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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 94A6FC10F14 for ; Tue, 15 Oct 2019 12:10:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 70B8021925 for ; Tue, 15 Oct 2019 12:10:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730640AbfJOMKA (ORCPT ); Tue, 15 Oct 2019 08:10:00 -0400 Received: from foss.arm.com ([217.140.110.172]:37244 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726540AbfJOMKA (ORCPT ); Tue, 15 Oct 2019 08:10:00 -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 4C606337; Tue, 15 Oct 2019 05:10:00 -0700 (PDT) Received: from [10.1.197.57] (e110467-lin.cambridge.arm.com [10.1.197.57]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8A0583F68E; Tue, 15 Oct 2019 05:09:59 -0700 (PDT) Subject: Re: [PATCH v4 2/7] iommu/qcom: Use the asid read from device-tree if specified To: kholk11@gmail.com, linux-arm-msm@vger.kernel.org Cc: marijns95@gmail.com, iommu@lists.linux-foundation.org, agross@kernel.org References: <20191001220205.6423-1-kholk11@gmail.com> <20191001220205.6423-3-kholk11@gmail.com> From: Robin Murphy Message-ID: <25f3e314-3fcc-fc4f-e7b5-4f28418ea02f@arm.com> Date: Tue, 15 Oct 2019 13:09:57 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20191001220205.6423-3-kholk11@gmail.com> 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 01/10/2019 23:02, kholk11@gmail.com wrote: > From: AngeloGioacchino Del Regno > > As specified in this driver, the context banks are 0x1000 apart. > Problem is that sometimes the context number (our asid) does not > match this logic and we end up using the wrong one: this starts > being a problem in the case that we need to send TZ commands > to do anything on a specific context. > > For this reason, read the ASID from the DT if the property > "qcom,ctx-num" is present on the IOMMU context node. Can you clarify exactly what the situation is here? Is the hypervisor broken in that it presents context banks at made-up offsets and fails to correctly associate those offsets with the real underlying hardware context in some cases? Or is the hypervisor actually intercepting TTBR/CONTEXTIDR/TLBI* writes such that we don't actually have control over the ASID used by a given context bank (which I would also consider broken)? Or is "context number" a specific thing in the SCM interface which represents neither of the above? At the moment, it seems like a bit too much is being conflated here just because of some implicit behaviour in the driver. Robin. > Signed-off-by: AngeloGioacchino Del Regno > --- > .../devicetree/bindings/iommu/qcom,iommu.txt | 1 + > drivers/iommu/qcom_iommu.c | 17 ++++++++++++++--- > 2 files changed, 15 insertions(+), 3 deletions(-) > > diff --git a/Documentation/devicetree/bindings/iommu/qcom,iommu.txt b/Documentation/devicetree/bindings/iommu/qcom,iommu.txt > index 059139abce35..ba0b77889f02 100644 > --- a/Documentation/devicetree/bindings/iommu/qcom,iommu.txt > +++ b/Documentation/devicetree/bindings/iommu/qcom,iommu.txt > @@ -46,6 +46,7 @@ to non-secure vs secure interrupt line. > for routing of context bank irq's to secure vs non- > secure lines. (Ie. if the iommu contains secure > context banks) > +- qcom,ctx-num : The number associated to the context bank > > > ** Examples: > diff --git a/drivers/iommu/qcom_iommu.c b/drivers/iommu/qcom_iommu.c > index c31e7bc4ccbe..504ca69adc5a 100644 > --- a/drivers/iommu/qcom_iommu.c > +++ b/drivers/iommu/qcom_iommu.c > @@ -585,7 +585,8 @@ static int qcom_iommu_of_xlate(struct device *dev, struct of_phandle_args *args) > * index into qcom_iommu->ctxs: > */ > if (WARN_ON(asid < 1) || > - WARN_ON(asid > qcom_iommu->num_ctxs)) > + WARN_ON(asid > qcom_iommu->num_ctxs) || > + WARN_ON(qcom_iommu->ctxs[asid - 1] == NULL)) > return -EINVAL; > > if (!fwspec->iommu_priv) { > @@ -693,7 +694,8 @@ static int qcom_iommu_sec_ptbl_init(struct device *dev) > > static int get_asid(const struct device_node *np) > { > - u32 reg; > + u32 reg, val; > + int asid; > > /* read the "reg" property directly to get the relative address > * of the context bank, and calculate the asid from that: > @@ -701,7 +703,16 @@ static int get_asid(const struct device_node *np) > if (of_property_read_u32_index(np, "reg", 0, ®)) > return -ENODEV; > > - return reg / 0x1000; /* context banks are 0x1000 apart */ > + /* Context banks are 0x1000 apart but, in some cases, the ASID > + * number doesn't match to this logic and needs to be passed > + * from the DT configuration explicitly. > + */ > + if (of_property_read_u32(np, "qcom,ctx-num", &val)) > + asid = reg / 0x1000; > + else > + asid = val; > + > + return asid; > } > > static int qcom_iommu_ctx_probe(struct platform_device *pdev) >