/*
* 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;
Error *err = NULL;
if (tc->init_cpu_bitmap) {
error_setg(errp, "Mixing CPU and node affinity not supported");
return;
}
visit_type_uint16List(v, name, &host_cpus, &err);
if (err) {
error_propagate(errp, err);
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;
Error *err = NULL;
int ret, i;
if (tc->init_cpu_bitmap) {
error_setg(errp, "Mixing CPU and node affinity not supported");
return;
}
visit_type_uint16List(v, name, &host_nodes, &err);
if (err) {
error_propagate(errp, err);
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);
}
