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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 3E2DEC433FE for ; Wed, 9 Dec 2020 09:19:04 +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 B8D9F238A0 for ; Wed, 9 Dec 2020 09:19:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B8D9F238A0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org 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.48050.84993 (Exim 4.92) (envelope-from ) id 1kmvcO-000886-UC; Wed, 09 Dec 2020 09:18:40 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 48050.84993; Wed, 09 Dec 2020 09:18:40 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kmvcO-00087z-RH; Wed, 09 Dec 2020 09:18:40 +0000 Received: by outflank-mailman (input) for mailman id 48050; Wed, 09 Dec 2020 09:18:39 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kmvcN-00087u-3h for xen-devel@lists.xenproject.org; Wed, 09 Dec 2020 09:18:39 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kmvcJ-0003J4-O2; Wed, 09 Dec 2020 09:18:35 +0000 Received: from [54.239.6.185] (helo=a483e7b01a66.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1kmvcJ-0001sv-EN; Wed, 09 Dec 2020 09:18:35 +0000 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" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:Content-Type:In-Reply-To: MIME-Version:Date:Message-ID:From:References:Cc:To:Subject; bh=DAahiC9NoYOt+ab4ncTjAy1i0GArZVsp5vJUbWwC1qM=; b=ovHP4iWyC2xDcIZMJVqBEoN5kz M2SiC4Jjt/UMig7sj3mL/5VMo3nb0UQ7qxKXHhK5Cn+wxdj8asRo/8jdQiWEbM/mzoQhwSouIb2Za g+olcCJ0kBnTLlca2xjT2abiEw7gv5lnSuVbP5uEmDLNSzQ8xCaJMJYAirxEw829vUjA=; Subject: Re: [PATCH v2 8/8] xen/arm: Add support for SMMUv3 driver To: Bertrand Marquis , Stefano Stabellini Cc: Rahul Singh , "xen-devel@lists.xenproject.org" , Andrew Cooper , George Dunlap , Ian Jackson , Jan Beulich , Wei Liu , Paul Durrant , Volodymyr Babchuk References: <9C890E87-D438-4232-8647-8EC64FF32C42@arm.com> <9F9A955B-815C-4771-9EC0-073E9CF3E995@arm.com> <156ab0f5-e46d-6b96-7ff1-28ad3a748950@xen.org> From: Julien Grall Message-ID: <47bf1e5d-9e9e-d455-f6d8-5ddec0367ef2@xen.org> Date: Wed, 9 Dec 2020 09:18:32 +0000 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 8bit On 09/12/2020 07:55, Bertrand Marquis wrote: > Hi, Hi, > I also agree with the issue on the spinlock but we have no equivalent of something > looking like a mutex for now in Xen so this would require some major redesign and > will take us far from the linux driver. I agree that keeping the Xen implementation close to the Linux one is important. However, I view this has a the secondary goal. The primary goal is to have a safe and secure driver. If it means introducing a new set of lock or diverging from Linux, then so it be. > > I would suggest to add a comment before this part of the code with a “TODO” so that > it is clear inside the code. > We could also add some comment in Kconfig to mention this possible “faulty” behaviour. I think it would be enough to write in the Kconfig that the driver is "experimental and should not be used in production". Ideally, I would like a list of known issues for the driver (could be in the cover letter or/and at the top of the source file) so we can track what's missing to get it supported. Cheers, -- Julien Grall