[Qemu-devel] [PATCH 6/6] target-i386: Call cpu_exec_init() on realize

[Eduardo Habkost <ehabkost@redhat.com>]

To allow new code to ask the CPU classes for CPU model information and
allow QOM properties to be queried by qmp_device_list_properties(), we
need to be able to safely instantiate a X86CPU object without any
side-effects.

cpu_exec_init() has lots of side-effects on global QEMU state, move it
to realize so it will be called only if the X86CPU instance is realized.

For reference, this is the current cpu_exec_init() code:

> void cpu_exec_init(CPUArchState *env)
> {
>     CPUState *cpu = ENV_GET_CPU(env);
>     CPUClass *cc = CPU_GET_CLASS(cpu);
>     CPUState *some_cpu;
>     int cpu_index;
>
> #ifndef CONFIG_USER_ONLY
>     cpu->as = &address_space_memory;
>     cpu->thread_id = qemu_get_thread_id();
> #endif

Those fields should be used only after actually starting the VCPU and can be
initialized on realize.

>
> #if defined(CONFIG_USER_ONLY)
>     cpu_list_lock();
> #endif
>     cpu_index = 0;
>     CPU_FOREACH(some_cpu) {
>         cpu_index++;
>     }
>     cpu->cpu_index = cpu_index;
>     QTAILQ_INSERT_TAIL(&cpus, cpu, node);
> #if defined(CONFIG_USER_ONLY)
>     cpu_list_unlock();
> #endif

The above initializes cpu_index and add the CPU to the global CPU list.
This affects QEMU global state and must be done only on realize.

>     if (qdev_get_vmsd(DEVICE(cpu)) == NULL) {
>         vmstate_register(NULL, cpu_index, &vmstate_cpu_common, cpu);
>     }
> #if defined(CPU_SAVE_VERSION) && !defined(CONFIG_USER_ONLY)
>     register_savevm(NULL, "cpu", cpu_index, CPU_SAVE_VERSION,
>                     cpu_save, cpu_load, env);
>     assert(cc->vmsd == NULL);
>     assert(qdev_get_vmsd(DEVICE(cpu)) == NULL);
> #endif
>     if (cc->vmsd != NULL) {
>         vmstate_register(NULL, cpu_index, cc->vmsd, cpu);
>     }

vmstate and savevm registration also affects global QEMU state and should be
done only on realize.

> }

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target-i386/cpu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 400b1e0..8b76604 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -2758,6 +2758,8 @@ static void x86_cpu_realizefn(DeviceState *dev, Error **errp)
     static bool ht_warned;
     static bool tcg_initialized;
 
+    cpu_exec_init(env);
+
     if (tcg_enabled() && !tcg_initialized) {
         tcg_initialized = 1;
         tcg_x86_init();
@@ -2840,7 +2842,6 @@ static void x86_cpu_initfn(Object *obj)
     CPUX86State *env = &cpu->env;
 
     cs->env_ptr = env;
-    cpu_exec_init(env);
 
     object_property_add(obj, "family", "int",
                         x86_cpuid_version_get_family,
-- 
2.1.0