO.\n");
2503                 }
2504                 break;
2505         }
2506
2507 out:
2508         pr_info("%s\n", srso_strings[srso_mitigation]);
2509 }
2510
2511 #undef pr_fmt
2512 #define pr_fmt(fmt) fmt
2513
2514 #ifdef CONFIG_SYSFS
2515
2516 #define L1TF_DEFAULT_MSG "Mitigation: PTE Inversion"
2517
2518 #if IS_ENABLED(CONFIG_KVM_INTEL)
2519 static const char * const l1tf_vmx_states[] = {
2520         [VMENTER_L1D_FLUSH_AUTO]                = "auto",
2521         [VMENTER_L1D_FLUSH_NEVER]               = "vulnerable",
2522         [VMENTER_L1D_FLUSH_COND]                = "conditional cache flushes",
2523         [VMENTER_L1D_FLUSH_ALWAYS]              = "cache flushes",
2524         [VMENTER_L1D_FLUSH_EPT_DISABLED]        = "EPT disabled",
2525         [VMENTER_L1D_FLUSH_NOT_REQUIRED]        = "flush not necessary"
2526 };
2527
2528 static ssize_t l1tf_show_state(char *buf)
2529 {
2530         if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_AUTO)
2531                 return sysfs_emit(buf, "%s\n", L1TF_DEFAULT_MSG);
2532
2533         if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_EPT_DISABLED ||
2534             (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_NEVER &&
2535              sched_smt_active())) {
2536                 return sysfs_emit(buf, "%s; VMX: %s\n", L1TF_DEFAULT_MSG,
2537                                   l1tf_vmx_states[l1tf_vmx_mitigation]);
2538         }
2539
2540         return sysfs_emit(buf, "%s; VMX: %s, SMT %s\n", L1TF_DEFAULT_MSG,
2541                           l1tf_vmx_states[l1tf_vmx_mitigation],
2542                           sched_smt_active() ? "vulnerable" : "disabled");
2543 }
2544
2545 static ssize_t itlb_multihit_show_state(char *buf)
2546 {
2547         if (!boot_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) ||
2548             !boot_cpu_has(X86_FEATURE_VMX))
2549                 return sysfs_emit(buf, "KVM: Mitigation: VMX unsupported\n");
2550         else if (!(cr4_read_shadow() & X86_CR4_VMXE))
2551                 return sysfs_emit(buf, "KVM: Mitigation: VMX disabled\n");
2552         else if (itlb_multihit_kvm_mitigation)
2553                 return sysfs_emit(buf, "KVM: Mitigation: Split huge pages\n");
2554         else
2555                 return sysfs_emit(buf, "KVM: Vulnerable\n");
2556 }
2557 #else
2558 static ssize_t l1tf_show_state(char *buf)
2559 {
2560         return sysfs_emit(buf, "%s\n", L1TF_DEFAULT_MSG);
2561 }
2562
2563 static ssize_t itlb_multihit_show_state(char *buf)
2564 {
2565         return sysfs_emit(buf, "Processor vulnerable\n");
2566 }
2567 #endif
2568
2569 static ssize_t mds_show_state(char *buf)
2570 {
2571         if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
2572                 return sysfs_emit(buf, "%s; SMT Host state unknown\n",
2573                                   mds_strings[mds_mitigation]);
2574         }
2575
2576         if (boot_cpu_has(X86_BUG_MSBDS_ONLY)) {
2577                 return sysfs_emit(buf, "%s; SMT %s\n", mds_strings[mds_mitigation],
2578                                   (mds_mitigation == MDS_MITIGATION_OFF ? "vulnerable" :
2579                                    sched_smt_active() ? "mitigated" : "disabled"));
2580         }
2581
2582         return sysfs_emit(buf, "%s; SMT %s\n", mds_strings[mds_mitigation],
2583                           sched_smt_active() ? "vulnerable" : "disabled");
2584 }
2585
2586 static ssize_t tsx_async_abort_show_state(char *buf)
2587 {
2588         if ((taa_mitigation == TAA_MITIGATION_TSX_DISABLED) ||
2589             (taa_mitigation == TAA_MITIGATION_OFF))
2590                 return sysfs_emit(buf, "%s\n", taa_strings[taa_mitigation]);
2591
2592         if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
2593                 return sysfs_emit(buf, "%s; SMT Host state unknown\n",
2594                                   taa_strings[taa_mitigation]);
2595         }
2596
2597         return sysfs_emit(buf, "%s; SMT %s\n", taa_strings[taa_mitigation],
2598                           sched_smt_active() ? "vulnerable" : "disabled");
2599 }
2600
2601 static ssize_t mmio_stale_data_show_state(char *buf)
2602 {
2603         if (boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN))
2604                 return sysfs_emit(buf, "Unknown: No mitigations\n");
2605
2606         if (mmio_mitigation == MMIO_MITIGATION_OFF)
2607                 return sysfs_emit(buf, "%s\n", mmio_strings[mmio_mitigation]);
2608
2609         if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
2610                 return sysfs_emit(buf, "%s; SMT Host state unknown\n",
2611                                   mmio_strings[mmio_mitigation]);
2612         }
2613
2614         return sysfs_emit(buf, "%s; SMT %s\n", mmio_strings[mmio_mitigation],
2615                           sched_smt_active() ? "vulnerable" : "disabled");
2616 }
2617
2618 static char *stibp_state(void)
2619 {
2620         if (spectre_v2_in_eibrs_mode(spectre_v2_enabled) &&
2621             !boot_cpu_has(X86_FEATURE_AUTOIBRS))
2622                 return "";
2623
2624         switch (spectre_v2_user_stibp) {
2625         case SPECTRE_V2_USER_NONE:
2626                 return ", STIBP: disabled";
2627         case SPECTRE_V2_USER_STRICT:
2628                 return ", STIBP: forced";
2629         case SPECTRE_V2_USER_STRICT_PREFERRED:
2630                 return ", STIBP: always-on";
2631         case SPECTRE_V2_USER_PRCTL:
2632         case SPECTRE_V2_USER_SECCOMP:
2633                 if (static_key_enabled(&switch_to_cond_stibp))
2634                         return ", STIBP: conditional";
2635         }
2636         return "";
2637 }
2638
2639 static char *ibpb_state(void)
2640 {
2641         if (boot_cpu_has(X86_FEATURE_IBPB)) {
2642                 if (static_key_enabled(&switch_mm_always_ibpb))
2643                         return ", IBPB: always-on";
2644                 if (static_key_enabled(&switch_mm_cond_ibpb))
2645                         return ", IBPB: conditional";
2646                 return ", IBPB: disabled";
2647         }
2648         return "";
2649 }
2650
2651 static char *pbrsb_eibrs_state(void)
2652 {
2653         if (boot_cpu_has_bug(X86_BUG_EIBRS_PBRSB)) {
2654                 if (boot_cpu_has(X86_FEATURE_RSB_VMEXIT_LITE) ||
2655                     boot_cpu_has(X86_FEATURE_RSB_VMEXIT))
2656                         return ", PBRSB-eIBRS: SW sequence";
2657                 else
2658                         return ", PBRSB-eIBRS: Vulnerable";
2659         } else {
2660                 return ", PBRSB-eIBRS: Not affected";
2661         }
2662 }
2663
2664 static ssize_t spectre_v2_show_state(char *buf)
2665 {
2666         if (spectre_v2_enabled == SPECTRE_V2_LFENCE)
2667                 return sysfs_emit(buf, "Vulnerable: LFENCE\n");
2668
2669         if (spectre_v2_enabled == SPECTRE_V2_EIBRS && unprivileged_ebpf_enabled())
2670                 return sysfs_emit(buf, "Vulnerable: eIBRS with unprivileged eBPF\n");
2671
2672         if (sched_smt_active() && unprivileged_ebpf_enabled() &&
2673             spectre_v2_enabled == SPECTRE_V2_EIBRS_LFENCE)
2674                 return sysfs_emit(buf, "Vulnerable: eIBRS+LFENCE with unprivileged eBPF and SMT\n");
2675
2676         return sysfs_emit(buf, "%s%s%s%s%s%s%s\n",
2677                           spectre_v2_strings[spectre_v2_enabled],
2678                           ibpb_state(),
2679                           boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "",
2680                           stibp_state(),
2681                           boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB filling" : "",
2682                           pbrsb_eibrs_state(),
2683                           spectre_v2_module_string());
2684 }
2685
2686 static ssize_t srbds_show_state(char *buf)
2687 {
2688         return sysfs_emit(buf, "%s\n", srbds_strings[srbds_mitigation]);
2689 }
2690
2691 static ssize_t retbleed_show_state(char *buf)
2692 {
2693         if (retbleed_mitigation == RETBLEED_MITIGATION_UNRET ||
2694             retbleed_mitigation == RETBLEED_MITIGATION_IBPB) {
2695                 if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
2696                     boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
2697                         return sysfs_emit(buf, "Vulnerable: untrained return thunk / IBPB on non-AMD based uarch\n");
2698
2699                 return sysfs_emit(buf, "%s; SMT %s\n", retbleed_strings[retbleed_mitigation],
2700                                   !sched_smt_active() ? "disabled" :
2701                                   spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT ||
2702                                   spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED ?
2703                                   "enabled with STIBP protection" : "vulnerable");
2704         }
2705
2706         return sysfs_emit(buf, "%s\n", retbleed_strings[retbleed_mitigation]);
2707 }
2708
2709 static ssize_t srso_show_state(char *buf)
2710 {
2711         if (boot_cpu_has(X86_FEATURE_SRSO_NO))
2712                 return sysfs_emit(buf, "Mitigation: SMT disabled\n");
2713
2714         return sysfs_emit(buf, "%s\n", srso_strings[srso_mitigation]);
2715 }
2716
2717 static ssize_t gds_show_state(char *buf)
2718 {
2719         return sysfs_emit(buf, "%s\n", gds_strings[gds_mitigation]);
2720 }
2721
2722 static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr,
2723                                char *buf, unsigned int bug)
2724 {
2725         if (!boot_cpu_has_bug(bug))
2726                 return sysfs_emit(buf, "Not affected\n");
2727
2728         switch (bug) {
2729         case X86_BUG_CPU_MELTDOWN:
2730                 if (boot_cpu_has(X86_FEATURE_PTI))
2731                         return sysfs_emit(buf, "Mitigation: PTI\n");
2732
2733                 if (hypervisor_is_type(X86_HYPER_XEN_PV))
2734                         return sysfs_emit(buf, "Unknown (XEN PV detected, hypervisor mitigation required)\n");
2735
2736                 break;
2737
2738         case X86_BUG_SPECTRE_V1:
2739                 return sysfs_emit(buf, "%s\n", spectre_v1_strings[spectre_v1_mitigation]);
2740
2741         case X86_BUG_SPECTRE_V2:
2742                 return spectre_v2_show_state(buf);
2743
2744         case X86_BUG_SPEC_STORE_BYPASS:
2745                 return sysfs_emit(buf, "%s\n", ssb_strings[ssb_mode]);
2746
2747         case X86_BUG_L1TF:
2748                 if (boot_cpu_has(X86_FEATURE_L1TF_PTEINV))
2749                         return l1tf_show_state(buf);
2750                 break;
2751
2752         case X86_BUG_MDS:
2753                 return mds_show_state(buf);
2754
2755         case X86_BUG_TAA:
2756                 return tsx_async_abort_show_state(buf);
2757
2758         case X86_BUG_ITLB_MULTIHIT:
2759                 return itlb_multihit_show_state(buf);
2760
2761         case X86_BUG_SRBDS:
2762                 return srbds_show_state(buf);
2763
2764         case X86_BUG_MMIO_STALE_DATA:
2765         case X86_BUG_MMIO_UNKNOWN:
2766                 return mmio_stale_data_show_state(buf);
2767
2768         case X86_BUG_RETBLEED:
2769                 return retbleed_show_state(buf);
2770
2771         case X86_BUG_SRSO:
2772                 return srso_show_state(buf);
2773
2774         case X86_BUG_GDS:
2775                 return gds_show_state(buf);
2776
2777         default:
2778                 break;
2779         }
2780
2781         return sysfs_emit(buf, "Vulnerable\n");
2782 }
2783
2784 ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
2785 {
2786         return cpu_show_common(dev, attr, buf, X86_BUG_CPU_MELTDOWN);
2787 }
2788
2789 ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf)
2790 {
2791         return cpu_show_common(dev, attr, buf, X86_BUG_SPECTRE_V1);
2792 }
2793
2794 ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
2795 {
2796         return cpu_show_common(dev, attr, buf, X86_BUG_SPECTRE_V2);
2797 }
2798
2799 ssize_t cpu_show_spec_store_bypass(struct device *dev, struct device_attribute *attr, char *buf)
2800 {
2801         return cpu_show_common(dev, attr, buf, X86_BUG_SPEC_STORE_BYPASS);
2802 }
2803
2804 ssize_t cpu_show_l1tf(struct device *dev, struct device_attribute *attr, char *buf)
2805 {
2806         return cpu_show_common(dev, attr, buf, X86_BUG_L1TF);
2807 }
2808
2809 ssize_t cpu_show_mds(struct device *dev, struct device_attribute *attr, char *buf)
2810 {
2811         return cpu_show_common(dev, attr, buf, X86_BUG_MDS);
2812 }
2813
2814 ssize_t cpu_show_tsx_async_abort(struct device *dev, struct device_attribute *attr, char *buf)
2815 {
2816         return cpu_show_common(dev, attr, buf, X86_BUG_TAA);
2817 }
2818
2819 ssize_t cpu_show_itlb_multihit(struct device *dev, struct device_attribute *attr, char *buf)
2820 {
2821         return cpu_show_common(dev, attr, buf, X86_BUG_ITLB_MULTIHIT);
2822 }
2823
2824 ssize_t cpu_show_srbds(struct device *dev, struct device_attribute *attr, char *buf)
2825 {
2826         return cpu_show_common(dev, attr, buf, X86_BUG_SRBDS);
2827 }
2828
2829 ssize_t cpu_show_mmio_stale_data(struct device *dev, struct device_attribute *attr, char *buf)
2830 {
2831         if (boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN))
2832                 return cpu_show_common(dev, attr, buf, X86_BUG_MMIO_UNKNOWN);
2833         else
2834                 return cpu_show_common(dev, attr, buf, X86_BUG_MMIO_STALE_DATA);
2835 }
2836
2837 ssize_t cpu_show_retbleed(struct device *dev, struct device_attribute *attr, char *buf)
2838 {
2839         return cpu_show_common(dev, attr, buf, X86_BUG_RETBLEED);
2840 }
2841
2842 ssize_t cpu_show_spec_rstack_overflow(struct device *dev, struct device_attribute *attr, char *buf)
2843 {
2844         return cpu_show_common(dev, attr, buf, X86_BUG_SRSO);
2845 }
2846
2847 ssize_t cpu_show_gds(struct device *dev, struct device_attribute *attr, char *buf)
2848 {
2849         return cpu_show_common(dev, attr, buf, X86_BUG_GDS);
2850 }
2851 #endif