[PATCH v4 0/8] Generalize start-powered-off property from ARM

[Thiago Jung Bauermann]

This version tries to fix an issue found by David Gibson when running
the Travis CI:

Unexpected error in qdev_prop_set_after_realize() at 
/home/travis/build/dgibson/qemu/hw/core/qdev-properties.c:30:
qemu-system-mips64el: Attempt to set property 'start-powered-off' on anonymous 
device (type 'I6400-mips64-cpu') after it was realized
Broken pipe
/home/travis/build/dgibson/qemu/tests/qtest/libqtest.c:175: kill_qemu() 
detected QEMU death from signal 6 (Aborted) (core dumped)
Aborted (core dumped)
ERROR qom-test - too few tests run (expected 8, got 0)
/home/travis/build/dgibson/qemu/tests/Makefile.include:650: recipe for target 
'check-qtest-mips64el' failed

Philippe Mathieu-Daudé spotted the problem:

> Good catch. hw/mips/cps.c, hw/ppc/e500.c and hw/sparc/sun4m.c are
> incorrectly setting the property after the cpu is realized because
> the cpu is created with cpu_create(). We need to create them with
> object_initialize_child() and realize them manually with qdev_realize().

But I found very few examples of CPUs initialized with
object_initialize_child() (e.g., atmega.c, rx62n.c, nrf51_soc.c)
so instead of using object_initialize_child(), I replaced the call to
cpu_create() with object_new() and a call to qdev_realize() shortly after
the  start-powered-off property is set. I thought this would be the more
prudent change, keeping the code as close to the previous one as possible.

I tried reproducing the Travis CI problem with
`make docker-test-misc@debian-mips64el-cross` but I didn't succeed, so
I'm not sure if this version solves the issue.


Original cover letter bellow, followed by changelog:

The ARM code has a start-powered-off property in ARMCPU, which is a
subclass of CPUState. This property causes arm_cpu_reset() to set
CPUState::halted to 1, signalling that the CPU should start in a halted
state. Other architectures also have code which aim to achieve the same
effect, but without using a property.

The ppc/spapr version has a bug where QEMU does a KVM_RUN on the vcpu
before cs->halted is set to 1, causing the vcpu to run while it's still in
an unitialized state (more details in patch 3).

Peter Maydell mentioned the ARM start-powered-off property and
Eduardo Habkost suggested making it generic, so this patch series does
that, for all cases which I was able to find via grep in the code.

The only problem is that I was only able to test these changes on a ppc64le
pseries KVM guest, so except for patches 2 and 3, all others are only
build-tested. Also, my grasp of QOM lifecycle is basically non-existant so
please be aware of that when reviewing this series.

The last patch may be wrong, as pointed out by Eduardo, so I marked it as
RFC. It may make sense to drop it.

Applies cleanly on yesterday's master.

Changes since v3:

General:
- Added David's, Greg's and Cornelia's Reviewed-by and Acked-by to some
  of the patches.
- Rebased on top of dgibson/ppc-for-5.2.

Patch "ppc/e500: Use start-powered-off CPUState property"
Patch "mips/cps: Use start-powered-off CPUState property"
Patch "sparc/sun4m: Use start-powered-off CPUState property"
- Initialize CPU object with object_new() and qdev_realize() instead
  of cpu_create().
- Removed Reviewed-by's and Acked-by's from these patches because of
  these changes.

Changes since v2:

General:
- Added Philippe's Reviewed-by to some of the patches.

Patch "ppc/spapr: Use start-powered-off CPUState property"
- Set the CPUState::start_powered_off variable directly rather than using
  object_property_set_bool(). Suggested by Philippe.

Patch "sparc/sun4m: Remove main_cpu_reset()"
- New patch. Suggested by Philippe.

Patch "sparc/sun4m: Use start-powered-off CPUState property"
- Remove secondary_cpu_reset(). Suggested by Philippe.
- Remove setting of `cs->halted = 1` from cpu_devinit(). Suggested by Philippe.

Patch "Don't set CPUState::halted in cpu_devinit()"
- Squashed into previous patch. Suggested by Philippe.

Patch "sparc/sun4m: Use one cpu_reset() function for main and secondary CPUs"
- Dropped.

Patch "target/s390x: Use start-powered-off CPUState property"
- Set the CPUState::start_powered_off variable directly rather than using
  object_property_set_bool(). Suggested by Philippe.
- Mention in the commit message Eduardo's observation that before this
  patch, the code didn't set cs->halted on reset.

Thiago Jung Bauermann (8):
  target/arm: Move start-powered-off property to generic CPUState
  target/arm: Move setting of CPU halted state to generic code
  ppc/spapr: Use start-powered-off CPUState property
  ppc/e500: Use start-powered-off CPUState property
  mips/cps: Use start-powered-off CPUState property
  sparc/sun4m: Remove main_cpu_reset()
  sparc/sun4m: Use start-powered-off CPUState property
  target/s390x: Use start-powered-off CPUState property

 exec.c                  |  1 +
 hw/core/cpu.c           |  2 +-
 hw/mips/cps.c           | 16 ++++++++++++----
 hw/ppc/e500.c           | 19 +++++++++++++++----
 hw/ppc/spapr_cpu_core.c | 10 +++++-----
 hw/sparc/sun4m.c        | 37 ++++++++++---------------------------
 include/hw/core/cpu.h   |  4 ++++
 target/arm/cpu.c        |  4 +---
 target/arm/cpu.h        |  3 ---
 target/arm/kvm32.c      |  2 +-
 target/arm/kvm64.c      |  2 +-
 target/s390x/cpu.c      |  2 +-
 12 files changed, 52 insertions(+), 50 deletions(-)