/*
 * CPU Microcode Update Driver for Linux
 *
 * Copyright (C) 2000-2006 Tigran Aivazian <aivazian.tigran@gmail.com>
 *            2006      Shaohua Li <shaohua.li@intel.com>
 *            2013-2016 Borislav Petkov <bp@alien8.de>
 *
 * X86 CPU microcode early update for Linux:
 *
 *      Copyright (C) 2012 Fenghua Yu <fenghua.yu@intel.com>
 *                         H Peter Anvin" <hpa@zytor.com>
 *                (C) 2015 Borislav Petkov <bp@alien8.de>
 *
 * This driver allows to upgrade microcode on x86 processors.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#define pr_fmt(fmt) "microcode: " fmt

#include <linux/platform_device.h>
#include <linux/stop_machine.h>
#include <linux/syscore_ops.h>
#include <linux/miscdevice.h>
#include <linux/capability.h>
#include <linux/firmware.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/mutex.h>
#include <linux/cpu.h>
#include <linux/nmi.h>
#include <linux/fs.h>
#include <linux/mm.h>

#include <asm/microcode_intel.h>
#include <asm/cpu_device_id.h>
#include <asm/microcode_amd.h>
#include <asm/perf_event.h>
#include <asm/microcode.h>
#include <asm/processor.h>
#include <asm/cmdline.h>
#include <asm/setup.h>

#define DRIVER_VERSION  "2.2"

static struct microcode_ops     *microcode_ops;
static bool dis_ucode_ldr = true;

bool initrd_gone;

LIST_HEAD(microcode_cache);

/*
 * Synchronization.
 *
 * All non cpu-hotplug-callback call sites use:
 *
 * - microcode_mutex to synchronize with each other;
 * - get/put_online_cpus() to synchronize with
 *   the cpu-hotplug-callback call sites.
 *
 * We guarantee that only a single cpu is being
 * updated at any particular moment of time.
 */
static DEFINE_MUTEX(microcode_mutex);

/*
 * Serialize late loading so that CPUs get updated one-by-one.
 */
static DEFINE_RAW_SPINLOCK(update_lock);

struct ucode_cpu_info           ucode_cpu_info[NR_CPUS];

struct cpu_info_ctx {
        struct cpu_signature    *cpu_sig;
        int                     err;
};

/*
 * Those patch levels cannot be updated to newer ones and thus should be final.
 */
static u32 final_levels[] = {
        0x01000098,
        0x0100009f,
        0x010000af,
        0, /* T-101 terminator */
};

/*
 * Check the current patch level on this CPU.
 *
 * Returns:
 *  - true: if update should stop
 *  - false: otherwise
 */
static bool amd_check_current_patch_level(void)
{
        u32 lvl, dummy, i;
        u32 *levels;

        native_rdmsr(MSR_AMD64_PATCH_LEVEL, lvl, dummy);

        if (IS_ENABLED(CONFIG_X86_32))
                levels = (u32 *)__pa_nodebug(&final_levels);
        else
                levels = final_levels;

        for (i = 0; levels[i]; i++) {
                if (lvl == levels[i])
                        return true;
        }
        return false;
}

static bool __init check_loader_disabled_bsp(void)
{
        static const char *__dis_opt_str = "dis_ucode_ldr";

#ifdef CONFIG_X86_32
        const char *cmdline = (const char *)__pa_nodebug(boot_command_line);
        const char *option  = (const char *)__pa_nodebug(__dis_opt_str);
        bool *res = (bool *)__pa_nodebug(&dis_ucode_ldr);

#else /* CONFIG_X86_64 */
        const char *cmdline = boot_command_line;
        const char *option  = __dis_opt_str;
        bool *res = &dis_ucode_ldr;
#endif

        /*
         * CPUID(1).ECX[31]: reserved for hypervisor use. This is still not
         * completely accurate as xen pv guests don't see that CPUID bit set but
         * that's good enough as they don't land on the BSP path anyway.
         */
        if (native_cpuid_ecx(1) & BIT(31))
                return *res;

        if (x86_cpuid_vendor() == X86_VENDOR_AMD) {
                if (amd_check_current_patch_level())
                        return *res;
        }

        if (cmdline_find_option_bool(cmdline, option) <= 0)
                *res = false;

        return *res;
}

extern struct builtin_fw __start_builtin_fw[];
extern struct builtin_fw __end_builtin_fw[];

bool get_builtin_firmware(struct cpio_data *cd, const char *name)
{
#ifdef CONFIG_FW_LOADER
        struct builtin_fw *b_fw;

        for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++) {
                if (!strcmp(name, b_fw->name)) {
                        cd->size = b_fw->size;
                        cd->data = b_fw->data;
                        return true;
                }
        }
#endif
        return false;
}

void __init load_ucode_bsp(void)
{
        unsigned int cpuid_1_eax;
        bool intel = true;

        if (!have_cpuid_p())
                return;

        cpuid_1_eax = native_cpuid_eax(1);

        switch (x86_cpuid_vendor()) {
        case X86_VENDOR_INTEL:
                if (x86_family(cpuid_1_eax) < 6)
                        return;
                break;

        case X86_VENDOR_AMD:
                if (x86_family(cpuid_1_eax) < 0x10)
                        return;
                intel = false;
                break;

        default:
                return;
        }

        if (check_loader_disabled_bsp())
                return;

        if (intel)
                load_ucode_intel_bsp();
        else
                load_ucode_amd_bsp(cpuid_1_eax);
}

static bool check_loader_disabled_ap(void)
{
#ifdef CONFIG_X86_32
        return *((bool *)__pa_nodebug(&dis_ucode_ldr));
#else
        return dis_ucode_ldr;
#endif
}

void load_ucode_ap(void)
{
        unsigned int cpuid_1_eax;

        if (check_loader_disabled_ap())
                return;

        cpuid_1_eax = native_cpuid_eax(1);

        switch (x86_cpuid_vendor()) {
        case X86_VENDOR_INTEL:
                if (x86_family(cpuid_1_eax) >= 6)
                        load_ucode_intel_ap();
                break;
        case X86_VENDOR_AMD:
                if (x86_family(cpuid_1_eax) >= 0x10)
                        load_ucode_amd_ap(cpuid_1_eax);
                break;
        default:
                break;
        }
}

static int __init save_microcode_in_initrd(void)
{
        struct cpuinfo_x86 *c = &boot_cpu_data;
        int ret = -EINVAL;

        switch (c->x86_vendor) {
        case X86_VENDOR_INTEL:
                if (c->x86 >= 6)
                        ret = save_microcode_in_initrd_intel();
                break;
        case X86_VENDOR_AMD:
                if (c->x86 >= 0x10)
                        ret = save_microcode_in_initrd_amd(cpuid_eax(1));
                break;
        default:
                break;
        }

        initrd_gone = true;

        return ret;
}

struct cpio_data find_microcode_in_initrd(const char *path, bool use_pa)
{
#ifdef CONFIG_BLK_DEV_INITRD
        unsigned long start = 0;
        size_t size;

#ifdef CONFIG_X86_32
        struct boot_params *params;

        if (use_pa)
                params = (struct boot_params *)__pa_nodebug(&boot_params);
        else
                params = &boot_params;

        size = params->hdr.ramdisk_size;

        /*
         * Set start only if we have an initrd image. We cannot use initrd_start
         * because it is not set that early yet.
         */
        if (size)
                start = params->hdr.ramdisk_image;

# else /* CONFIG_X86_64 */
        size  = (unsigned long)boot_params.ext_ramdisk_size << 32;
        size |= boot_params.hdr.ramdisk_size;

        if (size) {
                start  = (unsigned long)boot_params.ext_ramdisk_image << 32;
                start |= boot_params.hdr.ramdisk_image;

                start += PAGE_OFFSET;
        }
# endif

        /*
         * Fixup the start address: after reserve_initrd() runs, initrd_start
         * has the virtual address of the beginning of the initrd. It also
         * possibly relocates the ramdisk. In either case, initrd_start contains
         * the updated address so use that instead.
         *
         * initrd_gone is for the hotplug case where we've thrown out initrd
         * already.
         */
        if (!use_pa) {
                if (initrd_gone)
                        return (struct cpio_data){ NULL, 0, "" };
                if (initrd_start)
                        start = initrd_start;
        } else {
                /*
                 * The picture with physical addresses is a bit different: we
                 * need to get the *physical* address to which the ramdisk was
                 * relocated, i.e., relocated_ramdisk (not initrd_start) and
                 * since we're running from physical addresses, we need to access
                 * relocated_ramdisk through its *physical* address too.
                 */
                u64 *rr = (u64 *)__pa_nodebug(&relocated_ramdisk);
                if (*rr)
                        start = *rr;
        }

        return find_cpio_data(path, (void *)start, size, NULL);
#else /* !CONFIG_BLK_DEV_INITRD */
        return (struct cpio_data){ NULL, 0, "" };
#endif
}

void reload_early_microcode(void)
{
        int vendor, family;

        vendor = x86_cpuid_vendor();
        family = x86_cpuid_family();

        switch (vendor) {
        case X86_VENDOR_INTEL:
                if (family >= 6)
                        reload_ucode_intel();
                break;
        case X86_VENDOR_AMD:
                if (family >= 0x10)
                        reload_ucode_amd();
                break;
        default:
                break;
        }
}

static void collect_cpu_info_local(void *arg)
{
        struct cpu_info_ctx *ctx = arg;

        ctx->err = microcode_ops->collect_cpu_info(smp_processor_id(),
                                                   ctx->cpu_sig);
}

static int collect_cpu_info_on_target(int cpu, struct cpu_signature *cpu_sig)
{
        struct cpu_info_ctx ctx = { .cpu_sig = cpu_sig, .err = 0 };
        int ret;

        ret = smp_call_function_single(cpu, collect_cpu_info_local, &ctx, 1);
        if (!ret)
                ret = ctx.err;

        return ret;
}

static int collect_cpu_info(int cpu)
{
        struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
        int ret;

        memset(uci, 0, sizeof(*uci));

        ret = collect_cpu_info_on_target(cpu, &uci->cpu_sig);
        if (!ret)
                uci->valid = 1;

        return ret;
}

static void apply_microcode_local(void *arg)
{
        enum ucode_state *err = arg;

        *err = microcode_ops->apply_microcode(smp_processor_id());
}

static int apply_microcode_on_target(int cpu)
{
        enum ucode_state err;
        int ret;

        ret = smp_call_function_single(cpu, apply_microcode_local, &err, 1);
        if (!ret) {
                if (err == UCODE_ERROR)
                        ret = 1;
        }
        return ret;
}

#ifdef CONFIG_MICROCODE_OLD_INTERFACE
static int do_microcode_update(const void __user *buf, size_t size)
{
        int error = 0;
        int cpu;

        for_each_online_cpu(cpu) {
                struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
                enum ucode_state ustate;

                if (!uci->valid)
                        continue;

                ustate = microcode_ops->request_microcode_user(cpu, buf, size);
                if (ustate == UCODE_ERROR) {
                        error = -1;
                        break;
                } else if (ustate == UCODE_OK)
                        apply_microcode_on_target(cpu);
        }

        return error;
}

static int microcode_open(struct inode *inode, struct file *file)
{
        return capable(CAP_SYS_RAWIO) ? nonseekable_open(inode, file) : -EPERM;
}

static ssize_t microcode_write(struct file *file, const char __user *buf,
                               size_t len, loff_t *ppos)
{
        ssize_t ret = -EINVAL;

        if ((len >> PAGE_SHIFT) > totalram_pages) {
                pr_err("too much data (max %ld pages)\n", totalram_pages);
                return ret;
        }

        get_online_cpus();
        mutex_lock(&microcode_mutex);

        if (do_microcode_update(buf, len) == 0)
                ret = (ssize_t)len;

        if (ret > 0)
                perf_check_microcode();

        mutex_unlock(&microcode_mutex);
        put_online_cpus();

        return ret;
}

static const struct file_operations microcode_fops = {
        .owner                  = THIS_MODULE,
        .write                  = microcode_write,
        .open                   = microcode_open,
        .llseek         = no_llseek,
};

static struct miscdevice microcode_dev = {
        .minor                  = MICROCODE_MINOR,
        .name                   = "microcode",
        .nodename               = "cpu/microcode",
        .fops                   = &microcode_fops,
};

static int __init microcode_dev_init(void)
{
        int error;

        error = misc_register(&microcode_dev);
        if (error) {
                pr_err("can't misc_register on minor=%d\n", MICROCODE_MINOR);
                return error;
        }

        return 0;
}

static void __exit microcode_dev_exit(void)
{
        misc_deregister(&microcode_dev);
}
#else
#define microcode_dev_init()    0
#define microcode_dev_exit()    do { } while (0)
#endif

/* fake device for request_firmware */
static struct platform_device   *microcode_pdev;

/*
 * Late loading dance. Why the heavy-handed stomp_machine effort?
 *
 * - HT siblings must be idle and not execute other code while the other sibling
 *   is loading microcode in order to avoid any negative interactions caused by
 *   the loading.
 *
 * - In addition, microcode update on the cores must be serialized until this
 *   requirement can be relaxed in the future. Right now, this is conservative
 *   and good.
 */
#define SPINUNIT 100 /* 100 nsec */

static int check_online_cpus(void)
{
        if (num_online_cpus() == num_present_cpus())
                return 0;

        pr_err("Not all CPUs online, aborting microcode update.\n");

        return -EINVAL;
}

static atomic_t late_cpus_in;
static atomic_t late_cpus_out;

static int __wait_for_cpus(atomic_t *t, long long timeout)
{
        int all_cpus = num_online_cpus();

        atomic_inc(t);

        while (atomic_read(t) < all_cpus) {
                if (timeout < SPINUNIT) {
                        pr_err("Timeout while waiting for CPUs rendezvous, remaining: %d\n",
                                all_cpus - atomic_read(t));
                        return 1;
                }

                ndelay(SPINUNIT);
                timeout -= SPINUNIT;

                touch_nmi_watchdog();
        }
        return 0;
}

/*
 * Returns:
 * < 0 - on error
 *   0 - no update done
 *   1 - microcode was updated
 */
static int __reload_late(void *info)
{
        int cpu = smp_processor_id();
        enum ucode_state err;
        int ret = 0;

        /*
         * Wait for all CPUs to arrive. A load will not be attempted unless all
         * CPUs show up.
         * */
        if (__wait_for_cpus(&late_cpus_in, NSEC_PER_SEC))
                return -1;

        raw_spin_lock(&update_lock);
        apply_microcode_local(&err);
        raw_spin_unlock(&update_lock);

        /* siblings return UCODE_OK because their engine got updated already */
        if (err > UCODE_NFOUND) {
                pr_warn("Error reloading microcode on CPU %d\n", cpu);
                ret = -1;
        } else if (err == UCODE_UPDATED || err == UCODE_OK) {
                ret = 1;
        }

        /*
         * Increase the wait timeout to a safe value here since we're
         * serializing the microcode update and that could take a while on a
         * large number of CPUs. And that is fine as the *actual* timeout will
         * be determined by the last CPU finished updating and thus cut short.
         */
        if (__wait_for_cpus(&late_cpus_out, NSEC_PER_SEC * num_online_cpus()))
                panic("Timeout during microcode update!\n");

        return ret;
}

/*
 * Reload microcode late on all CPUs. Wait for a sec until they
 * all gather together.
 */
static int microcode_reload_late(void)
{
        int ret;

        atomic_set(&late_cpus_in,  0);
        atomic_set(&late_cpus_out, 0);

        ret = stop_machine_cpuslocked(__reload_late, NULL, cpu_online_mask);
        if (ret > 0)
                microcode_check();

        return ret;
}

static ssize_t reload_store(struct device *dev,
                            struct device_attribute *attr,
                            const char *buf, size_t size)
{
        enum ucode_state tmp_ret = UCODE_OK;
        int bsp = boot_cpu_data.cpu_index;
        unsigned long val;
        ssize_t ret = 0;

        ret = kstrtoul(buf, 0, &val);
        if (ret)
                return ret;

        if (val != 1)
                return size;

        tmp_ret = microcode_ops->request_microcode_fw(bsp, &microcode_pdev->dev, true);
        if (tmp_ret != UCODE_NEW)
                return size;

        get_online_cpus();

        ret = check_online_cpus();
        if (ret)
                goto put;

        mutex_lock(&microcode_mutex);
        ret = microcode_reload_late();
        mutex_unlock(&microcode_mutex);

put:
        put_online_cpus();

        if (ret >= 0)
                ret = size;

        return ret;
}

static ssize_t version_show(struct device *dev,
                        struct device_attribute *attr, char *buf)
{
        struct ucode_cpu_info *uci = ucode_cpu_info + dev->id;

        return sprintf(buf, "0x%x\n", uci->cpu_sig.rev);
}

static ssize_t pf_show(struct device *dev,
                        struct device_attribute *attr, char *buf)
{
        struct ucode_cpu_info *uci = ucode_cpu_info + dev->id;

        return sprintf(buf, "0x%x\n", uci->cpu_sig.pf);
}

static DEVICE_ATTR_WO(reload);
static DEVICE_ATTR(version, 0400, version_show, NULL);
static DEVICE_ATTR(processor_flags, 0400, pf_show, NULL);

static struct attribute *mc_default_attrs[] = {
        &dev_attr_version.attr,
        &dev_attr_processor_flags.attr,
        NULL
};

static const struct attribute_group mc_attr_group = {
        .attrs                  = mc_default_attrs,
        .name                   = "microcode",
};

static void microcode_fini_cpu(int cpu)
{
        if (microcode_ops->microcode_fini_cpu)
                microcode_ops->microcode_fini_cpu(cpu);
}

static enum ucode_state microcode_resume_cpu(int cpu)
{
        if (apply_microcode_on_target(cpu))
                return UCODE_ERROR;

        pr_debug("CPU%d updated upon resume\n", cpu);

        return UCODE_OK;
}

static enum ucode_state microcode_init_cpu(int cpu, bool refresh_fw)
{
        enum ucode_state ustate;
        struct ucode_cpu_info *uci = ucode_cpu_info + cpu;

        if (uci->valid)
                return UCODE_OK;

        if (collect_cpu_info(cpu))
                return UCODE_ERROR;

        /* --dimm. Trigger a delayed update? */
        if (system_state != SYSTEM_RUNNING)
                return UCODE_NFOUND;

        ustate = microcode_ops->request_microcode_fw(cpu, &microcode_pdev->dev, refresh_fw);
        if (ustate == UCODE_NEW) {
                pr_debug("CPU%d updated upon init\n", cpu);
                apply_microcode_on_target(cpu);
        }

        return ustate;
}

static enum ucode_state microcode_update_cpu(int cpu)
{
        struct ucode_cpu_info *uci = ucode_cpu_info + cpu;

        /* Refresh CPU microcode revision after resume. */
        collect_cpu_info(cpu);

        if (uci->valid)
                return microcode_resume_cpu(cpu);

        return microcode_init_cpu(cpu, false);
}

static int mc_device_add(struct device *dev, struct subsys_interface *sif)
{
        int err, cpu = dev->id;

        if (!cpu_online(cpu))
                return 0;

        pr_debug("CPU%d added\n", cpu);

        err = sysfs_create_group(&dev->kobj, &mc_attr_group);
        if (err)
                return err;

        if (microcode_init_cpu(cpu, true) == UCODE_ERROR)
                return -EINVAL;

        return err;
}

static void mc_device_remove(struct device *dev, struct subsys_interface *sif)
{
        int cpu = dev->id;

        if (!cpu_online(cpu))
                return;

        pr_debug("CPU%d removed\n", cpu);
        microcode_fini_cpu(cpu);
        sysfs_remove_group(&dev->kobj, &mc_attr_group);
}

static struct subsys_interface mc_cpu_interface = {
        .name                   = "microcode",
        .subsys                 = &cpu_subsys,
        .add_dev                = mc_device_add,
        .remove_dev             = mc_device_remove,
};

/**
 * mc_bp_resume - Update boot CPU microcode during resume.
 */
static void mc_bp_resume(void)
{
        int cpu = smp_processor_id();
        struct ucode_cpu_info *uci = ucode_cpu_info + cpu;

        if (uci->valid && uci->mc)
                microcode_ops->apply_microcode(cpu);
        else if (!uci->mc)
                reload_early_microcode();
}

static struct syscore_ops mc_syscore_ops = {
        .resume                 = mc_bp_resume,
};

static int mc_cpu_online(unsigned int cpu)
{
        struct device *dev;

        dev = get_cpu_device(cpu);
        microcode_update_cpu(cpu);
        pr_debug("CPU%d added\n", cpu);

        if (sysfs_create_group(&dev->kobj, &mc_attr_group))
                pr_err("Failed to create group for CPU%d\n", cpu);
        return 0;
}

static int mc_cpu_down_prep(unsigned int cpu)
{
        struct device *dev;

        dev = get_cpu_device(cpu);
        /* Suspend is in progress, only remove the interface */
        sysfs_remove_group(&dev->kobj, &mc_attr_group);
        pr_debug("CPU%d removed\n", cpu);

        return 0;
}

static struct attribute *cpu_root_microcode_attrs[] = {
        &dev_attr_reload.attr,
        NULL
};

static const struct attribute_group cpu_root_microcode_group = {
        .name  = "microcode",
        .attrs = cpu_root_microcode_attrs,
};

int __init microcode_init(void)
{
        struct cpuinfo_x86 *c = &boot_cpu_data;
        int error;

        if (dis_ucode_ldr)
                return -EINVAL;

        if (c->x86_vendor == X86_VENDOR_INTEL)
                microcode_ops = init_intel_microcode();
        else if (c->x86_vendor == X86_VENDOR_AMD)
                microcode_ops = init_amd_microcode();
        else
                pr_err("no support for this CPU vendor\n");

        if (!microcode_ops)
                return -ENODEV;

        microcode_pdev = platform_device_register_simple("microcode", -1,
                                                         NULL, 0);
        if (IS_ERR(microcode_pdev))
                return PTR_ERR(microcode_pdev);

        get_online_cpus();
        mutex_lock(&microcode_mutex);

        error = subsys_interface_register(&mc_cpu_interface);
        if (!error)
                perf_check_microcode();
        mutex_unlock(&microcode_mutex);
        put_online_cpus();

        if (error)
                goto out_pdev;

        error = sysfs_create_group(&cpu_subsys.dev_root->kobj,
                                   &cpu_root_microcode_group);

        if (error) {
                pr_err("Error creating microcode group!\n");
                goto out_driver;
        }

        error = microcode_dev_init();
        if (error)
                goto out_ucode_group;

        register_syscore_ops(&mc_syscore_ops);
        cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/microcode:online",
                                  mc_cpu_online, mc_cpu_down_prep);

        pr_info("Microcode Update Driver: v%s.", DRIVER_VERSION);

        return 0;

 out_ucode_group:
        sysfs_remove_group(&cpu_subsys.dev_root->kobj,
                           &cpu_root_microcode_group);

 out_driver:
        get_online_cpus();
        mutex_lock(&microcode_mutex);

        subsys_interface_unregister(&mc_cpu_interface);

        mutex_unlock(&microcode_mutex);
        put_online_cpus();

 out_pdev:
        platform_device_unregister(microcode_pdev);
        return error;

}
fs_initcall(save_microcode_in_initrd);
late_initcall(microcode_init);