QOM objects shouldn't access each other internals fields
except using the QOM API.

Declare the 'cpu' and 'base-addr' properties, set them
using object_property_set_link() and qdev_prop_set_uint32()
respectively. Since the _set_link() call can't fail, use
&error_abort in case there is a programming error.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/intc/apic_common.c    | 2 ++
 target/i386/cpu-sysemu.c | 9 ++++-----
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/hw/intc/apic_common.c b/hw/intc/apic_common.c
index 8a79eacdb0..be7cf3b332 100644
--- a/hw/intc/apic_common.c
+++ b/hw/intc/apic_common.c
@@ -398,6 +398,8 @@ static Property apic_properties_common[] = {
                     true),
     DEFINE_PROP_BOOL("legacy-instance-id", APICCommonState, legacy_instance_id,
                      false),
+    DEFINE_PROP_LINK("cpu", APICCommonState, cpu, TYPE_X86_CPU, X86CPU *),
+    DEFINE_PROP_UINT32("base-addr", APICCommonState, apicbase, 0),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/target/i386/cpu-sysemu.c b/target/i386/cpu-sysemu.c
index 373dc6b1c7..b084706531 100644
--- a/target/i386/cpu-sysemu.c
+++ b/target/i386/cpu-sysemu.c
@@ -265,7 +265,6 @@ APICCommonClass *apic_get_class(void)
 
 void x86_cpu_apic_new(X86CPU *cpu)
 {
-    APICCommonState *apic;
     APICCommonClass *apic_class = apic_get_class();
 
     cpu->apic_state = DEVICE(object_new_with_class(OBJECT_CLASS(apic_class)));
@@ -273,11 +272,11 @@ void x86_cpu_apic_new(X86CPU *cpu)
                               OBJECT(cpu->apic_state));
     object_unref(OBJECT(cpu->apic_state));
 
+    object_property_set_link(OBJECT(cpu->apic_state), "cpu",
+                             OBJECT(cpu), &error_abort);
     qdev_prop_set_uint32(cpu->apic_state, "id", cpu->apic_id);
-    /* TODO: convert to link<> */
-    apic = APIC_COMMON(cpu->apic_state);
-    apic->cpu = cpu;
-    apic->apicbase = APIC_DEFAULT_ADDRESS | MSR_IA32_APICBASE_ENABLE;
+    qdev_prop_set_uint32(cpu->apic_state, "base-addr",
+                         APIC_DEFAULT_ADDRESS | MSR_IA32_APICBASE_ENABLE);
 }
 
 void x86_cpu_apic_realize(X86CPU *cpu, Error **errp)
-- 
2.41.0

On 10/3/23 10:27, Philippe Mathieu-Daudé wrote:
> -    /* TODO: convert to link<> */
> -    apic = APIC_COMMON(cpu->apic_state);
> -    apic->cpu = cpu;
> -    apic->apicbase = APIC_DEFAULT_ADDRESS | MSR_IA32_APICBASE_ENABLE;
> +    qdev_prop_set_uint32(cpu->apic_state, "base-addr",
> +                         APIC_DEFAULT_ADDRESS | MSR_IA32_APIC

For this to use a link, it's missing the corresponding 
object_unref(apic->cpu) + apic->cpu = NULL assignment somewhere.  For 
example you can add it in apic_common_unrealize (called by 
device_unparent - which is called in turn by x86_cpu_unrealizefn).

Paolo

Hi Paolo,

On 6/10/23 01:04, Paolo Bonzini wrote:
> On 10/3/23 10:27, Philippe Mathieu-Daudé wrote:
>> -    /* TODO: convert to link<> */
>> -    apic = APIC_COMMON(cpu->apic_state);
>> -    apic->cpu = cpu;
>> -    apic->apicbase = APIC_DEFAULT_ADDRESS | MSR_IA32_APICBASE_ENABLE;
>> +    qdev_prop_set_uint32(cpu->apic_state, "base-addr",
>> +                         APIC_DEFAULT_ADDRESS | MSR_IA32_APIC
> 
> For this to use a link, it's missing the corresponding 
> object_unref(apic->cpu) + apic->cpu = NULL assignment somewhere.  For 
> example you can add it in apic_common_unrealize (called by 
> device_unparent - which is called in turn by x86_cpu_unrealizefn).

I am a bit confused.

DEFINE_PROP_LINK() sets OBJ_PROP_LINK_STRONG:

  * If the link property was created with
  * %OBJ_PROP_LINK_STRONG bit, the old target object is
  * unreferenced, and a reference is added to the new target object.

Is this what you are pointing at? If so, I agree this should be
unref in apic_common_unrealize().