drivers/xen/mcelog.c - kernel/common - Git at Google

 /******************************************************************************
  * 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.
  */

 #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;

 		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;
 	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 = 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("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);
	/******************************************************************************
	* 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.
	*/

	#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_LENsizeof(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;

	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;
	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 = 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("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);