Re: [PULL 00/30] ppc-for-5.2 queue 20200904

From: Laurent Vivier <lvivier@redhat.com>
To: Cornelia Huck <cohuck@redhat.com>
Cc: "Peter Maydell" <peter.maydell@linaro.org>,
	"David Hildenbrand" <david@redhat.com>,
	"Daniel Henrique Barboza" <danielhb413@gmail.com>,
	"QEMU Developers" <qemu-devel@nongnu.org>,
	"Greg Kurz" <groug@kaod.org>, qemu-ppc <qemu-ppc@nongnu.org>,
	"Philippe Mathieu-Daudé" <philmd@redhat.com>,
	"Thiago Jung Bauermann" <bauerman@linux.ibm.com>,
	"David Gibson" <david@gibson.dropbear.id.au>
Subject: Re: [PULL 00/30] ppc-for-5.2 queue 20200904
Date: Mon, 7 Sep 2020 18:29:07 +0200	[thread overview]
Message-ID: <f93673f9-3e83-ef5f-9628-819b25908e43@redhat.com> (raw)
In-Reply-To: <20200907165132.683d2880.cohuck@redhat.com>

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.

Thanks,
Laurent