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=-9.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 0EB57C4361B for ; Tue, 8 Dec 2020 14:54:58 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 B192F23A6C for ; Tue, 8 Dec 2020 14:54:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B192F23A6C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.47499.84040 (Exim 4.92) (envelope-from ) id 1kmeO8-0005Zp-1u; Tue, 08 Dec 2020 14:54:48 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 47499.84040; Tue, 08 Dec 2020 14:54:48 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kmeO7-0005Zi-UQ; Tue, 08 Dec 2020 14:54:47 +0000 Received: by outflank-mailman (input) for mailman id 47499; Tue, 08 Dec 2020 14:54:46 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kmeO6-0005Zb-BQ for xen-devel@lists.xenproject.org; Tue, 08 Dec 2020 14:54:46 +0000 Received: from mail-lf1-x144.google.com (unknown [2a00:1450:4864:20::144]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 3ce931cc-f0fa-49b9-bfc0-3956a563fd4b; Tue, 08 Dec 2020 14:54:45 +0000 (UTC) Received: by mail-lf1-x144.google.com with SMTP id m12so1900425lfo.7 for ; Tue, 08 Dec 2020 06:54:45 -0800 (PST) Received: from [192.168.1.7] ([212.22.223.21]) by smtp.gmail.com with ESMTPSA id o123sm722694lff.84.2020.12.08.06.54.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 08 Dec 2020 06:54:43 -0800 (PST) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 3ce931cc-f0fa-49b9-bfc0-3956a563fd4b DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding:content-language; bh=hE6E8q75/HbTu5s7bfWpn41dJTfyrwHIeTndrmaxDHo=; b=ZMDkTgT717PXEkxSl+izAJH9utq1o4z8uWAKHaYb5hl1MVw5PyGFyr3tO6xWcRWW/z BrBD+0wFGsuAcJLUqY/y1jjfIeS7AZSmLWM9ZEHUp7+wp9IOHQm1CyM+VXkvcho94PG8 Ca9EzW6NpiFQ/SDiBHSjbEWdA95KwM5GBJHX+/fBKjGYvzDv2tNBi2GFjebUyqQOb81B 9VSvlaywFXhFhENZzltNn08LRS7BhcVcYH0nsZYtbhMKcwUlgO1K3qXzWIQR+0GLK3FW NXuObCwC2+cVq/wSzD4VoB9wT+lE3KsBsoH5mX9rUQGquE4gE3SE0sNPb4jPaU0bWJzH fFdA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=hE6E8q75/HbTu5s7bfWpn41dJTfyrwHIeTndrmaxDHo=; b=pGSl8XbT4piho3ReC2WZ/r5DWsER0lsiBzvStjohzazfkpgAJKWeLBxmPwIEAWgek5 cCL87aF2A11WNmkkSiro0Q+uvFq1J4dMeADqwUGdbmPCkmmaRjbOjWh5yOdsP3ppsXPY 6SYiylTWIaKHOuklczNpfSbPnodYGz9Sr/qMlZKHXolijTG6sTXpgb7LmbuN+3K3s/zo LGm5BYRxjRbMAZK8MMAAvowZNO6CY8/+g07jjp8FdcFUBaXVgPQszAObMAwccKp8Pc7G t5y1hA7FgQzkNPEpIXfsxuRb24Id4curI+yI2kA0kIwxdDsvuQrnfe7INW4wS1lzjfHz PC5g== X-Gm-Message-State: AOAM532Kz46IKrE7eix7ueYV51pyYqrF/vC6zRmOTQ0ZRQtUw11gH//L Jv2pkFAQt9ChUh3GcEBY+pE1kvoiQG2l6Q== X-Google-Smtp-Source: ABdhPJxA1Z2GlI0KleWLlDrb2kdosArQuygD8wHkYJbD+A72MhSznOels8QIBISPGf1DZzuMw2TpXQ== X-Received: by 2002:a19:be0d:: with SMTP id o13mr447115lff.517.1607439283882; Tue, 08 Dec 2020 06:54:43 -0800 (PST) Subject: Re: [PATCH V3 09/23] xen/dm: Make x86's DM feature common To: Jan Beulich Cc: Julien Grall , Andrew Cooper , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Wei Liu , George Dunlap , Ian Jackson , Julien Grall , Stefano Stabellini , Daniel De Graaf , Oleksandr Tyshchenko , xen-devel@lists.xenproject.org References: <1606732298-22107-1-git-send-email-olekstysh@gmail.com> <1606732298-22107-10-git-send-email-olekstysh@gmail.com> <00c3df9f-760d-bb3d-d1d6-7c7df7f0c17c@suse.com> <24191fca-78e7-3e6b-ff02-c06e8ae79f56@gmail.com> <7c985117-2bb4-dd5b-53cf-e217e25b2e8e@suse.com> From: Oleksandr Message-ID: Date: Tue, 8 Dec 2020 16:54:37 +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: <7c985117-2bb4-dd5b-53cf-e217e25b2e8e@suse.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US On 08.12.20 11:30, Jan Beulich wrote: Hi Jan > On 07.12.2020 21:23, Oleksandr wrote: >> On 07.12.20 14:08, Jan Beulich wrote: >>> On 30.11.2020 11:31, Oleksandr Tyshchenko wrote: >>>> From: Julien Grall >>>> >>>> As a lot of x86 code can be re-used on Arm later on, this patch >>>> splits devicemodel support into common and arch specific parts. >>>> >>>> The common DM feature is supposed to be built with IOREQ_SERVER >>>> option enabled (as well as the IOREQ feature), which is selected >>>> for x86's config HVM for now. >>>> >>>> Also update XSM code a bit to let DM op be used on Arm. >>>> >>>> This support is going to be used on Arm to be able run device >>>> emulator outside of Xen hypervisor. >>>> >>>> Signed-off-by: Julien Grall >>>> Signed-off-by: Oleksandr Tyshchenko >>>> >>>> --- >>>> Please note, this is a split/cleanup/hardening of Julien's PoC: >>>> "Add support for Guest IO forwarding to a device emulator" >>>> >>>> Changes RFC -> V1: >>>> - update XSM, related changes were pulled from: >>>> [RFC PATCH V1 04/12] xen/arm: Introduce arch specific bits for IOREQ/DM features >>>> >>>> Changes V1 -> V2: >>>> - update the author of a patch >>>> - update patch description >>>> - introduce xen/dm.h and move definitions here >>>> >>>> Changes V2 -> V3: >>>> - no changes >>> And my concern regarding the common vs arch nesting also hasn't >>> changed. >> >> I am sorry, I might misread your comment, but I failed to see any >> obvious to me request(s) for changes. >> I have just re-read previous discussion... >> So the question about considering doing it the other way around (top >> level dm-op handling arch-specific >> and call into e.g. ioreq_server_dm_op() for otherwise unhandled ops) is >> exactly a concern which I should have addressed? > Well, on v2 you replied you didn't consider the alternative. I would > have expected that you would at least go through this consideration > process, and see whether there are better reasons to stick with the > apparently backwards arrangement than to change to the more > conventional one. If there are such reasons, I would expect them to > be called out in reply and perhaps also in the commit message; the > latter because down the road more people may wonder why the more > narrow / special set of cases gets handled at a higher layer than > the wider set of remaining ones, and they would then be able to find > an explanation without having to resort to searching through list > archives. Ah, will investigate. Sorry for not paying enough attention to it. Yes, IOREQ (I mean "common") ops are 7 out of 18 right now. The subsequent patch is adding one more DM op - XEN_DMOP_set_irq_level. There are several PCI related ops which might want to be common in the future (but I am not sure). -- Regards, Oleksandr Tyshchenko