From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755036AbYLBT2Z (ORCPT ); Tue, 2 Dec 2008 14:28:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751459AbYLBT2Q (ORCPT ); Tue, 2 Dec 2008 14:28:16 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:44157 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751122AbYLBT2P (ORCPT ); Tue, 2 Dec 2008 14:28:15 -0500 Date: Tue, 2 Dec 2008 20:27:59 +0100 From: Ingo Molnar To: Joerg Roedel Cc: Ingo Molnar , Thomas Gleixner , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org Subject: Re: [PATCH] x86: fix broken flushing in GART nofullflush path Message-ID: <20081202192759.GD15342@elte.hu> References: <1228245363-14909-1-git-send-email-joerg.roedel@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1228245363-14909-1-git-send-email-joerg.roedel@amd.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Joerg Roedel wrote: > In the non-default nofullflush case the GART is only flushed when > next_bit wraps around. But it can happen that an unmap operation unmaps > memory which is behind the current next_bit location. If these addresses > are reused it may result in stale GART IO/TLB entries. Fix this by > setting the GART next_bit always behind an unmapped location. > > Signed-off-by: Joerg Roedel > --- > arch/x86/kernel/pci-gart_64.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) applied to tip/x86/iommu, thanks Joerg! a stale iotlb should not cause any problems in this particular GART case, right? It might be a security leak in a security-domain enforcing iotlb case, but the GART is a DMA bouncing helper in essence. Can you see any failure mode of this bug? Ingo