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=-5.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_RED,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 735E4C433B4 for ; Fri, 16 Apr 2021 14:26:45 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (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 EC197610FC for ; Fri, 16 Apr 2021 14:26:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EC197610FC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id AC2436065D; Fri, 16 Apr 2021 14:26:44 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id NRs-sit8LT1W; Fri, 16 Apr 2021 14:26:44 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp3.osuosl.org (Postfix) with ESMTP id A9CFC60E0E; Fri, 16 Apr 2021 14:26:43 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 6EB16C000B; Fri, 16 Apr 2021 14:26:43 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [IPv6:2605:bc80:3010::138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 11FCDC000A for ; Fri, 16 Apr 2021 14:26:42 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id EC79B847AB for ; Fri, 16 Apr 2021 14:26:41 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Authentication-Results: smtp1.osuosl.org (amavisd-new); dkim=pass (1024-bit key) header.d=redhat.com Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id UWyJY3l2HGaV for ; Fri, 16 Apr 2021 14:26:41 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by smtp1.osuosl.org (Postfix) with ESMTPS id 3636883C44 for ; Fri, 16 Apr 2021 14:26:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1618583199; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=t1Hv2NbQ/MlDR82Y8nOIlqSLTEiVX08oupchgjJ9jRA=; b=O1rjioiI59LvC+S4nBSeMhvzoA5ceS7spb7jFCdkjrRNpFC6fI2SWlI3K6TOtlvalhf1eK N8JyO3WbCICOTkpav9TbWyRS8TN7sLxljNHIGja8vud0uQjveKKbJMfRJFUsKy+0WG39bV fUYD+aLmoTlKKHb4d/5H4oRLVS0daMQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-125-Zj04weCaOsqjgL2F0OCe8Q-1; Fri, 16 Apr 2021 10:26:35 -0400 X-MC-Unique: Zj04weCaOsqjgL2F0OCe8Q-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C4FE0BBEE4; Fri, 16 Apr 2021 14:26:32 +0000 (UTC) Received: from [10.36.113.21] (ovpn-113-21.ams2.redhat.com [10.36.113.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 321F25D9C0; Fri, 16 Apr 2021 14:26:21 +0000 (UTC) Subject: Re: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and allocation APIs To: Jason Gunthorpe References: <20210401134236.GF1463678@nvidia.com> <20210401160337.GJ1463678@nvidia.com> <4bea6eb9-08ad-4b6b-1e0f-c97ece58a078@redhat.com> <20210415230732.GG1370958@nvidia.com> <20210416140524.GI1370958@nvidia.com> From: Auger Eric Message-ID: Date: Fri, 16 Apr 2021 16:26:19 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <20210416140524.GI1370958@nvidia.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Cc: Jean-Philippe Brucker , "Tian, Kevin" , Alex Williamson , "Raj, Ashok" , Jonathan Corbet , Jean-Philippe Brucker , Li Zefan , LKML , "Jiang, Dave" , "iommu@lists.linux-foundation.org" , Johannes Weiner , Tejun Heo , "cgroups@vger.kernel.org" , "Wu, Hao" , David Woodhouse X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" Hi, On 4/16/21 4:05 PM, Jason Gunthorpe wrote: > On Fri, Apr 16, 2021 at 03:38:02PM +0200, Auger Eric wrote: > >> The redesign requirement came pretty late in the development process. >> The iommu user API is upstream for a while, the VFIO interfaces have >> been submitted a long time ago and under review for a bunch of time. >> Redesigning everything with a different API, undefined at this point, is >> a major setback for our work and will have a large impact on the >> introduction of features companies are looking forward, hence our >> frustration. > > I will answer both you and Jacob at once. > > This is uAPI, once it is set it can never be changed. > > The kernel process and philosophy is to invest heavily in uAPI > development and review to converge on the best uAPI possible. > > Many past submissions have take a long time to get this right, there > are several high profile uAPI examples. > > Do you think this case is so special, or the concerns so minor, that it > should get to bypass all of the normal process? That's not my intent to bypass any process. I am just trying to understand what needs to be re-designed and for what use case. > > Ask yourself, is anyone advocating for the current direction on > technical merits alone? > > Certainly the patches I last saw where completely disgusting from a > uAPI design perspective. > > It was against the development process to organize this work the way > it was done. Merging a wack of dead code to the kernel to support a > uAPI vision that was never clearly articulated was a big mistake. > > Start from the beginning. Invest heavily in defining a high quality > uAPI. Clearly describe the uAPI to all stake holders. This was largely done during several confs including plumber, KVM forum, for several years. Also API docs were shared on the ML. I don't remember any voice was raised at those moments. Break up the > implementation into patch series without dead code. Make the > patches. Remove the dead code this group has already added. > > None of this should be a surprise. The VDPA discussion and related > "what is a mdev" over a year ago made it pretty clear VFIO is not the > exclusive user of "IOMMU in userspace" and that places limits on what > kind of uAPIs expansion it should experience going forward. Maybe clear for you but most probably not for many other stakeholders. Anyway I do not intend to further argue and I will be happy to learn from you and work with you, Jacob, Liu and all other stakeholders to define a better integration. Thanks Eric > > Jason > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu