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Re: [PULL 00/30] ppc-for-5.2 queue 20200904
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [PULL 00/30] ppc-for-5.2 queue 20200904 |
Date: |
Mon, 7 Sep 2020 21:46:28 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 |
On 9/7/20 7:26 PM, Laurent Vivier wrote:
> On 07/09/2020 18:29, Laurent Vivier wrote:
>> On 07/09/2020 16:51, Cornelia Huck wrote:
>>> On Mon, 7 Sep 2020 16:31:24 +0200
>>> Laurent Vivier <lvivier@redhat.com> wrote:
>>>
>>>> On 07/09/2020 16:05, Philippe Mathieu-Daudé wrote:
>>>>> Hi Thiago,
>>>>>
>>>>> On 9/7/20 3:29 PM, Laurent Vivier wrote:
>>>>>> On 07/09/2020 04:38, David Gibson wrote:
>>>>>>> On Sun, Sep 06, 2020 at 04:20:10PM +0100, Peter Maydell wrote:
>>>
>>>>>>>> The 'check-tcg' tests for the linux-user static build also
>>>>>>>> failed on an s390x test:
>>>>>>>>
>>>>>>>> CHECK debian-s390x-cross
>>>>>>>> BUILD s390x-linux-user guest-tests with docker
>>>>>>>> qemu/debian-s390x-cross
>>>>>>>> RUN tests for s390x
>>>>>>>> TEST threadcount on s390x
>>>>>>>> Unhandled trap: 0x10003
>>>>>>
>>>>>> This is EXCP_HALTED (include/exec/cpu-all.h)
>>>>>>
>>>>>> The message error comes from cpu_loop() in linux-user/s390x/cpu_loop.c.
>>>>>>
>>>>>> The trap can only come from accel/tcg/cpu-exec.c
>>>>>>
>>>>>> 679 int cpu_exec(CPUState *cpu)
>>>>>> 680 {
>>>>>> ...
>>>>>> 688 if (cpu_handle_halt(cpu)) {
>>>>>> 689 return EXCP_HALTED;
>>>>>> 690 }
>>>>>>
>>>>>> and
>>>>>>
>>>>>> 428 static inline bool cpu_handle_halt(CPUState *cpu)
>>>>>> 429 {
>>>>>> 430 if (cpu->halted) {
>>>>>> ...
>>>>>> 441 if (!cpu_has_work(cpu)) {
>>>>>> 442 return true;
>>>>>> 443 }
>>>>>>
>>>>>> and
>>>>>>
>>>>>> 58 static bool s390_cpu_has_work(CPUState *cs)
>>>>>> 59 {
>>>>>> 60 S390CPU *cpu = S390_CPU(cs);
>>>>>> 61
>>>>>> 62 /* STOPPED cpus can never wake up */
>>>>>> 63 if (s390_cpu_get_state(cpu) != S390_CPU_STATE_LOAD &&
>>>>>> 64 s390_cpu_get_state(cpu) != S390_CPU_STATE_OPERATING) {
>>>>>> 65 return false;
>>>>>> 66 }
>>>>>> 67
>>>>>> 68 if (!(cs->interrupt_request & CPU_INTERRUPT_HARD)) {
>>>>>> 69 return false;
>>>>>> 70 }
>>>>>> 71
>>>>>> 72 return s390_cpu_has_int(cpu);
>>>>>> 73 }
>>>>>>
>>>>>> and in target/s390x/cpu.h:
>>>>>>
>>>>>> 772 #ifndef CONFIG_USER_ONLY
>>>>>> 773 unsigned int s390_cpu_set_state(uint8_t cpu_state, S390CPU *cpu);
>>>>>> 774 #else
>>>>>> 775 static inline unsigned int s390_cpu_set_state(uint8_t cpu_state,
>>>>>> S390CPU *cpu)
>>>>>> 776 {
>>>>>> 777 return 0;
>>>>>> 778 }
>>>>>> 779 #endif /* CONFIG_USER_ONLY */
>>>>>> 780 static inline uint8_t s390_cpu_get_state(S390CPU *cpu)
>>>>>> 781 {
>>>>>> 782 return cpu->env.cpu_state;
>>>>>> 783 }
>>>>>>
>>>>>> As cpu_state is never set, perhaps in case of linux-user it should
>>>>>> always return S390_CPU_STATE_OPERATING?
>>>
>>> Possibly, we should not have any state handling for linux-user.
>>>
>>
>> I did that, but now 390_cpu_has_work() is false because
>> CPU_INTERRUPT_HARD is not set in cs->interrupt_request.
>>
>> I think we should not enter in cpu_loop() with halted set to 1.
>>
>> Before the patch of this series, s390_cpu_reset() is called twice, and
>> on the second call, halted is already 0.
>>
>> With start_powered_off set to true in initfn, on the first reset
>> "halted" is 0 and on the second it is 1 (because it has been copied from
>> start_powered_off) and so cpu_loop() starts with halted set to 1 and fails.
>
> What is happening:
>
> [without start_powered_off]
>
> 1- halted is set to 1 in s390x_cpu_initfn()
> 2- halted is set to 0 in s390x_cpu_reset() by parent_reset()
> (cpu_common_reset()
> 3- cpu_loop() is always entered with halted set to 0
>
> [with start_powered_off]
>
> 1- halted is set to start_powered_off (1) in s390x_cpu_reset() by
> parent_reset() (cpu_common_reset()
> 2- cpu_loop() is always entered with halted set to 1
>
> So in the first case, cpu_loop() is always started with halted set to 0
> and in the second case with halted set to 1.
>
> And I think, with linux-user, it should never be started with halted set
> to 1.
>
> We can't add a "#ifdef CONFIG_USER_ONLY" in hw/core/cpu.c to set halted
> to 0 because it is in the common files, but we can do:
>
> diff --git a/target/s390x/cpu.c b/target/s390x/cpu.c
> index 73d7d6007e8e..749cd548f0f3 100644
> --- a/target/s390x/cpu.c
> +++ b/target/s390x/cpu.c
> @@ -291,9 +291,9 @@ static void s390_cpu_initfn(Object *obj)
> S390CPU *cpu = S390_CPU(obj);
>
> cpu_set_cpustate_pointers(cpu);
> - cs->start_powered_off = true;
> cs->exception_index = EXCP_HLT;
> #if !defined(CONFIG_USER_ONLY)
> + cs->start_powered_off = true;
> object_property_add(obj, "crash-information", "GuestPanicInformation",
> s390_cpu_get_crash_info_qom, NULL, NULL, NULL);
> cpu->env.tod_timer =
This looks like the correct fix indeed :)
(Maybe worth adding a comment around).
Thanks for investigating!
>
> Thanks,
> Laurent
- [PULL 30/30] spapr_numa: move NVLink2 associativity handling to spapr_numa.c, (continued)
- [PULL 30/30] spapr_numa: move NVLink2 associativity handling to spapr_numa.c, David Gibson, 2020/09/03
- [PULL 27/30] spapr: introduce SpaprMachineState::numa_assoc_array, David Gibson, 2020/09/03
- Re: [PULL 00/30] ppc-for-5.2 queue 20200904, Peter Maydell, 2020/09/06
- Re: [PULL 00/30] ppc-for-5.2 queue 20200904, David Gibson, 2020/09/06
- Re: [PULL 00/30] ppc-for-5.2 queue 20200904, Laurent Vivier, 2020/09/07
- Re: [PULL 00/30] ppc-for-5.2 queue 20200904, Philippe Mathieu-Daudé, 2020/09/07
- Re: [PULL 00/30] ppc-for-5.2 queue 20200904, Laurent Vivier, 2020/09/07
- Re: [PULL 00/30] ppc-for-5.2 queue 20200904, Cornelia Huck, 2020/09/07
- Re: [PULL 00/30] ppc-for-5.2 queue 20200904, Laurent Vivier, 2020/09/07
- Re: [PULL 00/30] ppc-for-5.2 queue 20200904, Laurent Vivier, 2020/09/07
- Re: [PULL 00/30] ppc-for-5.2 queue 20200904,
Philippe Mathieu-Daudé <=
- Re: [PULL 00/30] ppc-for-5.2 queue 20200904, David Gibson, 2020/09/07
- Re: [PULL 00/30] ppc-for-5.2 queue 20200904, Cornelia Huck, 2020/09/08
- Re: [PULL 00/30] ppc-for-5.2 queue 20200904, Thiago Jung Bauermann, 2020/09/08