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/module.h> 19 #include <linux/panic_notifier.h> 20 #include <linux/platform_device.h> 21 #include <linux/reboot.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 sys_off_handler *sys_off; 39 struct list_head list; 40 }; 41 42 static struct list_head pvpanic_list; 43 static spinlock_t pvpanic_lock; 44 45 static void 46 pvpanic_send_event(unsigned int event) 47 { 48 struct pvpanic_instance *pi_cur; 49 50 if (!spin_trylock(&pvpanic_lock)) 51 return; 52 53 list_for_each_entry(pi_cur, &pvpanic_list, list) { 54 if (event & pi_cur->capability & pi_cur->events) 55 iowrite8(event, pi_cur->base); 56 } 57 spin_unlock(&pvpanic_lock); 58 } 59 60 static int 61 pvpanic_panic_notify(struct notifier_block *nb, unsigned long code, void *unused) 62 { 63 unsigned int event = PVPANIC_PANICKED; 64 65 if (kexec_crash_loaded()) 66 event = PVPANIC_CRASH_LOADED; 67 68 pvpanic_send_event(event); 69 70 return NOTIFY_DONE; 71 } 72 73 /* 74 * Call our notifier very early on panic, deferring the 75 * action taken to the hypervisor. 76 */ 77 static struct notifier_block pvpanic_panic_nb = { 78 .notifier_call = pvpanic_panic_notify, 79 .priority = INT_MAX, 80 }; 81 82 static int pvpanic_sys_off(struct sys_off_data *data) 83 { 84 pvpanic_send_event(PVPANIC_SHUTDOWN); 85 86 return NOTIFY_DONE; 87 } 88 89 static void pvpanic_synchronize_sys_off_handler(struct device *dev, struct pvpanic_instance *pi) 90 { 91 /* The kernel core has logic to fall back to system halt if no 92 * sys_off_handler is registered. 93 * When the pvpanic sys_off_handler is disabled via sysfs the kernel 94 * should use that fallback logic, so the handler needs to be unregistered. 95 */ 96 97 struct sys_off_handler *sys_off; 98 99 if (!(pi->events & PVPANIC_SHUTDOWN) == !pi->sys_off) 100 return; 101 102 if (!pi->sys_off) { 103 sys_off = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF, SYS_OFF_PRIO_LOW, 104 pvpanic_sys_off, NULL); 105 if (IS_ERR(sys_off)) 106 dev_warn(dev, "Could not register sys_off_handler: %pe\n", sys_off); 107 else 108 pi->sys_off = sys_off; 109 } else { 110 unregister_sys_off_handler(pi->sys_off); 111 pi->sys_off = NULL; 112 } 113 } 114 115 static void pvpanic_remove(void *param) 116 { 117 struct pvpanic_instance *pi_cur, *pi_next; 118 struct pvpanic_instance *pi = param; 119 120 spin_lock(&pvpanic_lock); 121 list_for_each_entry_safe(pi_cur, pi_next, &pvpanic_list, list) { 122 if (pi_cur == pi) { 123 list_del(&pi_cur->list); 124 break; 125 } 126 } 127 spin_unlock(&pvpanic_lock); 128 129 unregister_sys_off_handler(pi->sys_off); 130 } 131 132 static ssize_t capability_show(struct device *dev, struct device_attribute *attr, char *buf) 133 { 134 struct pvpanic_instance *pi = dev_get_drvdata(dev); 135 136 return sysfs_emit(buf, "%x\n", pi->capability); 137 } 138 static DEVICE_ATTR_RO(capability); 139 140 static ssize_t events_show(struct device *dev, struct device_attribute *attr, char *buf) 141 { 142 struct pvpanic_instance *pi = dev_get_drvdata(dev); 143 144 return sysfs_emit(buf, "%x\n", pi->events); 145 } 146 147 static ssize_t events_store(struct device *dev, struct device_attribute *attr, 148 const char *buf, size_t count) 149 { 150 struct pvpanic_instance *pi = dev_get_drvdata(dev); 151 unsigned int tmp; 152 int err; 153 154 err = kstrtouint(buf, 16, &tmp); 155 if (err) 156 return err; 157 158 if ((tmp & pi->capability) != tmp) 159 return -EINVAL; 160 161 pi->events = tmp; 162 pvpanic_synchronize_sys_off_handler(dev, pi); 163 164 return count; 165 } 166 static DEVICE_ATTR_RW(events); 167 168 static struct attribute *pvpanic_dev_attrs[] = { 169 &dev_attr_capability.attr, 170 &dev_attr_events.attr, 171 NULL 172 }; 173 174 static const struct attribute_group pvpanic_dev_group = { 175 .attrs = pvpanic_dev_attrs, 176 }; 177 178 const struct attribute_group *pvpanic_dev_groups[] = { 179 &pvpanic_dev_group, 180 NULL 181 }; 182 EXPORT_SYMBOL_GPL(pvpanic_dev_groups); 183 184 int devm_pvpanic_probe(struct device *dev, void __iomem *base) 185 { 186 struct pvpanic_instance *pi; 187 188 if (!base) 189 return -EINVAL; 190 191 pi = devm_kmalloc(dev, sizeof(*pi), GFP_KERNEL); 192 if (!pi) 193 return -ENOMEM; 194 195 pi->base = base; 196 pi->capability = PVPANIC_PANICKED | PVPANIC_CRASH_LOADED | PVPANIC_SHUTDOWN; 197 198 /* initlize capability by RDPT */ 199 pi->capability &= ioread8(base); 200 pi->events = pi->capability; 201 202 pi->sys_off = NULL; 203 pvpanic_synchronize_sys_off_handler(dev, pi); 204 205 spin_lock(&pvpanic_lock); 206 list_add(&pi->list, &pvpanic_list); 207 spin_unlock(&pvpanic_lock); 208 209 dev_set_drvdata(dev, pi); 210 211 return devm_add_action_or_reset(dev, pvpanic_remove, pi); 212 } 213 EXPORT_SYMBOL_GPL(devm_pvpanic_probe); 214 215 static int pvpanic_init(void) 216 { 217 INIT_LIST_HEAD(&pvpanic_list); 218 spin_lock_init(&pvpanic_lock); 219 220 atomic_notifier_chain_register(&panic_notifier_list, &pvpanic_panic_nb); 221 222 return 0; 223 } 224 module_init(pvpanic_init); 225 226 static void pvpanic_exit(void) 227 { 228 atomic_notifier_chain_unregister(&panic_notifier_list, &pvpanic_panic_nb); 229 230 } 231 module_exit(pvpanic_exit); 232