Re: [PATCH v3 0/8] Generalize start-powered-off property from ARM

[David Gibson]

On Wed, Jul 22, 2020 at 11:56:49PM -0300, Thiago Jung Bauermann wrote:
> 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.

This series appears to break the Travis build for a MIPS target:

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

> 
> 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           |  6 +++---
>  hw/ppc/e500.c           | 10 +++++++---
>  hw/ppc/spapr_cpu_core.c | 10 +++++-----
>  hw/sparc/sun4m.c        | 28 ++--------------------------
>  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, 27 insertions(+), 47 deletions(-)
> 
> 

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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