1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
|
// SPDX-License-Identifier: GPL-2.0-only
//
// VCPU stall detector.
// Copyright (C) Google, 2022
#include <linux/cpu.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/nmi.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/param.h>
#include <linux/percpu.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#define VCPU_STALL_REG_STATUS (0x00)
#define VCPU_STALL_REG_LOAD_CNT (0x04)
#define VCPU_STALL_REG_CURRENT_CNT (0x08)
#define VCPU_STALL_REG_CLOCK_FREQ_HZ (0x0C)
#define VCPU_STALL_REG_LEN (0x10)
#define VCPU_STALL_DEFAULT_CLOCK_HZ (10)
#define VCPU_STALL_MAX_CLOCK_HZ (100)
#define VCPU_STALL_DEFAULT_TIMEOUT_SEC (8)
#define VCPU_STALL_MAX_TIMEOUT_SEC (600)
struct vcpu_stall_detect_config {
u32 clock_freq_hz;
u32 stall_timeout_sec;
void __iomem *membase;
struct platform_device *dev;
enum cpuhp_state hp_online;
};
struct vcpu_stall_priv {
struct hrtimer vcpu_hrtimer;
bool is_initialized;
};
/* The vcpu stall configuration structure which applies to all the CPUs */
static struct vcpu_stall_detect_config vcpu_stall_config;
#define vcpu_stall_reg_write(vcpu, reg, value) \
writel_relaxed((value), \
(void __iomem *)(vcpu_stall_config.membase + \
(vcpu) * VCPU_STALL_REG_LEN + (reg)))
static struct vcpu_stall_priv __percpu *vcpu_stall_detectors;
static enum hrtimer_restart
vcpu_stall_detect_timer_fn(struct hrtimer *hrtimer)
{
u32 ticks, ping_timeout_ms;
/* Reload the stall detector counter register every
* `ping_timeout_ms` to prevent the virtual device
* from decrementing it to 0. The virtual device decrements this
* register at 'clock_freq_hz' frequency.
*/
ticks = vcpu_stall_config.clock_freq_hz *
vcpu_stall_config.stall_timeout_sec;
vcpu_stall_reg_write(smp_processor_id(),
VCPU_STALL_REG_LOAD_CNT, ticks);
ping_timeout_ms = vcpu_stall_config.stall_timeout_sec *
MSEC_PER_SEC / 2;
hrtimer_forward_now(hrtimer,
ms_to_ktime(ping_timeout_ms));
return HRTIMER_RESTART;
}
static int start_stall_detector_cpu(unsigned int cpu)
{
u32 ticks, ping_timeout_ms;
struct vcpu_stall_priv *vcpu_stall_detector =
this_cpu_ptr(vcpu_stall_detectors);
struct hrtimer *vcpu_hrtimer = &vcpu_stall_detector->vcpu_hrtimer;
vcpu_stall_reg_write(cpu, VCPU_STALL_REG_CLOCK_FREQ_HZ,
vcpu_stall_config.clock_freq_hz);
/* Compute the number of ticks required for the stall detector
* counter register based on the internal clock frequency and the
* timeout value given from the device tree.
*/
ticks = vcpu_stall_config.clock_freq_hz *
vcpu_stall_config.stall_timeout_sec;
vcpu_stall_reg_write(cpu, VCPU_STALL_REG_LOAD_CNT, ticks);
/* Enable the internal clock and start the stall detector */
vcpu_stall_reg_write(cpu, VCPU_STALL_REG_STATUS, 1);
/* Pet the stall detector at half of its expiration timeout
* to prevent spurious resets.
*/
ping_timeout_ms = vcpu_stall_config.stall_timeout_sec *
MSEC_PER_SEC / 2;
hrtimer_init(vcpu_hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
vcpu_hrtimer->function = vcpu_stall_detect_timer_fn;
vcpu_stall_detector->is_initialized = true;
hrtimer_start(vcpu_hrtimer, ms_to_ktime(ping_timeout_ms),
HRTIMER_MODE_REL_PINNED);
return 0;
}
static int stop_stall_detector_cpu(unsigned int cpu)
{
struct vcpu_stall_priv *vcpu_stall_detector =
per_cpu_ptr(vcpu_stall_detectors, cpu);
if (!vcpu_stall_detector->is_initialized)
return 0;
/* Disable the stall detector for the current CPU */
hrtimer_cancel(&vcpu_stall_detector->vcpu_hrtimer);
vcpu_stall_reg_write(cpu, VCPU_STALL_REG_STATUS, 0);
vcpu_stall_detector->is_initialized = false;
return 0;
}
static int vcpu_stall_detect_probe(struct platform_device *pdev)
{
int ret;
struct resource *r;
void __iomem *membase;
u32 clock_freq_hz = VCPU_STALL_DEFAULT_CLOCK_HZ;
u32 stall_timeout_sec = VCPU_STALL_DEFAULT_TIMEOUT_SEC;
struct device_node *np = pdev->dev.of_node;
vcpu_stall_detectors = devm_alloc_percpu(&pdev->dev,
typeof(struct vcpu_stall_priv));
if (!vcpu_stall_detectors)
return -ENOMEM;
membase = devm_platform_get_and_ioremap_resource(pdev, 0, &r);
if (IS_ERR(membase)) {
dev_err(&pdev->dev, "Failed to get memory resource\n");
return PTR_ERR(membase);
}
if (!of_property_read_u32(np, "clock-frequency", &clock_freq_hz)) {
if (!(clock_freq_hz > 0 &&
clock_freq_hz < VCPU_STALL_MAX_CLOCK_HZ)) {
dev_warn(&pdev->dev, "clk out of range\n");
clock_freq_hz = VCPU_STALL_DEFAULT_CLOCK_HZ;
}
}
if (!of_property_read_u32(np, "timeout-sec", &stall_timeout_sec)) {
if (!(stall_timeout_sec > 0 &&
stall_timeout_sec < VCPU_STALL_MAX_TIMEOUT_SEC)) {
dev_warn(&pdev->dev, "stall timeout out of range\n");
stall_timeout_sec = VCPU_STALL_DEFAULT_TIMEOUT_SEC;
}
}
vcpu_stall_config = (struct vcpu_stall_detect_config) {
.membase = membase,
.clock_freq_hz = clock_freq_hz,
.stall_timeout_sec = stall_timeout_sec
};
ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
"virt/vcpu_stall_detector:online",
start_stall_detector_cpu,
stop_stall_detector_cpu);
if (ret < 0) {
dev_err(&pdev->dev, "failed to install cpu hotplug");
goto err;
}
vcpu_stall_config.hp_online = ret;
return 0;
err:
return ret;
}
static int vcpu_stall_detect_remove(struct platform_device *pdev)
{
int cpu;
cpuhp_remove_state(vcpu_stall_config.hp_online);
for_each_possible_cpu(cpu)
stop_stall_detector_cpu(cpu);
return 0;
}
static const struct of_device_id vcpu_stall_detect_of_match[] = {
{ .compatible = "qemu,vcpu-stall-detector", },
{}
};
MODULE_DEVICE_TABLE(of, vcpu_stall_detect_of_match);
static struct platform_driver vcpu_stall_detect_driver = {
.probe = vcpu_stall_detect_probe,
.remove = vcpu_stall_detect_remove,
.driver = {
.name = KBUILD_MODNAME,
.of_match_table = vcpu_stall_detect_of_match,
},
};
module_platform_driver(vcpu_stall_detect_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Sebastian Ene <sebastianene@google.com>");
MODULE_DESCRIPTION("VCPU stall detector");
|
