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         if (!have_cpuid_p())
 126                 return *res;
 127
 128         /*
 129          * CPUID(1).ECX[31]: reserved for hypervisor use. This is still not
 130          * completely accurate as xen pv guests don't see that CPUID bit set but
 131          * that's good enough as they don't land on the BSP path anyway.
 132          */
 133         if (native_cpuid_ecx(1) & BIT(31))
 134                 return *res;
 135
 136         if (x86_cpuid_vendor() == X86_VENDOR_AMD) {
 137                 if (amd_check_current_patch_level())
 138                         return *res;
 139         }
 140
 141         if (cmdline_find_option_bool(cmdline, option) <= 0)
 142                 *res = false;
 143
 144         return *res;
 145 }
 146
 147 extern struct builtin_fw __start_builtin_fw[];
 148 extern struct builtin_fw __end_builtin_fw[];
 149
 150 bool get_builtin_firmware(struct cpio_data *cd, const char *name)
 151 {
 152 #ifdef CONFIG_FW_LOADER
 153         struct builtin_fw *b_fw;
 154
 155         for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++) {
 156                 if (!strcmp(name, b_fw->name)) {
 157                         cd->size = b_fw->size;
 158                         cd->data = b_fw->data;
 159                         return true;
 160                 }
 161         }
 162 #endif
 163         return false;
 164 }
 165
 166 void __init load_ucode_bsp(void)
 167 {
 168         unsigned int cpuid_1_eax;
 169
 170         if (check_loader_disabled_bsp())
 171                 return;
 172
 173         cpuid_1_eax = native_cpuid_eax(1);
 174
 175         switch (x86_cpuid_vendor()) {
 176         case X86_VENDOR_INTEL:
 177                 if (x86_family(cpuid_1_eax) >= 6)
 178                         load_ucode_intel_bsp();
 179                 break;
 180         case X86_VENDOR_AMD:
 181                 if (x86_family(cpuid_1_eax) >= 0x10)
 182                         load_ucode_amd_bsp(cpuid_1_eax);
 183                 break;
 184         default:
 185                 break;
 186         }
 187 }
 188
 189 static bool check_loader_disabled_ap(void)
 190 {
 191 #ifdef CONFIG_X86_32
 192         return *((bool *)__pa_nodebug(&dis_ucode_ldr));
 193 #else
 194         return dis_ucode_ldr;
 195 #endif
 196 }
 197
 198 void load_ucode_ap(void)
 199 {
 200         unsigned int cpuid_1_eax;
 201
 202         if (check_loader_disabled_ap())
 203                 return;
 204
 205         cpuid_1_eax = native_cpuid_eax(1);
 206
 207         switch (x86_cpuid_vendor()) {
 208         case X86_VENDOR_INTEL:
 209                 if (x86_family(cpuid_1_eax) >= 6)
 210                         load_ucode_intel_ap();
 211                 break;
 212         case X86_VENDOR_AMD:
 213                 if (x86_family(cpuid_1_eax) >= 0x10)
 214                         load_ucode_amd_ap(cpuid_1_eax);
 215                 break;
 216         default:
 217                 break;
 218         }
 219 }
 220
 221 static int __init save_microcode_in_initrd(void)
 222 {
 223         struct cpuinfo_x86 *c = &boot_cpu_data;
 224         int ret = -EINVAL;
 225
 226         switch (c->x86_vendor) {
 227         case X86_VENDOR_INTEL:
 228                 if (c->x86 >= 6)
 229                         ret = save_microcode_in_initrd_intel();
 230                 break;
 231         case X86_VENDOR_AMD:
 232                 if (c->x86 >= 0x10)
 233                         return save_microcode_in_initrd_amd(cpuid_eax(1));
 234                 break;
 235         default:
 236                 break;
 237         }
 238
 239         initrd_gone = true;
 240
 241         return ret;
 242 }
 243
 244 struct cpio_data find_microcode_in_initrd(const char *path, bool use_pa)
 245 {
 246 #ifdef CONFIG_BLK_DEV_INITRD
 247         unsigned long start = 0;
 248         size_t size;
 249
 250 #ifdef CONFIG_X86_32
 251         struct boot_params *params;
 252
 253         if (use_pa)
 254                 params = (struct boot_params *)__pa_nodebug(&boot_params);
 255         else
 256                 params = &boot_params;
 257
 258         size = params->hdr.ramdisk_size;
 259
 260         /*
 261          * Set start only if we have an initrd image. We cannot use initrd_start
 262          * because it is not set that early yet.
 263          */
 264         if (size)
 265                 start = params->hdr.ramdisk_image;
 266
 267 # else /* CONFIG_X86_64 */
 268         size  = (unsigned long)boot_params.ext_ramdisk_size << 32;
 269         size |= boot_params.hdr.ramdisk_size;
 270
 271         if (size) {
 272                 start  = (unsigned long)boot_params.ext_ramdisk_image << 32;
 273                 start |= boot_params.hdr.ramdisk_image;
 274
 275                 start += PAGE_OFFSET;
 276         }
 277 # endif
 278
 279         /*
 280          * Fixup the start address: after reserve_initrd() runs, initrd_start
 281          * has the virtual address of the beginning of the initrd. It also
 282          * possibly relocates the ramdisk. In either case, initrd_start contains
 283          * the updated address so use that instead.
 284          *
 285          * initrd_gone is for the hotplug case where we've thrown out initrd
 286          * already.
 287          */
 288         if (!use_pa) {
 289                 if (initrd_gone)
 290                         return (struct cpio_data){ NULL, 0, "" };
 291                 if (initrd_start)
 292                         start = initrd_start;
 293         } else {
 294                 /*
 295                  * The picture with physical addresses is a bit different: we
 296                  * need to get the *physical* address to which the ramdisk was
 297                  * relocated, i.e., relocated_ramdisk (not initrd_start) and
 298                  * since we're running from physical addresses, we need to access
 299                  * relocated_ramdisk through its *physical* address too.
 300                  */
 301                 u64 *rr = (u64 *)__pa_nodebug(&relocated_ramdisk);
 302                 if (*rr)
 303                         start = *rr;
 304         }
 305
 306         return find_cpio_data(path, (void *)start, size, NULL);
 307 #else /* !CONFIG_BLK_DEV_INITRD */
 308         return (struct cpio_data){ NULL, 0, "" };
 309 #endif
 310 }
 311
 312 void reload_early_microcode(void)
 313 {
 314         int vendor, family;
 315
 316         vendor = x86_cpuid_vendor();
 317         family = x86_cpuid_family();
 318
 319         switch (vendor) {
 320         case X86_VENDOR_INTEL:
 321                 if (family >= 6)
 322                         reload_ucode_intel();
 323                 break;
 324         case X86_VENDOR_AMD:
 325                 if (family >= 0x10)
 326                         reload_ucode_amd();
 327                 break;
 328         default:
 329                 break;
 330         }
 331 }
 332
 333 static void collect_cpu_info_local(void *arg)
 334 {
 335         struct cpu_info_ctx *ctx = arg;
 336
 337         ctx->err = microcode_ops->collect_cpu_info(smp_processor_id(),
 338                                                    ctx->cpu_sig);
 339 }
 340
 341 static int collect_cpu_info_on_target(int cpu, struct cpu_signature *cpu_sig)
 342 {
 343         struct cpu_info_ctx ctx = { .cpu_sig = cpu_sig, .err = 0 };
 344         int ret;
 345
 346         ret = smp_call_function_single(cpu, collect_cpu_info_local, &ctx, 1);
 347         if (!ret)
 348                 ret = ctx.err;
 349
 350         return ret;
 351 }
 352
 353 static int collect_cpu_info(int cpu)
 354 {
 355         struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 356         int ret;
 357
 358         memset(uci, 0, sizeof(*uci));
 359
 360         ret = collect_cpu_info_on_target(cpu, &uci->cpu_sig);
 361         if (!ret)
 362                 uci->valid = 1;
 363
 364         return ret;
 365 }
 366
 367 struct apply_microcode_ctx {
 368         int err;
 369 };
 370
 371 static void apply_microcode_local(void *arg)
 372 {
 373         struct apply_microcode_ctx *ctx = arg;
 374
 375         ctx->err = microcode_ops->apply_microcode(smp_processor_id());
 376 }
 377
 378 static int apply_microcode_on_target(int cpu)
 379 {
 380         struct apply_microcode_ctx ctx = { .err = 0 };
 381         int ret;
 382
 383         ret = smp_call_function_single(cpu, apply_microcode_local, &ctx, 1);
 384         if (!ret)
 385                 ret = ctx.err;
 386
 387         return ret;
 388 }
 389
 390 #ifdef CONFIG_MICROCODE_OLD_INTERFACE
 391 static int do_microcode_update(const void __user *buf, size_t size)
 392 {
 393         int error = 0;
 394         int cpu;
 395
 396         for_each_online_cpu(cpu) {
 397                 struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 398                 enum ucode_state ustate;
 399
 400                 if (!uci->valid)
 401                         continue;
 402
 403                 ustate = microcode_ops->request_microcode_user(cpu, buf, size);
 404                 if (ustate == UCODE_ERROR) {
 405                         error = -1;
 406                         break;
 407                 } else if (ustate == UCODE_OK)
 408                         apply_microcode_on_target(cpu);
 409         }
 410
 411         return error;
 412 }
 413
 414 static int microcode_open(struct inode *inode, struct file *file)
 415 {
 416         return capable(CAP_SYS_RAWIO) ? nonseekable_open(inode, file) : -EPERM;
 417 }
 418
 419 static ssize_t microcode_write(struct file *file, const char __user *buf,
 420                                size_t len, loff_t *ppos)
 421 {
 422         ssize_t ret = -EINVAL;
 423
 424         if ((len >> PAGE_SHIFT) > totalram_pages) {
 425                 pr_err("too much data (max %ld pages)\n", totalram_pages);
 426                 return ret;
 427         }
 428
 429         get_online_cpus();
 430         mutex_lock(&microcode_mutex);
 431
 432         if (do_microcode_update(buf, len) == 0)
 433                 ret = (ssize_t)len;
 434
 435         if (ret > 0)
 436                 perf_check_microcode();
 437
 438         mutex_unlock(&microcode_mutex);
 439         put_online_cpus();
 440
 441         return ret;
 442 }
 443
 444 static const struct file_operations microcode_fops = {
 445         .owner                  = THIS_MODULE,
 446         .write                  = microcode_write,
 447         .open                   = microcode_open,
 448         .llseek         = no_llseek,
 449 };
 450
 451 static struct miscdevice microcode_dev = {
 452         .minor                  = MICROCODE_MINOR,
 453         .name                   = "microcode",
 454         .nodename               = "cpu/microcode",
 455         .fops                   = &microcode_fops,
 456 };
 457
 458 static int __init microcode_dev_init(void)
 459 {
 460         int error;
 461
 462         error = misc_register(&microcode_dev);
 463         if (error) {
 464                 pr_err("can't misc_register on minor=%d\n", MICROCODE_MINOR);
 465                 return error;
 466         }
 467
 468         return 0;
 469 }
 470
 471 static void __exit microcode_dev_exit(void)
 472 {
 473         misc_deregister(&microcode_dev);
 474 }
 475 #else
 476 #define microcode_dev_init()    0
 477 #define microcode_dev_exit()    do { } while (0)
 478 #endif
 479
 480 /* fake device for request_firmware */
 481 static struct platform_device   *microcode_pdev;
 482
 483 static int reload_for_cpu(int cpu)
 484 {
 485         struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 486         enum ucode_state ustate;
 487         int err = 0;
 488
 489         if (!uci->valid)
 490                 return err;
 491
 492         ustate = microcode_ops->request_microcode_fw(cpu, &microcode_pdev->dev, true);
 493         if (ustate == UCODE_OK)
 494                 apply_microcode_on_target(cpu);
 495         else
 496                 if (ustate == UCODE_ERROR)
 497                         err = -EINVAL;
 498         return err;
 499 }
 500
 501 static ssize_t reload_store(struct device *dev,
 502                             struct device_attribute *attr,
 503                             const char *buf, size_t size)
 504 {
 505         unsigned long val;
 506         int cpu;
 507         ssize_t ret = 0, tmp_ret;
 508
 509         ret = kstrtoul(buf, 0, &val);
 510         if (ret)
 511                 return ret;
 512
 513         if (val != 1)
 514                 return size;
 515
 516         get_online_cpus();
 517         mutex_lock(&microcode_mutex);
 518         for_each_online_cpu(cpu) {
 519                 tmp_ret = reload_for_cpu(cpu);
 520                 if (tmp_ret != 0)
 521                         pr_warn("Error reloading microcode on CPU %d\n", cpu);
 522
 523                 /* save retval of the first encountered reload error */
 524                 if (!ret)
 525                         ret = tmp_ret;
 526         }
 527         if (!ret)
 528                 perf_check_microcode();
 529         mutex_unlock(&microcode_mutex);
 530         put_online_cpus();
 531
 532         if (!ret)
 533                 ret = size;
 534
 535         return ret;
 536 }
 537
 538 static ssize_t version_show(struct device *dev,
 539                         struct device_attribute *attr, char *buf)
 540 {
 541         struct ucode_cpu_info *uci = ucode_cpu_info + dev->id;
 542
 543         return sprintf(buf, "0x%x\n", uci->cpu_sig.rev);
 544 }
 545
 546 static ssize_t pf_show(struct device *dev,
 547                         struct device_attribute *attr, char *buf)
 548 {
 549         struct ucode_cpu_info *uci = ucode_cpu_info + dev->id;
 550
 551         return sprintf(buf, "0x%x\n", uci->cpu_sig.pf);
 552 }
 553
 554 static DEVICE_ATTR(reload, 0200, NULL, reload_store);
 555 static DEVICE_ATTR(version, 0400, version_show, NULL);
 556 static DEVICE_ATTR(processor_flags, 0400, pf_show, NULL);
 557
 558 static struct attribute *mc_default_attrs[] = {
 559         &dev_attr_version.attr,
 560         &dev_attr_processor_flags.attr,
 561         NULL
 562 };
 563
 564 static struct attribute_group mc_attr_group = {
 565         .attrs                  = mc_default_attrs,
 566         .name                   = "microcode",
 567 };
 568
 569 static void microcode_fini_cpu(int cpu)
 570 {
 571         if (microcode_ops->microcode_fini_cpu)
 572                 microcode_ops->microcode_fini_cpu(cpu);
 573 }
 574
 575 static enum ucode_state microcode_resume_cpu(int cpu)
 576 {
 577         if (apply_microcode_on_target(cpu))
 578                 return UCODE_ERROR;
 579
 580         pr_debug("CPU%d updated upon resume\n", cpu);
 581
 582         return UCODE_OK;
 583 }
 584
 585 static enum ucode_state microcode_init_cpu(int cpu, bool refresh_fw)
 586 {
 587         enum ucode_state ustate;
 588         struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 589
 590         if (uci->valid)
 591                 return UCODE_OK;
 592
 593         if (collect_cpu_info(cpu))
 594                 return UCODE_ERROR;
 595
 596         /* --dimm. Trigger a delayed update? */
 597         if (system_state != SYSTEM_RUNNING)
 598                 return UCODE_NFOUND;
 599
 600         ustate = microcode_ops->request_microcode_fw(cpu, &microcode_pdev->dev,
 601                                                      refresh_fw);
 602
 603         if (ustate == UCODE_OK) {
 604                 pr_debug("CPU%d updated upon init\n", cpu);
 605                 apply_microcode_on_target(cpu);
 606         }
 607
 608         return ustate;
 609 }
 610
 611 static enum ucode_state microcode_update_cpu(int cpu)
 612 {
 613         struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 614
 615         /* Refresh CPU microcode revision after resume. */
 616         collect_cpu_info(cpu);
 617
 618         if (uci->valid)
 619                 return microcode_resume_cpu(cpu);
 620
 621         return microcode_init_cpu(cpu, false);
 622 }
 623
 624 static int mc_device_add(struct device *dev, struct subsys_interface *sif)
 625 {
 626         int err, cpu = dev->id;
 627
 628         if (!cpu_online(cpu))
 629                 return 0;
 630
 631         pr_debug("CPU%d added\n", cpu);
 632
 633         err = sysfs_create_group(&dev->kobj, &mc_attr_group);
 634         if (err)
 635                 return err;
 636
 637         if (microcode_init_cpu(cpu, true) == UCODE_ERROR)
 638                 return -EINVAL;
 639
 640         return err;
 641 }
 642
 643 static void mc_device_remove(struct device *dev, struct subsys_interface *sif)
 644 {
 645         int cpu = dev->id;
 646
 647         if (!cpu_online(cpu))
 648                 return;
 649
 650         pr_debug("CPU%d removed\n", cpu);
 651         microcode_fini_cpu(cpu);
 652         sysfs_remove_group(&dev->kobj, &mc_attr_group);
 653 }
 654
 655 static struct subsys_interface mc_cpu_interface = {
 656         .name                   = "microcode",
 657         .subsys                 = &cpu_subsys,
 658         .add_dev                = mc_device_add,
 659         .remove_dev             = mc_device_remove,
 660 };
 661
 662 /**
 663  * mc_bp_resume - Update boot CPU microcode during resume.
 664  */
 665 static void mc_bp_resume(void)
 666 {
 667         int cpu = smp_processor_id();
 668         struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 669
 670         if (uci->valid && uci->mc)
 671                 microcode_ops->apply_microcode(cpu);
 672         else if (!uci->mc)
 673                 reload_early_microcode();
 674 }
 675
 676 static struct syscore_ops mc_syscore_ops = {
 677         .resume                 = mc_bp_resume,
 678 };
 679
 680 static int mc_cpu_online(unsigned int cpu)
 681 {
 682         struct device *dev;
 683
 684         dev = get_cpu_device(cpu);
 685         microcode_update_cpu(cpu);
 686         pr_debug("CPU%d added\n", cpu);
 687
 688         if (sysfs_create_group(&dev->kobj, &mc_attr_group))
 689                 pr_err("Failed to create group for CPU%d\n", cpu);
 690         return 0;
 691 }
 692
 693 static int mc_cpu_down_prep(unsigned int cpu)
 694 {
 695         struct device *dev;
 696
 697         dev = get_cpu_device(cpu);
 698         /* Suspend is in progress, only remove the interface */
 699         sysfs_remove_group(&dev->kobj, &mc_attr_group);
 700         pr_debug("CPU%d removed\n", cpu);
 701
 702         return 0;
 703 }
 704
 705 static struct attribute *cpu_root_microcode_attrs[] = {
 706         &dev_attr_reload.attr,
 707         NULL
 708 };
 709
 710 static struct attribute_group cpu_root_microcode_group = {
 711         .name  = "microcode",
 712         .attrs = cpu_root_microcode_attrs,
 713 };
 714
 715 int __init microcode_init(void)
 716 {
 717         struct cpuinfo_x86 *c = &boot_cpu_data;
 718         int error;
 719
 720         if (dis_ucode_ldr)
 721                 return -EINVAL;
 722
 723         if (c->x86_vendor == X86_VENDOR_INTEL)
 724                 microcode_ops = init_intel_microcode();
 725         else if (c->x86_vendor == X86_VENDOR_AMD)
 726                 microcode_ops = init_amd_microcode();
 727         else
 728                 pr_err("no support for this CPU vendor\n");
 729
 730         if (!microcode_ops)
 731                 return -ENODEV;
 732
 733         microcode_pdev = platform_device_register_simple("microcode", -1,
 734                                                          NULL, 0);
 735         if (IS_ERR(microcode_pdev))
 736                 return PTR_ERR(microcode_pdev);
 737
 738         get_online_cpus();
 739         mutex_lock(&microcode_mutex);
 740
 741         error = subsys_interface_register(&mc_cpu_interface);
 742         if (!error)
 743                 perf_check_microcode();
 744         mutex_unlock(&microcode_mutex);
 745         put_online_cpus();
 746
 747         if (error)
 748                 goto out_pdev;
 749
 750         error = sysfs_create_group(&cpu_subsys.dev_root->kobj,
 751                                    &cpu_root_microcode_group);
 752
 753         if (error) {
 754                 pr_err("Error creating microcode group!\n");
 755                 goto out_driver;
 756         }
 757
 758         error = microcode_dev_init();
 759         if (error)
 760                 goto out_ucode_group;
 761
 762         register_syscore_ops(&mc_syscore_ops);
 763         cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/microcode:online",
 764                                   mc_cpu_online, mc_cpu_down_prep);
 765
 766         pr_info("Microcode Update Driver: v%s.", DRIVER_VERSION);
 767
 768         return 0;
 769
 770  out_ucode_group:
 771         sysfs_remove_group(&cpu_subsys.dev_root->kobj,
 772                            &cpu_root_microcode_group);
 773
 774  out_driver:
 775         get_online_cpus();
 776         mutex_lock(&microcode_mutex);
 777
 778         subsys_interface_unregister(&mc_cpu_interface);
 779
 780         mutex_unlock(&microcode_mutex);
 781         put_online_cpus();
 782
 783  out_pdev:
 784         platform_device_unregister(microcode_pdev);
 785         return error;
 786
 787 }
 788 fs_initcall(save_microcode_in_initrd);
 789 late_initcall(microcode_init);