/******************************************************************************
 * mcelog.c
 * Driver for receiving and transferring machine check error infomation
 *
 * Copyright (c) 2012 Intel Corporation
 * Author: Liu, Jinsong <jinsong.liu@intel.com>
 * Author: Jiang, Yunhong <yunhong.jiang@intel.com>
 * Author: Ke, Liping <liping.ke@intel.com>
 *
 * 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.
 */

#define pr_fmt(fmt) "xen_mcelog: " fmt

#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>

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 __poll_t xen_mce_chrdev_poll(struct file *file, poll_table *wait)
{
        poll_wait(file, &xen_mce_chrdev_wait, wait);

        if (xen_mcelog.next)
                return EPOLLIN | EPOLLRDNORM;

        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;

                flags = xchg(&xen_mcelog.flags, 0);

                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,
};

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;
        unsigned int i, j;

        mic = NULL;
        x86_mcinfo_lookup(&mic, mi, MC_TYPE_GLOBAL);
        if (unlikely(!mic)) {
                pr_warn("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_warn("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;
        for (j = 0; j < g_physinfo[i].mc_nmsrvals; ++j)
                switch (g_physinfo[i].mc_msrvalues[j].reg) {
                case MSR_IA32_MCG_CAP:
                        m.mcgcap = g_physinfo[i].mc_msrvalues[j].value;
                        break;

                case MSR_PPIN:
                case MSR_AMD_PPIN:
                        m.ppin = g_physinfo[i].mc_msrvalues[j].value;
                        break;
                }

        mic = NULL;
        x86_mcinfo_lookup(&mic, mi, MC_TYPE_BANK);
        if (unlikely(!mic)) {
                pr_warn("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;
        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("Failed to fetch %surgent error log\n",
                               flags == XEN_MC_URGENT ? "" : "non");
                        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_warn("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("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("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("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;
        set_xen_guest_handle(mc_op.u.mc_physcpuinfo.info, g_physinfo);
        ret = HYPERVISOR_mca(&mc_op);
        if (ret) {
                pr_err("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 = kzalloc_objs(struct mcinfo_logical_cpu, ncpus);
        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("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("Failed to bind virq\n");
                kfree(g_physinfo);
                return ret;
        }

        return 0;
}

static int __init xen_late_init_mcelog(void)
{
        int ret;

        /* Only DOM0 is responsible for MCE logging */
        if (!xen_initial_domain())
                return -ENODEV;

        /* register character device /dev/mcelog for xen mcelog */
        ret = misc_register(&xen_mce_chrdev_device);
        if (ret)
                return ret;

        ret = bind_virq_for_mce();
        if (ret)
                goto deregister;

        pr_info("/dev/mcelog registered by Xen\n");

        return 0;

deregister:
        misc_deregister(&xen_mce_chrdev_device);
        return ret;
}
device_initcall(xen_late_init_mcelog);