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-rw-r--r--include/qemu/thread.h4
-rw-r--r--meson.build16
-rw-r--r--util/qemu-thread-posix.c70
-rw-r--r--util/qemu-thread-win32.c12
4 files changed, 102 insertions, 0 deletions
diff --git a/include/qemu/thread.h b/include/qemu/thread.h
index af19f2b3fc..79e507c7f0 100644
--- a/include/qemu/thread.h
+++ b/include/qemu/thread.h
@@ -185,6 +185,10 @@ void qemu_event_destroy(QemuEvent *ev);
 void qemu_thread_create(QemuThread *thread, const char *name,
                         void *(*start_routine)(void *),
                         void *arg, int mode);
+int qemu_thread_set_affinity(QemuThread *thread, unsigned long *host_cpus,
+                             unsigned long nbits);
+int qemu_thread_get_affinity(QemuThread *thread, unsigned long **host_cpus,
+                             unsigned long *nbits);
 void *qemu_thread_join(QemuThread *thread);
 void qemu_thread_get_self(QemuThread *thread);
 bool qemu_thread_is_self(QemuThread *thread);
diff --git a/meson.build b/meson.build
index b686dfef75..3e0aa4925d 100644
--- a/meson.build
+++ b/meson.build
@@ -2114,7 +2114,23 @@ config_host_data.set('CONFIG_PTHREAD_CONDATTR_SETCLOCK', cc.links(gnu_source_pre
     pthread_condattr_setclock(&attr, CLOCK_MONOTONIC);
     return 0;
   }''', dependencies: threads))
+config_host_data.set('CONFIG_PTHREAD_AFFINITY_NP', cc.links(gnu_source_prefix + '''
+  #include <pthread.h>
 
+  static void *f(void *p) { return NULL; }
+  int main(void)
+  {
+    int setsize = CPU_ALLOC_SIZE(64);
+    pthread_t thread;
+    cpu_set_t *cpuset;
+    pthread_create(&thread, 0, f, 0);
+    cpuset = CPU_ALLOC(64);
+    CPU_ZERO_S(setsize, cpuset);
+    pthread_setaffinity_np(thread, setsize, cpuset);
+    pthread_getaffinity_np(thread, setsize, cpuset);
+    CPU_FREE(cpuset);
+    return 0;
+  }''', dependencies: threads))
 config_host_data.set('CONFIG_SIGNALFD', cc.links(gnu_source_prefix + '''
   #include <sys/signalfd.h>
   #include <stddef.h>
diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c
index ac1d56e673..bae938c670 100644
--- a/util/qemu-thread-posix.c
+++ b/util/qemu-thread-posix.c
@@ -16,6 +16,7 @@
 #include "qemu/notify.h"
 #include "qemu-thread-common.h"
 #include "qemu/tsan.h"
+#include "qemu/bitmap.h"
 
 static bool name_threads;
 
@@ -552,6 +553,75 @@ void qemu_thread_create(QemuThread *thread, const char *name,
     pthread_attr_destroy(&attr);
 }
 
+int qemu_thread_set_affinity(QemuThread *thread, unsigned long *host_cpus,
+                             unsigned long nbits)
+{
+#if defined(CONFIG_PTHREAD_AFFINITY_NP)
+    const size_t setsize = CPU_ALLOC_SIZE(nbits);
+    unsigned long value;
+    cpu_set_t *cpuset;
+    int err;
+
+    cpuset = CPU_ALLOC(nbits);
+    g_assert(cpuset);
+
+    CPU_ZERO_S(setsize, cpuset);
+    value = find_first_bit(host_cpus, nbits);
+    while (value < nbits) {
+        CPU_SET_S(value, setsize, cpuset);
+        value = find_next_bit(host_cpus, nbits, value + 1);
+    }
+
+    err = pthread_setaffinity_np(thread->thread, setsize, cpuset);
+    CPU_FREE(cpuset);
+    return err;
+#else
+    return -ENOSYS;
+#endif
+}
+
+int qemu_thread_get_affinity(QemuThread *thread, unsigned long **host_cpus,
+                             unsigned long *nbits)
+{
+#if defined(CONFIG_PTHREAD_AFFINITY_NP)
+    unsigned long tmpbits;
+    cpu_set_t *cpuset;
+    size_t setsize;
+    int i, err;
+
+    tmpbits = CPU_SETSIZE;
+    while (true) {
+        setsize = CPU_ALLOC_SIZE(tmpbits);
+        cpuset = CPU_ALLOC(tmpbits);
+        g_assert(cpuset);
+
+        err = pthread_getaffinity_np(thread->thread, setsize, cpuset);
+        if (err) {
+            CPU_FREE(cpuset);
+            if (err != -EINVAL) {
+                return err;
+            }
+            tmpbits *= 2;
+        } else {
+            break;
+        }
+    }
+
+    /* Convert the result into a proper bitmap. */
+    *nbits = tmpbits;
+    *host_cpus = bitmap_new(tmpbits);
+    for (i = 0; i < tmpbits; i++) {
+        if (CPU_ISSET(i, cpuset)) {
+            set_bit(i, *host_cpus);
+        }
+    }
+    CPU_FREE(cpuset);
+    return 0;
+#else
+    return -ENOSYS;
+#endif
+}
+
 void qemu_thread_get_self(QemuThread *thread)
 {
     thread->thread = pthread_self();
diff --git a/util/qemu-thread-win32.c b/util/qemu-thread-win32.c
index b9a467d7db..69db254ac7 100644
--- a/util/qemu-thread-win32.c
+++ b/util/qemu-thread-win32.c
@@ -477,6 +477,18 @@ void qemu_thread_create(QemuThread *thread, const char *name,
     thread->data = data;
 }
 
+int qemu_thread_set_affinity(QemuThread *thread, unsigned long *host_cpus,
+                             unsigned long nbits)
+{
+    return -ENOSYS;
+}
+
+int qemu_thread_get_affinity(QemuThread *thread, unsigned long **host_cpus,
+                             unsigned long *nbits)
+{
+    return -ENOSYS;
+}
+
 void qemu_thread_get_self(QemuThread *thread)
 {
     thread->data = qemu_thread_data;