From patchwork Fri May 11 19:06:38 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jean-Philippe Brucker X-Patchwork-Id: 10395095 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 91BD560153 for ; Fri, 11 May 2018 19:11:18 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 84B1328F8B for ; Fri, 11 May 2018 19:11:18 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 77E6B28F8E; Fri, 11 May 2018 19:11:18 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DE4B028F98 for ; Fri, 11 May 2018 19:11:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752407AbeEKTLB (ORCPT ); Fri, 11 May 2018 15:11:01 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:47476 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752418AbeEKTK5 (ORCPT ); Fri, 11 May 2018 15:10:57 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0B41719BF; Fri, 11 May 2018 12:10:57 -0700 (PDT) Received: from ostrya.cambridge.arm.com (ostrya.cambridge.arm.com [10.1.210.33]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id C20C93F23C; Fri, 11 May 2018 12:10:51 -0700 (PDT) From: Jean-Philippe Brucker To: linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org, devicetree@vger.kernel.org, iommu@lists.linux-foundation.org, kvm@vger.kernel.org, linux-mm@kvack.org Cc: joro@8bytes.org, will.deacon@arm.com, robin.murphy@arm.com, alex.williamson@redhat.com, tn@semihalf.com, liubo95@huawei.com, thunder.leizhen@huawei.com, xieyisheng1@huawei.com, xuzaibo@huawei.com, ilias.apalodimas@linaro.org, jonathan.cameron@huawei.com, liudongdong3@huawei.com, shunyong.yang@hxt-semitech.com, nwatters@codeaurora.org, okaya@codeaurora.org, jcrouse@codeaurora.org, rfranz@cavium.com, dwmw2@infradead.org, jacob.jun.pan@linux.intel.com, yi.l.liu@intel.com, ashok.raj@intel.com, kevin.tian@intel.com, baolu.lu@linux.intel.com, robdclark@gmail.com, christian.koenig@amd.com, bharatku@xilinx.com, rgummal@xilinx.com Subject: [PATCH v2 37/40] iommu/arm-smmu-v3: Disable tagged pointers Date: Fri, 11 May 2018 20:06:38 +0100 Message-Id: <20180511190641.23008-38-jean-philippe.brucker@arm.com> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180511190641.23008-1-jean-philippe.brucker@arm.com> References: <20180511190641.23008-1-jean-philippe.brucker@arm.com> Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The ARM architecture has a "Top Byte Ignore" (TBI) option that makes the MMU mask out bits [63:56] of an address, allowing a userspace application to store data in its pointers. This option is incompatible with PCI ATS. If TBI is enabled in the SMMU and userspace triggers DMA transactions on tagged pointers, the endpoint might create ATC entries for addresses that include a tag. Software would then have to send ATC invalidation packets for each 255 possible alias of an address, or just wipe the whole address space. This is not a viable option, so disable TBI. The impact of this change is unclear, since there are very few users of tagged pointers, much less SVA. But the requirement introduced by this patch doesn't seem excessive: a userspace application using both tagged pointers and SVA should now sanitize addresses (clear the tag) before using them for device DMA. Signed-off-by: Jean-Philippe Brucker --- drivers/iommu/arm-smmu-v3-context.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/iommu/arm-smmu-v3-context.c b/drivers/iommu/arm-smmu-v3-context.c index bdc9bfd1f35d..22e7b80a7682 100644 --- a/drivers/iommu/arm-smmu-v3-context.c +++ b/drivers/iommu/arm-smmu-v3-context.c @@ -200,7 +200,6 @@ static u64 arm_smmu_cpu_tcr_to_cd(struct arm_smmu_context_cfg *cfg, u64 tcr) val |= ARM_SMMU_TCR2CD(tcr, EPD0); val |= ARM_SMMU_TCR2CD(tcr, EPD1); val |= ARM_SMMU_TCR2CD(tcr, IPS); - val |= ARM_SMMU_TCR2CD(tcr, TBI0); if (cfg->hw_access) val |= ARM_SMMU_TCR2CD(tcr, HA);