From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752776AbcG2KGx (ORCPT ); Fri, 29 Jul 2016 06:06:53 -0400 Received: from foss.arm.com ([217.140.101.70]:52968 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752682AbcG2KGv (ORCPT ); Fri, 29 Jul 2016 06:06:51 -0400 Date: Fri, 29 Jul 2016 11:06:53 +0100 From: Will Deacon To: Mitchel Humpherys Cc: Joerg Roedel , iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Robin Murphy , Marek Szyprowski , Jordan Crouse , Jeremy Gebben , Patrick Daly , Pratik Patel , Thomas Zeng Subject: Re: [PATCH v5 0/6] Add support for privileged mappings Message-ID: <20160729100653.GC16593@arm.com> References: <20160727234208.2101-1-mitchelh@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160727234208.2101-1-mitchelh@codeaurora.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 27, 2016 at 04:42:02PM -0700, Mitchel Humpherys wrote: > The following patch to the ARM SMMU driver: > > commit d346180e70b91b3d5a1ae7e5603e65593d4622bc > Author: Robin Murphy > Date: Tue Jan 26 18:06:34 2016 +0000 > > iommu/arm-smmu: Treat all device transactions as unprivileged > > started forcing all SMMU transactions to come through as "unprivileged". > The rationale given was that: > > (1) There is no way in the IOMMU API to even request privileged mappings. > > (2) It's difficult to implement a DMA mapper that correctly models the > ARM VMSAv8 behavior of unprivileged-writeable => > privileged-execute-never. > > This series rectifies (1) by introducing an IOMMU API for privileged > mappings and implements it in io-pgtable-arm. > > This series rectifies (2) by introducing a new dma attribute > (DMA_ATTR_PRIVILEGED) for users of the DMA API that need privileged > mappings which are inaccessible to lesser-privileged execution levels, and > implements it in the arm64 IOMMU DMA mapper. The one known user (pl330.c) > is converted over to the new attribute. > > Jordan and Jeremy can provide more info on the use case if needed, but the > high level is that it's a security feature to prevent attacks such as [1]. > > Joerg, the v3 series was previously acked by Will [2]. He also recommended > that we take all of this through your tree since it's touching multiple > subsystems [3]. Can you please take a look? Thanks! You forgot to add my ack to the patches, so if you need it again: Acked-by: Will Deacon Will