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From: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <1683a32c-4ea8-c343-e972-095593819121@redhat.com>
Date: Wed, 25 Jan 2017 12:18:43 +0100
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Subject: Re: [Qemu-devel] [PATCH v7 03/14] replay: exception replay fix
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To: Pavel Dovgalyuk <dovgaluk@ispras.ru>, 'Pavel Dovgalyuk' <pavel.dovgaluk@ispras.ru>, qemu-devel@nongnu.org
Cc: kwolf@redhat.com, peter.maydell@linaro.org, mst@redhat.com, jasowang@redhat.com, quintela@redhat.com, kraxel@redhat.com



On 25/01/2017 12:12, Pavel Dovgalyuk wrote:
>> From: Paolo Bonzini [mailto:pbonzini@redhat.com]
>> On 24/01/2017 08:17, Pavel Dovgalyuk wrote:
>>> @@ -451,6 +451,10 @@ static inline bool cpu_handle_exception(CPUState *cpu, int *ret)
>>>  #ifndef CONFIG_USER_ONLY
>>>      } else if (replay_has_exception()
>>>                 && cpu->icount_decr.u16.low + cpu->icount_extra == 0) {
>>> +        /* Break the execution loop in case of running out of TB cache.
>>> +           This is needed to make flushing of the TB cache, because
>>> +           real flush is queued to be executed outside the cpu loop. */
>>> +        cpu->exception_index = EXCP_INTERRUPT;
>>>          /* try to cause an exception pending in the log */
>>>          cpu_exec_nocache(cpu, 1, tb_find(cpu, NULL, 0), true);
>>>          *ret = -1;
>>
>> Why is replay_has_exception() related to be running out of TB cache?
> 
> It doesn't.
> Calling tb_find when there is not space in cache causes tb_flush and cpu_loop_exit.
> But execution loop will continue, because there is no reason to break it
> (like setting exception_index).

What about setting cpu->exit_request?  queue_work_on_cpu calls
qemu_cpu_kick.

Paolo