In order to have a generic function creating threads,
introduce the thread_precreate() and cpu_thread_routine()
handlers.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 include/system/accel-ops.h |  5 ++++-
 accel/accel-common.c       | 16 +++++++++++++++-
 system/cpus.c              |  2 +-
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/include/system/accel-ops.h b/include/system/accel-ops.h
index b1b9dce27d0..b1a55ebe333 100644
--- a/include/system/accel-ops.h
+++ b/include/system/accel-ops.h
@@ -39,7 +39,10 @@ struct AccelOpsClass {
     bool (*cpu_target_realize)(CPUState *cpu, Error **errp);
     void (*cpu_reset_hold)(CPUState *cpu);
 
-    void (*create_vcpu_thread)(CPUState *cpu); /* MANDATORY NON-NULL */
+    /* Either cpu_thread_routine() or create_vcpu_thread() is mandatory */
+    void *(*cpu_thread_routine)(void *);
+    void (*thread_precreate)(CPUState *cpu);
+    void (*create_vcpu_thread)(CPUState *cpu);
     void (*kick_vcpu_thread)(CPUState *cpu);
     bool (*cpu_thread_is_idle)(CPUState *cpu);
 
diff --git a/accel/accel-common.c b/accel/accel-common.c
index d719917063e..24038acf4aa 100644
--- a/accel/accel-common.c
+++ b/accel/accel-common.c
@@ -11,6 +11,7 @@
 #include "qemu/accel.h"
 #include "qemu/target-info.h"
 #include "system/accel-ops.h"
+#include "system/cpus.h"
 #include "accel/accel-cpu.h"
 #include "accel-internal.h"
 
@@ -104,7 +105,20 @@ void accel_create_vcpu_thread(AccelState *accel, CPUState *cpu)
     if (ac->ops->create_vcpu_thread != NULL) {
         ac->ops->create_vcpu_thread(cpu);
     } else {
-        g_assert_not_reached();
+        char thread_name[VCPU_THREAD_NAME_SIZE];
+
+        assert(ac->name);
+        assert(ac->ops->cpu_thread_routine);
+
+        if (ac->ops->thread_precreate) {
+            ac->ops->thread_precreate(cpu);
+        }
+
+        snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/%s",
+                 cpu->cpu_index, ac->name);
+        qemu_thread_create(cpu->thread, thread_name,
+                           ac->ops->cpu_thread_routine,
+                           cpu, QEMU_THREAD_JOINABLE);
     }
 }
 
diff --git a/system/cpus.c b/system/cpus.c
index 1721b32fc3f..bd3fd1b31b6 100644
--- a/system/cpus.c
+++ b/system/cpus.c
@@ -671,7 +671,7 @@ void cpu_remove_sync(CPUState *cpu)
 void cpus_register_accel(const AccelOpsClass *ops)
 {
     assert(ops != NULL);
-    assert(ops->create_vcpu_thread != NULL); /* mandatory */
+    assert(ops->create_vcpu_thread || ops->cpu_thread_routine);
     cpus_accel = ops;
 }
 
-- 
2.49.0

On 6/20/25 10:13, Philippe Mathieu-Daudé wrote:
> In order to have a generic function creating threads,
> introduce the thread_precreate() and cpu_thread_routine()
> handlers.
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>   include/system/accel-ops.h |  5 ++++-
>   accel/accel-common.c       | 16 +++++++++++++++-
>   system/cpus.c              |  2 +-
>   3 files changed, 20 insertions(+), 3 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~