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From: Richard Henderson <rth@twiddle.net>
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Date: Wed, 10 May 2017 10:43:19 -0700
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Subject: Re: [Qemu-devel] [PATCH v3 4/6] target/s390x: Implement LOAD PAIR
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To: =?UTF-8?Q?=c3=89ric_Bischoff?= <ebischoff@nerim.net>, Aurelien Jarno <aurelien@aurel32.net>
Cc: qemu-devel@nongnu.org

On 05/10/2017 10:13 AM, Éric Bischoff wrote:
> Le mercredi 10 mai 2017, 12:16:20 Aurelien Jarno a écrit :
>>> +    /* In a parallel context, stop the world and single step.  */
>>> +    if (parallel_cpus) {
>>> +        potential_page_fault(s);
>>> +        gen_helper_exit_atomic(cpu_env);
>>> +        return EXIT_NORETURN;
>>> +    }
>>
>> One small additional comment about this patch I haven't spotted at the
>> first review. The exit_atomic helper is properly restoring the CPU state
>> passing the return address to cpu_loop_exit_atomic, so I believe the
>> potential_page_fault call is not necessary. That said, it doesn't hurt
>> either.
> 
> Merci pour la relecture Aurélien.
> 
> Richard, what do we do? We remove the potential_page_fault(s); or not?

I'm thinking of using gen_exception(EXCP_ATOMIC) instead.
The unwind associated with the regular helper_exit_atomic
has more overhead than potential_page_fault().


r~