mcelog.c

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/******************************************************************************
 * mcelog.c
 * Driver for receiving and transferring machine check error infomation
 *
 * Copyright (c) 2012 Intel Corporation
 * Author: Liu, Jinsong <[email protected]>
 * Author: Jiang, Yunhong <[email protected]>
 * Author: Ke, Liping <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#include <linux/init.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/miscdevice.h>
#include <linux/uaccess.h>
#include <linux/capability.h>
#include <linux/poll.h>
#include <linux/sched.h>

#include <xen/interface/xen.h>
#include <xen/events.h>
#include <xen/interface/vcpu.h>
#include <xen/xen.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>

#define XEN_MCELOG "xen_mcelog: "

static struct mc_info g_mi;
static struct mcinfo_logical_cpu *g_physinfo;
static uint32_t ncpus;

static DEFINE_MUTEX(mcelog_lock);

static struct xen_mce_log xen_mcelog = {
    .signature  = XEN_MCE_LOG_SIGNATURE,
    .len        = XEN_MCE_LOG_LEN,
    .recordlen  = sizeof(struct xen_mce),
};

static DEFINE_SPINLOCK(xen_mce_chrdev_state_lock);
static int xen_mce_chrdev_open_count;   /* #times opened */
static int xen_mce_chrdev_open_exclu;   /* already open exclusive? */

static DECLARE_WAIT_QUEUE_HEAD(xen_mce_chrdev_wait);

static int xen_mce_chrdev_open(struct inode *inode, struct file *file)
{
    spin_lock(&xen_mce_chrdev_state_lock);

    if (xen_mce_chrdev_open_exclu ||
        (xen_mce_chrdev_open_count && (file->f_flags & O_EXCL))) {
        spin_unlock(&xen_mce_chrdev_state_lock);

        return -EBUSY;
    }

    if (file->f_flags & O_EXCL)
        xen_mce_chrdev_open_exclu = 1;
    xen_mce_chrdev_open_count++;

    spin_unlock(&xen_mce_chrdev_state_lock);

    return nonseekable_open(inode, file);
}

static int xen_mce_chrdev_release(struct inode *inode, struct file *file)
{
    spin_lock(&xen_mce_chrdev_state_lock);

    xen_mce_chrdev_open_count--;
    xen_mce_chrdev_open_exclu = 0;

    spin_unlock(&xen_mce_chrdev_state_lock);

    return 0;
}

static ssize_t xen_mce_chrdev_read(struct file *filp, char __user *ubuf,
                size_t usize, loff_t *off)
{
    char __user *buf = ubuf;
    unsigned num;
    int i, err;

    mutex_lock(&mcelog_lock);

    num = xen_mcelog.next;

    /* Only supports full reads right now */
    err = -EINVAL;
    if (*off != 0 || usize < XEN_MCE_LOG_LEN*sizeof(struct xen_mce))
        goto out;

    err = 0;
    for (i = 0; i < num; i++) {
        struct xen_mce *m = &xen_mcelog.entry[i];

        err |= copy_to_user(buf, m, sizeof(*m));
        buf += sizeof(*m);
    }

    memset(xen_mcelog.entry, 0, num * sizeof(struct xen_mce));
    xen_mcelog.next = 0;

    if (err)
        err = -EFAULT;

out:
    mutex_unlock(&mcelog_lock);

    return err ? err : buf - ubuf;
}

static unsigned int xen_mce_chrdev_poll(struct file *file, poll_table *wait)
{
    poll_wait(file, &xen_mce_chrdev_wait, wait);

    if (xen_mcelog.next)
        return POLLIN | POLLRDNORM;

    return 0;
}

static long xen_mce_chrdev_ioctl(struct file *f, unsigned int cmd,
                unsigned long arg)
{
    int __user *p = (int __user *)arg;

    if (!capable(CAP_SYS_ADMIN))
        return -EPERM;

    switch (cmd) {
    case MCE_GET_RECORD_LEN:
        return put_user(sizeof(struct xen_mce), p);
    case MCE_GET_LOG_LEN:
        return put_user(XEN_MCE_LOG_LEN, p);
    case MCE_GETCLEAR_FLAGS: {
        unsigned flags;

        do {
            flags = xen_mcelog.flags;
        } while (cmpxchg(&xen_mcelog.flags, flags, 0) != flags);

        return put_user(flags, p);
    }
    default:
        return -ENOTTY;
    }
}

static const struct file_operations xen_mce_chrdev_ops = {
    .open           = xen_mce_chrdev_open,
    .release        = xen_mce_chrdev_release,
    .read           = xen_mce_chrdev_read,
    .poll           = xen_mce_chrdev_poll,
    .unlocked_ioctl     = xen_mce_chrdev_ioctl,
    .llseek         = no_llseek,
};

static struct miscdevice xen_mce_chrdev_device = {
    MISC_MCELOG_MINOR,
    "mcelog",
    &xen_mce_chrdev_ops,
};

/*
 * Caller should hold the mcelog_lock
 */
static void xen_mce_log(struct xen_mce *mce)
{
    unsigned entry;

    entry = xen_mcelog.next;

    /*
     * When the buffer fills up discard new entries.
     * Assume that the earlier errors are the more
     * interesting ones:
     */
    if (entry >= XEN_MCE_LOG_LEN) {
        set_bit(XEN_MCE_OVERFLOW,
            (unsigned long *)&xen_mcelog.flags);
        return;
    }

    memcpy(xen_mcelog.entry + entry, mce, sizeof(struct xen_mce));

    xen_mcelog.next++;
}

static int convert_log(struct mc_info *mi)
{
    struct mcinfo_common *mic;
    struct mcinfo_global *mc_global;
    struct mcinfo_bank *mc_bank;
    struct xen_mce m;
    uint32_t i;

    mic = NULL;
    x86_mcinfo_lookup(&mic, mi, MC_TYPE_GLOBAL);
    if (unlikely(!mic)) {
        pr_warning(XEN_MCELOG "Failed to find global error info\n");
        return -ENODEV;
    }

    memset(&m, 0, sizeof(struct xen_mce));

    mc_global = (struct mcinfo_global *)mic;
    m.mcgstatus = mc_global->mc_gstatus;
    m.apicid = mc_global->mc_apicid;

    for (i = 0; i < ncpus; i++)
        if (g_physinfo[i].mc_apicid == m.apicid)
            break;
    if (unlikely(i == ncpus)) {
        pr_warning(XEN_MCELOG "Failed to match cpu with apicid %d\n",
               m.apicid);
        return -ENODEV;
    }

    m.socketid = g_physinfo[i].mc_chipid;
    m.cpu = m.extcpu = g_physinfo[i].mc_cpunr;
    m.cpuvendor = (__u8)g_physinfo[i].mc_vendor;
    m.mcgcap = g_physinfo[i].mc_msrvalues[__MC_MSR_MCGCAP].value;

    mic = NULL;
    x86_mcinfo_lookup(&mic, mi, MC_TYPE_BANK);
    if (unlikely(!mic)) {
        pr_warning(XEN_MCELOG "Fail to find bank error info\n");
        return -ENODEV;
    }

    do {
        if ((!mic) || (mic->size == 0) ||
            (mic->type != MC_TYPE_GLOBAL   &&
             mic->type != MC_TYPE_BANK     &&
             mic->type != MC_TYPE_EXTENDED &&
             mic->type != MC_TYPE_RECOVERY))
            break;

        if (mic->type == MC_TYPE_BANK) {
            mc_bank = (struct mcinfo_bank *)mic;
            m.misc = mc_bank->mc_misc;
            m.status = mc_bank->mc_status;
            m.addr = mc_bank->mc_addr;
            m.tsc = mc_bank->mc_tsc;
            m.bank = mc_bank->mc_bank;
            m.finished = 1;
            /*log this record*/
            xen_mce_log(&m);
        }
        mic = x86_mcinfo_next(mic);
    } while (1);

    return 0;
}

static int mc_queue_handle(uint32_t flags)
{
    struct xen_mc mc_op;
    int ret = 0;

    mc_op.cmd = XEN_MC_fetch;
    mc_op.interface_version = XEN_MCA_INTERFACE_VERSION;
    set_xen_guest_handle(mc_op.u.mc_fetch.data, &g_mi);
    do {
        mc_op.u.mc_fetch.flags = flags;
        ret = HYPERVISOR_mca(&mc_op);
        if (ret) {
            pr_err(XEN_MCELOG "Failed to fetch %s error log\n",
                   (flags == XEN_MC_URGENT) ?
                   "urgnet" : "nonurgent");
            break;
        }

        if (mc_op.u.mc_fetch.flags & XEN_MC_NODATA ||
            mc_op.u.mc_fetch.flags & XEN_MC_FETCHFAILED)
            break;
        else {
            ret = convert_log(&g_mi);
            if (ret)
                pr_warning(XEN_MCELOG
                       "Failed to convert this error log, "
                       "continue acking it anyway\n");

            mc_op.u.mc_fetch.flags = flags | XEN_MC_ACK;
            ret = HYPERVISOR_mca(&mc_op);
            if (ret) {
                pr_err(XEN_MCELOG
                       "Failed to ack previous error log\n");
                break;
            }
        }
    } while (1);

    return ret;
}

/* virq handler for machine check error info*/
static void xen_mce_work_fn(struct work_struct *work)
{
    int err;

    mutex_lock(&mcelog_lock);

    /* urgent mc_info */
    err = mc_queue_handle(XEN_MC_URGENT);
    if (err)
        pr_err(XEN_MCELOG
               "Failed to handle urgent mc_info queue, "
               "continue handling nonurgent mc_info queue anyway.\n");

    /* nonurgent mc_info */
    err = mc_queue_handle(XEN_MC_NONURGENT);
    if (err)
        pr_err(XEN_MCELOG
               "Failed to handle nonurgent mc_info queue.\n");

    /* wake processes polling /dev/mcelog */
    wake_up_interruptible(&xen_mce_chrdev_wait);

    mutex_unlock(&mcelog_lock);
}
static DECLARE_WORK(xen_mce_work, xen_mce_work_fn);

static irqreturn_t xen_mce_interrupt(int irq, void *dev_id)
{
    schedule_work(&xen_mce_work);
    return IRQ_HANDLED;
}

static int bind_virq_for_mce(void)
{
    int ret;
    struct xen_mc mc_op;

    memset(&mc_op, 0, sizeof(struct xen_mc));

    /* Fetch physical CPU Numbers */
    mc_op.cmd = XEN_MC_physcpuinfo;
    mc_op.interface_version = XEN_MCA_INTERFACE_VERSION;
    set_xen_guest_handle(mc_op.u.mc_physcpuinfo.info, g_physinfo);
    ret = HYPERVISOR_mca(&mc_op);
    if (ret) {
        pr_err(XEN_MCELOG "Failed to get CPU numbers\n");
        return ret;
    }

    /* Fetch each CPU Physical Info for later reference*/
    ncpus = mc_op.u.mc_physcpuinfo.ncpus;
    g_physinfo = kcalloc(ncpus, sizeof(struct mcinfo_logical_cpu),
                 GFP_KERNEL);
    if (!g_physinfo)
        return -ENOMEM;
    set_xen_guest_handle(mc_op.u.mc_physcpuinfo.info, g_physinfo);
    ret = HYPERVISOR_mca(&mc_op);
    if (ret) {
        pr_err(XEN_MCELOG "Failed to get CPU info\n");
        kfree(g_physinfo);
        return ret;
    }

    ret  = bind_virq_to_irqhandler(VIRQ_MCA, 0,
                       xen_mce_interrupt, 0, "mce", NULL);
    if (ret < 0) {
        pr_err(XEN_MCELOG "Failed to bind virq\n");
        kfree(g_physinfo);
        return ret;
    }

    return 0;
}

static int __init xen_late_init_mcelog(void)
{
    /* Only DOM0 is responsible for MCE logging */
    if (xen_initial_domain()) {
        /* register character device /dev/mcelog for xen mcelog */
        if (misc_register(&xen_mce_chrdev_device))
            return -ENODEV;
        return bind_virq_for_mce();
    }

    return -ENODEV;
}
device_initcall(xen_late_init_mcelog);