aboutsummaryrefslogtreecommitdiff
path: root/util/thread-context.c
blob: 2bc7883b9e011427045e05a9968690d72123aa1f (plain)
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
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
/*
 * QEMU Thread Context
 *
 * Copyright Red Hat Inc., 2022
 *
 * Authors:
 *  David Hildenbrand <david@redhat.com>
 *
 * This work is licensed under the terms of the GNU GPL, version 2 or later.
 * See the COPYING file in the top-level directory.
 */

#include "qemu/osdep.h"
#include "qemu/thread-context.h"
#include "qapi/error.h"
#include "qapi/qapi-builtin-visit.h"
#include "qapi/visitor.h"
#include "qemu/config-file.h"
#include "qapi/qapi-builtin-visit.h"
#include "qom/object_interfaces.h"
#include "qemu/module.h"
#include "qemu/bitmap.h"

#ifdef CONFIG_NUMA
#include <numa.h>
#endif

enum {
    TC_CMD_NONE = 0,
    TC_CMD_STOP,
    TC_CMD_NEW,
};

typedef struct ThreadContextCmdNew {
    QemuThread *thread;
    const char *name;
    void *(*start_routine)(void *);
    void *arg;
    int mode;
} ThreadContextCmdNew;

static void *thread_context_run(void *opaque)
{
    ThreadContext *tc = opaque;

    tc->thread_id = qemu_get_thread_id();
    qemu_sem_post(&tc->sem);

    while (true) {
        /*
         * Threads inherit the CPU affinity of the creating thread. For this
         * reason, we create new (especially short-lived) threads from our
         * persistent context thread.
         *
         * Especially when QEMU is not allowed to set the affinity itself,
         * management tools can simply set the affinity of the context thread
         * after creating the context, to have new threads created via
         * the context inherit the CPU affinity automatically.
         */
        switch (tc->thread_cmd) {
        case TC_CMD_NONE:
            break;
        case TC_CMD_STOP:
            tc->thread_cmd = TC_CMD_NONE;
            qemu_sem_post(&tc->sem);
            return NULL;
        case TC_CMD_NEW: {
            ThreadContextCmdNew *cmd_new = tc->thread_cmd_data;

            qemu_thread_create(cmd_new->thread, cmd_new->name,
                               cmd_new->start_routine, cmd_new->arg,
                               cmd_new->mode);
            tc->thread_cmd = TC_CMD_NONE;
            tc->thread_cmd_data = NULL;
            qemu_sem_post(&tc->sem);
            break;
        }
        default:
            g_assert_not_reached();
        }
        qemu_sem_wait(&tc->sem_thread);
    }
}

static void thread_context_set_cpu_affinity(Object *obj, Visitor *v,
                                            const char *name, void *opaque,
                                            Error **errp)
{
    ThreadContext *tc = THREAD_CONTEXT(obj);
    uint16List *l, *host_cpus = NULL;
    unsigned long *bitmap = NULL;
    int nbits = 0, ret;

    if (tc->init_cpu_bitmap) {
        error_setg(errp, "Mixing CPU and node affinity not supported");
        return;
    }

    if (!visit_type_uint16List(v, name, &host_cpus, errp)) {
        return;
    }

    if (!host_cpus) {
        error_setg(errp, "CPU list is empty");
        goto out;
    }

    for (l = host_cpus; l; l = l->next) {
        nbits = MAX(nbits, l->value + 1);
    }
    bitmap = bitmap_new(nbits);
    for (l = host_cpus; l; l = l->next) {
        set_bit(l->value, bitmap);
    }

    if (tc->thread_id != -1) {
        /*
         * Note: we won't be adjusting the affinity of any thread that is still
         * around, but only the affinity of the context thread.
         */
        ret = qemu_thread_set_affinity(&tc->thread, bitmap, nbits);
        if (ret) {
            error_setg(errp, "Setting CPU affinity failed: %s", strerror(ret));
        }
    } else {
        tc->init_cpu_bitmap = bitmap;
        bitmap = NULL;
        tc->init_cpu_nbits = nbits;
    }
out:
    g_free(bitmap);
    qapi_free_uint16List(host_cpus);
}

static void thread_context_get_cpu_affinity(Object *obj, Visitor *v,
                                            const char *name, void *opaque,
                                            Error **errp)
{
    unsigned long *bitmap, nbits, value;
    ThreadContext *tc = THREAD_CONTEXT(obj);
    uint16List *host_cpus = NULL;
    uint16List **tail = &host_cpus;
    int ret;

    if (tc->thread_id == -1) {
        error_setg(errp, "Object not initialized yet");
        return;
    }

    ret = qemu_thread_get_affinity(&tc->thread, &bitmap, &nbits);
    if (ret) {
        error_setg(errp, "Getting CPU affinity failed: %s", strerror(ret));
        return;
    }

    value = find_first_bit(bitmap, nbits);
    while (value < nbits) {
        QAPI_LIST_APPEND(tail, value);

        value = find_next_bit(bitmap, nbits, value + 1);
    }
    g_free(bitmap);

    visit_type_uint16List(v, name, &host_cpus, errp);
    qapi_free_uint16List(host_cpus);
}

static void thread_context_set_node_affinity(Object *obj, Visitor *v,
                                             const char *name, void *opaque,
                                             Error **errp)
{
#ifdef CONFIG_NUMA
    const int nbits = numa_num_possible_cpus();
    ThreadContext *tc = THREAD_CONTEXT(obj);
    uint16List *l, *host_nodes = NULL;
    unsigned long *bitmap = NULL;
    struct bitmask *tmp_cpus;
    int ret, i;

    if (tc->init_cpu_bitmap) {
        error_setg(errp, "Mixing CPU and node affinity not supported");
        return;
    }

    if (!visit_type_uint16List(v, name, &host_nodes, errp)) {
        return;
    }

    if (!host_nodes) {
        error_setg(errp, "Node list is empty");
        goto out;
    }

    bitmap = bitmap_new(nbits);
    tmp_cpus = numa_allocate_cpumask();
    for (l = host_nodes; l; l = l->next) {
        numa_bitmask_clearall(tmp_cpus);
        ret = numa_node_to_cpus(l->value, tmp_cpus);
        if (ret) {
            /* We ignore any errors, such as impossible nodes. */
            continue;
        }
        for (i = 0; i < nbits; i++) {
            if (numa_bitmask_isbitset(tmp_cpus, i)) {
                set_bit(i, bitmap);
            }
        }
    }
    numa_free_cpumask(tmp_cpus);

    if (bitmap_empty(bitmap, nbits)) {
        error_setg(errp, "The nodes select no CPUs");
        goto out;
    }

    if (tc->thread_id != -1) {
        /*
         * Note: we won't be adjusting the affinity of any thread that is still
         * around for now, but only the affinity of the context thread.
         */
        ret = qemu_thread_set_affinity(&tc->thread, bitmap, nbits);
        if (ret) {
            error_setg(errp, "Setting CPU affinity failed: %s", strerror(ret));
        }
    } else {
        tc->init_cpu_bitmap = bitmap;
        bitmap = NULL;
        tc->init_cpu_nbits = nbits;
    }
out:
    g_free(bitmap);
    qapi_free_uint16List(host_nodes);
#else
    error_setg(errp, "NUMA node affinity is not supported by this QEMU");
#endif
}

static void thread_context_get_thread_id(Object *obj, Visitor *v,
                                         const char *name, void *opaque,
                                         Error **errp)
{
    ThreadContext *tc = THREAD_CONTEXT(obj);
    uint64_t value = tc->thread_id;

    visit_type_uint64(v, name, &value, errp);
}

static void thread_context_instance_complete(UserCreatable *uc, Error **errp)
{
    ThreadContext *tc = THREAD_CONTEXT(uc);
    char *thread_name;
    int ret;

    thread_name = g_strdup_printf("TC %s",
                               object_get_canonical_path_component(OBJECT(uc)));
    qemu_thread_create(&tc->thread, thread_name, thread_context_run, tc,
                       QEMU_THREAD_JOINABLE);
    g_free(thread_name);

    /* Wait until initialization of the thread is done. */
    while (tc->thread_id == -1) {
        qemu_sem_wait(&tc->sem);
    }

    if (tc->init_cpu_bitmap) {
        ret = qemu_thread_set_affinity(&tc->thread, tc->init_cpu_bitmap,
                                       tc->init_cpu_nbits);
        if (ret) {
            error_setg(errp, "Setting CPU affinity failed: %s", strerror(ret));
        }
        g_free(tc->init_cpu_bitmap);
        tc->init_cpu_bitmap = NULL;
    }
}

static void thread_context_class_init(ObjectClass *oc, void *data)
{
    UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);

    ucc->complete = thread_context_instance_complete;
    object_class_property_add(oc, "thread-id", "int",
                              thread_context_get_thread_id, NULL, NULL,
                              NULL);
    object_class_property_add(oc, "cpu-affinity", "int",
                              thread_context_get_cpu_affinity,
                              thread_context_set_cpu_affinity, NULL, NULL);
    object_class_property_add(oc, "node-affinity", "int", NULL,
                              thread_context_set_node_affinity, NULL, NULL);
}

static void thread_context_instance_init(Object *obj)
{
    ThreadContext *tc = THREAD_CONTEXT(obj);

    tc->thread_id = -1;
    qemu_sem_init(&tc->sem, 0);
    qemu_sem_init(&tc->sem_thread, 0);
    qemu_mutex_init(&tc->mutex);
}

static void thread_context_instance_finalize(Object *obj)
{
    ThreadContext *tc = THREAD_CONTEXT(obj);

    if (tc->thread_id != -1) {
        tc->thread_cmd = TC_CMD_STOP;
        qemu_sem_post(&tc->sem_thread);
        qemu_thread_join(&tc->thread);
    }
    qemu_sem_destroy(&tc->sem);
    qemu_sem_destroy(&tc->sem_thread);
    qemu_mutex_destroy(&tc->mutex);
}

static const TypeInfo thread_context_info = {
    .name = TYPE_THREAD_CONTEXT,
    .parent = TYPE_OBJECT,
    .class_init = thread_context_class_init,
    .instance_size = sizeof(ThreadContext),
    .instance_init = thread_context_instance_init,
    .instance_finalize = thread_context_instance_finalize,
    .interfaces = (InterfaceInfo[]) {
        { TYPE_USER_CREATABLE },
        { }
    }
};

static void thread_context_register_types(void)
{
    type_register_static(&thread_context_info);
}
type_init(thread_context_register_types)

void thread_context_create_thread(ThreadContext *tc, QemuThread *thread,
                                  const char *name,
                                  void *(*start_routine)(void *), void *arg,
                                  int mode)
{
    ThreadContextCmdNew data = {
        .thread = thread,
        .name = name,
        .start_routine = start_routine,
        .arg = arg,
        .mode = mode,
    };

    qemu_mutex_lock(&tc->mutex);
    tc->thread_cmd = TC_CMD_NEW;
    tc->thread_cmd_data = &data;
    qemu_sem_post(&tc->sem_thread);

    while (tc->thread_cmd != TC_CMD_NONE) {
        qemu_sem_wait(&tc->sem);
    }
    qemu_mutex_unlock(&tc->mutex);
}