From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755894Ab1KPK2u (ORCPT ); Wed, 16 Nov 2011 05:28:50 -0500 Received: from sous-sol.org ([216.99.217.87]:41073 "EHLO sequoia.sous-sol.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755854Ab1KPK2r (ORCPT ); Wed, 16 Nov 2011 05:28:47 -0500 Date: Wed, 16 Nov 2011 02:28:29 -0800 From: Chris Wright To: Alex Williamson Cc: dwmw2@infradead.org, iommu@lists.linux-foundation.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, chrisw@sous-sol.org, ddutile@redhat.com Subject: Re: [PATCH] intel-iommu: Manage iommu_coherency globally Message-ID: <20111116102829.GA3477@sequoia.sous-sol.org> References: <20111116040752.11878.18642.stgit@bling.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20111116040752.11878.18642.stgit@bling.home> User-Agent: Mutt/1.5.20 (2009-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Alex Williamson (alex.williamson@redhat.com) wrote: > We currently manage iommu_coherency on a per domain basis, > choosing the safest setting across the iommus attached to a > particular domain. This unfortunately has a bug that when > no iommus are attached, the domain defaults to coherent. > If we fall into this mode, then later add a device behind a > non-coherent iommu to that domain, the context entry is > updated using the wrong coherency setting, and we get dmar > faults. > > Since we expect chipsets to be consistent in their coherency > setting, we can instead determine the coherency once and use > it globally. > > Signed-off-by: Alex Williamson Looks good to me. Acked-by: Chris Wright