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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 4D2C4C10F27 for ; Tue, 10 Mar 2020 16:44:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2F97B222C3 for ; Tue, 10 Mar 2020 16:44:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726415AbgCJQoY (ORCPT ); Tue, 10 Mar 2020 12:44:24 -0400 Received: from foss.arm.com ([217.140.110.172]:39442 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726307AbgCJQoY (ORCPT ); Tue, 10 Mar 2020 12:44:24 -0400 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 0E0AB1FB; Tue, 10 Mar 2020 09:44:24 -0700 (PDT) Received: from [10.1.196.37] (e121345-lin.cambridge.arm.com [10.1.196.37]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 09A613F67D; Tue, 10 Mar 2020 09:44:19 -0700 (PDT) Subject: Re: [PATCH 0/3] Request direct mapping for modem firmware subdevice To: Joerg Roedel , Sibi Sankar Cc: ohad@wizery.com, devicetree@vger.kernel.org, linux-kernel-owner@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org, bjorn.andersson@linaro.org, iommu@lists.linux-foundation.org, robh+dt@kernel.org, agross@kernel.org References: <20200309182255.20142-1-sibis@codeaurora.org> <20200310112332.GG3794@8bytes.org> <4ed6ddd667a3e6f670084a443d141474@codeaurora.org> <20200310162320.GL3794@8bytes.org> From: Robin Murphy Message-ID: Date: Tue, 10 Mar 2020 16:44:12 +0000 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20200310162320.GL3794@8bytes.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On 10/03/2020 4:23 pm, Joerg Roedel wrote: > On Tue, Mar 10, 2020 at 07:30:50PM +0530, Sibi Sankar wrote: >> The accesses are initiated by the firmware >> and they access modem reserved regions. >> However as explained in ^^ any accesses >> outside the region will result in a violation >> and is controlled through XPUs (protection units). > > Okay, this sounds like a case for arm_smmu_get_resv_region(). It should > return an entry for the reserved memory region the firmware needs to > access, so that generic iommu can setup this mapping. > > Note that it should return that entry only for your device, not for all > devices. Maybe there is a property in DT or IORT you can set to > transport this information into the arm-smmu driver. > > This is pretty similar to RMRR mapping on the Intel VT-d IOMMU or > Unity-mapped ranges in the AMD-Vi IOMMU. Yup, a way to describe boot-time memory regions in IORT is in the process of being specced out; the first attempt at an equivalent for DT is here: https://lore.kernel.org/linux-iommu/20191209150748.2471814-1-thierry.reding@gmail.com/ If that's not enough and the SMMU still needs to treat certain Stream IDs specially because they may be untranslatable (due to having direct access to memory as a side-channel), then that should be handled in the SoC-specific corner of the SMMU driver, not delegated to individual endpoint drivers. Robin.