powerpc/eeh: Fix race with driver un/bind

[mirror_ubuntu-bionic-kernel.git] / arch / powerpc / kernel / eeh_driver.c

/*
 * PCI Error Recovery Driver for RPA-compliant PPC64 platform.
 * Copyright IBM Corp. 2004 2005
 * Copyright Linas Vepstas <linas@linas.org> 2004, 2005
 *
 * All rights reserved.
 *
 * 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, GOOD TITLE or
 * NON INFRINGEMENT.  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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * Send comments and feedback to Linas Vepstas <linas@austin.ibm.com>
 */
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <asm/eeh.h>
#include <asm/eeh_event.h>
#include <asm/ppc-pci.h>
#include <asm/pci-bridge.h>
#include <asm/prom.h>
#include <asm/rtas.h>

struct eeh_rmv_data {
        struct list_head edev_list;
        int removed;
};

/**
 * eeh_pcid_name - Retrieve name of PCI device driver
 * @pdev: PCI device
 *
 * This routine is used to retrieve the name of PCI device driver
 * if that's valid.
 */
static inline const char *eeh_pcid_name(struct pci_dev *pdev)
{
        if (pdev && pdev->dev.driver)
                return pdev->dev.driver->name;
        return "";
}

/**
 * eeh_pcid_get - Get the PCI device driver
 * @pdev: PCI device
 *
 * The function is used to retrieve the PCI device driver for
 * the indicated PCI device. Besides, we will increase the reference
 * of the PCI device driver to prevent that being unloaded on
 * the fly. Otherwise, kernel crash would be seen.
 */
static inline struct pci_driver *eeh_pcid_get(struct pci_dev *pdev)
{
        if (!pdev || !pdev->driver)
                return NULL;

        if (!try_module_get(pdev->driver->driver.owner))
                return NULL;

        return pdev->driver;
}

/**
 * eeh_pcid_put - Dereference on the PCI device driver
 * @pdev: PCI device
 *
 * The function is called to do dereference on the PCI device
 * driver of the indicated PCI device.
 */
static inline void eeh_pcid_put(struct pci_dev *pdev)
{
        if (!pdev || !pdev->driver)
                return;

        module_put(pdev->driver->driver.owner);
}

/**
 * eeh_disable_irq - Disable interrupt for the recovering device
 * @dev: PCI device
 *
 * This routine must be called when reporting temporary or permanent
 * error to the particular PCI device to disable interrupt of that
 * device. If the device has enabled MSI or MSI-X interrupt, we needn't
 * do real work because EEH should freeze DMA transfers for those PCI
 * devices encountering EEH errors, which includes MSI or MSI-X.
 */
static void eeh_disable_irq(struct pci_dev *dev)
{
        struct eeh_dev *edev = pci_dev_to_eeh_dev(dev);

        /* Don't disable MSI and MSI-X interrupts. They are
         * effectively disabled by the DMA Stopped state
         * when an EEH error occurs.
         */
        if (dev->msi_enabled || dev->msix_enabled)
                return;

        if (!irq_has_action(dev->irq))
                return;

        edev->mode |= EEH_DEV_IRQ_DISABLED;
        disable_irq_nosync(dev->irq);
}

/**
 * eeh_enable_irq - Enable interrupt for the recovering device
 * @dev: PCI device
 *
 * This routine must be called to enable interrupt while failed
 * device could be resumed.
 */
static void eeh_enable_irq(struct pci_dev *dev)
{
        struct eeh_dev *edev = pci_dev_to_eeh_dev(dev);

        if ((edev->mode) & EEH_DEV_IRQ_DISABLED) {
                edev->mode &= ~EEH_DEV_IRQ_DISABLED;
                /*
                 * FIXME !!!!!
                 *
                 * This is just ass backwards. This maze has
                 * unbalanced irq_enable/disable calls. So instead of
                 * finding the root cause it works around the warning
                 * in the irq_enable code by conditionally calling
                 * into it.
                 *
                 * That's just wrong.The warning in the core code is
                 * there to tell people to fix their asymmetries in
                 * their own code, not by abusing the core information
                 * to avoid it.
                 *
                 * I so wish that the assymetry would be the other way
                 * round and a few more irq_disable calls render that
                 * shit unusable forever.
                 *
                 *      tglx
                 */
                if (irqd_irq_disabled(irq_get_irq_data(dev->irq)))
                        enable_irq(dev->irq);
        }
}

static bool eeh_dev_removed(struct eeh_dev *edev)
{
        /* EEH device removed ? */
        if (!edev || (edev->mode & EEH_DEV_REMOVED))
                return true;

        return false;
}

static void *eeh_dev_save_state(void *data, void *userdata)
{
        struct eeh_dev *edev = data;
        struct pci_dev *pdev;

        if (!edev)
                return NULL;

        /*
         * We cannot access the config space on some adapters.
         * Otherwise, it will cause fenced PHB. We don't save
         * the content in their config space and will restore
         * from the initial config space saved when the EEH
         * device is created.
         */
        if (edev->pe && (edev->pe->state & EEH_PE_CFG_RESTRICTED))
                return NULL;

        pdev = eeh_dev_to_pci_dev(edev);
        if (!pdev)
                return NULL;

        pci_save_state(pdev);
        return NULL;
}

/**
 * eeh_report_error - Report pci error to each device driver
 * @data: eeh device
 * @userdata: return value
 *
 * Report an EEH error to each device driver, collect up and
 * merge the device driver responses. Cumulative response
 * passed back in "userdata".
 */
static void *eeh_report_error(void *data, void *userdata)
{
        struct eeh_dev *edev = (struct eeh_dev *)data;
        struct pci_dev *dev = eeh_dev_to_pci_dev(edev);
        enum pci_ers_result rc, *res = userdata;
        struct pci_driver *driver;

        if (!dev || eeh_dev_removed(edev) || eeh_pe_passed(edev->pe))
                return NULL;

        device_lock(&dev->dev);
        dev->error_state = pci_channel_io_frozen;

        driver = eeh_pcid_get(dev);
        if (!driver) goto out_no_dev;

        eeh_disable_irq(dev);

        if (!driver->err_handler ||
            !driver->err_handler->error_detected)
                goto out;

        rc = driver->err_handler->error_detected(dev, pci_channel_io_frozen);

        /* A driver that needs a reset trumps all others */
        if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
        if (*res == PCI_ERS_RESULT_NONE) *res = rc;

        edev->in_error = true;
out:
        eeh_pcid_put(dev);
out_no_dev:
        device_unlock(&dev->dev);
        return NULL;
}

/**
 * eeh_report_mmio_enabled - Tell drivers that MMIO has been enabled
 * @data: eeh device
 * @userdata: return value
 *
 * Tells each device driver that IO ports, MMIO and config space I/O
 * are now enabled. Collects up and merges the device driver responses.
 * Cumulative response passed back in "userdata".
 */
static void *eeh_report_mmio_enabled(void *data, void *userdata)
{
        struct eeh_dev *edev = (struct eeh_dev *)data;
        struct pci_dev *dev = eeh_dev_to_pci_dev(edev);
        enum pci_ers_result rc, *res = userdata;
        struct pci_driver *driver;

        if (!dev || eeh_dev_removed(edev) || eeh_pe_passed(edev->pe))
                return NULL;

        device_lock(&dev->dev);
        driver = eeh_pcid_get(dev);
        if (!driver) goto out_no_dev;

        if (!driver->err_handler ||
            !driver->err_handler->mmio_enabled ||
            (edev->mode & EEH_DEV_NO_HANDLER))
                goto out;

        rc = driver->err_handler->mmio_enabled(dev);

        /* A driver that needs a reset trumps all others */
        if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
        if (*res == PCI_ERS_RESULT_NONE) *res = rc;

out:
        eeh_pcid_put(dev);
out_no_dev:
        device_unlock(&dev->dev);
        return NULL;
}

/**
 * eeh_report_reset - Tell device that slot has been reset
 * @data: eeh device
 * @userdata: return value
 *
 * This routine must be called while EEH tries to reset particular
 * PCI device so that the associated PCI device driver could take
 * some actions, usually to save data the driver needs so that the
 * driver can work again while the device is recovered.
 */
static void *eeh_report_reset(void *data, void *userdata)
{
        struct eeh_dev *edev = (struct eeh_dev *)data;
        struct pci_dev *dev = eeh_dev_to_pci_dev(edev);
        enum pci_ers_result rc, *res = userdata;
        struct pci_driver *driver;

        if (!dev || eeh_dev_removed(edev) || eeh_pe_passed(edev->pe))
                return NULL;

        device_lock(&dev->dev);
        dev->error_state = pci_channel_io_normal;

        driver = eeh_pcid_get(dev);
        if (!driver) goto out_no_dev;

        eeh_enable_irq(dev);

        if (!driver->err_handler ||
            !driver->err_handler->slot_reset ||
            (edev->mode & EEH_DEV_NO_HANDLER) ||
            (!edev->in_error))
                goto out;

        rc = driver->err_handler->slot_reset(dev);
        if ((*res == PCI_ERS_RESULT_NONE) ||
            (*res == PCI_ERS_RESULT_RECOVERED)) *res = rc;
        if (*res == PCI_ERS_RESULT_DISCONNECT &&
             rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;

out:
        eeh_pcid_put(dev);
out_no_dev:
        device_unlock(&dev->dev);
        return NULL;
}

static void *eeh_dev_restore_state(void *data, void *userdata)
{
        struct eeh_dev *edev = data;
        struct pci_dev *pdev;

        if (!edev)
                return NULL;

        /*
         * The content in the config space isn't saved because
         * the blocked config space on some adapters. We have
         * to restore the initial saved config space when the
         * EEH device is created.
         */
        if (edev->pe && (edev->pe->state & EEH_PE_CFG_RESTRICTED)) {
                if (list_is_last(&edev->list, &edev->pe->edevs))
                        eeh_pe_restore_bars(edev->pe);

                return NULL;
        }

        pdev = eeh_dev_to_pci_dev(edev);
        if (!pdev)
                return NULL;

        pci_restore_state(pdev);
        return NULL;
}

/**
 * eeh_report_resume - Tell device to resume normal operations
 * @data: eeh device
 * @userdata: return value
 *
 * This routine must be called to notify the device driver that it
 * could resume so that the device driver can do some initialization
 * to make the recovered device work again.
 */
static void *eeh_report_resume(void *data, void *userdata)
{
        struct eeh_dev *edev = (struct eeh_dev *)data;
        struct pci_dev *dev = eeh_dev_to_pci_dev(edev);
        bool was_in_error;
        struct pci_driver *driver;

        if (!dev || eeh_dev_removed(edev) || eeh_pe_passed(edev->pe))
                return NULL;

        device_lock(&dev->dev);
        dev->error_state = pci_channel_io_normal;

        driver = eeh_pcid_get(dev);
        if (!driver) goto out_no_dev;

        was_in_error = edev->in_error;
        edev->in_error = false;
        eeh_enable_irq(dev);

        if (!driver->err_handler ||
            !driver->err_handler->resume ||
            (edev->mode & EEH_DEV_NO_HANDLER) || !was_in_error) {
                edev->mode &= ~EEH_DEV_NO_HANDLER;
                goto out;
        }

        driver->err_handler->resume(dev);

out:
        eeh_pcid_put(dev);
out_no_dev:
        device_unlock(&dev->dev);
        return NULL;
}

/**
 * eeh_report_failure - Tell device driver that device is dead.
 * @data: eeh device
 * @userdata: return value
 *
 * This informs the device driver that the device is permanently
 * dead, and that no further recovery attempts will be made on it.
 */
static void *eeh_report_failure(void *data, void *userdata)
{
        struct eeh_dev *edev = (struct eeh_dev *)data;
        struct pci_dev *dev = eeh_dev_to_pci_dev(edev);
        struct pci_driver *driver;

        if (!dev || eeh_dev_removed(edev) || eeh_pe_passed(edev->pe))
                return NULL;

        device_lock(&dev->dev);
        dev->error_state = pci_channel_io_perm_failure;

        driver = eeh_pcid_get(dev);
        if (!driver) goto out_no_dev;

        eeh_disable_irq(dev);

        if (!driver->err_handler ||
            !driver->err_handler->error_detected)
                goto out;

        driver->err_handler->error_detected(dev, pci_channel_io_perm_failure);

out:
        eeh_pcid_put(dev);
out_no_dev:
        device_unlock(&dev->dev);
        return NULL;
}

static void *eeh_add_virt_device(void *data, void *userdata)
{
        struct pci_driver *driver;
        struct eeh_dev *edev = (struct eeh_dev *)data;
        struct pci_dev *dev = eeh_dev_to_pci_dev(edev);
        struct pci_dn *pdn = eeh_dev_to_pdn(edev);

        if (!(edev->physfn)) {
                pr_warn("%s: EEH dev %04x:%02x:%02x.%01x not for VF\n",
                        __func__, pdn->phb->global_number, pdn->busno,
                        PCI_SLOT(pdn->devfn), PCI_FUNC(pdn->devfn));
                return NULL;
        }

        driver = eeh_pcid_get(dev);
        if (driver) {
                eeh_pcid_put(dev);
                if (driver->err_handler)
                        return NULL;
        }

#ifdef CONFIG_PPC_POWERNV
        pci_iov_add_virtfn(edev->physfn, pdn->vf_index);
#endif
        return NULL;
}

static void *eeh_rmv_device(void *data, void *userdata)
{
        struct pci_driver *driver;
        struct eeh_dev *edev = (struct eeh_dev *)data;
        struct pci_dev *dev = eeh_dev_to_pci_dev(edev);
        struct eeh_rmv_data *rmv_data = (struct eeh_rmv_data *)userdata;
        int *removed = rmv_data ? &rmv_data->removed : NULL;

        /*
         * Actually, we should remove the PCI bridges as well.
         * However, that's lots of complexity to do that,
         * particularly some of devices under the bridge might
         * support EEH. So we just care about PCI devices for
         * simplicity here.
         */
        if (!dev || (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE))
                return NULL;

        /*
         * We rely on count-based pcibios_release_device() to
         * detach permanently offlined PEs. Unfortunately, that's
         * not reliable enough. We might have the permanently
         * offlined PEs attached, but we needn't take care of
         * them and their child devices.
         */
        if (eeh_dev_removed(edev))
                return NULL;

        driver = eeh_pcid_get(dev);
        if (driver) {
                eeh_pcid_put(dev);
                if (removed &&
                    eeh_pe_passed(edev->pe))
                        return NULL;
                if (removed &&
                    driver->err_handler &&
                    driver->err_handler->error_detected &&
                    driver->err_handler->slot_reset)
                        return NULL;
        }

        /* Remove it from PCI subsystem */
        pr_debug("EEH: Removing %s without EEH sensitive driver\n",
                 pci_name(dev));
        edev->bus = dev->bus;
        edev->mode |= EEH_DEV_DISCONNECTED;
        if (removed)
                (*removed)++;

        if (edev->physfn) {
#ifdef CONFIG_PPC_POWERNV
                struct pci_dn *pdn = eeh_dev_to_pdn(edev);

                pci_iov_remove_virtfn(edev->physfn, pdn->vf_index);
                edev->pdev = NULL;

                /*
                 * We have to set the VF PE number to invalid one, which is
                 * required to plug the VF successfully.
                 */
                pdn->pe_number = IODA_INVALID_PE;
#endif
                if (rmv_data)
                        list_add(&edev->rmv_list, &rmv_data->edev_list);
        } else {
                pci_lock_rescan_remove();
                pci_stop_and_remove_bus_device(dev);
                pci_unlock_rescan_remove();
        }

        return NULL;
}

static void *eeh_pe_detach_dev(void *data, void *userdata)
{
        struct eeh_pe *pe = (struct eeh_pe *)data;
        struct eeh_dev *edev, *tmp;

        eeh_pe_for_each_dev(pe, edev, tmp) {
                if (!(edev->mode & EEH_DEV_DISCONNECTED))
                        continue;

                edev->mode &= ~(EEH_DEV_DISCONNECTED | EEH_DEV_IRQ_DISABLED);
                eeh_rmv_from_parent_pe(edev);
        }

        return NULL;
}

/*
 * Explicitly clear PE's frozen state for PowerNV where
 * we have frozen PE until BAR restore is completed. It's
 * harmless to clear it for pSeries. To be consistent with
 * PE reset (for 3 times), we try to clear the frozen state
 * for 3 times as well.
 */
static void *__eeh_clear_pe_frozen_state(void *data, void *flag)
{
        struct eeh_pe *pe = (struct eeh_pe *)data;
        bool clear_sw_state = *(bool *)flag;
        int i, rc = 1;

        for (i = 0; rc && i < 3; i++)
                rc = eeh_unfreeze_pe(pe, clear_sw_state);

        /* Stop immediately on any errors */
        if (rc) {
                pr_warn("%s: Failure %d unfreezing PHB#%x-PE#%x\n",
                        __func__, rc, pe->phb->global_number, pe->addr);
                return (void *)pe;
        }

        return NULL;
}

static int eeh_clear_pe_frozen_state(struct eeh_pe *pe,
                                     bool clear_sw_state)
{
        void *rc;

        rc = eeh_pe_traverse(pe, __eeh_clear_pe_frozen_state, &clear_sw_state);
        if (!rc)
                eeh_pe_state_clear(pe, EEH_PE_ISOLATED);

        return rc ? -EIO : 0;
}

int eeh_pe_reset_and_recover(struct eeh_pe *pe)
{
        int ret;

        /* Bail if the PE is being recovered */
        if (pe->state & EEH_PE_RECOVERING)
                return 0;

        /* Put the PE into recovery mode */
        eeh_pe_state_mark(pe, EEH_PE_RECOVERING);

        /* Save states */
        eeh_pe_dev_traverse(pe, eeh_dev_save_state, NULL);

        /* Issue reset */
        ret = eeh_pe_reset_full(pe);
        if (ret) {
                eeh_pe_state_clear(pe, EEH_PE_RECOVERING);
                return ret;
        }

        /* Unfreeze the PE */
        ret = eeh_clear_pe_frozen_state(pe, true);
        if (ret) {
                eeh_pe_state_clear(pe, EEH_PE_RECOVERING);
                return ret;
        }

        /* Restore device state */
        eeh_pe_dev_traverse(pe, eeh_dev_restore_state, NULL);

        /* Clear recovery mode */
        eeh_pe_state_clear(pe, EEH_PE_RECOVERING);

        return 0;
}

/**
 * eeh_reset_device - Perform actual reset of a pci slot
 * @pe: EEH PE
 * @bus: PCI bus corresponding to the isolcated slot
 *
 * This routine must be called to do reset on the indicated PE.
 * During the reset, udev might be invoked because those affected
 * PCI devices will be removed and then added.
 */
static int eeh_reset_device(struct eeh_pe *pe, struct pci_bus *bus,
                                struct eeh_rmv_data *rmv_data)
{
        struct pci_bus *frozen_bus = eeh_pe_bus_get(pe);
        time64_t tstamp;
        int cnt, rc;
        struct eeh_dev *edev;

        /* pcibios will clear the counter; save the value */
        cnt = pe->freeze_count;
        tstamp = pe->tstamp;

        /*
         * We don't remove the corresponding PE instances because
         * we need the information afterwords. The attached EEH
         * devices are expected to be attached soon when calling
         * into pci_hp_add_devices().
         */
        eeh_pe_state_mark(pe, EEH_PE_KEEP);
        if (bus) {
                if (pe->type & EEH_PE_VF) {
                        eeh_pe_dev_traverse(pe, eeh_rmv_device, NULL);
                } else {
                        pci_lock_rescan_remove();
                        pci_hp_remove_devices(bus);
                        pci_unlock_rescan_remove();
                }
        } else if (frozen_bus) {
                eeh_pe_dev_traverse(pe, eeh_rmv_device, rmv_data);
        }

        /*
         * Reset the pci controller. (Asserts RST#; resets config space).
         * Reconfigure bridges and devices. Don't try to bring the system
         * up if the reset failed for some reason.
         *
         * During the reset, it's very dangerous to have uncontrolled PCI
         * config accesses. So we prefer to block them. However, controlled
         * PCI config accesses initiated from EEH itself are allowed.
         */
        rc = eeh_pe_reset_full(pe);
        if (rc)
                return rc;

        pci_lock_rescan_remove();

        /* Restore PE */
        eeh_ops->configure_bridge(pe);
        eeh_pe_restore_bars(pe);

        /* Clear frozen state */
        rc = eeh_clear_pe_frozen_state(pe, false);
        if (rc) {
                pci_unlock_rescan_remove();
                return rc;
        }

        /* Give the system 5 seconds to finish running the user-space
         * hotplug shutdown scripts, e.g. ifdown for ethernet.  Yes,
         * this is a hack, but if we don't do this, and try to bring
         * the device up before the scripts have taken it down,
         * potentially weird things happen.
         */
        if (bus) {
                pr_info("EEH: Sleep 5s ahead of complete hotplug\n");
                ssleep(5);

                /*
                 * The EEH device is still connected with its parent
                 * PE. We should disconnect it so the binding can be
                 * rebuilt when adding PCI devices.
                 */
                edev = list_first_entry(&pe->edevs, struct eeh_dev, list);
                eeh_pe_traverse(pe, eeh_pe_detach_dev, NULL);
                if (pe->type & EEH_PE_VF) {
                        eeh_add_virt_device(edev, NULL);
                } else {
                        eeh_pe_state_clear(pe, EEH_PE_PRI_BUS);
                        pci_hp_add_devices(bus);
                }
        } else if (frozen_bus && rmv_data->removed) {
                pr_info("EEH: Sleep 5s ahead of partial hotplug\n");
                ssleep(5);

                edev = list_first_entry(&pe->edevs, struct eeh_dev, list);
                eeh_pe_traverse(pe, eeh_pe_detach_dev, NULL);
                if (pe->type & EEH_PE_VF)
                        eeh_add_virt_device(edev, NULL);
                else
                        pci_hp_add_devices(frozen_bus);
        }
        eeh_pe_state_clear(pe, EEH_PE_KEEP);

        pe->tstamp = tstamp;
        pe->freeze_count = cnt;

        pci_unlock_rescan_remove();
        return 0;
}

/* The longest amount of time to wait for a pci device
 * to come back on line, in seconds.
 */
#define MAX_WAIT_FOR_RECOVERY 300

/**
 * eeh_handle_normal_event - Handle EEH events on a specific PE
 * @pe: EEH PE
 *
 * Attempts to recover the given PE.  If recovery fails or the PE has failed
 * too many times, remove the PE.
 *
 * Returns true if @pe should no longer be used, else false.
 */
static bool eeh_handle_normal_event(struct eeh_pe *pe)
{
        struct pci_bus *frozen_bus;
        struct eeh_dev *edev, *tmp;
        int rc = 0;
        enum pci_ers_result result = PCI_ERS_RESULT_NONE;
        struct eeh_rmv_data rmv_data = {LIST_HEAD_INIT(rmv_data.edev_list), 0};

        frozen_bus = eeh_pe_bus_get(pe);
        if (!frozen_bus) {
                pr_err("%s: Cannot find PCI bus for PHB#%x-PE#%x\n",
                        __func__, pe->phb->global_number, pe->addr);
                return false;
        }

        eeh_pe_update_time_stamp(pe);
        pe->freeze_count++;
        if (pe->freeze_count > eeh_max_freezes) {
                pr_err("EEH: PHB#%x-PE#%x has failed %d times in the\n"
                       "last hour and has been permanently disabled.\n",
                       pe->phb->global_number, pe->addr,
                       pe->freeze_count);
                goto hard_fail;
        }
        pr_warn("EEH: This PCI device has failed %d times in the last hour\n",
                pe->freeze_count);

        /* Walk the various device drivers attached to this slot through
         * a reset sequence, giving each an opportunity to do what it needs
         * to accomplish the reset.  Each child gets a report of the
         * status ... if any child can't handle the reset, then the entire
         * slot is dlpar removed and added.
         *
         * When the PHB is fenced, we have to issue a reset to recover from
         * the error. Override the result if necessary to have partially
         * hotplug for this case.
         */
        pr_info("EEH: Notify device drivers to shutdown\n");
        eeh_pe_dev_traverse(pe, eeh_report_error, &result);
        if ((pe->type & EEH_PE_PHB) &&
            result != PCI_ERS_RESULT_NONE &&
            result != PCI_ERS_RESULT_NEED_RESET)
                result = PCI_ERS_RESULT_NEED_RESET;

        /* Get the current PCI slot state. This can take a long time,
         * sometimes over 300 seconds for certain systems.
         */
        rc = eeh_ops->wait_state(pe, MAX_WAIT_FOR_RECOVERY*1000);
        if (rc < 0 || rc == EEH_STATE_NOT_SUPPORT) {
                pr_warn("EEH: Permanent failure\n");
                goto hard_fail;
        }

        /* Since rtas may enable MMIO when posting the error log,
         * don't post the error log until after all dev drivers
         * have been informed.
         */
        pr_info("EEH: Collect temporary log\n");
        eeh_slot_error_detail(pe, EEH_LOG_TEMP);

        /* If all device drivers were EEH-unaware, then shut
         * down all of the device drivers, and hope they
         * go down willingly, without panicing the system.
         */
        if (result == PCI_ERS_RESULT_NONE) {
                pr_info("EEH: Reset with hotplug activity\n");
                rc = eeh_reset_device(pe, frozen_bus, NULL);
                if (rc) {
                        pr_warn("%s: Unable to reset, err=%d\n",
                                __func__, rc);
                        goto hard_fail;
                }
        }

        /* If all devices reported they can proceed, then re-enable MMIO */
        if (result == PCI_ERS_RESULT_CAN_RECOVER) {
                pr_info("EEH: Enable I/O for affected devices\n");
                rc = eeh_pci_enable(pe, EEH_OPT_THAW_MMIO);

                if (rc < 0)
                        goto hard_fail;
                if (rc) {
                        result = PCI_ERS_RESULT_NEED_RESET;
                } else {
                        pr_info("EEH: Notify device drivers to resume I/O\n");
                        eeh_pe_dev_traverse(pe, eeh_report_mmio_enabled, &result);
                }
        }

        /* If all devices reported they can proceed, then re-enable DMA */
        if (result == PCI_ERS_RESULT_CAN_RECOVER) {
                pr_info("EEH: Enabled DMA for affected devices\n");
                rc = eeh_pci_enable(pe, EEH_OPT_THAW_DMA);

                if (rc < 0)
                        goto hard_fail;
                if (rc) {
                        result = PCI_ERS_RESULT_NEED_RESET;
                } else {
                        /*
                         * We didn't do PE reset for the case. The PE
                         * is still in frozen state. Clear it before
                         * resuming the PE.
                         */
                        eeh_pe_state_clear(pe, EEH_PE_ISOLATED);
                        result = PCI_ERS_RESULT_RECOVERED;
                }
        }

        /* If any device has a hard failure, then shut off everything. */
        if (result == PCI_ERS_RESULT_DISCONNECT) {
                pr_warn("EEH: Device driver gave up\n");
                goto hard_fail;
        }

        /* If any device called out for a reset, then reset the slot */
        if (result == PCI_ERS_RESULT_NEED_RESET) {
                pr_info("EEH: Reset without hotplug activity\n");
                rc = eeh_reset_device(pe, NULL, &rmv_data);
                if (rc) {
                        pr_warn("%s: Cannot reset, err=%d\n",
                                __func__, rc);
                        goto hard_fail;
                }

                pr_info("EEH: Notify device drivers "
                        "the completion of reset\n");
                result = PCI_ERS_RESULT_NONE;
                eeh_pe_dev_traverse(pe, eeh_report_reset, &result);
        }

        /* All devices should claim they have recovered by now. */
        if ((result != PCI_ERS_RESULT_RECOVERED) &&
            (result != PCI_ERS_RESULT_NONE)) {
                pr_warn("EEH: Not recovered\n");
                goto hard_fail;
        }

        /*
         * For those hot removed VFs, we should add back them after PF get
         * recovered properly.
         */
        list_for_each_entry_safe(edev, tmp, &rmv_data.edev_list, rmv_list) {
                eeh_add_virt_device(edev, NULL);
                list_del(&edev->rmv_list);
        }

        /* Tell all device drivers that they can resume operations */
        pr_info("EEH: Notify device driver to resume\n");
        eeh_pe_dev_traverse(pe, eeh_report_resume, NULL);

        return false;

hard_fail:
        /*
         * About 90% of all real-life EEH failures in the field
         * are due to poorly seated PCI cards. Only 10% or so are
         * due to actual, failed cards.
         */
        pr_err("EEH: Unable to recover from failure from PHB#%x-PE#%x.\n"
               "Please try reseating or replacing it\n",
                pe->phb->global_number, pe->addr);

        eeh_slot_error_detail(pe, EEH_LOG_PERM);

        /* Notify all devices that they're about to go down. */
        eeh_pe_dev_traverse(pe, eeh_report_failure, NULL);

        /* Mark the PE to be removed permanently */
        eeh_pe_state_mark(pe, EEH_PE_REMOVED);

        /*
         * Shut down the device drivers for good. We mark
         * all removed devices correctly to avoid access
         * the their PCI config any more.
         */
        if (frozen_bus) {
                if (pe->type & EEH_PE_VF) {
                        eeh_pe_dev_traverse(pe, eeh_rmv_device, NULL);
                        eeh_pe_dev_mode_mark(pe, EEH_DEV_REMOVED);
                } else {
                        eeh_pe_state_clear(pe, EEH_PE_PRI_BUS);
                        eeh_pe_dev_mode_mark(pe, EEH_DEV_REMOVED);

                        pci_lock_rescan_remove();
                        pci_hp_remove_devices(frozen_bus);
                        pci_unlock_rescan_remove();

                        /* The passed PE should no longer be used */
                        return true;
                }
        }
        return false;
}

/**
 * eeh_handle_special_event - Handle EEH events without a specific failing PE
 *
 * Called when an EEH event is detected but can't be narrowed down to a
 * specific PE.  Iterates through possible failures and handles them as
 * necessary.
 */
static void eeh_handle_special_event(void)
{
        struct eeh_pe *pe, *phb_pe;
        struct pci_bus *bus;
        struct pci_controller *hose;
        unsigned long flags;
        int rc;


        do {
                rc = eeh_ops->next_error(&pe);

                switch (rc) {
                case EEH_NEXT_ERR_DEAD_IOC:
                        /* Mark all PHBs in dead state */
                        eeh_serialize_lock(&flags);

                        /* Purge all events */
                        eeh_remove_event(NULL, true);

                        list_for_each_entry(hose, &hose_list, list_node) {
                                phb_pe = eeh_phb_pe_get(hose);
                                if (!phb_pe) continue;

                                eeh_pe_state_mark(phb_pe, EEH_PE_ISOLATED);
                        }

                        eeh_serialize_unlock(flags);

                        break;
                case EEH_NEXT_ERR_FROZEN_PE:
                case EEH_NEXT_ERR_FENCED_PHB:
                case EEH_NEXT_ERR_DEAD_PHB:
                        /* Mark the PE in fenced state */
                        eeh_serialize_lock(&flags);

                        /* Purge all events of the PHB */
                        eeh_remove_event(pe, true);

                        if (rc == EEH_NEXT_ERR_DEAD_PHB)
                                eeh_pe_state_mark(pe, EEH_PE_ISOLATED);
                        else
                                eeh_pe_state_mark(pe,
                                        EEH_PE_ISOLATED | EEH_PE_RECOVERING);

                        eeh_serialize_unlock(flags);

                        break;
                case EEH_NEXT_ERR_NONE:
                        return;
                default:
                        pr_warn("%s: Invalid value %d from next_error()\n",
                                __func__, rc);
                        return;
                }

                /*
                 * For fenced PHB and frozen PE, it's handled as normal
                 * event. We have to remove the affected PHBs for dead
                 * PHB and IOC
                 */
                if (rc == EEH_NEXT_ERR_FROZEN_PE ||
                    rc == EEH_NEXT_ERR_FENCED_PHB) {
                        /*
                         * eeh_handle_normal_event() can make the PE stale if it
                         * determines that the PE cannot possibly be recovered.
                         * Don't modify the PE state if that's the case.
                         */
                        if (eeh_handle_normal_event(pe))
                                continue;

                        eeh_pe_state_clear(pe, EEH_PE_RECOVERING);
                } else {
                        pci_lock_rescan_remove();
                        list_for_each_entry(hose, &hose_list, list_node) {
                                phb_pe = eeh_phb_pe_get(hose);
                                if (!phb_pe ||
                                    !(phb_pe->state & EEH_PE_ISOLATED) ||
                                    (phb_pe->state & EEH_PE_RECOVERING))
                                        continue;

                                /* Notify all devices to be down */
                                eeh_pe_state_clear(pe, EEH_PE_PRI_BUS);
                                eeh_pe_dev_traverse(pe,
                                        eeh_report_failure, NULL);
                                bus = eeh_pe_bus_get(phb_pe);
                                if (!bus) {
                                        pr_err("%s: Cannot find PCI bus for "
                                               "PHB#%x-PE#%x\n",
                                               __func__,
                                               pe->phb->global_number,
                                               pe->addr);
                                        break;
                                }
                                pci_hp_remove_devices(bus);
                        }
                        pci_unlock_rescan_remove();
                }

                /*
                 * If we have detected dead IOC, we needn't proceed
                 * any more since all PHBs would have been removed
                 */
                if (rc == EEH_NEXT_ERR_DEAD_IOC)
                        break;
        } while (rc != EEH_NEXT_ERR_NONE);
}

/**
 * eeh_handle_event - Reset a PCI device after hard lockup.
 * @pe: EEH PE
 *
 * While PHB detects address or data parity errors on particular PCI
 * slot, the associated PE will be frozen. Besides, DMA's occurring
 * to wild addresses (which usually happen due to bugs in device
 * drivers or in PCI adapter firmware) can cause EEH error. #SERR,
 * #PERR or other misc PCI-related errors also can trigger EEH errors.
 *
 * Recovery process consists of unplugging the device driver (which
 * generated hotplug events to userspace), then issuing a PCI #RST to
 * the device, then reconfiguring the PCI config space for all bridges
 * & devices under this slot, and then finally restarting the device
 * drivers (which cause a second set of hotplug events to go out to
 * userspace).
 */
void eeh_handle_event(struct eeh_pe *pe)
{
        if (pe)
                eeh_handle_normal_event(pe);
        else
                eeh_handle_special_event();
}