Re: [PULL 20/71] target/arm: teach arm_cpu_has_work about halting reasons

["Alex Bennée" <alex.bennee@linaro.org>]

Philippe Mathieu-Daudé <philmd@oss.qualcomm.com> writes:

> Hi,
>
> On 10/6/26 18:11, Peter Maydell wrote:
>> From: Alex Bennée <alex.bennee@linaro.org>
>> With the advent of WFE and WFI we need to pay closer attention to
>> the
>> reason why the vCPU may be sleeping to figure out if we should wake
>> it up.
>> Create env->halt_reason to track this and then re-order the tests so
>> we:
>>    - ignore everything is the vCPU is powered off
>>    - wake up if the event_register is set and we were in a WFE
>>    - otherwise any IRQ event does wake the vCPU up.
>> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>> Message-id: 20260529082948.363931-3-alex.bennee@linaro.org
>> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
>> ---
>>   target/arm/arm-powerctl.c  |  6 +++---
>>   target/arm/cpu.c           | 40 +++++++++++++++++++++++++++-----------
>>   target/arm/cpu.h           | 16 +++++++++++++++
>>   target/arm/internals.h     | 11 +++++++++++
>>   target/arm/kvm.c           |  5 +++--
>>   target/arm/machine.c       |  2 +-
>>   target/arm/tcg/op_helper.c |  3 +++
>>   7 files changed, 66 insertions(+), 17 deletions(-)
>
> This patch updated TCG and KVM but missed HVF and WHPX:
>
>  - target/arm/hvf/hvf.c
>  - target/arm/whpx/whpx-all.c

Do they need it if they implement cpus_accel->cpu_thread_is_idle?

>
>
>> diff --git a/target/arm/internals.h b/target/arm/internals.h
>> index 21cbd2b1db..b2035b9417 100644
>> --- a/target/arm/internals.h
>> +++ b/target/arm/internals.h
>> @@ -2063,4 +2063,15 @@ bool arm_cpu_match_cpreg_mig_tolerance(ARMCPU *cpu, uint64_t kvmidx,
>>                                          ARMCPRegMigToleranceType type);
>>     +/**
>> + * arm_set_cpu_power_state() - set power state synced with halt_reason
>> + */
>> +static inline void arm_set_cpu_power_state(ARMCPU *cpu, ARMPSCIState state)
>> +{
>> +    CPUARMState *env = &cpu->env;
>> +
>> +    cpu->power_state = state;
>> +    env->halt_reason = state == PSCI_OFF ? HALT_PSCI : NOT_HALTED;
>> +}
>> +
>>   #endif
> Why not add/use a getter()?

How do you mean? Add it as a CPUClass API? Seems overkill for what is
currently handled internally by Arm.

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro