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=-7.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 A92F8C433E0 for ; Thu, 23 Jul 2020 07:03:15 +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 7F86F20771 for ; Thu, 23 Jul 2020 07:03:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7F86F20771 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=siemens.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:42952 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jyVG6-0006HH-O3 for qemu-devel@archiver.kernel.org; Thu, 23 Jul 2020 03:03:14 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60178) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jyVFC-0005p4-3O for qemu-devel@nongnu.org; Thu, 23 Jul 2020 03:02:18 -0400 Received: from goliath.siemens.de ([192.35.17.28]:50516) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jyVFA-0004Pr-3C for qemu-devel@nongnu.org; Thu, 23 Jul 2020 03:02:17 -0400 Received: from mail2.sbs.de (mail2.sbs.de [192.129.41.66]) by goliath.siemens.de (8.15.2/8.15.2) with ESMTPS id 06N72ABC031190 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 23 Jul 2020 09:02:10 +0200 Received: from [139.22.112.247] ([139.22.112.247]) by mail2.sbs.de (8.15.2/8.15.2) with ESMTP id 06N729ci005475; Thu, 23 Jul 2020 09:02:09 +0200 Subject: Re: [virtio-comment] [RFC] ivshmem v2: Shared memory device specification To: Stefan Hajnoczi References: <20200715132748.GA20677@stefanha-x1.localdomain> <88a33034-783a-07d2-85e0-c1a1ecd2721f@siemens.com> <20200723065423.GE268427@stefanha-x1.localdomain> From: Jan Kiszka Message-ID: <10df6427-eab0-d3b8-4624-ede98ff7ef09@siemens.com> Date: Thu, 23 Jul 2020 09:02:09 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200723065423.GE268427@stefanha-x1.localdomain> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=192.35.17.28; envelope-from=jan.kiszka@siemens.com; helo=goliath.siemens.de X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/23 03:02:13 X-ACL-Warn: Detected OS = Linux 3.1-3.10 X-Spam_score_int: -68 X-Spam_score: -6.9 X-Spam_bar: ------ X-Spam_report: (-6.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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: Jailhouse , liang yan , "Michael S. Tsirkin" , qemu-devel , "virtio-comment@lists.oasis-open.org" , =?UTF-8?Q?Alex_Benn=c3=a9e?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 23.07.20 08:54, Stefan Hajnoczi wrote: > On Fri, Jul 17, 2020 at 06:15:58PM +0200, Jan Kiszka wrote: >> On 15.07.20 15:27, Stefan Hajnoczi wrote: >>> On Mon, May 25, 2020 at 09:58:28AM +0200, Jan Kiszka wrote: > > Thanks for the responses. It would be great to update the spec with > these clarifications. > >>>> If BAR 2 is not present, the shared memory region is not relocatable >>>> by the user. In that case, the hypervisor has to implement the Base >>>> Address register in the vendor-specific capability. >>> >>> What does relocatable mean in this context? >> >> That the guest can decide (via BAR) where the resource should show up in the >> physical guest address space. We do not want to support this in setups like >> for static partitioning hypervisors, and then we use that side-channel >> read-only configuration. > > I see. I'm not sure what is vendor-specific about non-relocatable shared > memory. I guess it could be added to the spec too? That "vendor-specific" comes from the PCI spec which - to my understanding - provides us no other means to introduce registers to the config space that are outside of the PCI spec. I could introduce a name for the ivshmem vendor cap and use that name here - would that be better? > > In any case, since "relocatable" hasn't been fully defined, I suggest > making the statement more general: > > If BAR 2 is not present the hypervisor has to implement the Base > Address Register in the vendor-specific capability. This can be used > for vendor-specific shared memory functionality. > Will integrate this. Thanks, Jan -- Siemens AG, Corporate Technology, CT RDA IOT SES-DE Corporate Competence Center Embedded Linux