From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42251) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1g0ouP-00079t-6x for qemu-devel@nongnu.org; Fri, 14 Sep 2018 10:17:24 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1g0ouM-0001F1-Gx for qemu-devel@nongnu.org; Fri, 14 Sep 2018 10:17:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41956) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1g0ouK-0001Bg-El for qemu-devel@nongnu.org; Fri, 14 Sep 2018 10:17:17 -0400 References: <20180912081747.3228.21861.stgit@pasha-VirtualBox> <20180912081950.3228.68987.stgit@pasha-VirtualBox> <002101d44bee$9edf9720$dc9ec560$@ru> <002301d44bfc$603513c0$209f3b40$@ru> From: John Snow Message-ID: <1b1d35c1-31e4-767d-b687-5df11895c26b@redhat.com> Date: Fri, 14 Sep 2018 10:17:05 -0400 MIME-Version: 1.0 In-Reply-To: <002301d44bfc$603513c0$209f3b40$@ru> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v6 21/25] replay: replay BH for IDE trim operation 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, war2jordan@live.com, pbonzini@redhat.com, quintela@redhat.com, ciro.santilli@gmail.com, jasowang@redhat.com, crosthwaite.peter@gmail.com, zuban32s@gmail.com, armbru@redhat.com, maria.klimushenkova@ispras.ru, mst@redhat.com, kraxel@redhat.com, boost.lists@gmail.com, thomas.dullien@googlemail.com, mreitz@redhat.com, alex.bennee@linaro.org, dgilbert@redhat.com, rth@twiddle.net On 09/14/2018 03:27 AM, Pavel Dovgalyuk wrote: >> From: Pavel Dovgalyuk [mailto:dovgaluk@ispras.ru] >>> From: John Snow [mailto:jsnow@redhat.com] >>> On 09/12/2018 04:19 AM, Pavel Dovgalyuk wrote: >>>> This patch makes IDE trim BH deterministic, because it affects >>>> the device state. Therefore its invocation should be replayed >>>> instead of running at the random moment. >>>> >>>> Signed-off-by: Pavel Dovgalyuk >>>> Reviewed-by: Paolo Bonzini >>>> --- >>>> hw/ide/core.c | 3 ++- >>>> 1 file changed, 2 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/hw/ide/core.c b/hw/ide/core.c >>>> index 2c62efc..04e22e7 100644 >>>> --- a/hw/ide/core.c >>>> +++ b/hw/ide/core.c >>>> @@ -35,6 +35,7 @@ >>>> #include "sysemu/block-backend.h" >>>> #include "qapi/error.h" >>>> #include "qemu/cutils.h" >>>> +#include "sysemu/replay.h" >>>> >>>> #include "hw/ide/internal.h" >>>> #include "trace.h" >>>> @@ -479,7 +480,7 @@ static void ide_issue_trim_cb(void *opaque, int ret) >>>> done: >>>> iocb->aiocb = NULL; >>>> if (iocb->bh) { >>>> - qemu_bh_schedule(iocb->bh); >>>> + replay_bh_schedule_event(iocb->bh); >>>> } >>>> } >>>> >>> Just passing by: Why do we need to change this call, but nothing else in >>> IDE? >> >> This call is responsible for a bug that was reproducible. >> >>> I don't mind conceptually, but it's odd to me that of all the calls I >>> make in this emulator that change state somewhere that this is the only >>> one you need to hijack for the replay feature. >>> >>> Is this a necessarily complete change? > > > I found one more BH in ide/core: > > static void ide_restart_cb(void *opaque, int running, RunState state) > { > IDEBus *bus = opaque; > > if (!running) > return; > > if (!bus->bh) { > bus->bh = qemu_bh_new(ide_restart_bh, bus); > qemu_bh_schedule(bus->bh); > } > } > > void ide_register_restart_cb(IDEBus *bus) > { > if (bus->dma->ops->restart_dma) { > bus->vmstate = qemu_add_vm_change_state_handler(ide_restart_cb, bus); > } > } > > As I understand, it is called when VM start/stop event happen. > These events are not related to the guest state. > > Does this BH change the guest state somehow? > > Pavel Dovgalyuk > > Shouldn't change guest state all by itself. ide_restart_bh does, though. (Changes device registers, can cause block IO to occur, etc.) --js