From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH v2 1/2] iommu/tegra: gart: Optionally check for overwriting of page mappings Date: Tue, 10 Oct 2017 11:53:42 +0200 Message-ID: <20171010095342.jyvzl2zex2pynqvv@8bytes.org> References: <7eea4a30b0f4fdbe14351cf2c6cf537365080d2d.1507078770.git.digetx@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <7eea4a30b0f4fdbe14351cf2c6cf537365080d2d.1507078770.git.digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Dmitry Osipenko Cc: linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Thierry Reding , Jonathan Hunter List-Id: iommu@lists.linux-foundation.org On Wed, Oct 04, 2017 at 04:02:31AM +0300, Dmitry Osipenko wrote: > Due to a bug in IOVA allocator, page mapping could accidentally overwritten. > We can catch this case by checking 'VALID' bit of GART's page entry prior to > mapping of a page. Since that check introduces a noticeable performance > impact, it should be enabled explicitly by a new CONFIG_TEGRA_IOMMU_GART_DEBUG > option. Which bug in the IOVA allocator are you talking about? Joerg