From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757969AbZBKTDu (ORCPT ); Wed, 11 Feb 2009 14:03:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755778AbZBKTDk (ORCPT ); Wed, 11 Feb 2009 14:03:40 -0500 Received: from sous-sol.org ([216.99.217.87]:56052 "EHLO sequoia.sous-sol.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752567AbZBKTDj (ORCPT ); Wed, 11 Feb 2009 14:03:39 -0500 Date: Wed, 11 Feb 2009 10:59:45 -0800 From: Chris Wright To: Fenghua Yu Cc: David Woodhouse , Ingo Molnar , Stephen Rothwell , Andrew Morton , Johannes Berg , Emmanuel Grumbach , Tomas Winkler , Zhu Yi , Chris Wright , LKML , iommu@lists.linux-foundation.org Subject: Re: [PATCH]iwlan dma mapping read and write changes Message-ID: <20090211185945.GQ27684@sequoia.sous-sol.org> References: <20081001165606.GA21279@linux-os.sc.intel.com> <20090211182648.GA1661@linux-os.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090211182648.GA1661@linux-os.sc.intel.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Fenghua Yu (fenghua.yu@intel.com) wrote: > When iwlan runs on IOMMU, IOMMU generates a lot of PTE write faults because PTE > write bit is not set on some of PTE's. This is because iwlan driver calls DMA > mapping with PCI_DMA_TODEVICE which is read only in mapping PTE. But iwlan device > actually writes to the mapped page to update its contents. This issue is not > exposed in swiotlb. But VT-d hardware can capture this fault and stop the fault > transaction. > > The following patch fixes the issue. Yes, plain old driver bug! This fixes the iwlagn vt-d issue. > Signed-off-by: Fenghua Yu Tested-by: Chris Wright thanks, chris