eeh.c

来自「LINUX 2.6.17.4的源码」· C语言 代码 · 共 1,030 行 · 第 1/2 页

/*
 * eeh.c
 * Copyright (C) 2001 Dave Engebretsen & Todd Inglett IBM Corporation
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <linux/delay.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/pci.h>
#include <linux/proc_fs.h>
#include <linux/rbtree.h>
#include <linux/seq_file.h>
#include <linux/spinlock.h>
#include <asm/atomic.h>
#include <asm/eeh.h>
#include <asm/eeh_event.h>
#include <asm/io.h>
#include <asm/machdep.h>
#include <asm/ppc-pci.h>
#include <asm/rtas.h>

#undef DEBUG

/** Overview:
 *  EEH, or "Extended Error Handling" is a PCI bridge technology for
 *  dealing with PCI bus errors that can't be dealt with within the
 *  usual PCI framework, except by check-stopping the CPU.  Systems
 *  that are designed for high-availability/reliability cannot afford
 *  to crash due to a "mere" PCI error, thus the need for EEH.
 *  An EEH-capable bridge operates by converting a detected error
 *  into a "slot freeze", taking the PCI adapter off-line, making
 *  the slot behave, from the OS'es point of view, as if the slot
 *  were "empty": all reads return 0xff's and all writes are silently
 *  ignored.  EEH slot isolation events can be triggered by parity
 *  errors on the address or data busses (e.g. during posted writes),
 *  which in turn might be caused by low voltage on the bus, dust,
 *  vibration, humidity, radioactivity or plain-old failed hardware.
 *
 *  Note, however, that one of the leading causes of EEH slot
 *  freeze events are buggy device drivers, buggy device microcode,
 *  or buggy device hardware.  This is because any attempt by the
 *  device to bus-master data to a memory address that is not
 *  assigned to the device will trigger a slot freeze.   (The idea
 *  is to prevent devices-gone-wild from corrupting system memory).
 *  Buggy hardware/drivers will have a miserable time co-existing
 *  with EEH.
 *
 *  Ideally, a PCI device driver, when suspecting that an isolation
 *  event has occured (e.g. by reading 0xff's), will then ask EEH
 *  whether this is the case, and then take appropriate steps to
 *  reset the PCI slot, the PCI device, and then resume operations.
 *  However, until that day,  the checking is done here, with the
 *  eeh_check_failure() routine embedded in the MMIO macros.  If
 *  the slot is found to be isolated, an "EEH Event" is synthesized
 *  and sent out for processing.
 */

/* If a device driver keeps reading an MMIO register in an interrupt
 * handler after a slot isolation event has occurred, we assume it
 * is broken and panic.  This sets the threshold for how many read
 * attempts we allow before panicking.
 */
#define EEH_MAX_FAILS	100000

/* RTAS tokens */
static int ibm_set_eeh_option;
static int ibm_set_slot_reset;
static int ibm_read_slot_reset_state;
static int ibm_read_slot_reset_state2;
static int ibm_slot_error_detail;
static int ibm_get_config_addr_info;
static int ibm_configure_bridge;

int eeh_subsystem_enabled;
EXPORT_SYMBOL(eeh_subsystem_enabled);

/* Lock to avoid races due to multiple reports of an error */
static DEFINE_SPINLOCK(confirm_error_lock);

/* Buffer for reporting slot-error-detail rtas calls */
static unsigned char slot_errbuf[RTAS_ERROR_LOG_MAX];
static DEFINE_SPINLOCK(slot_errbuf_lock);
static int eeh_error_buf_size;

/* System monitoring statistics */
static unsigned long no_device;
static unsigned long no_dn;
static unsigned long no_cfg_addr;
static unsigned long ignored_check;
static unsigned long total_mmio_ffs;
static unsigned long false_positives;
static unsigned long ignored_failures;
static unsigned long slot_resets;

#define IS_BRIDGE(class_code) (((class_code)<<16) == PCI_BASE_CLASS_BRIDGE)

/* --------------------------------------------------------------- */
/* Below lies the EEH event infrastructure */

void eeh_slot_error_detail (struct pci_dn *pdn, int severity)
{
	int config_addr;
	unsigned long flags;
	int rc;

	/* Log the error with the rtas logger */
	spin_lock_irqsave(&slot_errbuf_lock, flags);
	memset(slot_errbuf, 0, eeh_error_buf_size);

	/* Use PE configuration address, if present */
	config_addr = pdn->eeh_config_addr;
	if (pdn->eeh_pe_config_addr)
		config_addr = pdn->eeh_pe_config_addr;

	rc = rtas_call(ibm_slot_error_detail,
	               8, 1, NULL, config_addr,
	               BUID_HI(pdn->phb->buid),
	               BUID_LO(pdn->phb->buid), NULL, 0,
	               virt_to_phys(slot_errbuf),
	               eeh_error_buf_size,
	               severity);

	if (rc == 0)
		log_error(slot_errbuf, ERR_TYPE_RTAS_LOG, 0);
	spin_unlock_irqrestore(&slot_errbuf_lock, flags);
}

/**
 * read_slot_reset_state - Read the reset state of a device node's slot
 * @dn: device node to read
 * @rets: array to return results in
 */
static int read_slot_reset_state(struct pci_dn *pdn, int rets[])
{
	int token, outputs;
	int config_addr;

	if (ibm_read_slot_reset_state2 != RTAS_UNKNOWN_SERVICE) {
		token = ibm_read_slot_reset_state2;
		outputs = 4;
	} else {
		token = ibm_read_slot_reset_state;
		rets[2] = 0; /* fake PE Unavailable info */
		outputs = 3;
	}

	/* Use PE configuration address, if present */
	config_addr = pdn->eeh_config_addr;
	if (pdn->eeh_pe_config_addr)
		config_addr = pdn->eeh_pe_config_addr;

	return rtas_call(token, 3, outputs, rets, config_addr,
			 BUID_HI(pdn->phb->buid), BUID_LO(pdn->phb->buid));
}

/**
 * eeh_token_to_phys - convert EEH address token to phys address
 * @token i/o token, should be address in the form 0xA....
 */
static inline unsigned long eeh_token_to_phys(unsigned long token)
{
	pte_t *ptep;
	unsigned long pa;

	ptep = find_linux_pte(init_mm.pgd, token);
	if (!ptep)
		return token;
	pa = pte_pfn(*ptep) << PAGE_SHIFT;

	return pa | (token & (PAGE_SIZE-1));
}

/** 
 * Return the "partitionable endpoint" (pe) under which this device lies
 */
struct device_node * find_device_pe(struct device_node *dn)
{
	while ((dn->parent) && PCI_DN(dn->parent) &&
	      (PCI_DN(dn->parent)->eeh_mode & EEH_MODE_SUPPORTED)) {
		dn = dn->parent;
	}
	return dn;
}

/** Mark all devices that are peers of this device as failed.
 *  Mark the device driver too, so that it can see the failure
 *  immediately; this is critical, since some drivers poll
 *  status registers in interrupts ... If a driver is polling,
 *  and the slot is frozen, then the driver can deadlock in
 *  an interrupt context, which is bad.
 */

static void __eeh_mark_slot (struct device_node *dn, int mode_flag)
{
	while (dn) {
		if (PCI_DN(dn)) {
			/* Mark the pci device driver too */
			struct pci_dev *dev = PCI_DN(dn)->pcidev;

			PCI_DN(dn)->eeh_mode |= mode_flag;

			if (dev && dev->driver)
				dev->error_state = pci_channel_io_frozen;

			if (dn->child)
				__eeh_mark_slot (dn->child, mode_flag);
		}
		dn = dn->sibling;
	}
}

void eeh_mark_slot (struct device_node *dn, int mode_flag)
{
	dn = find_device_pe (dn);

	/* Back up one, since config addrs might be shared */
	if (PCI_DN(dn) && PCI_DN(dn)->eeh_pe_config_addr)
		dn = dn->parent;

	PCI_DN(dn)->eeh_mode |= mode_flag;
	__eeh_mark_slot (dn->child, mode_flag);
}

static void __eeh_clear_slot (struct device_node *dn, int mode_flag)
{
	while (dn) {
		if (PCI_DN(dn)) {
			PCI_DN(dn)->eeh_mode &= ~mode_flag;
			PCI_DN(dn)->eeh_check_count = 0;
			if (dn->child)
				__eeh_clear_slot (dn->child, mode_flag);
		}
		dn = dn->sibling;
	}
}

void eeh_clear_slot (struct device_node *dn, int mode_flag)
{
	unsigned long flags;
	spin_lock_irqsave(&confirm_error_lock, flags);
	
	dn = find_device_pe (dn);
	
	/* Back up one, since config addrs might be shared */
	if (PCI_DN(dn) && PCI_DN(dn)->eeh_pe_config_addr)
		dn = dn->parent;

	PCI_DN(dn)->eeh_mode &= ~mode_flag;
	PCI_DN(dn)->eeh_check_count = 0;
	__eeh_clear_slot (dn->child, mode_flag);
	spin_unlock_irqrestore(&confirm_error_lock, flags);
}

/**
 * eeh_dn_check_failure - check if all 1's data is due to EEH slot freeze
 * @dn device node
 * @dev pci device, if known
 *
 * Check for an EEH failure for the given device node.  Call this
 * routine if the result of a read was all 0xff's and you want to
 * find out if this is due to an EEH slot freeze.  This routine
 * will query firmware for the EEH status.
 *
 * Returns 0 if there has not been an EEH error; otherwise returns
 * a non-zero value and queues up a slot isolation event notification.
 *
 * It is safe to call this routine in an interrupt context.
 */
int eeh_dn_check_failure(struct device_node *dn, struct pci_dev *dev)
{
	int ret;
	int rets[3];
	unsigned long flags;
	struct pci_dn *pdn;
	enum pci_channel_state state;
	int rc = 0;

	total_mmio_ffs++;

	if (!eeh_subsystem_enabled)
		return 0;

	if (!dn) {
		no_dn++;
		return 0;
	}
	pdn = PCI_DN(dn);

	/* Access to IO BARs might get this far and still not want checking. */
	if (!(pdn->eeh_mode & EEH_MODE_SUPPORTED) ||
	    pdn->eeh_mode & EEH_MODE_NOCHECK) {
		ignored_check++;
#ifdef DEBUG
		printk ("EEH:ignored check (%x) for %s %s\n", 
		        pdn->eeh_mode, pci_name (dev), dn->full_name);
#endif
		return 0;
	}

	if (!pdn->eeh_config_addr && !pdn->eeh_pe_config_addr) {
		no_cfg_addr++;
		return 0;
	}

	/* If we already have a pending isolation event for this
	 * slot, we know it's bad already, we don't need to check.
	 * Do this checking under a lock; as multiple PCI devices
	 * in one slot might report errors simultaneously, and we
	 * only want one error recovery routine running.
	 */
	spin_lock_irqsave(&confirm_error_lock, flags);
	rc = 1;
	if (pdn->eeh_mode & EEH_MODE_ISOLATED) {
		pdn->eeh_check_count ++;
		if (pdn->eeh_check_count >= EEH_MAX_FAILS) {
			printk (KERN_ERR "EEH: Device driver ignored %d bad reads, panicing\n",
			        pdn->eeh_check_count);
			dump_stack();
			
			/* re-read the slot reset state */
			if (read_slot_reset_state(pdn, rets) != 0)
				rets[0] = -1;	/* reset state unknown */

			/* If we are here, then we hit an infinite loop. Stop. */
			panic("EEH: MMIO halt (%d) on device:%s\n", rets[0], pci_name(dev));
		}
		goto dn_unlock;
	}

	/*
	 * Now test for an EEH failure.  This is VERY expensive.
	 * Note that the eeh_config_addr may be a parent device
	 * in the case of a device behind a bridge, or it may be
	 * function zero of a multi-function device.
	 * In any case they must share a common PHB.
	 */
	ret = read_slot_reset_state(pdn, rets);

	/* If the call to firmware failed, punt */
	if (ret != 0) {
		printk(KERN_WARNING "EEH: read_slot_reset_state() failed; rc=%d dn=%s\n",
		       ret, dn->full_name);
		false_positives++;
		rc = 0;
		goto dn_unlock;
	}

	/* If EEH is not supported on this device, punt. */
	if (rets[1] != 1) {
		printk(KERN_WARNING "EEH: event on unsupported device, rc=%d dn=%s\n",
		       ret, dn->full_name);
		false_positives++;
		rc = 0;
		goto dn_unlock;
	}

	/* If not the kind of error we know about, punt. */
	if (rets[0] != 2 && rets[0] != 4 && rets[0] != 5) {
		false_positives++;
		rc = 0;
		goto dn_unlock;
	}

	/* Note that config-io to empty slots may fail;
	 * we recognize empty because they don't have children. */
	if ((rets[0] == 5) && (dn->child == NULL)) {
		false_positives++;
		rc = 0;
		goto dn_unlock;
	}

	slot_resets++;
 
	/* Avoid repeated reports of this failure, including problems
	 * with other functions on this device, and functions under
	 * bridges. */
	eeh_mark_slot (dn, EEH_MODE_ISOLATED);
	spin_unlock_irqrestore(&confirm_error_lock, flags);

	state = pci_channel_io_normal;
	if ((rets[0] == 2) || (rets[0] == 4))
		state = pci_channel_io_frozen;
	if (rets[0] == 5)
		state = pci_channel_io_perm_failure;
	eeh_send_failure_event (dn, dev, state, rets[2]);

	/* Most EEH events are due to device driver bugs.  Having
	 * a stack trace will help the device-driver authors figure
	 * out what happened.  So print that out. */
	if (rets[0] != 5) dump_stack();
	return 1;

dn_unlock:
	spin_unlock_irqrestore(&confirm_error_lock, flags);
	return rc;
}

EXPORT_SYMBOL_GPL(eeh_dn_check_failure);

/**
 * eeh_check_failure - check if all 1's data is due to EEH slot freeze
 * @token i/o token, should be address in the form 0xA....
 * @val value, should be all 1's (XXX why do we need this arg??)
 *
 * Check for an EEH failure at the given token address.  Call this
 * routine if the result of a read was all 0xff's and you want to
 * find out if this is due to an EEH slot freeze event.  This routine
 * will query firmware for the EEH status.
 *
 * Note this routine is safe to call in an interrupt context.
 */
unsigned long eeh_check_failure(const volatile void __iomem *token, unsigned long val)
{
	unsigned long addr;
	struct pci_dev *dev;
	struct device_node *dn;

	/* Finding the phys addr + pci device; this is pretty quick. */
	addr = eeh_token_to_phys((unsigned long __force) token);
	dev = pci_get_device_by_addr(addr);
	if (!dev) {
		no_device++;
		return val;
	}

	dn = pci_device_to_OF_node(dev);
	eeh_dn_check_failure (dn, dev);

	pci_dev_put(dev);
	return val;
}

EXPORT_SYMBOL(eeh_check_failure);

/* ------------------------------------------------------------- */
/* The code below deals with error recovery */

/** Return negative value if a permanent error, else return
 * a number of milliseconds to wait until the PCI slot is
 * ready to be used.
 */
static int
eeh_slot_availability(struct pci_dn *pdn)
{
	int rc;
	int rets[3];

	rc = read_slot_reset_state(pdn, rets);

	if (rc) return rc;

	if (rets[1] == 0) return -1;  /* EEH is not supported */
	if (rets[0] == 0) return 0;   /* Oll Korrect */
	if (rets[0] == 5) {
		if (rets[2] == 0) return -1; /* permanently unavailable */
		return rets[2]; /* number of millisecs to wait */
	}
	if (rets[0] == 1)
		return 250;

	printk (KERN_ERR "EEH: Slot unavailable: rc=%d, rets=%d %d %d\n",
		rc, rets[0], rets[1], rets[2]);
	return -1;
}

/** rtas_pci_slot_reset raises/lowers the pci #RST line
 *  state: 1/0 to raise/lower the #RST
 *
 * Clear the EEH-frozen condition on a slot.  This routine
 * asserts the PCI #RST line if the 'state' argument is '1',
 * and drops the #RST line if 'state is '0'.  This routine is
 * safe to call in an interrupt context.
 *
 */

static void
rtas_pci_slot_reset(struct pci_dn *pdn, int state)
{
	int config_addr;
	int rc;

	BUG_ON (pdn==NULL); 

	if (!pdn->phb) {
		printk (KERN_WARNING "EEH: in slot reset, device node %s has no phb\n",
		        pdn->node->full_name);
		return;
	}

	/* Use PE configuration address, if present */
	config_addr = pdn->eeh_config_addr;
	if (pdn->eeh_pe_config_addr)
		config_addr = pdn->eeh_pe_config_addr;

	rc = rtas_call(ibm_set_slot_reset,4,1, NULL,
	               config_addr,
	               BUID_HI(pdn->phb->buid),
	               BUID_LO(pdn->phb->buid),
	               state);
	if (rc) {
		printk (KERN_WARNING "EEH: Unable to reset the failed slot, (%d) #RST=%d dn=%s\n",