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=-4.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 507F5C07E95 for ; Tue, 13 Jul 2021 11:25:21 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 16EB061006 for ; Tue, 13 Jul 2021 11:25:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 16EB061006 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=+sTgCV4bKyl8a8ssAlHUjMFaXYmMvYOB5ZX+cysb69U=; b=dvY9yW8t+YXScp Ai6ivZmK1DAiyl3Sm+fgq1ocIUQX4nST9QPf38EPUmIaRqRoDg89QXq3DOhl74lai5gGxd2E2Ksm5 8XZ53YgwkuN6RzLYGjQv/sdXMhRHJDSo4XVMdwsr9WR1+UdP1nG967CondkLfHxcz+Z6zxB5JXAYV NrqC1CxVEX3/ymgdMGhycbk90rvSLp1fKcPFzroyTNdw085Ti+OZ7t4dRBSYLRGw44UFtDNZL2HgT U4OcP1mMeQNMzMhi8o3wlsbEHCBPBajdTvvUc40IBED2qNOiY9O/uQvHdaErxIgfilP4zEOSzs9SF Io210BPpiV32nwd6YDGQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m3GV0-00A9sl-Cz; Tue, 13 Jul 2021 11:22:52 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m3GLN-00A6lD-Qf for linux-arm-kernel@lists.infradead.org; Tue, 13 Jul 2021 11:12:55 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 461F61FB; Tue, 13 Jul 2021 04:12:50 -0700 (PDT) Received: from bogus (unknown [10.57.79.213]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C08BA3F7D8; Tue, 13 Jul 2021 04:12:45 -0700 (PDT) Date: Tue, 13 Jul 2021 12:11:43 +0100 From: Sudeep Holla To: Etienne CARRIERE Cc: Sumit Garg , Marc Zyngier , Jens Wiklander , Linux Kernel Mailing List , linux-arm-kernel , OP-TEE TrustedFirmware , "devicetree@vger.kernel.org" , Linux Doc Mailing List , Jerome Forissier , Vincent Guittot , Rob Herring , Jonathan Corbet , Ard Biesheuvel , Etienne Carriere Subject: Re: [PATCH v2 0/7] Asynchronous notifications from secure world Message-ID: <20210713111143.g6ztdakegs6ck25s@bogus> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210713_041254_039834_272F06FB X-CRM114-Status: GOOD ( 33.83 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jul 09, 2021 at 08:05:57AM +0000, Etienne CARRIERE wrote: > Hello Sudeep and all, > > On Wed, 7 Jul 2021 at 19:52, Sudeep Holla wrote: > > > > Hi Sumit, > > > > I was holding off you reply as I didn't have all the background on this. > > Achin did mention that this is preparatory work for FFA notifications. > > I did mention to him that this is more than that, it is custom extension > > to address what FF-A notification is trying to in standard way. > > > > I share same opinion as Marc Z. > > > > On Wed, Jul 07, 2021 at 11:22:23AM +0530, Sumit Garg wrote: > > > On Tue, 6 Jul 2021 at 18:16, Marc Zyngier wrote: > > > > [...] > > > > > > > > > > I don't care about OP-TEE. If you are proposing a contract between S > > > > and NS, it has to be TEE and OS independent. That's how the > > > > architecture works. > > > > > > > > > > Agree, here we are not proposing a common contract among the S and NS > > > world that every TEE (based on Arm TrustZone) will use to communicate > > > with REE (Linux in our case) but rather an OP-TEE specific > > > notifications feature that is built on top of OP-TEE specific ABIs. > > > > > > And I can see your arguments coming from an FFA perspective but there > > > are platforms like the ones based on Armv7 which don't support FFA > > > ABI. Maybe Jens can elaborate how this feature will fit in when FFA > > > comes into picture? > > > > > > > I can understand that but won't those platforms add the support both in > > the kernel(current series) and secure world to address notifications. > > While you could argue that it is small extension to what is already present > > but I prefer they support FF-A is they need such a support instead of adding > > custom mechanisms. It is hard to maintain and each vendor will deviate > > from this custom mechanism and soon we will have bunch of them to handle. > > There exist armv7-a platforms that expect OP-TEE notification support and > will not move the FF-A, like the stm32mp15. This platform won't move to FF-A > mainly due to the memory cost of the added SPM layer and the device physical > constraints. Fair enough on the use-case and the analysis for not being able to use FF-A. As you may already know it doesn't simply this problem. This has been discussed for years and FF-A was assumed to be the solution when FF-A spec work started. > We have a usecase for OP-TEE notification. We're working on the integration > of an SCMI server in OP-TEE. SCMI notification is a feature needed is this > scope and it requires OP-TEE async notification means as those proposed > here. > I am aware of this use-case, I understand. But I can only share rants which I know doesn't help much. > This OP-TEE async notif also brings a lot of value in OP-TEE as it allows a > OP-TEE secure thread (i.e. executing a trusted application service) to > gently wait on a secure interrupt (as a slow bus transaction completion or > many other usecase) with the CPU relaxed. This support is provided by the > proposed series. I believe existing device should be able to leverage this > OP-TEE feature without needing their OP-TEE to move to the new FF-A > interface. > While I agree these are nice to have in OPTEE, the timing is just odd. We are trying hard to push FF-A as standard solution to address all such issues that couldn't be solved with OPTEE + DT, now we are back to address the same in parallel to FF-A. -- Regards, Sudeep _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel