From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53090) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cWNW9-00032M-3g for qemu-devel@nongnu.org; Wed, 25 Jan 2017 08:21:42 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cWNW6-0006Vr-G5 for qemu-devel@nongnu.org; Wed, 25 Jan 2017 08:21:41 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54708) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cWNW6-0006VQ-9l for qemu-devel@nongnu.org; Wed, 25 Jan 2017 08:21:38 -0500 References: <20170124071654.4572.41407.stgit@PASHA-ISP> <20170124071713.4572.36636.stgit@PASHA-ISP> <96675d3f-9d53-bde1-f6da-7cb0b1f41316@redhat.com> <000501d276fb$fbcde7d0$f369b770$@ru> <1683a32c-4ea8-c343-e972-095593819121@redhat.com> <000601d276fe$e71b9140$b552b3c0$@ru> <10ac3f7d-6ae8-4657-7135-d9a05b5a3d39@redhat.com> <000901d27706$6f054090$4d0fc1b0$@ru> From: Paolo Bonzini Message-ID: <66b50426-1fc7-7730-1d5e-b7d4ad0e761b@redhat.com> Date: Wed, 25 Jan 2017 14:21:32 +0100 MIME-Version: 1.0 In-Reply-To: <000901d27706$6f054090$4d0fc1b0$@ru> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v7 03/14] replay: exception replay fix List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Pavel Dovgalyuk , 'Pavel Dovgalyuk' , qemu-devel@nongnu.org Cc: kwolf@redhat.com, peter.maydell@linaro.org, mst@redhat.com, jasowang@redhat.com, quintela@redhat.com, kraxel@redhat.com On 25/01/2017 13:27, Pavel Dovgalyuk wrote: >> From: Paolo Bonzini [mailto:pbonzini@redhat.com] >> On 25/01/2017 12:33, Pavel Dovgalyuk wrote: >>>> From: Paolo Bonzini [mailto:pbonzini@redhat.com] >>>> On 25/01/2017 12:12, Pavel Dovgalyuk wrote: >>>>>> From: Paolo Bonzini [mailto:pbonzini@redhat.com] >>>>>> 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. Paolo > Pavel Dovgalyuk >