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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, T_HK_NAME_DR,USER_AGENT_MUTT autolearn=ham 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 2AB3EC28CC5 for ; Wed, 5 Jun 2019 18:38:58 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 09056206B8 for ; Wed, 5 Jun 2019 18:38:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 09056206B8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([127.0.0.1]:48261 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hYaoL-0003nG-6t for qemu-devel@archiver.kernel.org; Wed, 05 Jun 2019 14:38:57 -0400 Received: from eggs.gnu.org ([209.51.188.92]:45471) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hYami-0002dD-BV for qemu-devel@nongnu.org; Wed, 05 Jun 2019 14:37:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hYah9-000111-5H for qemu-devel@nongnu.org; Wed, 05 Jun 2019 14:31:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47784) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hYah8-0000zh-WA for qemu-devel@nongnu.org; Wed, 05 Jun 2019 14:31:31 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BD3442F8BCD; Wed, 5 Jun 2019 18:31:29 +0000 (UTC) Received: from work-vm (ovpn-117-13.ams2.redhat.com [10.36.117.13]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1FABD60BC3; Wed, 5 Jun 2019 18:31:24 +0000 (UTC) Date: Wed, 5 Jun 2019 19:31:22 +0100 From: "Dr. David Alan Gilbert" To: Paolo Bonzini Message-ID: <20190605183122.GJ2669@work-vm> References: <1554688616-18583-1-git-send-email-catherine.hecx@gmail.com> <1554712933-18682-1-git-send-email-catherine.hecx@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1554712933-18682-1-git-send-email-catherine.hecx@gmail.com> User-Agent: Mutt/1.11.4 (2019-03-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Wed, 05 Jun 2019 18:31:29 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v4] migration: do not rom_reset() during incoming migration X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juan Quintela , qemu-devel@nongnu.org, Peter Xu , Markus Armbruster , Catherine Ho , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Paolo, can you take this one please. * Catherine Ho (catherine.hecx@gmail.com) wrote: > Commit 18269069c310 ("migration: Introduce ignore-shared capability") > addes ignore-shared capability to bypass the shared ramblock (e,g, > membackend + numa node). It does good to live migration. > > As told by Yury,this commit expectes that QEMU doesn't write to guest RAM > until VM starts, but it does on aarch64 qemu: > Backtrace: > 1 0x000055f4a296dd84 in address_space_write_rom_internal () at > exec.c:3458 > 2 0x000055f4a296de3a in address_space_write_rom () at exec.c:3479 > 3 0x000055f4a2d519ff in rom_reset () at hw/core/loader.c:1101 > 4 0x000055f4a2d475ec in qemu_devices_reset () at hw/core/reset.c:69 > 5 0x000055f4a2c90a28 in qemu_system_reset () at vl.c:1675 > 6 0x000055f4a2c9851d in main () at vl.c:4552 > > Actually, on arm64 virt marchine, ramblock "dtb" will be filled into ram > druing rom_reset. In ignore-shared incoming case, this rom filling > is not required since all the data has been stored in memory backend > file. > > Further more, as suggested by Peter Xu, if we do rom_reset() now with > these ROMs then the RAM data should be re-filled again too with the > migration stream coming in. > > Fixes: commit 18269069c310 ("migration: Introduce ignore-shared > capability") > Suggested-by: Yury Kotov > Suggested-by: Peter Xu > Signed-off-by: Catherine Ho > --- > hw/core/loader.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/hw/core/loader.c b/hw/core/loader.c > index fe5cb24122..040109464b 100644 > --- a/hw/core/loader.c > +++ b/hw/core/loader.c > @@ -1087,6 +1087,15 @@ static void rom_reset(void *unused) > { > Rom *rom; > > + /* > + * We don't need to fill in the RAM with ROM data because we'll fill > + * the data in during the next incoming migration in all cases. Note > + * that some of those RAMs can actually be modified by the guest on ARM > + * so this is probably the only right thing to do here. > + */ > + if (runstate_check(RUN_STATE_INMIGRATE)) > + return; > + > QTAILQ_FOREACH(rom, &roms, next) { > if (rom->fw_file) { > continue; > -- > 2.17.1 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK