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From: Juan Quintela <quintela@redhat.com>
In-Reply-To: <50112283.70201@siemens.com> (Jan Kiszka's message of "Thu, 26
	Jul 2012 12:57:07 +0200")
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Date: Thu, 26 Jul 2012 13:16:01 +0200
Message-ID: <874nou7oy6.fsf@trasno.org>
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Subject: Re: [Qemu-devel] [RFC 00/27] Migration thread (WIP)
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To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: qemu-devel@nongnu.org

Jan Kiszka <jan.kiszka@siemens.com> wrote:
> On 2012-07-24 20:36, Juan Quintela wrote:
>> Hi

>> Appart of the review:
>> - Are there any locking issues that I have missed (I guess so)
>> - stop all cpus correctly.  vm_stop should be called from the iothread,
>>   I use the trick of using a bottom half to get that working correctly.
>>   but this _implementation_ is ugly as hell.  Is there an easy way
>>   of doing it?
>
> vm_stop is prepared to be called from vcpu context as well. I'm not sure
> right now if we actually do, but the code is there.

But this is a migation_thread (i.e. neither iothread of vcpu), and we
need to wait for vm_stop to finish.  My reading is that in vcpu context,
we just ask the iothread to stop all cpus.

void vm_stop(RunState state)
{
    if (!qemu_thread_is_self(&io_thread)) {
        qemu_system_vmstop_request(state);
        /*
         * FIXME: should not return to device code in case
         * vm_stop() has been requested.
         */
        cpu_stop_current();
        return;
    }
    do_vm_stop(state);
}

Or I am reading it wrong?

Later, Juan.