diff mbox series

[PULL,v2,01/28] hw: apply accel compat properties without touching globals

Message ID 20190107122304.22997-2-marcandre.lureau@redhat.com (mailing list archive)
State New, archived
Headers show
Series [PULL,v2,01/28] hw: apply accel compat properties without touching globals | expand

Commit Message

Marc-André Lureau Jan. 7, 2019, 12:22 p.m. UTC 
Instead of registering compat properties as globals, let's keep them
in their own array, to avoid mixing with user globals.

Introduce object_apply_global_props() function, to apply compatibility
properties from a GPtrArray.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Acked-by: Eduardo Habkost <ehabkost@redhat.com>
---
 include/hw/qdev-core.h | 10 ++++++++++
 include/qom/object.h   |  3 +++
 include/sysemu/accel.h |  4 +---
 accel/accel.c          | 12 ------------
 hw/core/qdev.c         |  9 +++++++++
 hw/xen/xen-common.c    |  9 ++++++---
 qom/object.c           | 25 +++++++++++++++++++++++++
 vl.c                   |  1 -
 8 files changed, 54 insertions(+), 19 deletions(-)

Comments

Peter Maydell Jan. 14, 2019, 3:50 p.m. UTC | #1 
On Mon, 7 Jan 2019 at 12:23, Marc-André Lureau
<marcandre.lureau@redhat.com> wrote:
>
> Instead of registering compat properties as globals, let's keep them
> in their own array, to avoid mixing with user globals.
>
> Introduce object_apply_global_props() function, to apply compatibility
> properties from a GPtrArray.

> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> index 6b3cc55b27..53b507164f 100644
> --- a/hw/core/qdev.c
> +++ b/hw/core/qdev.c
> @@ -972,6 +972,15 @@ static void device_initfn(Object *obj)
>
>  static void device_post_init(Object *obj)
>  {
> +    if (object_dynamic_cast(qdev_get_machine(), TYPE_MACHINE)) {
> +        MachineState *m = MACHINE(qdev_get_machine());
> +        AccelClass *ac = ACCEL_GET_CLASS(m->accelerator);
> +
> +        if (ac->compat_props) {
> +            object_apply_global_props(obj, ac->compat_props, &error_abort);
> +        }
> +    }
> +
>      qdev_prop_set_globals(DEVICE(obj));
>  }


Hi; I've just noticed that this commit seems to break
"-device whatever,help" :

$ gdb --args ./build/x86/arm-softmmu/qemu-system-arm -device iotkit,help -M virt
GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5) 7.11.1
[...]
(gdb) r
Starting program:
/home/petmay01/linaro/qemu-from-laptop/qemu/build/x86/arm-softmmu/qemu-system-arm
-device iotkit,help -M virt
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffce6c1700 (LWP 23277)]

Thread 1 "qemu-system-arm" received signal SIGSEGV, Segmentation fault.
0x0000555555d985d1 in object_get_class (obj=0x0)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:857
857         return obj->class;
(gdb) bt
#0  0x0000555555d985d1 in object_get_class (obj=0x0)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:857
#1  0x0000555555b5675d in object_apply_compat_props (obj=0x555556b42600)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/hw/core/qdev.c:978
#2  0x0000555555b567f0 in device_post_init (obj=0x555556b42600)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/hw/core/qdev.c:989
#3  0x0000555555d97294 in object_post_init_with_type
(obj=0x555556b42600, ti=0x5555569f7840)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:365
#4  0x0000555555d972c2 in object_post_init_with_type
(obj=0x555556b42600, ti=0x5555569f8640)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:369
#5  0x0000555555d972c2 in object_post_init_with_type
(obj=0x555556b42600, ti=0x555556a12c60)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:369
#6  0x0000555555d97572 in object_initialize_with_type
(data=0x555556b42600, size=1056, type=0x555556a12c60) at
/home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:425
#7  0x0000555555d975b0 in object_initialize (data=0x555556b42600,
size=1056, typename=0x555555ff3ee1 "armv7m_systick") at
/home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:432
#8  0x0000555555d976fd in object_initialize_childv
(parentobj=0x555556b40fa0, propname=0x555555ff3f36 "systick-reg-ns",
childobj=0x555556b42600, size=1056, type=0x555555ff3ee1
"armv7m_systick", errp=0x5555569775f8 <error_abort>,
vargs=0x7fffffffd7c0)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:455
#9  0x0000555555d97689 in object_initialize_child
(parentobj=0x555556b40fa0, propname=0x555555ff3f36 "systick-reg-ns",
childobj=0x555556b42600, size=1056, type=0x555555ff3ee1
"armv7m_systick", errp=0x5555569775f8 <error_abort>) at
/home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:442
#10 0x0000555555b5d049 in sysbus_init_child_obj
(parent=0x555556b40fa0, childname=0x555555ff3f36 "systick-reg-ns",
child=0x555556b42600, childsize=1056, childtype=0x555555ff3ee1
"armv7m_systick")
    at /home/petmay01/linaro/qemu-from-laptop/qemu/hw/core/sysbus.c:376
#11 0x00005555559231b0 in armv7m_nvic_instance_init (obj=0x555556b40fa0)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/hw/intc/armv7m_nvic.c:2393
#12 0x0000555555d97263 in object_init_with_type (obj=0x555556b40fa0,
ti=0x5555569cbce0)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:358
#13 0x0000555555d9755f in object_initialize_with_type
(data=0x555556b40fa0, size=7840, type=0x5555569cbce0) at
/home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:424
#14 0x0000555555d975b0 in object_initialize (data=0x555556b40fa0,
size=7840, typename=0x555556019af8 "armv7m_nvic") at
/home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:432
#15 0x0000555555d976fd in object_initialize_childv
(parentobj=0x555556b40c90, propname=0x555556019b04 "nvnic",
childobj=0x555556b40fa0, size=7840, type=0x555556019af8 "armv7m_nvic",
errp=0x5555569775f8 <error_abort>, vargs=0x7fffffffda90)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:455
#16 0x0000555555d97689 in object_initialize_child
(parentobj=0x555556b40c90, propname=0x555556019b04 "nvnic",
childobj=0x555556b40fa0, size=7840, type=0x555556019af8 "armv7m_nvic",
errp=0x5555569775f8 <error_abort>) at
/home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:442
#17 0x0000555555b5d049 in sysbus_init_child_obj
(parent=0x555556b40c90, childname=0x555556019b04 "nvnic",
child=0x555556b40fa0, childsize=7840, childtype=0x555556019af8
"armv7m_nvic")
    at /home/petmay01/linaro/qemu-from-laptop/qemu/hw/core/sysbus.c:376
#18 0x00005555559c63ba in armv7m_instance_init (obj=0x555556b40c90)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/hw/arm/armv7m.c:137
#19 0x0000555555d97263 in object_init_with_type (obj=0x555556b40c90,
ti=0x5555569db4c0)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:358
#20 0x0000555555d9755f in object_initialize_with_type
(data=0x555556b40c90, size=11152, type=0x5555569db4c0) at
/home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:424
#21 0x0000555555d975b0 in object_initialize (data=0x555556b40c90,
size=11152, typename=0x555556022fd1 "armv7m") at
/home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:432
#22 0x0000555555d976fd in object_initialize_childv
(parentobj=0x555556b40980, propname=0x555556022fd1 "armv7m",
childobj=0x555556b40c90, size=11152, type=0x555556022fd1 "armv7m",
errp=0x5555569775f8 <error_abort>, vargs=0x7fffffffdd50)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:455
#23 0x0000555555d97689 in object_initialize_child
(parentobj=0x555556b40980, propname=0x555556022fd1 "armv7m",
childobj=0x555556b40c90, size=11152, type=0x555556022fd1 "armv7m",
errp=0x5555569775f8 <error_abort>) at
/home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:442
#24 0x0000555555b5d049 in sysbus_init_child_obj
(parent=0x555556b40980, childname=0x555556022fd1 "armv7m",
child=0x555556b40c90, childsize=11152, childtype=0x555556022fd1
"armv7m")
    at /home/petmay01/linaro/qemu-from-laptop/qemu/hw/core/sysbus.c:376
#25 0x00005555559f3fdc in iotkit_init (obj=0x555556b40980)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/hw/arm/iotkit.c:115
#26 0x0000555555d97263 in object_init_with_type (obj=0x555556b40980,
ti=0x5555569df840)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:358
#27 0x0000555555d9755f in object_initialize_with_type
(data=0x555556b40980, size=50080, type=0x5555569df840) at
/home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:424
#28 0x0000555555d97bb9 in object_new_with_type (type=0x5555569df840)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:588
#29 0x0000555555d97bf6 in object_new (typename=0x555556a2b230 "iotkit")
    at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:598
#30 0x0000555555aafe8c in qmp_device_list_properties
(typename=0x555556a2b230 "iotkit", errp=0x7fffffffe050) at
/home/petmay01/linaro/qemu-from-laptop/qemu/qmp.c:519
#31 0x0000555555a8607a in qdev_device_help (opts=0x555556a2b1c0)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/qdev-monitor.c:283
#32 0x0000555555a8f77e in device_help_func (opaque=0x0,
opts=0x555556a2b1c0, errp=0x0)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/vl.c:2299
#33 0x0000555555ef5b21 in qemu_opts_foreach (list=0x555556787040
<qemu_device_opts>, func=0x555555a8f75e <device_help_func>,
opaque=0x0, errp=0x0)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/util/qemu-option.c:1171
#34 0x0000555555a94310 in main (argc=5, argv=0x7fffffffe408,
envp=0x7fffffffe438)
    at /home/petmay01/linaro/qemu-from-laptop/qemu/vl.c:4323

Looking at the backtrace, this seems to happen because in
device_post_init we look at m->accelerator, but m->accelerator
is only set when vl.c calls configure_accelerator(), so if
this function gets called before then, it will cause an assert.
In particular, the handling of -device foo,help happens before the
accelerator is configured. (Possibly other things may cause
device init before then too?)

thanks
-- PMM
Marc-André Lureau Jan. 14, 2019, 6:23 p.m. UTC | #2 
Hi Peter

On Mon, Jan 14, 2019 at 7:50 PM Peter Maydell <peter.maydell@linaro.org> wrote:
>
> On Mon, 7 Jan 2019 at 12:23, Marc-André Lureau
> <marcandre.lureau@redhat.com> wrote:
> >
> > Instead of registering compat properties as globals, let's keep them
> > in their own array, to avoid mixing with user globals.
> >
> > Introduce object_apply_global_props() function, to apply compatibility
> > properties from a GPtrArray.
>
> > diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> > index 6b3cc55b27..53b507164f 100644
> > --- a/hw/core/qdev.c
> > +++ b/hw/core/qdev.c
> > @@ -972,6 +972,15 @@ static void device_initfn(Object *obj)
> >
> >  static void device_post_init(Object *obj)
> >  {
> > +    if (object_dynamic_cast(qdev_get_machine(), TYPE_MACHINE)) {
> > +        MachineState *m = MACHINE(qdev_get_machine());
> > +        AccelClass *ac = ACCEL_GET_CLASS(m->accelerator);
> > +
> > +        if (ac->compat_props) {
> > +            object_apply_global_props(obj, ac->compat_props, &error_abort);
> > +        }
> > +    }
> > +
> >      qdev_prop_set_globals(DEVICE(obj));
> >  }
>
>
> Hi; I've just noticed that this commit seems to break
> "-device whatever,help" :

[Qemu-devel] [PATCH] qdev: fix -device scsi-hd,help regression

This should now be queued, afaik.

>
> $ gdb --args ./build/x86/arm-softmmu/qemu-system-arm -device iotkit,help -M virt
> GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5) 7.11.1
> [...]
> (gdb) r
> Starting program:
> /home/petmay01/linaro/qemu-from-laptop/qemu/build/x86/arm-softmmu/qemu-system-arm
> -device iotkit,help -M virt
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
> [New Thread 0x7fffce6c1700 (LWP 23277)]
>
> Thread 1 "qemu-system-arm" received signal SIGSEGV, Segmentation fault.
> 0x0000555555d985d1 in object_get_class (obj=0x0)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:857
> 857         return obj->class;
> (gdb) bt
> #0  0x0000555555d985d1 in object_get_class (obj=0x0)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:857
> #1  0x0000555555b5675d in object_apply_compat_props (obj=0x555556b42600)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/hw/core/qdev.c:978
> #2  0x0000555555b567f0 in device_post_init (obj=0x555556b42600)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/hw/core/qdev.c:989
> #3  0x0000555555d97294 in object_post_init_with_type
> (obj=0x555556b42600, ti=0x5555569f7840)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:365
> #4  0x0000555555d972c2 in object_post_init_with_type
> (obj=0x555556b42600, ti=0x5555569f8640)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:369
> #5  0x0000555555d972c2 in object_post_init_with_type
> (obj=0x555556b42600, ti=0x555556a12c60)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:369
> #6  0x0000555555d97572 in object_initialize_with_type
> (data=0x555556b42600, size=1056, type=0x555556a12c60) at
> /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:425
> #7  0x0000555555d975b0 in object_initialize (data=0x555556b42600,
> size=1056, typename=0x555555ff3ee1 "armv7m_systick") at
> /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:432
> #8  0x0000555555d976fd in object_initialize_childv
> (parentobj=0x555556b40fa0, propname=0x555555ff3f36 "systick-reg-ns",
> childobj=0x555556b42600, size=1056, type=0x555555ff3ee1
> "armv7m_systick", errp=0x5555569775f8 <error_abort>,
> vargs=0x7fffffffd7c0)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:455
> #9  0x0000555555d97689 in object_initialize_child
> (parentobj=0x555556b40fa0, propname=0x555555ff3f36 "systick-reg-ns",
> childobj=0x555556b42600, size=1056, type=0x555555ff3ee1
> "armv7m_systick", errp=0x5555569775f8 <error_abort>) at
> /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:442
> #10 0x0000555555b5d049 in sysbus_init_child_obj
> (parent=0x555556b40fa0, childname=0x555555ff3f36 "systick-reg-ns",
> child=0x555556b42600, childsize=1056, childtype=0x555555ff3ee1
> "armv7m_systick")
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/hw/core/sysbus.c:376
> #11 0x00005555559231b0 in armv7m_nvic_instance_init (obj=0x555556b40fa0)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/hw/intc/armv7m_nvic.c:2393
> #12 0x0000555555d97263 in object_init_with_type (obj=0x555556b40fa0,
> ti=0x5555569cbce0)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:358
> #13 0x0000555555d9755f in object_initialize_with_type
> (data=0x555556b40fa0, size=7840, type=0x5555569cbce0) at
> /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:424
> #14 0x0000555555d975b0 in object_initialize (data=0x555556b40fa0,
> size=7840, typename=0x555556019af8 "armv7m_nvic") at
> /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:432
> #15 0x0000555555d976fd in object_initialize_childv
> (parentobj=0x555556b40c90, propname=0x555556019b04 "nvnic",
> childobj=0x555556b40fa0, size=7840, type=0x555556019af8 "armv7m_nvic",
> errp=0x5555569775f8 <error_abort>, vargs=0x7fffffffda90)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:455
> #16 0x0000555555d97689 in object_initialize_child
> (parentobj=0x555556b40c90, propname=0x555556019b04 "nvnic",
> childobj=0x555556b40fa0, size=7840, type=0x555556019af8 "armv7m_nvic",
> errp=0x5555569775f8 <error_abort>) at
> /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:442
> #17 0x0000555555b5d049 in sysbus_init_child_obj
> (parent=0x555556b40c90, childname=0x555556019b04 "nvnic",
> child=0x555556b40fa0, childsize=7840, childtype=0x555556019af8
> "armv7m_nvic")
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/hw/core/sysbus.c:376
> #18 0x00005555559c63ba in armv7m_instance_init (obj=0x555556b40c90)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/hw/arm/armv7m.c:137
> #19 0x0000555555d97263 in object_init_with_type (obj=0x555556b40c90,
> ti=0x5555569db4c0)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:358
> #20 0x0000555555d9755f in object_initialize_with_type
> (data=0x555556b40c90, size=11152, type=0x5555569db4c0) at
> /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:424
> #21 0x0000555555d975b0 in object_initialize (data=0x555556b40c90,
> size=11152, typename=0x555556022fd1 "armv7m") at
> /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:432
> #22 0x0000555555d976fd in object_initialize_childv
> (parentobj=0x555556b40980, propname=0x555556022fd1 "armv7m",
> childobj=0x555556b40c90, size=11152, type=0x555556022fd1 "armv7m",
> errp=0x5555569775f8 <error_abort>, vargs=0x7fffffffdd50)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:455
> #23 0x0000555555d97689 in object_initialize_child
> (parentobj=0x555556b40980, propname=0x555556022fd1 "armv7m",
> childobj=0x555556b40c90, size=11152, type=0x555556022fd1 "armv7m",
> errp=0x5555569775f8 <error_abort>) at
> /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:442
> #24 0x0000555555b5d049 in sysbus_init_child_obj
> (parent=0x555556b40980, childname=0x555556022fd1 "armv7m",
> child=0x555556b40c90, childsize=11152, childtype=0x555556022fd1
> "armv7m")
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/hw/core/sysbus.c:376
> #25 0x00005555559f3fdc in iotkit_init (obj=0x555556b40980)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/hw/arm/iotkit.c:115
> #26 0x0000555555d97263 in object_init_with_type (obj=0x555556b40980,
> ti=0x5555569df840)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:358
> #27 0x0000555555d9755f in object_initialize_with_type
> (data=0x555556b40980, size=50080, type=0x5555569df840) at
> /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:424
> #28 0x0000555555d97bb9 in object_new_with_type (type=0x5555569df840)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:588
> #29 0x0000555555d97bf6 in object_new (typename=0x555556a2b230 "iotkit")
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/qom/object.c:598
> #30 0x0000555555aafe8c in qmp_device_list_properties
> (typename=0x555556a2b230 "iotkit", errp=0x7fffffffe050) at
> /home/petmay01/linaro/qemu-from-laptop/qemu/qmp.c:519
> #31 0x0000555555a8607a in qdev_device_help (opts=0x555556a2b1c0)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/qdev-monitor.c:283
> #32 0x0000555555a8f77e in device_help_func (opaque=0x0,
> opts=0x555556a2b1c0, errp=0x0)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/vl.c:2299
> #33 0x0000555555ef5b21 in qemu_opts_foreach (list=0x555556787040
> <qemu_device_opts>, func=0x555555a8f75e <device_help_func>,
> opaque=0x0, errp=0x0)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/util/qemu-option.c:1171
> #34 0x0000555555a94310 in main (argc=5, argv=0x7fffffffe408,
> envp=0x7fffffffe438)
>     at /home/petmay01/linaro/qemu-from-laptop/qemu/vl.c:4323
>
> Looking at the backtrace, this seems to happen because in
> device_post_init we look at m->accelerator, but m->accelerator
> is only set when vl.c calls configure_accelerator(), so if
> this function gets called before then, it will cause an assert.
> In particular, the handling of -device foo,help happens before the
> accelerator is configured. (Possibly other things may cause
> device init before then too?)
>
> thanks
> -- PMM
diff mbox series

Patch

diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index 92851e55df..84e612f473 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -267,6 +267,16 @@  typedef struct GlobalProperty {
     Error **errp;
 } GlobalProperty;
 
+static inline void
+compat_props_add(GPtrArray *arr,
+                 GlobalProperty props[], size_t nelem)
+{
+    int i;
+    for (i = 0; i < nelem; i++) {
+        g_ptr_array_add(arr, (void *)&props[i]);
+    }
+}
+
 /*** Board API.  This should go away once we have a machine config file.  ***/
 
 DeviceState *qdev_create(BusState *bus, const char *name);
diff --git a/include/qom/object.h b/include/qom/object.h
index bcae3f4951..e0262962b5 100644
--- a/include/qom/object.h
+++ b/include/qom/object.h
@@ -675,6 +675,9 @@  Object *object_new_with_propv(const char *typename,
                               Error **errp,
                               va_list vargs);
 
+void object_apply_global_props(Object *obj, const GPtrArray *props,
+                               Error **errp);
+
 /**
  * object_set_props:
  * @obj: the object instance to set properties on
diff --git a/include/sysemu/accel.h b/include/sysemu/accel.h
index 637358f430..f331d128e9 100644
--- a/include/sysemu/accel.h
+++ b/include/sysemu/accel.h
@@ -49,7 +49,7 @@  typedef struct AccelClass {
      * global properties may be overridden by machine-type
      * compat_props or user-provided global properties.
      */
-    GlobalProperty *global_props;
+    GPtrArray *compat_props;
 } AccelClass;
 
 #define TYPE_ACCEL "accel"
@@ -67,8 +67,6 @@  typedef struct AccelClass {
 extern unsigned long tcg_tb_size;
 
 void configure_accelerator(MachineState *ms);
-/* Register accelerator specific global properties */
-void accel_register_compat_props(AccelState *accel);
 /* Called just before os_setup_post (ie just before drop OS privs) */
 void accel_setup_post(MachineState *ms);
 
diff --git a/accel/accel.c b/accel/accel.c
index 3da26eb90f..6db5d8f4df 100644
--- a/accel/accel.c
+++ b/accel/accel.c
@@ -119,18 +119,6 @@  void configure_accelerator(MachineState *ms)
     }
 }
 
-void accel_register_compat_props(AccelState *accel)
-{
-    AccelClass *class = ACCEL_GET_CLASS(accel);
-    GlobalProperty *prop = class->global_props;
-
-    for (; prop && prop->driver; prop++) {
-        /* Any compat_props must never cause error */
-        prop->errp = &error_abort;
-        qdev_prop_register_global(prop);
-    }
-}
-
 void accel_setup_post(MachineState *ms)
 {
     AccelState *accel = ms->accelerator;
diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 6b3cc55b27..53b507164f 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -972,6 +972,15 @@  static void device_initfn(Object *obj)
 
 static void device_post_init(Object *obj)
 {
+    if (object_dynamic_cast(qdev_get_machine(), TYPE_MACHINE)) {
+        MachineState *m = MACHINE(qdev_get_machine());
+        AccelClass *ac = ACCEL_GET_CLASS(m->accelerator);
+
+        if (ac->compat_props) {
+            object_apply_global_props(obj, ac->compat_props, &error_abort);
+        }
+    }
+
     qdev_prop_set_globals(DEVICE(obj));
 }
 
diff --git a/hw/xen/xen-common.c b/hw/xen/xen-common.c
index 6ec14c73ca..4532aa8632 100644
--- a/hw/xen/xen-common.c
+++ b/hw/xen/xen-common.c
@@ -174,18 +174,21 @@  static GlobalProperty xen_compat_props[] = {
         .driver = "migration",
         .property = "send-section-footer",
         .value = "off",
-    },
-    { /* end of list */ },
+    }
 };
 
 static void xen_accel_class_init(ObjectClass *oc, void *data)
 {
     AccelClass *ac = ACCEL_CLASS(oc);
+
     ac->name = "Xen";
     ac->init_machine = xen_init;
     ac->setup_post = xen_setup_post;
     ac->allowed = &xen_allowed;
-    ac->global_props = xen_compat_props;
+    ac->compat_props = g_ptr_array_new();
+
+    compat_props_add(ac->compat_props,
+                     xen_compat_props, G_N_ELEMENTS(xen_compat_props));
 }
 
 #define TYPE_XEN_ACCEL ACCEL_CLASS_NAME("xen")
diff --git a/qom/object.c b/qom/object.c
index 17921c0a71..dbdab0aead 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -370,6 +370,31 @@  static void object_post_init_with_type(Object *obj, TypeImpl *ti)
     }
 }
 
+void object_apply_global_props(Object *obj, const GPtrArray *props, Error **errp)
+{
+    Error *err = NULL;
+    int i;
+
+    if (!props) {
+        return;
+    }
+
+    for (i = 0; i < props->len; i++) {
+        GlobalProperty *p = g_ptr_array_index(props, i);
+
+        if (object_dynamic_cast(obj, p->driver) == NULL) {
+            continue;
+        }
+        p->used = true;
+        object_property_parse(obj, p->value, p->property, &err);
+        if (err != NULL) {
+            error_prepend(&err, "can't apply global %s.%s=%s: ",
+                          p->driver, p->property, p->value);
+            error_propagate(errp, err);
+        }
+    }
+}
+
 static void object_initialize_with_type(void *data, size_t size, TypeImpl *type)
 {
     Object *obj = data;
diff --git a/vl.c b/vl.c
index 0db5ad0246..936d0c2587 100644
--- a/vl.c
+++ b/vl.c
@@ -2996,7 +2996,6 @@  static void user_register_global_props(void)
  */
 static void register_global_properties(MachineState *ms)
 {
-    accel_register_compat_props(ms->accelerator);
     machine_register_compat_props(ms);
     user_register_global_props();
 }