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 ws5-mx01.kavi.com (ws5-mx01.kavi.com [34.193.7.191]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7DC45C61DF4 for ; Fri, 24 Nov 2023 05:40:14 +0000 (UTC) Received: from lists.oasis-open.org (oasis.ws5.connectedcommunity.org [10.110.1.242]) by ws5-mx01.kavi.com (Postfix) with ESMTP id BAEC43309F for ; Fri, 24 Nov 2023 05:40:13 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id A36129868A6 for ; Fri, 24 Nov 2023 05:40:13 +0000 (UTC) Received: from host09.ws5.connectedcommunity.org (host09.ws5.connectedcommunity.org [10.110.1.97]) by lists.oasis-open.org (Postfix) with QMQP id 870D79862D9; Fri, 24 Nov 2023 05:40:13 +0000 (UTC) Mailing-List: contact virtio-comment-help@lists.oasis-open.org; run by ezmlm List-ID: Sender: Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 766A89868A5 for ; Fri, 24 Nov 2023 05:40:13 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: pssyTWAvOTqgFYXJ8MkCgw-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700804409; x=1701409209; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=KmUizR27pQdltc/spHnwh2BlcdmGF4gSC0jhWNmNInw=; b=EaUEVeDkeaRYWu2IMCMjtqDa7C0PitfjvtxXt3g6FwYdk3Vl72GOz3JWX/U0OGZGme 7cdx9qmpzJgsfa2ZY/jKUnemduU9gm76I2GsonF+xt7vXiTz79979ruGizlyloXVvZ9P phuo1Ly5UiVwf4C10PWwUq41pmUN0gkzOnrUctfZxHJiXn89rZGyhNmjAK4N6EgUsyMq CWwtU4QD4u5JQvm7+yarHsZYP1kFBMuNEHiCo68GafJgDh9j5oFm0dJJSIeRg/LXTpu5 sI/GvuvFoDnOJlZCyStwWOVioZDFCHemS8aL5K+/rTQ8kCPqTGOnOtwqGo5Er+Tks+ZE Dk4g== X-Gm-Message-State: AOJu0YwyMDPGFT5Qekc6upuyrD/TZcZMpji+vj4Y6q3P89fnhOuNsEuk 1OkIiqhS88PZKeNRP5W1Qg8oLs7M9QEdePFxypqwpAemlVlMcL/KT0jrELkStkE3E9XdbJInRLN uE9uj9R60ZefUnXMpJQ8UWt+rPBS7RgpnEw== X-Received: by 2002:a50:d69a:0:b0:548:55aa:a592 with SMTP id r26-20020a50d69a000000b0054855aaa592mr1144248edi.9.1700804409532; Thu, 23 Nov 2023 21:40:09 -0800 (PST) X-Google-Smtp-Source: AGHT+IGiSyh/nEfnXvEqFZc+hHmd6lLuNQAEH8xO/itkFqjeXeKpnb//le+1aIP8z2i6Ds+opV3Cow== X-Received: by 2002:a50:d69a:0:b0:548:55aa:a592 with SMTP id r26-20020a50d69a000000b0054855aaa592mr1144237edi.9.1700804409172; Thu, 23 Nov 2023 21:40:09 -0800 (PST) Date: Fri, 24 Nov 2023 00:40:03 -0500 From: "Michael S. Tsirkin" To: Jason Wang Cc: Parav Pandit , "Zhu, Lingshan" , "virtio-comment@lists.oasis-open.org" , "cohuck@redhat.com" , "sburla@marvell.com" , Shahaf Shuler , Maor Gottlieb , Yishai Hadas Message-ID: <20231124003337-mutt-send-email-mst@kernel.org> References: <20231116012208-mutt-send-email-mst@kernel.org> <20231122024459-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Subject: Re: [virtio-comment] [PATCH v1 1/8] admin: Add theory of operation for device migration On Fri, Nov 24, 2023 at 11:56:16AM +0800, Jason Wang wrote: > On Wed, Nov 22, 2023 at 3:48 PM Michael S. Tsirkin wrote: > > > > On Wed, Nov 22, 2023 at 12:13:34PM +0800, Jason Wang wrote: > > > > > What's wrong if we just allow them to be R/W over adminq/cmmands? > > > > > > > > > As explained before, > > > > Each guest has its own dedicated non mediated interface as defined in virtio spec to not involve hypervisor. > > > > > > So what's wrong with inventing per VF queue to do that? For example > > > transport virtqueue. > > > > Nothing is wrong with this. > > > > But what is problematic is just re-using config space for migration because > > It's not a reusing, it works exactly like this proposal: > > 1) VF config space is assigned to guest > 2) using PF queue to migrate > > The only difference is the command: > > In this proposal, it is > > 1) virtio_dev_ctx_pci_vq_cfg structure > 2) in transport virtqueue, it introduce a set of commands to access > one or several fields on the common cfg > > Thanks The problem with 2) is no one seems to bother building it right now, so I'm not sure we can with a straight face require people to use this infrastructure which does not exist. And the need this patchset is trying to address is real. So I think we should address this proposal on its own merits not on how well it compares with a theoretical transport virtqueue. > > it means we can not just say "don't access device after it is stopped" > > because yes you need to access it to save/restore state. > > And a new interface over admin cmds just for this side-steps the > > issue nicely. > > > > -- > > MST > > This publicly archived list offers a means to provide input to the OASIS Virtual I/O Device (VIRTIO) TC. In order to verify user consent to the Feedback License terms and to minimize spam in the list archive, subscription is required before posting. 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