From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:53510) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hGECS-0003En-6Y for qemu-devel@nongnu.org; Mon, 15 Apr 2019 22:51:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hGECR-0003S8-71 for qemu-devel@nongnu.org; Mon, 15 Apr 2019 22:51:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49604) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hGECQ-0003Qz-VN for qemu-devel@nongnu.org; Mon, 15 Apr 2019 22:51:55 -0400 Date: Tue, 16 Apr 2019 10:51:47 +0800 From: Peter Xu Message-ID: <20190416025147.GA20550@xz-x1> 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=utf-8 Content-Disposition: inline In-Reply-To: <1554712933-18682-1-git-send-email-catherine.hecx@gmail.com> Subject: Re: [Qemu-devel] [PATCH v4] migration: do not rom_reset() during incoming migration List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Catherine Ho Cc: Paolo Bonzini , Richard Henderson , "Dr. David Alan Gilbert" , Markus Armbruster , Juan Quintela , qemu-devel@nongnu.org On Mon, Apr 08, 2019 at 04:42:13AM -0400, Catherine Ho 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 Acked-by: Peter Xu -- Peter Xu 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=-5.4 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,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 2E5AFC10F0E for ; Tue, 16 Apr 2019 02:52:46 +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 EE9BD2075B for ; Tue, 16 Apr 2019 02:52:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EE9BD2075B 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]:58392 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hGEDF-0003Vi-2c for qemu-devel@archiver.kernel.org; Mon, 15 Apr 2019 22:52:45 -0400 Received: from eggs.gnu.org ([209.51.188.92]:53510) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hGECS-0003En-6Y for qemu-devel@nongnu.org; Mon, 15 Apr 2019 22:51:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hGECR-0003S8-71 for qemu-devel@nongnu.org; Mon, 15 Apr 2019 22:51:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49604) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hGECQ-0003Qz-VN for qemu-devel@nongnu.org; Mon, 15 Apr 2019 22:51:55 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 3D5863092645; Tue, 16 Apr 2019 02:51:52 +0000 (UTC) Received: from xz-x1 (dhcp-14-116.nay.redhat.com [10.66.14.116]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8095019C6A; Tue, 16 Apr 2019 02:51:49 +0000 (UTC) Date: Tue, 16 Apr 2019 10:51:47 +0800 From: Peter Xu To: Catherine Ho Message-ID: <20190416025147.GA20550@xz-x1> 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="UTF-8" Content-Disposition: inline In-Reply-To: <1554712933-18682-1-git-send-email-catherine.hecx@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Tue, 16 Apr 2019 02:51:52 +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 , Markus Armbruster , qemu-devel@nongnu.org, "Dr. David Alan Gilbert" , Paolo Bonzini , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Message-ID: <20190416025147.G0zZQcpqbvfyNF-_Er-21tLAKz6exz0C6eTicCVU52Q@z> On Mon, Apr 08, 2019 at 04:42:13AM -0400, Catherine Ho 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 Acked-by: Peter Xu -- Peter Xu