LXR linux/drivers/xen/mcelog.c

   1/******************************************************************************
   2 * mcelog.c
   3 * Driver for receiving and transferring machine check error infomation
   4 *
   5 * Copyright (c) 2012 Intel Corporation
   6 * Author: Liu, Jinsong <jinsong.liu@intel.com>
   7 * Author: Jiang, Yunhong <yunhong.jiang@intel.com>
   8 * Author: Ke, Liping <liping.ke@intel.com>
   9 *
  10 * This program is free software; you can redistribute it and/or
  11 * modify it under the terms of the GNU General Public License version 2
  12 * as published by the Free Software Foundation; or, when distributed
  13 * separately from the Linux kernel or incorporated into other
  14 * software packages, subject to the following license:
  15 *
  16 * Permission is hereby granted, free of charge, to any person obtaining a copy
  17 * of this source file (the "Software"), to deal in the Software without
  18 * restriction, including without limitation the rights to use, copy, modify,
  19 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  20 * and to permit persons to whom the Software is furnished to do so, subject to
  21 * the following conditions:
  22 *
  23 * The above copyright notice and this permission notice shall be included in
  24 * all copies or substantial portions of the Software.
  25 *
  26 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  27 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  28 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  29 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  30 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  31 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  32 * IN THE SOFTWARE.
  33 */
  34
  35#define pr_fmt(fmt) "xen_mcelog: " fmt
  36
  37#include <linux/init.h>
  38#include <linux/types.h>
  39#include <linux/kernel.h>
  40#include <linux/slab.h>
  41#include <linux/fs.h>
  42#include <linux/device.h>
  43#include <linux/miscdevice.h>
  44#include <linux/uaccess.h>
  45#include <linux/capability.h>
  46#include <linux/poll.h>
  47#include <linux/sched.h>
  48
  49#include <xen/interface/xen.h>
  50#include <xen/events.h>
  51#include <xen/interface/vcpu.h>
  52#include <xen/xen.h>
  53#include <asm/xen/hypercall.h>
  54#include <asm/xen/hypervisor.h>
  55
  56static struct mc_info g_mi;
  57static struct mcinfo_logical_cpu *g_physinfo;
  58static uint32_t ncpus;
  59
  60static DEFINE_MUTEX(mcelog_lock);
  61
  62static struct xen_mce_log xen_mcelog = {
  63        .signature      = XEN_MCE_LOG_SIGNATURE,
  64        .len            = XEN_MCE_LOG_LEN,
  65        .recordlen      = sizeof(struct xen_mce),
  66};
  67
  68static DEFINE_SPINLOCK(xen_mce_chrdev_state_lock);
  69static int xen_mce_chrdev_open_count;   /* #times opened */
  70static int xen_mce_chrdev_open_exclu;   /* already open exclusive? */
  71
  72static DECLARE_WAIT_QUEUE_HEAD(xen_mce_chrdev_wait);
  73
  74static int xen_mce_chrdev_open(struct inode *inode, struct file *file)
  75{
  76        spin_lock(&xen_mce_chrdev_state_lock);
  77
  78        if (xen_mce_chrdev_open_exclu ||
  79            (xen_mce_chrdev_open_count && (file->f_flags & O_EXCL))) {
  80                spin_unlock(&xen_mce_chrdev_state_lock);
  81
  82                return -EBUSY;
  83        }
  84
  85        if (file->f_flags & O_EXCL)
  86                xen_mce_chrdev_open_exclu = 1;
  87        xen_mce_chrdev_open_count++;
  88
  89        spin_unlock(&xen_mce_chrdev_state_lock);
  90
  91        return nonseekable_open(inode, file);
  92}
  93
  94static int xen_mce_chrdev_release(struct inode *inode, struct file *file)
  95{
  96        spin_lock(&xen_mce_chrdev_state_lock);
  97
  98        xen_mce_chrdev_open_count--;
  99        xen_mce_chrdev_open_exclu = 0;
 100
 101        spin_unlock(&xen_mce_chrdev_state_lock);
 102
 103        return 0;
 104}
 105
 106static ssize_t xen_mce_chrdev_read(struct file *filp, char __user *ubuf,
 107                                size_t usize, loff_t *off)
 108{
 109        char __user *buf = ubuf;
 110        unsigned num;
 111        int i, err;
 112
 113        mutex_lock(&mcelog_lock);
 114
 115        num = xen_mcelog.next;
 116
 117        /* Only supports full reads right now */
 118        err = -EINVAL;
 119        if (*off != 0 || usize < XEN_MCE_LOG_LEN*sizeof(struct xen_mce))
 120                goto out;
 121
 122        err = 0;
 123        for (i = 0; i < num; i++) {
 124                struct xen_mce *m = &xen_mcelog.entry[i];
 125
 126                err |= copy_to_user(buf, m, sizeof(*m));
 127                buf += sizeof(*m);
 128        }
 129
 130        memset(xen_mcelog.entry, 0, num * sizeof(struct xen_mce));
 131        xen_mcelog.next = 0;
 132
 133        if (err)
 134                err = -EFAULT;
 135
 136out:
 137        mutex_unlock(&mcelog_lock);
 138
 139        return err ? err : buf - ubuf;
 140}
 141
 142static __poll_t xen_mce_chrdev_poll(struct file *file, poll_table *wait)
 143{
 144        poll_wait(file, &xen_mce_chrdev_wait, wait);
 145
 146        if (xen_mcelog.next)
 147                return EPOLLIN | EPOLLRDNORM;
 148
 149        return 0;
 150}
 151
 152static long xen_mce_chrdev_ioctl(struct file *f, unsigned int cmd,
 153                                unsigned long arg)
 154{
 155        int __user *p = (int __user *)arg;
 156
 157        if (!capable(CAP_SYS_ADMIN))
 158                return -EPERM;
 159
 160        switch (cmd) {
 161        case MCE_GET_RECORD_LEN:
 162                return put_user(sizeof(struct xen_mce), p);
 163        case MCE_GET_LOG_LEN:
 164                return put_user(XEN_MCE_LOG_LEN, p);
 165        case MCE_GETCLEAR_FLAGS: {
 166                unsigned flags;
 167
 168                do {
 169                        flags = xen_mcelog.flags;
 170                } while (cmpxchg(&xen_mcelog.flags, flags, 0) != flags);
 171
 172                return put_user(flags, p);
 173        }
 174        default:
 175                return -ENOTTY;
 176        }
 177}
 178
 179static const struct file_operations xen_mce_chrdev_ops = {
 180        .open                   = xen_mce_chrdev_open,
 181        .release                = xen_mce_chrdev_release,
 182        .read                   = xen_mce_chrdev_read,
 183        .poll                   = xen_mce_chrdev_poll,
 184        .unlocked_ioctl         = xen_mce_chrdev_ioctl,
 185        .llseek                 = no_llseek,
 186};
 187
 188static struct miscdevice xen_mce_chrdev_device = {
 189        MISC_MCELOG_MINOR,
 190        "mcelog",
 191        &xen_mce_chrdev_ops,
 192};
 193
 194/*
 195 * Caller should hold the mcelog_lock
 196 */
 197static void xen_mce_log(struct xen_mce *mce)
 198{
 199        unsigned entry;
 200
 201        entry = xen_mcelog.next;
 202
 203        /*
 204         * When the buffer fills up discard new entries.
 205         * Assume that the earlier errors are the more
 206         * interesting ones:
 207         */
 208        if (entry >= XEN_MCE_LOG_LEN) {
 209                set_bit(XEN_MCE_OVERFLOW,
 210                        (unsigned long *)&xen_mcelog.flags);
 211                return;
 212        }
 213
 214        memcpy(xen_mcelog.entry + entry, mce, sizeof(struct xen_mce));
 215
 216        xen_mcelog.next++;
 217}
 218
 219static int convert_log(struct mc_info *mi)
 220{
 221        struct mcinfo_common *mic;
 222        struct mcinfo_global *mc_global;
 223        struct mcinfo_bank *mc_bank;
 224        struct xen_mce m;
 225        uint32_t i;
 226
 227        mic = NULL;
 228        x86_mcinfo_lookup(&mic, mi, MC_TYPE_GLOBAL);
 229        if (unlikely(!mic)) {
 230                pr_warn("Failed to find global error info\n");
 231                return -ENODEV;
 232        }
 233
 234        memset(&m, 0, sizeof(struct xen_mce));
 235
 236        mc_global = (struct mcinfo_global *)mic;
 237        m.mcgstatus = mc_global->mc_gstatus;
 238        m.apicid = mc_global->mc_apicid;
 239
 240        for (i = 0; i < ncpus; i++)
 241                if (g_physinfo[i].mc_apicid == m.apicid)
 242                        break;
 243        if (unlikely(i == ncpus)) {
 244                pr_warn("Failed to match cpu with apicid %d\n", m.apicid);
 245                return -ENODEV;
 246        }
 247
 248        m.socketid = g_physinfo[i].mc_chipid;
 249        m.cpu = m.extcpu = g_physinfo[i].mc_cpunr;
 250        m.cpuvendor = (__u8)g_physinfo[i].mc_vendor;
 251        m.mcgcap = g_physinfo[i].mc_msrvalues[__MC_MSR_MCGCAP].value;
 252
 253        mic = NULL;
 254        x86_mcinfo_lookup(&mic, mi, MC_TYPE_BANK);
 255        if (unlikely(!mic)) {
 256                pr_warn("Fail to find bank error info\n");
 257                return -ENODEV;
 258        }
 259
 260        do {
 261                if ((!mic) || (mic->size == 0) ||
 262                    (mic->type != MC_TYPE_GLOBAL   &&
 263                     mic->type != MC_TYPE_BANK     &&
 264                     mic->type != MC_TYPE_EXTENDED &&
 265                     mic->type != MC_TYPE_RECOVERY))
 266                        break;
 267
 268                if (mic->type == MC_TYPE_BANK) {
 269                        mc_bank = (struct mcinfo_bank *)mic;
 270                        m.misc = mc_bank->mc_misc;
 271                        m.status = mc_bank->mc_status;
 272                        m.addr = mc_bank->mc_addr;
 273                        m.tsc = mc_bank->mc_tsc;
 274                        m.bank = mc_bank->mc_bank;
 275                        m.finished = 1;
 276                        /*log this record*/
 277                        xen_mce_log(&m);
 278                }
 279                mic = x86_mcinfo_next(mic);
 280        } while (1);
 281
 282        return 0;
 283}
 284
 285static int mc_queue_handle(uint32_t flags)
 286{
 287        struct xen_mc mc_op;
 288        int ret = 0;
 289
 290        mc_op.cmd = XEN_MC_fetch;
 291        set_xen_guest_handle(mc_op.u.mc_fetch.data, &g_mi);
 292        do {
 293                mc_op.u.mc_fetch.flags = flags;
 294                ret = HYPERVISOR_mca(&mc_op);
 295                if (ret) {
 296                        pr_err("Failed to fetch %surgent error log\n",
 297                               flags == XEN_MC_URGENT ? "" : "non");
 298                        break;
 299                }
 300
 301                if (mc_op.u.mc_fetch.flags & XEN_MC_NODATA ||
 302                    mc_op.u.mc_fetch.flags & XEN_MC_FETCHFAILED)
 303                        break;
 304                else {
 305                        ret = convert_log(&g_mi);
 306                        if (ret)
 307                                pr_warn("Failed to convert this error log, continue acking it anyway\n");
 308
 309                        mc_op.u.mc_fetch.flags = flags | XEN_MC_ACK;
 310                        ret = HYPERVISOR_mca(&mc_op);
 311                        if (ret) {
 312                                pr_err("Failed to ack previous error log\n");
 313                                break;
 314                        }
 315                }
 316        } while (1);
 317
 318        return ret;
 319}
 320
 321/* virq handler for machine check error info*/
 322static void xen_mce_work_fn(struct work_struct *work)
 323{
 324        int err;
 325
 326        mutex_lock(&mcelog_lock);
 327
 328        /* urgent mc_info */
 329        err = mc_queue_handle(XEN_MC_URGENT);
 330        if (err)
 331                pr_err("Failed to handle urgent mc_info queue, continue handling nonurgent mc_info queue anyway\n");
 332
 333        /* nonurgent mc_info */
 334        err = mc_queue_handle(XEN_MC_NONURGENT);
 335        if (err)
 336                pr_err("Failed to handle nonurgent mc_info queue\n");
 337
 338        /* wake processes polling /dev/mcelog */
 339        wake_up_interruptible(&xen_mce_chrdev_wait);
 340
 341        mutex_unlock(&mcelog_lock);
 342}
 343static DECLARE_WORK(xen_mce_work, xen_mce_work_fn);
 344
 345static irqreturn_t xen_mce_interrupt(int irq, void *dev_id)
 346{
 347        schedule_work(&xen_mce_work);
 348        return IRQ_HANDLED;
 349}
 350
 351static int bind_virq_for_mce(void)
 352{
 353        int ret;
 354        struct xen_mc mc_op;
 355
 356        memset(&mc_op, 0, sizeof(struct xen_mc));
 357
 358        /* Fetch physical CPU Numbers */
 359        mc_op.cmd = XEN_MC_physcpuinfo;
 360        set_xen_guest_handle(mc_op.u.mc_physcpuinfo.info, g_physinfo);
 361        ret = HYPERVISOR_mca(&mc_op);
 362        if (ret) {
 363                pr_err("Failed to get CPU numbers\n");
 364                return ret;
 365        }
 366
 367        /* Fetch each CPU Physical Info for later reference*/
 368        ncpus = mc_op.u.mc_physcpuinfo.ncpus;
 369        g_physinfo = kcalloc(ncpus, sizeof(struct mcinfo_logical_cpu),
 370                             GFP_KERNEL);
 371        if (!g_physinfo)
 372                return -ENOMEM;
 373        set_xen_guest_handle(mc_op.u.mc_physcpuinfo.info, g_physinfo);
 374        ret = HYPERVISOR_mca(&mc_op);
 375        if (ret) {
 376                pr_err("Failed to get CPU info\n");
 377                kfree(g_physinfo);
 378                return ret;
 379        }
 380
 381        ret  = bind_virq_to_irqhandler(VIRQ_MCA, 0,
 382                                       xen_mce_interrupt, 0, "mce", NULL);
 383        if (ret < 0) {
 384                pr_err("Failed to bind virq\n");
 385                kfree(g_physinfo);
 386                return ret;
 387        }
 388
 389        return 0;
 390}
 391
 392static int __init xen_late_init_mcelog(void)
 393{
 394        int ret;
 395
 396        /* Only DOM0 is responsible for MCE logging */
 397        if (!xen_initial_domain())
 398                return -ENODEV;
 399
 400        /* register character device /dev/mcelog for xen mcelog */
 401        ret = misc_register(&xen_mce_chrdev_device);
 402        if (ret)
 403                return ret;
 404
 405        ret = bind_virq_for_mce();
 406        if (ret)
 407                goto deregister;
 408
 409        pr_info("/dev/mcelog registered by Xen\n");
 410
 411        return 0;
 412
 413deregister:
 414        misc_deregister(&xen_mce_chrdev_device);
 415        return ret;
 416}
 417device_initcall(xen_late_init_mcelog);
 418