1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Pvpanic Device Support 4 * 5 * Copyright (C) 2013 Fujitsu. 6 * Copyright (C) 2018 ZTE. 7 * Copyright (C) 2021 Oracle. 8 */ 9 10 #include <linux/device.h> 11 #include <linux/errno.h> 12 #include <linux/gfp_types.h> 13 #include <linux/io.h> 14 #include <linux/kexec.h> 15 #include <linux/kstrtox.h> 16 #include <linux/limits.h> 17 #include <linux/list.h> 18 #include <linux/mod_devicetable.h> 19 #include <linux/module.h> 20 #include <linux/panic_notifier.h> 21 #include <linux/platform_device.h> 22 #include <linux/spinlock.h> 23 #include <linux/sysfs.h> 24 #include <linux/types.h> 25 26 #include <uapi/misc/pvpanic.h> 27 28 #include "pvpanic.h" 29 30 MODULE_AUTHOR("Mihai Carabas <mihai.carabas@oracle.com>"); 31 MODULE_DESCRIPTION("pvpanic device driver"); 32 MODULE_LICENSE("GPL"); 33 34 struct pvpanic_instance { 35 void __iomem *base; 36 unsigned int capability; 37 unsigned int events; 38 struct list_head list; 39 }; 40 41 static struct list_head pvpanic_list; 42 static spinlock_t pvpanic_lock; 43 44 static void 45 pvpanic_send_event(unsigned int event) 46 { 47 struct pvpanic_instance *pi_cur; 48 49 if (!spin_trylock(&pvpanic_lock)) 50 return; 51 52 list_for_each_entry(pi_cur, &pvpanic_list, list) { 53 if (event & pi_cur->capability & pi_cur->events) 54 iowrite8(event, pi_cur->base); 55 } 56 spin_unlock(&pvpanic_lock); 57 } 58 59 static int 60 pvpanic_panic_notify(struct notifier_block *nb, unsigned long code, void *unused) 61 { 62 unsigned int event = PVPANIC_PANICKED; 63 64 if (kexec_crash_loaded()) 65 event = PVPANIC_CRASH_LOADED; 66 67 pvpanic_send_event(event); 68 69 return NOTIFY_DONE; 70 } 71 72 /* 73 * Call our notifier very early on panic, deferring the 74 * action taken to the hypervisor. 75 */ 76 static struct notifier_block pvpanic_panic_nb = { 77 .notifier_call = pvpanic_panic_notify, 78 .priority = INT_MAX, 79 }; 80 81 static void pvpanic_remove(void *param) 82 { 83 struct pvpanic_instance *pi_cur, *pi_next; 84 struct pvpanic_instance *pi = param; 85 86 spin_lock(&pvpanic_lock); 87 list_for_each_entry_safe(pi_cur, pi_next, &pvpanic_list, list) { 88 if (pi_cur == pi) { 89 list_del(&pi_cur->list); 90 break; 91 } 92 } 93 spin_unlock(&pvpanic_lock); 94 } 95 96 static ssize_t capability_show(struct device *dev, struct device_attribute *attr, char *buf) 97 { 98 struct pvpanic_instance *pi = dev_get_drvdata(dev); 99 100 return sysfs_emit(buf, "%x\n", pi->capability); 101 } 102 static DEVICE_ATTR_RO(capability); 103 104 static ssize_t events_show(struct device *dev, struct device_attribute *attr, char *buf) 105 { 106 struct pvpanic_instance *pi = dev_get_drvdata(dev); 107 108 return sysfs_emit(buf, "%x\n", pi->events); 109 } 110 111 static ssize_t events_store(struct device *dev, struct device_attribute *attr, 112 const char *buf, size_t count) 113 { 114 struct pvpanic_instance *pi = dev_get_drvdata(dev); 115 unsigned int tmp; 116 int err; 117 118 err = kstrtouint(buf, 16, &tmp); 119 if (err) 120 return err; 121 122 if ((tmp & pi->capability) != tmp) 123 return -EINVAL; 124 125 pi->events = tmp; 126 127 return count; 128 } 129 static DEVICE_ATTR_RW(events); 130 131 static struct attribute *pvpanic_dev_attrs[] = { 132 &dev_attr_capability.attr, 133 &dev_attr_events.attr, 134 NULL 135 }; 136 137 static const struct attribute_group pvpanic_dev_group = { 138 .attrs = pvpanic_dev_attrs, 139 }; 140 141 const struct attribute_group *pvpanic_dev_groups[] = { 142 &pvpanic_dev_group, 143 NULL 144 }; 145 EXPORT_SYMBOL_GPL(pvpanic_dev_groups); 146 147 int devm_pvpanic_probe(struct device *dev, void __iomem *base) 148 { 149 struct pvpanic_instance *pi; 150 151 if (!base) 152 return -EINVAL; 153 154 pi = devm_kmalloc(dev, sizeof(*pi), GFP_KERNEL); 155 if (!pi) 156 return -ENOMEM; 157 158 pi->base = base; 159 pi->capability = PVPANIC_PANICKED | PVPANIC_CRASH_LOADED; 160 161 /* initlize capability by RDPT */ 162 pi->capability &= ioread8(base); 163 pi->events = pi->capability; 164 165 spin_lock(&pvpanic_lock); 166 list_add(&pi->list, &pvpanic_list); 167 spin_unlock(&pvpanic_lock); 168 169 dev_set_drvdata(dev, pi); 170 171 return devm_add_action_or_reset(dev, pvpanic_remove, pi); 172 } 173 EXPORT_SYMBOL_GPL(devm_pvpanic_probe); 174 175 static int pvpanic_init(void) 176 { 177 INIT_LIST_HEAD(&pvpanic_list); 178 spin_lock_init(&pvpanic_lock); 179 180 atomic_notifier_chain_register(&panic_notifier_list, &pvpanic_panic_nb); 181 182 return 0; 183 } 184 module_init(pvpanic_init); 185 186 static void pvpanic_exit(void) 187 { 188 atomic_notifier_chain_unregister(&panic_notifier_list, &pvpanic_panic_nb); 189 190 } 191 module_exit(pvpanic_exit); 192