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
pvpanic_send_event(unsigned int event)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
pvpanic_panic_notify(struct notifier_block * nb,unsigned long code,void * unused)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
pvpanic_remove(void * param)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
capability_show(struct device * dev,struct device_attribute * attr,char * buf)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
events_show(struct device * dev,struct device_attribute * attr,char * buf)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
events_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)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
devm_pvpanic_probe(struct device * dev,void __iomem * base)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
pvpanic_init(void)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
pvpanic_exit(void)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