From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B1CE2C433DF for ; Mon, 18 May 2020 09:42:03 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 793CE2067D for ; Mon, 18 May 2020 09:42:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b="KyBPXgZ7" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 793CE2067D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=yandex-team.ru Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:49750 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jacHa-000700-K3 for qemu-devel@archiver.kernel.org; Mon, 18 May 2020 05:42:02 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:54060) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jacGs-0006Ur-Qa; Mon, 18 May 2020 05:41:18 -0400 Received: from forwardcorp1o.mail.yandex.net ([95.108.205.193]:54668) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jacGo-00071u-HH; Mon, 18 May 2020 05:41:16 -0400 Received: from mxbackcorp1g.mail.yandex.net (mxbackcorp1g.mail.yandex.net [IPv6:2a02:6b8:0:1402::301]) by forwardcorp1o.mail.yandex.net (Yandex) with ESMTP id B9EE42E1452; Mon, 18 May 2020 12:41:08 +0300 (MSK) Received: from sas2-32987e004045.qloud-c.yandex.net (sas2-32987e004045.qloud-c.yandex.net [2a02:6b8:c08:b889:0:640:3298:7e00]) by mxbackcorp1g.mail.yandex.net (mxbackcorp/Yandex) with ESMTP id 0cJM0dkw6Z-f2rCjawl; Mon, 18 May 2020 12:41:08 +0300 Precedence: bulk DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1589794868; bh=T1sDVsJ39HpGW/DnxK1vSUFcUNSyFJ7Kmb/9yZ4a11A=; h=In-Reply-To:Message-ID:Subject:To:From:References:Date:Cc; b=KyBPXgZ7OTa+tUPX4mzObBOVM9dA7Ak/LAiyB91CAsrYDY0Bl5UOphsYFYL+VXdxb q9o7WLIc4AlVbn3ZX7S6GiopGXF9DGgkDQ4W4jxA1V+DBNoWsxPhSx/udcO+ZMHqYz R1lRjYSv4j2KscCXuErKdbDOfRJ7PMMObO9YGxHY= Authentication-Results: mxbackcorp1g.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Received: from dynamic-vpn.dhcp.yndx.net (dynamic-vpn.dhcp.yndx.net [2a02:6b8:b080:7514::1:b]) by sas2-32987e004045.qloud-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id e847zFcFjF-f1W4c7Lj; Mon, 18 May 2020 12:41:02 +0300 (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client certificate not present) Date: Mon, 18 May 2020 12:41:00 +0300 From: Dima Stepanov To: Jason Wang Subject: Re: [PATCH v2 5/5] vhost: add device started check in migration set log Message-ID: <20200518094053.GA6552@dimastep-nix> References: <20200511092541.GA27558@dimastep-nix> <20200512093521.GA5363@dimastep-nix> <20200512235934-mutt-send-email-mst@kernel.org> <20200513094703.GA15906@dimastep-nix> <722839b2-9412-b768-3ce6-d1b697d6d5dd@redhat.com> <20200515165449.GA1627@dimastep-nix> <553370a5-926b-d9c4-a8ec-8bdc07c94e6e@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <553370a5-926b-d9c4-a8ec-8bdc07c94e6e@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) Received-SPF: pass client-ip=95.108.205.193; envelope-from=dimastep@yandex-team.ru; helo=forwardcorp1o.mail.yandex.net X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/18 05:41:09 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: fam@euphon.net, kwolf@redhat.com, yc-core@yandex-team.ru, qemu-block@nongnu.org, "Michael S. Tsirkin" , qemu-devel@nongnu.org, dgilbert@redhat.com, arei.gonglei@huawei.com, fengli@smartx.com, stefanha@redhat.com, marcandre.lureau@redhat.com, pbonzini@redhat.com, raphael.norwitz@nutanix.com, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, May 18, 2020 at 10:50:39AM +0800, Jason Wang wrote: > > On 2020/5/16 上午12:54, Dima Stepanov wrote: > >On Thu, May 14, 2020 at 03:34:24PM +0800, Jason Wang wrote: > >>On 2020/5/13 下午5:47, Dima Stepanov wrote: > >>>>> case CHR_EVENT_CLOSED: > >>>>> /* a close event may happen during a read/write, but vhost > >>>>> * code assumes the vhost_dev remains setup, so delay the > >>>>> * stop & clear to idle. > >>>>> * FIXME: better handle failure in vhost code, remove bh > >>>>> */ > >>>>> if (s->watch) { > >>>>> AioContext *ctx = qemu_get_current_aio_context(); > >>>>> > >>>>> g_source_remove(s->watch); > >>>>> s->watch = 0; > >>>>> qemu_chr_fe_set_handlers(&s->chr, NULL, NULL, NULL, NULL, > >>>>> NULL, NULL, false); > >>>>> > >>>>> aio_bh_schedule_oneshot(ctx, chr_closed_bh, opaque); > >>>>> } > >>>>> break; > >>>>> > >>>>>I think it's time we dropped the FIXME and moved the handling to common > >>>>>code. Jason? Marc-André? > >>>>I agree. Just to confirm, do you prefer bh or doing changes like what is > >>>>done in this series? It looks to me bh can have more easier codes. > >>>Could it be a good idea just to make disconnect in the char device but > >>>postphone clean up in the vhost-user-blk (or any other vhost-user > >>>device) itself? So we are moving the postphone logic and decision from > >>>the char device to vhost-user device. One of the idea i have is as > >>>follows: > >>> - Put ourself in the INITIALIZATION state > >>> - Start these vhost-user "handshake" commands > >>> - If we got a disconnect error, perform disconnect, but don't clean up > >>> device (it will be clean up on the roll back). I can be done by > >>> checking the state in vhost_user_..._disconnect routine or smth like it > >> > >>Any issue you saw just using the aio bh as Michael posted above. > >> > >>Then we don't need to deal with the silent vhost_dev_stop() and we will have > >>codes that is much more easier to understand. > >I've implemented this solution inside > >hw/block/vhost-user-blk.c:vhost_user_blk_event() in the similar way by > >using the s->connected field. Looks good and more correct fix ). I have > >two questions here before i'll rework the fixes: > >1. Is it okay to make the similar fix inside vhost_user_blk_event() or > >we are looking for more generic vhost-user solution? What do you think? > > > I think I agree with Michael, it's better to have a generic vhost-user > solution. But if it turns out to be not easy, we can start from fixing > vhost-user-blk. I also agree, but as i see it right now the connect/disconnect events are handled inside each vhost-user device implementation file. So it will need some global refactoring. So i suggest having this fix first and after it refactoring the code: - more devices will be involved - i see there is some difference in device handling > > > >2. For migration we require an additional information that for the > >vhost-user device it isn't an error, because i'm trigerring the > >following assert error: > > Core was generated by `x86_64-softmmu/qemu-system-x86_64 -nodefaults -no-user-config -M q35,sata=false'. > > Program terminated with signal SIGABRT, Aborted. > > #0 0x00007fb56e729428 in raise () from /lib/x86_64-linux-gnu/libc.so.6 > > [Current thread is 1 (Thread 0x7fb486ef5700 (LWP 527734))] > > > > (gdb) bt > > #0 0x00007fb56e729428 in raise () from /lib/x86_64-linux-gnu/libc.so.6 > > #1 0x00007fb56e72b02a in abort () from /lib/x86_64-linux-gnu/libc.so.6 > > #2 0x00005648ea376ee6 in vhost_log_global_start > > (listener=0x5648ece4eb08) at ./hw/virtio/vhost.c:857 > > #3 0x00005648ea2dde7e in memory_global_dirty_log_start () > > at ./memory.c:2611 > > #4 0x00005648ea2e68e7 in ram_init_bitmaps (rs=0x7fb4740008c0) > > at ./migration/ram.c:2305 > > #5 0x00005648ea2e698b in ram_init_all (rsp=0x5648eb1f0f20 ) > > at ./migration/ram.c:2323 > > #6 0x00005648ea2e6cc5 in ram_save_setup (f=0x5648ec609e00, > > opaque=0x5648eb1f0f20 ) > > at ./migration/ram.c:2436 > > #7 0x00005648ea67b7d3 in qemu_savevm_state_setup (f=0x5648ec609e00) at > > migration/savevm.c:1176 > > #8 0x00005648ea674511 in migration_thread (opaque=0x5648ec031ff0) at > > migration/migration.c:3416 > > #9 0x00005648ea85d65d in qemu_thread_start (args=0x5648ec6057f0) at > > util/qemu-thread-posix.c:519 > > #10 0x00007fb56eac56ba in start_thread () from > > /lib/x86_64-linux-gnu/libpthread.so.0 > > #11 0x00007fb56e7fb41d in clone () from /lib/x86_64-linux-gnu/libc.so.6 > > (gdb) frame 2 > > #2 0x00005648ea376ee6 in vhost_log_global_start > > (listener=0x5648ece4eb08) at ./hw/virtio/vhost.c:857 > > 857 abort(); > > (gdb) list > > 852 { > > 853 int r; > > 854 > > 855 r = vhost_migration_log(listener, true); > > 856 if (r < 0) { > > 857 abort(); > > 858 } > > 859 } > > 860 > > 861 static void vhost_log_global_stop(MemoryListener *listener) > >Since bh postphone the clean up, we can't use the ->started field. > >Do we have any mechanism to get the device type/state in the common > >vhost_migration_log() routine? So for example for the vhost-user/disconnect > >device we will be able to return 0. Or should we implement it and introduce > >it in this patch set? > > > This requires more thought, I will reply in Feng's mail. Okay, let's continue discussion there. No other comments mixed in below. Thanks, Dima. > > Thanks > > > > > >Thanks, Dima. > > > >>Thank > >> > >> > >>> - vhost-user command returns error back to the _start() routine > >>> - Rollback in one place in the start() routine, by calling this > >>> postphoned clean up for the disconnect > >>> >