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=-5.5 required=3.0 tests=BAYES_00, 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 48FD8C433E7 for ; Fri, 17 Jul 2020 14:00:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 238B420717 for ; Fri, 17 Jul 2020 14:00:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727065AbgGQOAW (ORCPT ); Fri, 17 Jul 2020 10:00:22 -0400 Received: from mga09.intel.com ([134.134.136.24]:3715 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726974AbgGQOAV (ORCPT ); Fri, 17 Jul 2020 10:00:21 -0400 IronPort-SDR: GnzOEVjkuiEQXiUQqjrgnYwZqa3R0ryCx064clUnyv2IBy8kLq0L00DH6bF49OopUm/AkTtYyR qOvfVrb7i0+w== X-IronPort-AV: E=McAfee;i="6000,8403,9684"; a="150967788" X-IronPort-AV: E=Sophos;i="5.75,362,1589266800"; d="scan'208";a="150967788" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jul 2020 07:00:21 -0700 IronPort-SDR: i/FAwqn6mQcDVNwTNQo1ZPyUsFNo8bNK44NhJq0QPcmArDfLo44GHNN1eyDzDF3mOD1+xMqsbt WU1VhRCMoepQ== X-IronPort-AV: E=Sophos;i="5.75,362,1589266800"; d="scan'208";a="430846386" Received: from paulmurp-mobl.ger.corp.intel.com (HELO [192.168.153.165]) ([10.213.219.68]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jul 2020 07:00:18 -0700 Subject: Re: [PATCH] firmware: arm_scmi: Pass shmem address to SMCCC call To: Florian Fainelli , Daniele Alessandrelli , Sudeep Holla , linux-arm-kernel@lists.infradead.org Cc: Peng Fan , "Paul J. Murphy" , linux-kernel@vger.kernel.org, Daniele Alessandrelli References: <20200715165518.57558-1-daniele.alessandrelli@linux.intel.com> <5f74221b-aec7-7715-19d1-5cbb406f1bdc@gmail.com> From: Paul Murphy Message-ID: <1117fc3b-3c35-c66c-bf73-cb879a08bde5@linux.intel.com> Date: Fri, 17 Jul 2020 15:00:16 +0100 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: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Florian On 7/16/20 20:57, Florian Fainelli wrote: >>> >>> Given that the kernel must somehow reserve this memory as a shared >>> memory area for obvious reasons, and the trusted firmware must also >>> ensure it treats this memory region with specific permissions in its >>> translation regime, does it really make sense to give that much >>> flexibility? >> >> Well, the trusted firmware might reserve a bigger region to be used for >> other service as well. In other words, the MMU of TF-A is not necessary >> specifically set up for this region, but, possibly, for a bigger >> general shared region. > > But presumably the Linux shared memory area should be mapped in a > slightly different way than > Sorry - could you clarify what you mean by that? Just checking if we are doing everything correctly. I didn't understand that there is a connection between the TF-A MMU tables for this region and the normal world MMU tables? For example: TF-A may map physical address range: 0x0 -> 0x400_000 as 'normal' memory for various purposes. Linux SCMI driver could map physical address range, eg: 0x300_000 -> 0x301_000 as IO memory for mailbox purpose only. Is there any issue here? Regards, Paul