From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755984AbYIPPwk (ORCPT ); Tue, 16 Sep 2008 11:52:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752784AbYIPPwc (ORCPT ); Tue, 16 Sep 2008 11:52:32 -0400 Received: from outbound-va3.frontbridge.com ([216.32.180.16]:20645 "EHLO VA3EHSOBE006.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751705AbYIPPwb (ORCPT ); Tue, 16 Sep 2008 11:52:31 -0400 X-BigFish: VPS-24(zz1432R98dR1805M936fQ873fnzz10d3izzz32i6bh43j61h) X-Spam-TCS-SCL: 0:0 X-FB-SS: 5, X-WSS-ID: 0K7APEW-03-SJ9-01 Date: Tue, 16 Sep 2008 17:52:11 +0200 From: Joerg Roedel To: FUJITA Tomonori CC: andi@firstfloor.org, mingo@elte.hu, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/3] fix GART to respect device's dma_mask about virtual mappings Message-ID: <20080916155211.GW24392@amd.com> References: <1221216155-17640-1-git-send-email-fujita.tomonori@lab.ntt.co.jp> <87hc8grjuf.fsf@basil.nowhere.org> <20080916222032O.fujita.tomonori@lab.ntt.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20080916222032O.fujita.tomonori@lab.ntt.co.jp> User-Agent: mutt-ng/devel-r804 (Linux) X-OriginalArrivalTime: 16 Sep 2008 15:52:11.0585 (UTC) FILETIME=[2E880B10:01C91814] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 16, 2008 at 10:20:40PM +0900, FUJITA Tomonori wrote: > On Tue, 16 Sep 2008 02:54:32 +0200 > Andi Kleen wrote: > > > FUJITA Tomonori writes: > > > > > Currently, gart IOMMU ignores device's dma_mask when it does virtual > > > mappings. So it could give a device a virtual address that the device > > > can't access to. > > > > Huh? That is what the need_iommu() logic in gart_map_sg() > > does. An I'm not aware of any bugs in this area. > > What the need_iommu() does is seeing if GART needs to do virtual > mappings or not. > > (After need_iommu() checking) What this patchset does is to guarantee > that GART provides a virtual address that a device can access to. > > > > Did you actually see that failure in practice? I don't see > > how it could happen. > > No, I did not. This patchset does the right thing theoretically, I > think, but if such problem never happens for GART, I'll drop the patch > for GART. Joerg? I am not aware of any failures which are fixed by these patches. But in theory there could be failures. Joerg -- | AMD Saxony Limited Liability Company & Co. KG Operating | Wilschdorfer Landstr. 101, 01109 Dresden, Germany System | Register Court Dresden: HRA 4896 Research | General Partner authorized to represent: Center | AMD Saxony LLC (Wilmington, Delaware, US) | General Manager of AMD Saxony LLC: Dr. Hans-R. Deppe, Thomas McCoy