arch/powerpc/kernel/eeh_event.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *
   4  * Copyright (c) 2005 Linas Vepstas <[email protected]>
   5  */
   6
   7 #include <linux/delay.h>
   8 #include <linux/list.h>
   9 #include <linux/sched.h>
  10 #include <linux/semaphore.h>
  11 #include <linux/pci.h>
  12 #include <linux/slab.h>
  13 #include <linux/kthread.h>
  14 #include <asm/eeh_event.h>
  15 #include <asm/ppc-pci.h>
  16
  17 /** Overview:
  18  *  EEH error states may be detected within exception handlers;
  19  *  however, the recovery processing needs to occur asynchronously
  20  *  in a normal kernel context and not an interrupt context.
  21  *  This pair of routines creates an event and queues it onto a
  22  *  work-queue, where a worker thread can drive recovery.
  23  */
  24
  25 static DEFINE_SPINLOCK(eeh_eventlist_lock);
  26 static DECLARE_COMPLETION(eeh_eventlist_event);
  27 static LIST_HEAD(eeh_eventlist);
  28
  29 /**
  30  * eeh_event_handler - Dispatch EEH events.
  31  * @dummy - unused
  32  *
  33  * The detection of a frozen slot can occur inside an interrupt,
  34  * where it can be hard to do anything about it.  The goal of this
  35  * routine is to pull these detection events out of the context
  36  * of the interrupt handler, and re-dispatch them for processing
  37  * at a later time in a normal context.
  38  */
  39 static int eeh_event_handler(void * dummy)
  40 {
  41         unsigned long flags;
  42         struct eeh_event *event;
  43         struct eeh_pe *pe;
  44
  45         while (!kthread_should_stop()) {
  46                 if (wait_for_completion_interruptible(&eeh_eventlist_event))
  47                         break;
  48
  49                 /* Fetch EEH event from the queue */
  50                 spin_lock_irqsave(&eeh_eventlist_lock, flags);
  51                 event = NULL;
  52                 if (!list_empty(&eeh_eventlist)) {
  53                         event = list_entry(eeh_eventlist.next,
  54                                            struct eeh_event, list);
  55                         list_del(&event->list);
  56                 }
  57                 spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
  58                 if (!event)
  59                         continue;
  60
  61                 /* We might have event without binding PE */
  62                 pe = event->pe;
  63                 if (pe) {
  64                         if (pe->type & EEH_PE_PHB)
  65                                 pr_info("EEH: Detected error on PHB#%x\n",
  66                                          pe->phb->global_number);
  67                         else
  68                                 pr_info("EEH: Detected PCI bus error on "
  69                                         "PHB#%x-PE#%x\n",
  70                                         pe->phb->global_number, pe->addr);
  71                         eeh_handle_normal_event(pe);
  72                 } else {
  73                         eeh_handle_special_event();
  74                 }
  75
  76                 kfree(event);
  77         }
  78
  79         return 0;
  80 }
  81
  82 /**
  83  * eeh_event_init - Start kernel thread to handle EEH events
  84  *
  85  * This routine is called to start the kernel thread for processing
  86  * EEH event.
  87  */
  88 int eeh_event_init(void)
  89 {
  90         struct task_struct *t;
  91         int ret = 0;
  92
  93         t = kthread_run(eeh_event_handler, NULL, "eehd");
  94         if (IS_ERR(t)) {
  95                 ret = PTR_ERR(t);
  96                 pr_err("%s: Failed to start EEH daemon (%d)\n",
  97                         __func__, ret);
  98                 return ret;
  99         }
 100
 101         return 0;
 102 }
 103
 104 /**
 105  * eeh_send_failure_event - Generate a PCI error event
 106  * @pe: EEH PE
 107  *
 108  * This routine can be called within an interrupt context;
 109  * the actual event will be delivered in a normal context
 110  * (from a workqueue).
 111  */
 112 int __eeh_send_failure_event(struct eeh_pe *pe)
 113 {
 114         unsigned long flags;
 115         struct eeh_event *event;
 116
 117         event = kzalloc(sizeof(*event), GFP_ATOMIC);
 118         if (!event) {
 119                 pr_err("EEH: out of memory, event not handled\n");
 120                 return -ENOMEM;
 121         }
 122         event->pe = pe;
 123
 124         /* We may or may not be called in an interrupt context */
 125         spin_lock_irqsave(&eeh_eventlist_lock, flags);
 126         list_add(&event->list, &eeh_eventlist);
 127         spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
 128
 129         /* For EEH deamon to knick in */
 130         complete(&eeh_eventlist_event);
 131
 132         return 0;
 133 }
 134
 135 int eeh_send_failure_event(struct eeh_pe *pe)
 136 {
 137         /*
 138          * If we've manually supressed recovery events via debugfs
 139          * then just drop it on the floor.
 140          */
 141         if (eeh_debugfs_no_recover) {
 142                 pr_err("EEH: Event dropped due to no_recover setting\n");
 143                 return 0;
 144         }
 145
 146         return __eeh_send_failure_event(pe);
 147 }
 148
 149 /**
 150  * eeh_remove_event - Remove EEH event from the queue
 151  * @pe: Event binding to the PE
 152  * @force: Event will be removed unconditionally
 153  *
 154  * On PowerNV platform, we might have subsequent coming events
 155  * is part of the former one. For that case, those subsequent
 156  * coming events are totally duplicated and unnecessary, thus
 157  * they should be removed.
 158  */
 159 void eeh_remove_event(struct eeh_pe *pe, bool force)
 160 {
 161         unsigned long flags;
 162         struct eeh_event *event, *tmp;
 163
 164         /*
 165          * If we have NULL PE passed in, we have dead IOC
 166          * or we're sure we can report all existing errors
 167          * by the caller.
 168          *
 169          * With "force", the event with associated PE that
 170          * have been isolated, the event won't be removed
 171          * to avoid event lost.
 172          */
 173         spin_lock_irqsave(&eeh_eventlist_lock, flags);
 174         list_for_each_entry_safe(event, tmp, &eeh_eventlist, list) {
 175                 if (!force && event->pe &&
 176                     (event->pe->state & EEH_PE_ISOLATED))
 177                         continue;
 178
 179                 if (!pe) {
 180                         list_del(&event->list);
 181                         kfree(event);
 182                 } else if (pe->type & EEH_PE_PHB) {
 183                         if (event->pe && event->pe->phb == pe->phb) {
 184                                 list_del(&event->list);
 185                                 kfree(event);
 186                         }
 187                 } else if (event->pe == pe) {
 188                         list_del(&event->list);
 189                         kfree(event);
 190                 }
 191         }
 192         spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
 193 }