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=-5.2 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 80BB7C07E95 for ; Wed, 7 Jul 2021 17:53:46 +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 4859561CC8 for ; Wed, 7 Jul 2021 17:53:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4859561CC8 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=5+wKzQUH65tQnEc35FdsKlYPaK/CV85EtwZVmdY0cmg=; b=C4eMtDUx5f+b9c 0/lsbfziHG5CguXRa9dD7equpS/zYUzLEKxk60g6P09loh0I/t6mQyqM2oL17OgTpIPrJr0CnZVUd /+4MQHcCXuAtOfCz2HzAvsOQpwuPm2/zMKwz8pEkFtRPgkxr2bDkMhWCVsQnEPIufLMElW8z1OwuH RsgsTgpwDgfApWhcorSpGBtg8BiTSJ6PYyobNTbkdxSCwixMno9gHTCiM4xkLd/d0aioWlW2WHKLr txMvnADWnwb25iqEtf51tNpHwDqDvwwnLNrZXqNPThfU57USvNyuWXvIuEfaCVQV6BQ4ikKT59CU7 w9deaOE81hcjamZHljog==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m1Bie-00FQdo-DO; Wed, 07 Jul 2021 17:52:20 +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 1m1BiZ-00FQd9-Tl for linux-arm-kernel@lists.infradead.org; Wed, 07 Jul 2021 17:52:17 +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 AA4571042; Wed, 7 Jul 2021 10:52:11 -0700 (PDT) Received: from bogus (unknown [10.57.78.75]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6095D3F694; Wed, 7 Jul 2021 10:52:08 -0700 (PDT) Date: Wed, 7 Jul 2021 18:51:23 +0100 From: Sudeep Holla To: Sumit Garg Cc: Marc Zyngier , Jens Wiklander , Sudeep Holla , Linux Kernel Mailing List , linux-arm-kernel , OP-TEE TrustedFirmware , Devicetree List , Linux Doc Mailing List , Jerome Forissier , Etienne Carriere , Vincent Guittot , Rob Herring , Jonathan Corbet , Ard Biesheuvel Subject: Re: [PATCH v2 0/7] Asynchronous notifications from secure world Message-ID: <20210707175123.xdotr3lsy3e32plm@bogus> References: <20210616103649.2662395-1-jens.wiklander@linaro.org> <87czrv91b2.wl-maz@kernel.org> <87a6mz8vaj.wl-maz@kernel.org> 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-20210707_105216_103950_7A02CF61 X-CRM114-Status: GOOD ( 33.56 ) 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 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. > > > > > > > > In general, cross world SGIs are a really bad idea. Yes, some people > > > > like them. I still think they are misguided, and I don't intend to > > > > provide a generic request interface for this. > > > > > > Okay, as I mentioned above having it specific to OP-TEE driver > > > requesting secure world donated SGI would work for you? > > > > No. I want a proper architecture between secure and non-secure that > > explain how messages are conveyed between the two world, how > > signalling is done, how CPU PM is handled, how targeting is > > negotiated. And at the end of the day, this is starting to look a lot > > like FFA. > > AFAIK when FFA comes in picture than OP-TEE will use the standard > interface provided by FFA ABIs but if FFA isn't supported by a > particular platform (eg. based on Armv7) then we need to rely on TEE > specific ABI like what OP-TEE currently provides: > Who are asking for this ? Can we ask them to migrate to FF-A if this (new) notification support is needed on their platforms ? It is help to know the requesters so that they can be included in FF-A spec discussions. > > that. You'll even get to keep the pieces once it breaks. But if you > > are going to invent a new universal way of signalling things across > > world, you'd better start specifying things the right way, taking into > > considerations systems where the interrupt controller doesn't allow > > cross-world signalling. > > As I mentioned above, this patch-set adds an OP-TEE specific > notifications feature. AFAIK, the interrupt controllers supported by > OP-TEE (GICv2, GICv3 etc.) don't restrict cross-world signaling. > > So given the explanation above, if you still think requesting an SGI > as an IRQ by drivers isn't allowed then I am fine with the approach > that Jens has already implemented in this patch-set to use platform > specific SPI. > And I assume these platforms in question have SPI to spare and way to trigger it from secure world ? -- Regards, Sudeep _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel