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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 90199C433F5 for ; Wed, 6 Oct 2021 14:38:53 +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 13713610C8 for ; Wed, 6 Oct 2021 14:38:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 13713610C8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:50400 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mY84K-0003IB-9f for qemu-devel@archiver.kernel.org; Wed, 06 Oct 2021 10:38:52 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38256) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mY83R-0001gg-KC for qemu-devel@nongnu.org; Wed, 06 Oct 2021 10:37:57 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:21483) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mY83M-0003dx-OO for qemu-devel@nongnu.org; Wed, 06 Oct 2021 10:37:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1633531072; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=wPxu3IvTAfJAU19KYf5BM/vF3S8DxDd7WYXM7nwLI4w=; b=E7fwvjSwoxLMzVSy59YTsChHyVmdB+0iC6ejZzHhFfG0FKlm/bMKPLfS1vGHiVkKqteLxP psS3THGRVUOeb/9hfWwhV5LjH5vsv1MNaoWvK162xu9Oy9luwkMVp1jqHSZogh9tQvNvaH q7R7721G9FQccNxWHCocPLepz4KYgr0= Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-346-TDj2_nouMI28kEkwNJealQ-1; Wed, 06 Oct 2021 10:37:51 -0400 X-MC-Unique: TDj2_nouMI28kEkwNJealQ-1 Received: by mail-ed1-f69.google.com with SMTP id r11-20020aa7cfcb000000b003d4fbd652b9so813603edy.14 for ; Wed, 06 Oct 2021 07:37:50 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=wPxu3IvTAfJAU19KYf5BM/vF3S8DxDd7WYXM7nwLI4w=; b=SCrWKTkUlp6FYpPtkWpX5+vsrEOJhyFgxSLa+xh1GO6UZgllu0L2f1eHelUYGHnZYL 7xfL3XSG+i50zIdYOX/cGfBAThM1c/pluFH7VHb506lfaGlLSwhxzbGX3q8etFw031O1 LV8nWtofr87/QNneuUiVzF5EjmvUvLm2RSl8op0J6Lr2ygG/0rZBnRmc0DNRpGsaH6bq LT4WjyW6ShBCXETXoLLR5zrsXE6ontPcgO9gSCI1AEy4NE0q+dINs6sUZgweWL/0Vq8n ZSvfFdu3ErvCPVPwH5SdDTBlXc8Vni3sSzwm0RN7i8iPu6hWQ+1X6empyftF+2qb+dDp yswA== X-Gm-Message-State: AOAM532mmvQUlpjggIVgveLLuyNK3zxMCFChr0IttzSg7/t00OB1J57V yUzfRViVQttydxGgXhPURsUtV4Z0HvAEkIG1r3clvQdDRJRy7KrymHZX0/BVGl7DAVqq+5RKMhJ PFQqRrQ5zWs8k6pc= X-Received: by 2002:a17:906:774f:: with SMTP id o15mr32544302ejn.200.1633531069767; Wed, 06 Oct 2021 07:37:49 -0700 (PDT) X-Google-Smtp-Source: ABdhPJz9dwD6BQBvP2dvvl3chyVpWIL+jAzxXaIv4R6igubR6Hft3w8COV3KPjMNqgX8TS6Tn+7l3A== X-Received: by 2002:a17:906:774f:: with SMTP id o15mr32544277ejn.200.1633531069546; Wed, 06 Oct 2021 07:37:49 -0700 (PDT) Received: from redhat.com ([2.55.143.13]) by smtp.gmail.com with ESMTPSA id f4sm8971974ejf.61.2021.10.06.07.37.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Oct 2021 07:37:49 -0700 (PDT) Date: Wed, 6 Oct 2021 10:37:45 -0400 From: "Michael S. Tsirkin" To: "Dr. David Alan Gilbert" Subject: Re: [PATCH v0 0/2] virtio-blk and vhost-user-blk cross-device migration Message-ID: <20211006103705-mutt-send-email-mst@kernel.org> References: <20211005175503-mutt-send-email-mst@kernel.org> <20211006041419-mutt-send-email-mst@kernel.org> <20211006043314-mutt-send-email-mst@kernel.org> <20211006081653-mutt-send-email-mst@kernel.org> <20211006093707-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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, DKIMWL_WL_HIGH=-0.05, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_PASS=-0.001, T_SPF_HELO_TEMPERROR=0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, Denis Plotnikov , Eduardo Habkost , qemu-block@nongnu.org, qemu-devel@nongnu.org, raphael.norwitz@nutanix.com, Roman Kagan , yc-core@yandex-team.ru, pbonzini@redhat.com, Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Oct 06, 2021 at 03:27:59PM +0100, Dr. David Alan Gilbert wrote: > * Michael S. Tsirkin (mst@redhat.com) wrote: > > On Wed, Oct 06, 2021 at 02:29:37PM +0100, Dr. David Alan Gilbert wrote: > > > * Michael S. Tsirkin (mst@redhat.com) wrote: > > > > On Wed, Oct 06, 2021 at 09:43:52AM +0100, Dr. David Alan Gilbert wrote: > > > > > * Michael S. Tsirkin (mst@redhat.com) wrote: > > > > > > On Wed, Oct 06, 2021 at 09:28:50AM +0100, Dr. David Alan Gilbert wrote: > > > > > > > To me it feels the same as the distinction between vhost-kernel and qemu > > > > > > > backended virtio that we get in net and others - in principal it's just > > > > > > > another implementation. > > > > > > > > > > > > In net it's actually like this. Same -device, a different netdev. > > > > > > > > > > > > > A tricky part is guaranteeing the set of visible virtio features between > > > > > > > implementations; we have that problem when we use vhost-kernel and run > > > > > > > on a newer/older kernel and gain virtio features; the same will be true > > > > > > > with vhost-user implementations. > > > > > > > > > > > > That's not new but yes we need to work on this. > > > > > > > > > > > > > But this would make the structure of a vhost-user implementation quite > > > > > > > different. > > > > > > > > > > > > > > Dave > > > > > > > > > > > > Right. That's why I'm reluctant to just add a new device type that > > > > > > has special compatibility requirements. > > > > > > > > > > Hmm but there's already another layer of hack^Wabstraction in there isn't there - > > > > > there's already: > > > > > virtio-blk-pci > > > > > virtio-blk-device > > > > > > > > > > created when the user specifies a virtio-blk device? > > > > > > > > > > Dave > > > > > > > > virtio-*-pci is there because it was felt these devices look > > > > differently from e.g. virtio-ccw so should have a different name. > > > > virtio-blk-device is an internal thingy, users and guests have no idea. > > > > > > Right, so to do what we're asking here, should we keep the > > > virtio-blk-pci and instantiate virtio-blk-vhost-user instead of > > > virtio-blk-device? > > > > > > Dave > > > > I guess that's possible, but we need to pass a bunch of parameters. > > -drive is probably the right want to do that, right? > > I'm not sure about -drive - isn't that very tied into the block layer? > > Dave If not, we'll need to add some other object, and tie it's id to the device. > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > MST > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > > > > > > > > > > > > > > > -- > > > > > > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > > > > > > > > > > > -- > > > > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > > > > > > > -- > > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > > > -- > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK