arch/x86/kernel/cpu/microcode/core.c

   1 /*
   2  * CPU Microcode Update Driver for Linux
   3  *
   4  * Copyright (C) 2000-2006 Tigran Aivazian <aivazian.tigran@gmail.com>
   5  *            2006      Shaohua Li <shaohua.li@intel.com>
   6  *            2013-2016 Borislav Petkov <bp@alien8.de>
   7  *
   8  * X86 CPU microcode early update for Linux:
   9  *
  10  *      Copyright (C) 2012 Fenghua Yu <fenghua.yu@intel.com>
  11  *                         H Peter Anvin" <hpa@zytor.com>
  12  *                (C) 2015 Borislav Petkov <bp@alien8.de>
  13  *
  14  * This driver allows to upgrade microcode on x86 processors.
  15  *
  16  * This program is free software; you can redistribute it and/or
  17  * modify it under the terms of the GNU General Public License
  18  * as published by the Free Software Foundation; either version
  19  * 2 of the License, or (at your option) any later version.
  20  */
  21
  22 #define pr_fmt(fmt) "microcode: " fmt
  23
  24 #include <linux/platform_device.h>
  25 #include <linux/syscore_ops.h>
  26 #include <linux/miscdevice.h>
  27 #include <linux/capability.h>
  28 #include <linux/firmware.h>
  29 #include <linux/kernel.h>
  30 #include <linux/mutex.h>
  31 #include <linux/cpu.h>
  32 #include <linux/fs.h>
  33 #include <linux/mm.h>
  34
  35 #include <asm/microcode_intel.h>
  36 #include <asm/cpu_device_id.h>
  37 #include <asm/microcode_amd.h>
  38 #include <asm/perf_event.h>
  39 #include <asm/microcode.h>
  40 #include <asm/processor.h>
  41 #include <asm/cmdline.h>
  42 #include <asm/setup.h>
  43
  44 #define DRIVER_VERSION  "2.2"
  45
  46 static struct microcode_ops     *microcode_ops;
  47 static bool dis_ucode_ldr = true;
  48
  49 bool initrd_gone;
  50
  51 LIST_HEAD(microcode_cache);
  52
  53 /*
  54  * Synchronization.
  55  *
  56  * All non cpu-hotplug-callback call sites use:
  57  *
  58  * - microcode_mutex to synchronize with each other;
  59  * - get/put_online_cpus() to synchronize with
  60  *   the cpu-hotplug-callback call sites.
  61  *
  62  * We guarantee that only a single cpu is being
  63  * updated at any particular moment of time.
  64  */
  65 static DEFINE_MUTEX(microcode_mutex);
  66
  67 struct ucode_cpu_info           ucode_cpu_info[NR_CPUS];
  68
  69 struct cpu_info_ctx {
  70         struct cpu_signature    *cpu_sig;
  71         int                     err;
  72 };
  73
  74 /*
  75  * Those patch levels cannot be updated to newer ones and thus should be final.
  76  */
  77 static u32 final_levels[] = {
  78         0x01000098,
  79         0x0100009f,
  80         0x010000af,
  81         0, /* T-101 terminator */
  82 };
  83
  84 /*
  85  * Check the current patch level on this CPU.
  86  *
  87  * Returns:
  88  *  - true: if update should stop
  89  *  - false: otherwise
  90  */
  91 static bool amd_check_current_patch_level(void)
  92 {
  93         u32 lvl, dummy, i;
  94         u32 *levels;
  95
  96         native_rdmsr(MSR_AMD64_PATCH_LEVEL, lvl, dummy);
  97
  98         if (IS_ENABLED(CONFIG_X86_32))
  99                 levels = (u32 *)__pa_nodebug(&final_levels);
 100         else
 101                 levels = final_levels;
 102
 103         for (i = 0; levels[i]; i++) {
 104                 if (lvl == levels[i])
 105                         return true;
 106         }
 107         return false;
 108 }
 109
 110 static bool __init check_loader_disabled_bsp(void)
 111 {
 112         static const char *__dis_opt_str = "dis_ucode_ldr";
 113
 114 #ifdef CONFIG_X86_32
 115         const char *cmdline = (const char *)__pa_nodebug(boot_command_line);
 116         const char *option  = (const char *)__pa_nodebug(__dis_opt_str);
 117         bool *res = (bool *)__pa_nodebug(&dis_ucode_ldr);
 118
 119 #else /* CONFIG_X86_64 */
 120         const char *cmdline = boot_command_line;
 121         const char *option  = __dis_opt_str;
 122         bool *res = &dis_ucode_ldr;
 123 #endif
 124
 125         /*
 126          * CPUID(1).ECX[31]: reserved for hypervisor use. This is still not
 127          * completely accurate as xen pv guests don't see that CPUID bit set but
 128          * that's good enough as they don't land on the BSP path anyway.
 129          */
 130         if (native_cpuid_ecx(1) & BIT(31))
 131                 return *res;
 132
 133         if (x86_cpuid_vendor() == X86_VENDOR_AMD) {
 134                 if (amd_check_current_patch_level())
 135                         return *res;
 136         }
 137
 138         if (cmdline_find_option_bool(cmdline, option) <= 0)
 139                 *res = false;
 140
 141         return *res;
 142 }
 143
 144 extern struct builtin_fw __start_builtin_fw[];
 145 extern struct builtin_fw __end_builtin_fw[];
 146
 147 bool get_builtin_firmware(struct cpio_data *cd, const char *name)
 148 {
 149 #ifdef CONFIG_FW_LOADER
 150         struct builtin_fw *b_fw;
 151
 152         for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++) {
 153                 if (!strcmp(name, b_fw->name)) {
 154                         cd->size = b_fw->size;
 155                         cd->data = b_fw->data;
 156                         return true;
 157                 }
 158         }
 159 #endif
 160         return false;
 161 }
 162
 163 void __init load_ucode_bsp(void)
 164 {
 165         unsigned int cpuid_1_eax;
 166         bool intel = true;
 167
 168         if (!have_cpuid_p())
 169                 return;
 170
 171         cpuid_1_eax = native_cpuid_eax(1);
 172
 173         switch (x86_cpuid_vendor()) {
 174         case X86_VENDOR_INTEL:
 175                 if (x86_family(cpuid_1_eax) < 6)
 176                         return;
 177                 break;
 178
 179         case X86_VENDOR_AMD:
 180                 if (x86_family(cpuid_1_eax) < 0x10)
 181                         return;
 182                 intel = false;
 183                 break;
 184
 185         default:
 186                 return;
 187         }
 188
 189         if (check_loader_disabled_bsp())
 190                 return;
 191
 192         if (intel)
 193                 load_ucode_intel_bsp();
 194         else
 195                 load_ucode_amd_bsp(cpuid_1_eax);
 196 }
 197
 198 static bool check_loader_disabled_ap(void)
 199 {
 200 #ifdef CONFIG_X86_32
 201         return *((bool *)__pa_nodebug(&dis_ucode_ldr));
 202 #else
 203         return dis_ucode_ldr;
 204 #endif
 205 }
 206
 207 void load_ucode_ap(void)
 208 {
 209         unsigned int cpuid_1_eax;
 210
 211         if (check_loader_disabled_ap())
 212                 return;
 213
 214         cpuid_1_eax = native_cpuid_eax(1);
 215
 216         switch (x86_cpuid_vendor()) {
 217         case X86_VENDOR_INTEL:
 218                 if (x86_family(cpuid_1_eax) >= 6)
 219                         load_ucode_intel_ap();
 220                 break;
 221         case X86_VENDOR_AMD:
 222                 if (x86_family(cpuid_1_eax) >= 0x10)
 223                         load_ucode_amd_ap(cpuid_1_eax);
 224                 break;
 225         default:
 226                 break;
 227         }
 228 }
 229
 230 static int __init save_microcode_in_initrd(void)
 231 {
 232         struct cpuinfo_x86 *c = &boot_cpu_data;
 233         int ret = -EINVAL;
 234
 235         switch (c->x86_vendor) {
 236         case X86_VENDOR_INTEL:
 237                 if (c->x86 >= 6)
 238                         ret = save_microcode_in_initrd_intel();
 239                 break;
 240         case X86_VENDOR_AMD:
 241                 if (c->x86 >= 0x10)
 242                         ret = save_microcode_in_initrd_amd(cpuid_eax(1));
 243                 break;
 244         default:
 245                 break;
 246         }
 247
 248         initrd_gone = true;
 249
 250         return ret;
 251 }
 252
 253 struct cpio_data find_microcode_in_initrd(const char *path, bool use_pa)
 254 {
 255 #ifdef CONFIG_BLK_DEV_INITRD
 256         unsigned long start = 0;
 257         size_t size;
 258
 259 #ifdef CONFIG_X86_32
 260         struct boot_params *params;
 261
 262         if (use_pa)
 263                 params = (struct boot_params *)__pa_nodebug(&boot_params);
 264         else
 265                 params = &boot_params;
 266
 267         size = params->hdr.ramdisk_size;
 268
 269         /*
 270          * Set start only if we have an initrd image. We cannot use initrd_start
 271          * because it is not set that early yet.
 272          */
 273         if (size)
 274                 start = params->hdr.ramdisk_image;
 275
 276 # else /* CONFIG_X86_64 */
 277         size  = (unsigned long)boot_params.ext_ramdisk_size << 32;
 278         size |= boot_params.hdr.ramdisk_size;
 279
 280         if (size) {
 281                 start  = (unsigned long)boot_params.ext_ramdisk_image << 32;
 282                 start |= boot_params.hdr.ramdisk_image;
 283
 284                 start += PAGE_OFFSET;
 285         }
 286 # endif
 287
 288         /*
 289          * Fixup the start address: after reserve_initrd() runs, initrd_start
 290          * has the virtual address of the beginning of the initrd. It also
 291          * possibly relocates the ramdisk. In either case, initrd_start contains
 292          * the updated address so use that instead.
 293          *
 294          * initrd_gone is for the hotplug case where we've thrown out initrd
 295          * already.
 296          */
 297         if (!use_pa) {
 298                 if (initrd_gone)
 299                         return (struct cpio_data){ NULL, 0, "" };
 300                 if (initrd_start)
 301                         start = initrd_start;
 302         } else {
 303                 /*
 304                  * The picture with physical addresses is a bit different: we
 305                  * need to get the *physical* address to which the ramdisk was
 306                  * relocated, i.e., relocated_ramdisk (not initrd_start) and
 307                  * since we're running from physical addresses, we need to access
 308                  * relocated_ramdisk through its *physical* address too.
 309                  */
 310                 u64 *rr = (u64 *)__pa_nodebug(&relocated_ramdisk);
 311                 if (*rr)
 312                         start = *rr;
 313         }
 314
 315         return find_cpio_data(path, (void *)start, size, NULL);
 316 #else /* !CONFIG_BLK_DEV_INITRD */
 317         return (struct cpio_data){ NULL, 0, "" };
 318 #endif
 319 }
 320
 321 void reload_early_microcode(void)
 322 {
 323         int vendor, family;
 324
 325         vendor = x86_cpuid_vendor();
 326         family = x86_cpuid_family();
 327
 328         switch (vendor) {
 329         case X86_VENDOR_INTEL:
 330                 if (family >= 6)
 331                         reload_ucode_intel();
 332                 break;
 333         case X86_VENDOR_AMD:
 334                 if (family >= 0x10)
 335                         reload_ucode_amd();
 336                 break;
 337         default:
 338                 break;
 339         }
 340 }
 341
 342 static void collect_cpu_info_local(void *arg)
 343 {
 344         struct cpu_info_ctx *ctx = arg;
 345
 346         ctx->err = microcode_ops->collect_cpu_info(smp_processor_id(),
 347                                                    ctx->cpu_sig);
 348 }
 349
 350 static int collect_cpu_info_on_target(int cpu, struct cpu_signature *cpu_sig)
 351 {
 352         struct cpu_info_ctx ctx = { .cpu_sig = cpu_sig, .err = 0 };
 353         int ret;
 354
 355         ret = smp_call_function_single(cpu, collect_cpu_info_local, &ctx, 1);
 356         if (!ret)
 357                 ret = ctx.err;
 358
 359         return ret;
 360 }
 361
 362 static int collect_cpu_info(int cpu)
 363 {
 364         struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 365         int ret;
 366
 367         memset(uci, 0, sizeof(*uci));
 368
 369         ret = collect_cpu_info_on_target(cpu, &uci->cpu_sig);
 370         if (!ret)
 371                 uci->valid = 1;
 372
 373         return ret;
 374 }
 375
 376 struct apply_microcode_ctx {
 377         int err;
 378 };
 379
 380 static void apply_microcode_local(void *arg)
 381 {
 382         struct apply_microcode_ctx *ctx = arg;
 383
 384         ctx->err = microcode_ops->apply_microcode(smp_processor_id());
 385 }
 386
 387 static int apply_microcode_on_target(int cpu)
 388 {
 389         struct apply_microcode_ctx ctx = { .err = 0 };
 390         int ret;
 391
 392         ret = smp_call_function_single(cpu, apply_microcode_local, &ctx, 1);
 393         if (!ret)
 394                 ret = ctx.err;
 395
 396         return ret;
 397 }
 398
 399 #ifdef CONFIG_MICROCODE_OLD_INTERFACE
 400 static int do_microcode_update(const void __user *buf, size_t size)
 401 {
 402         int error = 0;
 403         int cpu;
 404
 405         for_each_online_cpu(cpu) {
 406                 struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 407                 enum ucode_state ustate;
 408
 409                 if (!uci->valid)
 410                         continue;
 411
 412                 ustate = microcode_ops->request_microcode_user(cpu, buf, size);
 413                 if (ustate == UCODE_ERROR) {
 414                         error = -1;
 415                         break;
 416                 } else if (ustate == UCODE_OK)
 417                         apply_microcode_on_target(cpu);
 418         }
 419
 420         return error;
 421 }
 422
 423 static int microcode_open(struct inode *inode, struct file *file)
 424 {
 425         return capable(CAP_SYS_RAWIO) ? nonseekable_open(inode, file) : -EPERM;
 426 }
 427
 428 static ssize_t microcode_write(struct file *file, const char __user *buf,
 429                                size_t len, loff_t *ppos)
 430 {
 431         ssize_t ret = -EINVAL;
 432
 433         if ((len >> PAGE_SHIFT) > totalram_pages) {
 434                 pr_err("too much data (max %ld pages)\n", totalram_pages);
 435                 return ret;
 436         }
 437
 438         get_online_cpus();
 439         mutex_lock(&microcode_mutex);
 440
 441         if (do_microcode_update(buf, len) == 0)
 442                 ret = (ssize_t)len;
 443
 444         if (ret > 0)
 445                 perf_check_microcode();
 446
 447         mutex_unlock(&microcode_mutex);
 448         put_online_cpus();
 449
 450         return ret;
 451 }
 452
 453 static const struct file_operations microcode_fops = {
 454         .owner                  = THIS_MODULE,
 455         .write                  = microcode_write,
 456         .open                   = microcode_open,
 457         .llseek         = no_llseek,
 458 };
 459
 460 static struct miscdevice microcode_dev = {
 461         .minor                  = MICROCODE_MINOR,
 462         .name                   = "microcode",
 463         .nodename               = "cpu/microcode",
 464         .fops                   = &microcode_fops,
 465 };
 466
 467 static int __init microcode_dev_init(void)
 468 {
 469         int error;
 470
 471         error = misc_register(&microcode_dev);
 472         if (error) {
 473                 pr_err("can't misc_register on minor=%d\n", MICROCODE_MINOR);
 474                 return error;
 475         }
 476
 477         return 0;
 478 }
 479
 480 static void __exit microcode_dev_exit(void)
 481 {
 482         misc_deregister(&microcode_dev);
 483 }
 484 #else
 485 #define microcode_dev_init()    0
 486 #define microcode_dev_exit()    do { } while (0)
 487 #endif
 488
 489 /* fake device for request_firmware */
 490 static struct platform_device   *microcode_pdev;
 491
 492 static int reload_for_cpu(int cpu)
 493 {
 494         struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 495         enum ucode_state ustate;
 496         int err = 0;
 497
 498         if (!uci->valid)
 499                 return err;
 500
 501         ustate = microcode_ops->request_microcode_fw(cpu, &microcode_pdev->dev, true);
 502         if (ustate == UCODE_OK)
 503                 apply_microcode_on_target(cpu);
 504         else
 505                 if (ustate == UCODE_ERROR)
 506                         err = -EINVAL;
 507         return err;
 508 }
 509
 510 static ssize_t reload_store(struct device *dev,
 511                             struct device_attribute *attr,
 512                             const char *buf, size_t size)
 513 {
 514         unsigned long val;
 515         int cpu;
 516         ssize_t ret = 0, tmp_ret;
 517
 518         ret = kstrtoul(buf, 0, &val);
 519         if (ret)
 520                 return ret;
 521
 522         if (val != 1)
 523                 return size;
 524
 525         get_online_cpus();
 526         mutex_lock(&microcode_mutex);
 527         for_each_online_cpu(cpu) {
 528                 tmp_ret = reload_for_cpu(cpu);
 529                 if (tmp_ret != 0)
 530                         pr_warn("Error reloading microcode on CPU %d\n", cpu);
 531
 532                 /* save retval of the first encountered reload error */
 533                 if (!ret)
 534                         ret = tmp_ret;
 535         }
 536         if (!ret)
 537                 perf_check_microcode();
 538         mutex_unlock(&microcode_mutex);
 539         put_online_cpus();
 540
 541         if (!ret)
 542                 ret = size;
 543
 544         return ret;
 545 }
 546
 547 static ssize_t version_show(struct device *dev,
 548                         struct device_attribute *attr, char *buf)
 549 {
 550         struct ucode_cpu_info *uci = ucode_cpu_info + dev->id;
 551
 552         return sprintf(buf, "0x%x\n", uci->cpu_sig.rev);
 553 }
 554
 555 static ssize_t pf_show(struct device *dev,
 556                         struct device_attribute *attr, char *buf)
 557 {
 558         struct ucode_cpu_info *uci = ucode_cpu_info + dev->id;
 559
 560         return sprintf(buf, "0x%x\n", uci->cpu_sig.pf);
 561 }
 562
 563 static DEVICE_ATTR_WO(reload);
 564 static DEVICE_ATTR(version, 0400, version_show, NULL);
 565 static DEVICE_ATTR(processor_flags, 0400, pf_show, NULL);
 566
 567 static struct attribute *mc_default_attrs[] = {
 568         &dev_attr_version.attr,
 569         &dev_attr_processor_flags.attr,
 570         NULL
 571 };
 572
 573 static const struct attribute_group mc_attr_group = {
 574         .attrs                  = mc_default_attrs,
 575         .name                   = "microcode",
 576 };
 577
 578 static void microcode_fini_cpu(int cpu)
 579 {
 580         if (microcode_ops->microcode_fini_cpu)
 581                 microcode_ops->microcode_fini_cpu(cpu);
 582 }
 583
 584 static enum ucode_state microcode_resume_cpu(int cpu)
 585 {
 586         if (apply_microcode_on_target(cpu))
 587                 return UCODE_ERROR;
 588
 589         pr_debug("CPU%d updated upon resume\n", cpu);
 590
 591         return UCODE_OK;
 592 }
 593
 594 static enum ucode_state microcode_init_cpu(int cpu, bool refresh_fw)
 595 {
 596         enum ucode_state ustate;
 597         struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 598
 599         if (uci->valid)
 600                 return UCODE_OK;
 601
 602         if (collect_cpu_info(cpu))
 603                 return UCODE_ERROR;
 604
 605         /* --dimm. Trigger a delayed update? */
 606         if (system_state != SYSTEM_RUNNING)
 607                 return UCODE_NFOUND;
 608
 609         ustate = microcode_ops->request_microcode_fw(cpu, &microcode_pdev->dev,
 610                                                      refresh_fw);
 611
 612         if (ustate == UCODE_OK) {
 613                 pr_debug("CPU%d updated upon init\n", cpu);
 614                 apply_microcode_on_target(cpu);
 615         }
 616
 617         return ustate;
 618 }
 619
 620 static enum ucode_state microcode_update_cpu(int cpu)
 621 {
 622         struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 623
 624         /* Refresh CPU microcode revision after resume. */
 625         collect_cpu_info(cpu);
 626
 627         if (uci->valid)
 628                 return microcode_resume_cpu(cpu);
 629
 630         return microcode_init_cpu(cpu, false);
 631 }
 632
 633 static int mc_device_add(struct device *dev, struct subsys_interface *sif)
 634 {
 635         int err, cpu = dev->id;
 636
 637         if (!cpu_online(cpu))
 638                 return 0;
 639
 640         pr_debug("CPU%d added\n", cpu);
 641
 642         err = sysfs_create_group(&dev->kobj, &mc_attr_group);
 643         if (err)
 644                 return err;
 645
 646         if (microcode_init_cpu(cpu, true) == UCODE_ERROR)
 647                 return -EINVAL;
 648
 649         return err;
 650 }
 651
 652 static void mc_device_remove(struct device *dev, struct subsys_interface *sif)
 653 {
 654         int cpu = dev->id;
 655
 656         if (!cpu_online(cpu))
 657                 return;
 658
 659         pr_debug("CPU%d removed\n", cpu);
 660         microcode_fini_cpu(cpu);
 661         sysfs_remove_group(&dev->kobj, &mc_attr_group);
 662 }
 663
 664 static struct subsys_interface mc_cpu_interface = {
 665         .name                   = "microcode",
 666         .subsys                 = &cpu_subsys,
 667         .add_dev                = mc_device_add,
 668         .remove_dev             = mc_device_remove,
 669 };
 670
 671 /**
 672  * mc_bp_resume - Update boot CPU microcode during resume.
 673  */
 674 static void mc_bp_resume(void)
 675 {
 676         int cpu = smp_processor_id();
 677         struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 678
 679         if (uci->valid && uci->mc)
 680                 microcode_ops->apply_microcode(cpu);
 681         else if (!uci->mc)
 682                 reload_early_microcode();
 683 }
 684
 685 static struct syscore_ops mc_syscore_ops = {
 686         .resume                 = mc_bp_resume,
 687 };
 688
 689 static int mc_cpu_online(unsigned int cpu)
 690 {
 691         struct device *dev;
 692
 693         dev = get_cpu_device(cpu);
 694         microcode_update_cpu(cpu);
 695         pr_debug("CPU%d added\n", cpu);
 696
 697         if (sysfs_create_group(&dev->kobj, &mc_attr_group))
 698                 pr_err("Failed to create group for CPU%d\n", cpu);
 699         return 0;
 700 }
 701
 702 static int mc_cpu_down_prep(unsigned int cpu)
 703 {
 704         struct device *dev;
 705
 706         dev = get_cpu_device(cpu);
 707         /* Suspend is in progress, only remove the interface */
 708         sysfs_remove_group(&dev->kobj, &mc_attr_group);
 709         pr_debug("CPU%d removed\n", cpu);
 710
 711         return 0;
 712 }
 713
 714 static struct attribute *cpu_root_microcode_attrs[] = {
 715         &dev_attr_reload.attr,
 716         NULL
 717 };
 718
 719 static const struct attribute_group cpu_root_microcode_group = {
 720         .name  = "microcode",
 721         .attrs = cpu_root_microcode_attrs,
 722 };
 723
 724 int __init microcode_init(void)
 725 {
 726         struct cpuinfo_x86 *c = &boot_cpu_data;
 727         int error;
 728
 729         if (dis_ucode_ldr)
 730                 return -EINVAL;
 731
 732         if (c->x86_vendor == X86_VENDOR_INTEL)
 733                 microcode_ops = init_intel_microcode();
 734         else if (c->x86_vendor == X86_VENDOR_AMD)
 735                 microcode_ops = init_amd_microcode();
 736         else
 737                 pr_err("no support for this CPU vendor\n");
 738
 739         if (!microcode_ops)
 740                 return -ENODEV;
 741
 742         microcode_pdev = platform_device_register_simple("microcode", -1,
 743                                                          NULL, 0);
 744         if (IS_ERR(microcode_pdev))
 745                 return PTR_ERR(microcode_pdev);
 746
 747         get_online_cpus();
 748         mutex_lock(&microcode_mutex);
 749
 750         error = subsys_interface_register(&mc_cpu_interface);
 751         if (!error)
 752                 perf_check_microcode();
 753         mutex_unlock(&microcode_mutex);
 754         put_online_cpus();
 755
 756         if (error)
 757                 goto out_pdev;
 758
 759         error = sysfs_create_group(&cpu_subsys.dev_root->kobj,
 760                                    &cpu_root_microcode_group);
 761
 762         if (error) {
 763                 pr_err("Error creating microcode group!\n");
 764                 goto out_driver;
 765         }
 766
 767         error = microcode_dev_init();
 768         if (error)
 769                 goto out_ucode_group;
 770
 771         register_syscore_ops(&mc_syscore_ops);
 772         cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/microcode:online",
 773                                   mc_cpu_online, mc_cpu_down_prep);
 774
 775         pr_info("Microcode Update Driver: v%s.", DRIVER_VERSION);
 776
 777         return 0;
 778
 779  out_ucode_group:
 780         sysfs_remove_group(&cpu_subsys.dev_root->kobj,
 781                            &cpu_root_microcode_group);
 782
 783  out_driver:
 784         get_online_cpus();
 785         mutex_lock(&microcode_mutex);
 786
 787         subsys_interface_unregister(&mc_cpu_interface);
 788
 789         mutex_unlock(&microcode_mutex);
 790         put_online_cpus();
 791
 792  out_pdev:
 793         platform_device_unregister(microcode_pdev);
 794         return error;
 795
 796 }
 797 fs_initcall(save_microcode_in_initrd);
 798 late_initcall(microcode_init);