1 /* 2 * QEMU Thread Context 3 * 4 * Copyright Red Hat Inc., 2022 5 * 6 * Authors: 7 * David Hildenbrand <david@redhat.com> 8 * 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. 11 */ 12 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" 23 24 #ifdef CONFIG_NUMA 25 #include <numa.h> 26 #endif 27 28 enum { 29 TC_CMD_NONE = 0, 30 TC_CMD_STOP, 31 TC_CMD_NEW, 32 }; 33 34 typedef struct ThreadContextCmdNew { 35 QemuThread *thread; 36 const char *name; 37 void *(*start_routine)(void *); 38 void *arg; 39 int mode; 40 } ThreadContextCmdNew; 41 42 static void *thread_context_run(void *opaque) 43 { 44 ThreadContext *tc = opaque; 45 46 tc->thread_id = qemu_get_thread_id(); 47 qemu_sem_post(&tc->sem); 48 49 while (true) { 50 /* 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. 54 * 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. 59 */ 60 switch (tc->thread_cmd) { 61 case TC_CMD_NONE: 62 break; 63 case TC_CMD_STOP: 64 tc->thread_cmd = TC_CMD_NONE; 65 qemu_sem_post(&tc->sem); 66 return NULL; 67 case TC_CMD_NEW: { 68 ThreadContextCmdNew *cmd_new = tc->thread_cmd_data; 69 70 qemu_thread_create(cmd_new->thread, cmd_new->name, 71 cmd_new->start_routine, cmd_new->arg, 72 cmd_new->mode); 73 tc->thread_cmd = TC_CMD_NONE; 74 tc->thread_cmd_data = NULL; 75 qemu_sem_post(&tc->sem); 76 break; 77 } 78 default: 79 g_assert_not_reached(); 80 } 81 qemu_sem_wait(&tc->sem_thread); 82 } 83 } 84 85 static void thread_context_set_cpu_affinity(Object *obj, Visitor *v, 86 const char *name, void *opaque, 87 Error **errp) 88 { 89 ThreadContext *tc = THREAD_CONTEXT(obj); 90 uint16List *l, *host_cpus = NULL; 91 unsigned long *bitmap = NULL; 92 int nbits = 0, ret; 93 94 if (tc->init_cpu_bitmap) { 95 error_setg(errp, "Mixing CPU and node affinity not supported"); 96 return; 97 } 98 99 if (!visit_type_uint16List(v, name, &host_cpus, errp)) { 100 return; 101 } 102 103 if (!host_cpus) { 104 error_setg(errp, "CPU list is empty"); 105 goto out; 106 } 107 108 for (l = host_cpus; l; l = l->next) { 109 nbits = MAX(nbits, l->value + 1); 110 } 111 bitmap = bitmap_new(nbits); 112 for (l = host_cpus; l; l = l->next) { 113 set_bit(l->value, bitmap); 114 } 115 116 if (tc->thread_id != -1) { 117 /* 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. 120 */ 121 ret = qemu_thread_set_affinity(&tc->thread, bitmap, nbits); 122 if (ret) { 123 error_setg(errp, "Setting CPU affinity failed: %s", strerror(ret)); 124 } 125 } else { 126 tc->init_cpu_bitmap = bitmap; 127 bitmap = NULL; 128 tc->init_cpu_nbits = nbits; 129 } 130 out: 131 g_free(bitmap); 132 qapi_free_uint16List(host_cpus); 133 } 134 135 static void thread_context_get_cpu_affinity(Object *obj, Visitor *v, 136 const char *name, void *opaque, 137 Error **errp) 138 { 139 unsigned long *bitmap, nbits, value; 140 ThreadContext *tc = THREAD_CONTEXT(obj); 141 uint16List *host_cpus = NULL; 142 uint16List **tail = &host_cpus; 143 int ret; 144 145 if (tc->thread_id == -1) { 146 error_setg(errp, "Object not initialized yet"); 147 return; 148 } 149 150 ret = qemu_thread_get_affinity(&tc->thread, &bitmap, &nbits); 151 if (ret) { 152 error_setg(errp, "Getting CPU affinity failed: %s", strerror(ret)); 153 return; 154 } 155 156 value = find_first_bit(bitmap, nbits); 157 while (value < nbits) { 158 QAPI_LIST_APPEND(tail, value); 159 160 value = find_next_bit(bitmap, nbits, value + 1); 161 } 162 g_free(bitmap); 163 164 visit_type_uint16List(v, name, &host_cpus, errp); 165 qapi_free_uint16List(host_cpus); 166 } 167 168 static void thread_context_set_node_affinity(Object *obj, Visitor *v, 169 const char *name, void *opaque, 170 Error **errp) 171 { 172 #ifdef CONFIG_NUMA 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; 178 int ret, i; 179 180 if (tc->init_cpu_bitmap) { 181 error_setg(errp, "Mixing CPU and node affinity not supported"); 182 return; 183 } 184 185 if (!visit_type_uint16List(v, name, &host_nodes, errp)) { 186 return; 187 } 188 189 if (!host_nodes) { 190 error_setg(errp, "Node list is empty"); 191 goto out; 192 } 193 194 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); 199 if (ret) { 200 /* We ignore any errors, such as impossible nodes. */ 201 continue; 202 } 203 for (i = 0; i < nbits; i++) { 204 if (numa_bitmask_isbitset(tmp_cpus, i)) { 205 set_bit(i, bitmap); 206 } 207 } 208 } 209 numa_free_cpumask(tmp_cpus); 210 211 if (bitmap_empty(bitmap, nbits)) { 212 error_setg(errp, "The nodes select no CPUs"); 213 goto out; 214 } 215 216 if (tc->thread_id != -1) { 217 /* 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. 220 */ 221 ret = qemu_thread_set_affinity(&tc->thread, bitmap, nbits); 222 if (ret) { 223 error_setg(errp, "Setting CPU affinity failed: %s", strerror(ret)); 224 } 225 } else { 226 tc->init_cpu_bitmap = bitmap; 227 bitmap = NULL; 228 tc->init_cpu_nbits = nbits; 229 } 230 out: 231 g_free(bitmap); 232 qapi_free_uint16List(host_nodes); 233 #else 234 error_setg(errp, "NUMA node affinity is not supported by this QEMU"); 235 #endif 236 } 237 238 static void thread_context_get_thread_id(Object *obj, Visitor *v, 239 const char *name, void *opaque, 240 Error **errp) 241 { 242 ThreadContext *tc = THREAD_CONTEXT(obj); 243 uint64_t value = tc->thread_id; 244 245 visit_type_uint64(v, name, &value, errp); 246 } 247 248 static void thread_context_instance_complete(UserCreatable *uc, Error **errp) 249 { 250 ThreadContext *tc = THREAD_CONTEXT(uc); 251 char *thread_name; 252 int ret; 253 254 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); 258 g_free(thread_name); 259 260 /* Wait until initialization of the thread is done. */ 261 while (tc->thread_id == -1) { 262 qemu_sem_wait(&tc->sem); 263 } 264 265 if (tc->init_cpu_bitmap) { 266 ret = qemu_thread_set_affinity(&tc->thread, tc->init_cpu_bitmap, 267 tc->init_cpu_nbits); 268 if (ret) { 269 error_setg(errp, "Setting CPU affinity failed: %s", strerror(ret)); 270 } 271 g_free(tc->init_cpu_bitmap); 272 tc->init_cpu_bitmap = NULL; 273 } 274 } 275 276 static void thread_context_class_init(ObjectClass *oc, void *data) 277 { 278 UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc); 279 280 ucc->complete = thread_context_instance_complete; 281 object_class_property_add(oc, "thread-id", "int", 282 thread_context_get_thread_id, NULL, NULL, 283 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); 289 } 290 291 static void thread_context_instance_init(Object *obj) 292 { 293 ThreadContext *tc = THREAD_CONTEXT(obj); 294 295 tc->thread_id = -1; 296 qemu_sem_init(&tc->sem, 0); 297 qemu_sem_init(&tc->sem_thread, 0); 298 qemu_mutex_init(&tc->mutex); 299 } 300 301 static void thread_context_instance_finalize(Object *obj) 302 { 303 ThreadContext *tc = THREAD_CONTEXT(obj); 304 305 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); 309 } 310 qemu_sem_destroy(&tc->sem); 311 qemu_sem_destroy(&tc->sem_thread); 312 qemu_mutex_destroy(&tc->mutex); 313 } 314 315 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 }, 324 { } 325 } 326 }; 327 328 static void thread_context_register_types(void) 329 { 330 type_register_static(&thread_context_info); 331 } 332 type_init(thread_context_register_types) 333 334 void thread_context_create_thread(ThreadContext *tc, QemuThread *thread, 335 const char *name, 336 void *(*start_routine)(void *), void *arg, 337 int mode) 338 { 339 ThreadContextCmdNew data = { 340 .thread = thread, 341 .name = name, 342 .start_routine = start_routine, 343 .arg = arg, 344 .mode = mode, 345 }; 346 347 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); 351 352 while (tc->thread_cmd != TC_CMD_NONE) { 353 qemu_sem_wait(&tc->sem); 354 } 355 qemu_mutex_unlock(&tc->mutex); 356 } 357