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From: Alex =?utf-8?Q?Benn=C3=A9e?= <alex.bennee@linaro.org>
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Date: Tue, 07 Mar 2017 15:03:41 +0000
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Subject: Re: [Qemu-devel] [PATCH] target/i386: move nested exception check
 to x86_cpu_exec_interrupt
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To: Richard Henderson <rth@twiddle.net>
Cc: alexander.boettcher@genode-labs.com, qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>, Eduardo Habkost <ehabkost@redhat.com>


Richard Henderson <rth@twiddle.net> writes:

> On 03/07/2017 02:57 AM, Alex Bennée wrote:
>>      cs->exception_index = intno;
>>      env->error_code = error_code;
>>      env->exception_is_int = is_int;
>>      env->exception_next_eip = env->eip + next_eip_addend;
>> +    env->exception_retaddr = retaddr;
>>      cpu_loop_exit_restore(cs, retaddr);
>
> Since you've restored state here, I don't see that you need to save
> the retaddr at all ...
>
>> +    if (!env->exception_is_int) {
>> +        cpu_svm_check_intercept_param(env,
>> +                                      SVM_EXIT_EXCP_BASE + cs->exception_index,
>> +                                      env->error_code,
>> +                                      env->exception_retaddr);
>> +        cs->exception_index = check_exception(env, cs->exception_index,
>> +                                              &env->error_code,
>> +                                              env->exception_retaddr);
>> +    } else {
>> +        cpu_svm_check_intercept_param(env, SVM_EXIT_SWINT, 0,
>> +                                      env->exception_retaddr);
>> +    }
>
> ... simply pass zero here instead.
>
> But do I see correctly from the thread that we don't have a reproducer?

Yeah - I've nabbed Paolo's much cleaner and more informed fix and that
seems fine.

--
Alex Bennée