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Re: [Qemu-devel] [PATCH v7 03/14] replay: exception replay fix
From: |
Pavel Dovgalyuk |
Subject: |
Re: [Qemu-devel] [PATCH v7 03/14] replay: exception replay fix |
Date: |
Wed, 25 Jan 2017 16:26:51 +0300 |
> From: Paolo Bonzini [mailto:address@hidden
> On 25/01/2017 13:27, Pavel Dovgalyuk wrote:
> >> From: Paolo Bonzini [mailto:address@hidden
> >> On 25/01/2017 12:33, Pavel Dovgalyuk wrote:
> >>>> From: Paolo Bonzini [mailto:address@hidden
> >>>> On 25/01/2017 12:12, Pavel Dovgalyuk wrote:
> >>>>>> From: Paolo Bonzini [mailto:address@hidden
> >>>>>> 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.
> >>>
> >>> cpu->exit_request does not checked in this loop.
> >>> We have to add this checking somewhere then?
> >>
> >> It's checked by cpu_handle_interrupt. Are you not reaching
> >> cpu_handle_interrupt then? Why?
> >
> > Execution doesn't reach cpu_handle_interrupt, because tb_find
> > calls cpu_loop_exit. And the execution loop enters cpu_handle_exception
> > again and again.
>
> Perhaps tb_gen_code should set cpu->exception_index before calling
> cpu_loop_exit.
Maybe it would be better, because tb_gen_code is called in many other paths.
I'll fix the patch.
Pavel Dovgalyuk
- [Qemu-devel] [PATCH v7 01/14] icount: update instruction counter on apic patching, (continued)
- [Qemu-devel] [PATCH v7 01/14] icount: update instruction counter on apic patching, Pavel Dovgalyuk, 2017/01/24
- [Qemu-devel] [PATCH v7 02/14] replay: improve interrupt handling, Pavel Dovgalyuk, 2017/01/24
- [Qemu-devel] [PATCH v7 03/14] replay: exception replay fix, Pavel Dovgalyuk, 2017/01/24
- Re: [Qemu-devel] [PATCH v7 03/14] replay: exception replay fix, Paolo Bonzini, 2017/01/25
- Re: [Qemu-devel] [PATCH v7 03/14] replay: exception replay fix, Pavel Dovgalyuk, 2017/01/25
- Re: [Qemu-devel] [PATCH v7 03/14] replay: exception replay fix, Paolo Bonzini, 2017/01/25
- Re: [Qemu-devel] [PATCH v7 03/14] replay: exception replay fix, Pavel Dovgalyuk, 2017/01/25
- Re: [Qemu-devel] [PATCH v7 03/14] replay: exception replay fix, Paolo Bonzini, 2017/01/25
- Re: [Qemu-devel] [PATCH v7 03/14] replay: exception replay fix, Pavel Dovgalyuk, 2017/01/25
- Re: [Qemu-devel] [PATCH v7 03/14] replay: exception replay fix, Paolo Bonzini, 2017/01/25
- Re: [Qemu-devel] [PATCH v7 03/14] replay: exception replay fix,
Pavel Dovgalyuk <=
[Qemu-devel] [PATCH v7 04/14] icount: exit cpu loop on expire, Pavel Dovgalyuk, 2017/01/24
[Qemu-devel] [PATCH v7 05/14] apic: save apic_delivered flag, Pavel Dovgalyuk, 2017/01/24