From patchwork Wed Apr 17 18:24:48 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jean-Philippe Brucker X-Patchwork-Id: 10905811 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-2.web.codeaurora.org (Postfix) with ESMTP id 9B39217E6 for ; Wed, 17 Apr 2019 18:28:37 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8D26828B75 for ; Wed, 17 Apr 2019 18:28:37 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 80BB628B7E; Wed, 17 Apr 2019 18:28:37 +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 3750B28B75 for ; Wed, 17 Apr 2019 18:28:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731912AbfDQS2g (ORCPT ); Wed, 17 Apr 2019 14:28:36 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:49924 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728373AbfDQS2g (ORCPT ); Wed, 17 Apr 2019 14:28:36 -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 B93E21713; Wed, 17 Apr 2019 11:28:35 -0700 (PDT) Received: from ostrya.cambridge.arm.com (ostrya.cambridge.arm.com [10.1.196.129]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 168DC3F59C; Wed, 17 Apr 2019 11:28:32 -0700 (PDT) From: Jean-Philippe Brucker To: will.deacon@arm.com, lorenzo.pieralisi@arm.com, bhelgaas@google.com Cc: iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org, robin.murphy@arm.com, joro@8bytes.org, hanjun.guo@linaro.org, sudeep.holla@arm.com, rjw@rjwysocki.net, lenb@kernel.org, okaya@kernel.org, zhongmiao@hisilicon.com, eric.auger@redhat.com, linux-pci@vger.kernel.org Subject: [PATCH v3 9/9] iommu/arm-smmu-v3: Disable tagged pointers Date: Wed, 17 Apr 2019 19:24:48 +0100 Message-Id: <20190417182448.12382-10-jean-philippe.brucker@arm.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190417182448.12382-1-jean-philippe.brucker@arm.com> References: <20190417182448.12382-1-jean-philippe.brucker@arm.com> MIME-Version: 1.0 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.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c index 3bde137a3755..99b83fda11e4 100644 --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -1057,7 +1057,6 @@ static u64 arm_smmu_cpu_tcr_to_cd(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); return val; }