4 * Copyright Red Hat Inc., 2022
7 * David Hildenbrand <david@redhat.com>
9 * This work is licensed under the terms of the GNU GPL, version 2 or later.
10 * See the COPYING file in the top-level directory.
13 #include "qemu/osdep.h"
14 #include "qemu/thread-context.h"
15 #include "qapi/error.h"
16 #include "qapi/qapi-builtin-visit.h"
17 #include "qapi/visitor.h"
18 #include "qemu/config-file.h"
19 #include "qapi/qapi-builtin-visit.h"
20 #include "qom/object_interfaces.h"
21 #include "qemu/module.h"
22 #include "qemu/bitmap.h"
34 typedef struct ThreadContextCmdNew {
37 void *(*start_routine)(void *);
40 } ThreadContextCmdNew;
42 static void *thread_context_run(void *opaque)
44 ThreadContext *tc = opaque;
46 tc->thread_id = qemu_get_thread_id();
47 qemu_sem_post(&tc->sem);
51 * Threads inherit the CPU affinity of the creating thread. For this
52 * reason, we create new (especially short-lived) threads from our
53 * persistent context thread.
55 * Especially when QEMU is not allowed to set the affinity itself,
56 * management tools can simply set the affinity of the context thread
57 * after creating the context, to have new threads created via
58 * the context inherit the CPU affinity automatically.
60 switch (tc->thread_cmd) {
64 tc->thread_cmd = TC_CMD_NONE;
65 qemu_sem_post(&tc->sem);
68 ThreadContextCmdNew *cmd_new = tc->thread_cmd_data;
70 qemu_thread_create(cmd_new->thread, cmd_new->name,
71 cmd_new->start_routine, cmd_new->arg,
73 tc->thread_cmd = TC_CMD_NONE;
74 tc->thread_cmd_data = NULL;
75 qemu_sem_post(&tc->sem);
79 g_assert_not_reached();
81 qemu_sem_wait(&tc->sem_thread);
85 static void thread_context_set_cpu_affinity(Object *obj, Visitor *v,
86 const char *name, void *opaque,
89 ThreadContext *tc = THREAD_CONTEXT(obj);
90 uint16List *l, *host_cpus = NULL;
91 unsigned long *bitmap = NULL;
94 if (tc->init_cpu_bitmap) {
95 error_setg(errp, "Mixing CPU and node affinity not supported");
99 if (!visit_type_uint16List(v, name, &host_cpus, errp)) {
104 error_setg(errp, "CPU list is empty");
108 for (l = host_cpus; l; l = l->next) {
109 nbits = MAX(nbits, l->value + 1);
111 bitmap = bitmap_new(nbits);
112 for (l = host_cpus; l; l = l->next) {
113 set_bit(l->value, bitmap);
116 if (tc->thread_id != -1) {
118 * Note: we won't be adjusting the affinity of any thread that is still
119 * around, but only the affinity of the context thread.
121 ret = qemu_thread_set_affinity(&tc->thread, bitmap, nbits);
123 error_setg(errp, "Setting CPU affinity failed: %s", strerror(ret));
126 tc->init_cpu_bitmap = bitmap;
128 tc->init_cpu_nbits = nbits;
132 qapi_free_uint16List(host_cpus);
135 static void thread_context_get_cpu_affinity(Object *obj, Visitor *v,
136 const char *name, void *opaque,
139 unsigned long *bitmap, nbits, value;
140 ThreadContext *tc = THREAD_CONTEXT(obj);
141 uint16List *host_cpus = NULL;
142 uint16List **tail = &host_cpus;
145 if (tc->thread_id == -1) {
146 error_setg(errp, "Object not initialized yet");
150 ret = qemu_thread_get_affinity(&tc->thread, &bitmap, &nbits);
152 error_setg(errp, "Getting CPU affinity failed: %s", strerror(ret));
156 value = find_first_bit(bitmap, nbits);
157 while (value < nbits) {
158 QAPI_LIST_APPEND(tail, value);
160 value = find_next_bit(bitmap, nbits, value + 1);
164 visit_type_uint16List(v, name, &host_cpus, errp);
165 qapi_free_uint16List(host_cpus);
168 static void thread_context_set_node_affinity(Object *obj, Visitor *v,
169 const char *name, void *opaque,
173 const int nbits = numa_num_possible_cpus();
174 ThreadContext *tc = THREAD_CONTEXT(obj);
175 uint16List *l, *host_nodes = NULL;
176 unsigned long *bitmap = NULL;
177 struct bitmask *tmp_cpus;
180 if (tc->init_cpu_bitmap) {
181 error_setg(errp, "Mixing CPU and node affinity not supported");
185 if (!visit_type_uint16List(v, name, &host_nodes, errp)) {
190 error_setg(errp, "Node list is empty");
194 bitmap = bitmap_new(nbits);
195 tmp_cpus = numa_allocate_cpumask();
196 for (l = host_nodes; l; l = l->next) {
197 numa_bitmask_clearall(tmp_cpus);
198 ret = numa_node_to_cpus(l->value, tmp_cpus);
200 /* We ignore any errors, such as impossible nodes. */
203 for (i = 0; i < nbits; i++) {
204 if (numa_bitmask_isbitset(tmp_cpus, i)) {
209 numa_free_cpumask(tmp_cpus);
211 if (bitmap_empty(bitmap, nbits)) {
212 error_setg(errp, "The nodes select no CPUs");
216 if (tc->thread_id != -1) {
218 * Note: we won't be adjusting the affinity of any thread that is still
219 * around for now, but only the affinity of the context thread.
221 ret = qemu_thread_set_affinity(&tc->thread, bitmap, nbits);
223 error_setg(errp, "Setting CPU affinity failed: %s", strerror(ret));
226 tc->init_cpu_bitmap = bitmap;
228 tc->init_cpu_nbits = nbits;
232 qapi_free_uint16List(host_nodes);
234 error_setg(errp, "NUMA node affinity is not supported by this QEMU");
238 static void thread_context_get_thread_id(Object *obj, Visitor *v,
239 const char *name, void *opaque,
242 ThreadContext *tc = THREAD_CONTEXT(obj);
243 uint64_t value = tc->thread_id;
245 visit_type_uint64(v, name, &value, errp);
248 static void thread_context_instance_complete(UserCreatable *uc, Error **errp)
250 ThreadContext *tc = THREAD_CONTEXT(uc);
254 thread_name = g_strdup_printf("TC %s",
255 object_get_canonical_path_component(OBJECT(uc)));
256 qemu_thread_create(&tc->thread, thread_name, thread_context_run, tc,
257 QEMU_THREAD_JOINABLE);
260 /* Wait until initialization of the thread is done. */
261 while (tc->thread_id == -1) {
262 qemu_sem_wait(&tc->sem);
265 if (tc->init_cpu_bitmap) {
266 ret = qemu_thread_set_affinity(&tc->thread, tc->init_cpu_bitmap,
269 error_setg(errp, "Setting CPU affinity failed: %s", strerror(ret));
271 g_free(tc->init_cpu_bitmap);
272 tc->init_cpu_bitmap = NULL;
276 static void thread_context_class_init(ObjectClass *oc, void *data)
278 UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);
280 ucc->complete = thread_context_instance_complete;
281 object_class_property_add(oc, "thread-id", "int",
282 thread_context_get_thread_id, NULL, NULL,
284 object_class_property_add(oc, "cpu-affinity", "int",
285 thread_context_get_cpu_affinity,
286 thread_context_set_cpu_affinity, NULL, NULL);
287 object_class_property_add(oc, "node-affinity", "int", NULL,
288 thread_context_set_node_affinity, NULL, NULL);
291 static void thread_context_instance_init(Object *obj)
293 ThreadContext *tc = THREAD_CONTEXT(obj);
296 qemu_sem_init(&tc->sem, 0);
297 qemu_sem_init(&tc->sem_thread, 0);
298 qemu_mutex_init(&tc->mutex);
301 static void thread_context_instance_finalize(Object *obj)
303 ThreadContext *tc = THREAD_CONTEXT(obj);
305 if (tc->thread_id != -1) {
306 tc->thread_cmd = TC_CMD_STOP;
307 qemu_sem_post(&tc->sem_thread);
308 qemu_thread_join(&tc->thread);
310 qemu_sem_destroy(&tc->sem);
311 qemu_sem_destroy(&tc->sem_thread);
312 qemu_mutex_destroy(&tc->mutex);
315 static const TypeInfo thread_context_info = {
316 .name = TYPE_THREAD_CONTEXT,
317 .parent = TYPE_OBJECT,
318 .class_init = thread_context_class_init,
319 .instance_size = sizeof(ThreadContext),
320 .instance_init = thread_context_instance_init,
321 .instance_finalize = thread_context_instance_finalize,
322 .interfaces = (InterfaceInfo[]) {
323 { TYPE_USER_CREATABLE },
328 static void thread_context_register_types(void)
330 type_register_static(&thread_context_info);
332 type_init(thread_context_register_types)
334 void thread_context_create_thread(ThreadContext *tc, QemuThread *thread,
336 void *(*start_routine)(void *), void *arg,
339 ThreadContextCmdNew data = {
342 .start_routine = start_routine,
347 qemu_mutex_lock(&tc->mutex);
348 tc->thread_cmd = TC_CMD_NEW;
349 tc->thread_cmd_data = &data;
350 qemu_sem_post(&tc->sem_thread);
352 while (tc->thread_cmd != TC_CMD_NONE) {
353 qemu_sem_wait(&tc->sem);
355 qemu_mutex_unlock(&tc->mutex);