[PATCH v7 0/8] Generalize start-powered-off property from ARM

[Thiago Jung Bauermann]

This version fixes `make check` failures in ppc/e500.c, mips/cps.c and
sparc/sun4m.c. This was done by moving the qdev_realize_and_unref() call as
close as possible to the object_new() call, in order to keep the CPU object
construction as similar as possible to the earlier version which used
cpu_create().

I also had to change the patch which removed the main_cpu_reset() function
from sparc/sun4m.c. It was causing a `make check` failure but I can't
really explain why. See this message for a few more details:

https://lists.nongnu.org/archive/html/qemu-ppc/2020-08/msg00419.html

I dropped the Reviewed-by's on the changed patches because of these
changes.

Original cover letter below, 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.

Changes since v6:

Patch "ppc/e500: Use start-powered-off CPUState property"
Patch "mips/cps: Use start-powered-off CPUState property"
- Moved setting of start-powered-off property and qdev_realize_and_unref()
  to right after object_new(machine->cpu_type).
- Dropped Philippe's Reviewed-by due to this change.

Patch "sparc/sun4m: Remove main_cpu_reset()"
- Dropped.

Patch "sparc/sun4m: Don't set cs->halted = 0 in main_cpu_reset()"
- New patch.

Patch "sparc/sun4m: Use start-powered-off CPUState property"
- Merged secondary_cpu_reset() with main_cpu_reset().
- Dropped Philippe's Reviewed-by due to this change.

Changes since v5:

Patch "ppc/e500: Use start-powered-off CPUState property"
Patch "mips/cps: Use start-powered-off CPUState property"
Patch "sparc/sun4m: Remove main_cpu_reset()"
Patch "target/s390x: Use start-powered-off CPUState property"
- Added Philippe's Reviewed-by.

Patch "sparc/sun4m: Use start-powered-off CPUState property"
- Move call to qdev_realize_and_unref() right after object_property_set_bool(),
  as suggested by Philippe.

Changes since v4:

Patch "ppc/e500: Use start-powered-off CPUState property"
Patch "sparc/sun4m: Use start-powered-off CPUState property"
- Use qdev_realize_and_unref() instead of qdev_realize(), as suggested
  by Igor.
- Pass &error_fatal to qdev_realize_and_unref() instead of manually
  reporting the error and exiting QEMU, as suggested by Philippe.
- Changed object_property_set_bool() to use &error_fatal instead of
  &error_abort.

Patch "mips/cps: Use start-powered-off CPUState property"
- Use qdev_realize_and_unref() instead of qdev_realize(), as suggested
  by Igor.
- Use existing errp argument to propagate error back to the caller, as
  suggested by Philippe.
- Changed object_property_set_bool() to use existing errp argument to
  propagate error back to the caller instead of using &error_abort.

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: Don't set cs->halted = 0 in 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           | 15 +++++++++++----
 hw/ppc/e500.c           | 13 +++++++++----
 hw/ppc/spapr_cpu_core.c | 10 +++++-----
 hw/sparc/sun4m.c        | 26 ++++++--------------------
 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, 41 insertions(+), 43 deletions(-)