On 05/01/2017 15:01, Paolo Bonzini wrote:
>
>
> On 05/01/2017 14:50, Vincent Palatin wrote:
>> Sorry I missed it.
>> I move it to qemu_cpu_kick() as asked in the Darwin patch.
>>
>>> Apart from the above change, can you check if there are some less
>>> heavyeight methods to force an exit? I can think of QueueUserAPC with
>>> an empty pfnAPC here, and SleepEx(0, TRUE) in qemu_hax_cpu_thread_fn
>>> before qemu_wait_io_event_common.
>>
>> Actually I don't know a good test case to verify such a change, any advice ?
In fact there is a race anyway:
if (cpu->exit_request) {
ret = 1;
break;
}
cpu->exit_request
SuspendThread
ResumeThread
hax_vcpu_interrupt(env);
qemu_mutex_unlock_iothread();
hax_ret = hax_vcpu_run(vcpu);
and the same race is true for QueueUserAPC. It's rare enough that I
guess we can accept the patches with just a FIXME comment, but... Yu
Ning, can you tell us what user_event_pending is for? :) My hunch is
that we should call hax_raise_event after setting cpu->exit_request, like
hax_raise_event();
/* write user_event_pending before exit_request */
smp_wmb();
cpu->exit_request = 1;
SuspendThread/ResumeThread
(or QueueUserAPC)
and in the hax thread:
if (cpu->exit_request) {
cpu->hax_vcpu->tunnel->user_event_pending = 0;
ret = 1;
break;
}
hax_vcpu_interrupt(env);
qemu_mutex_unlock_iothread();
/* read exit_request before user_event_pending */
smp_rmb();
hax_ret = hax_vcpu_run(vcpu);
but I would like some more official documentation than my own reverse
engineering of the brain of whoever wrote the interface (I have not
looked at the HAXM driver binary).
Paolo
