Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752869AbbKVWLR (ORCPT ); Sun, 22 Nov 2015 17:11:17 -0500 Received: from mx1.redhat.com ([209.132.183.28]:33876 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752239AbbKVWLP (ORCPT ); Sun, 22 Nov 2015 17:11:15 -0500 Date: Mon, 23 Nov 2015 00:11:09 +0200 From: "Michael S. Tsirkin" To: David Woodhouse Cc: marcel@redhat.com, Joerg Roedel , linux-s390 , KVM , Benjamin Herrenschmidt , Sebastian Ott , "linux-kernel@vger.kernel.org" , Andy Lutomirski , Christian Borntraeger , Andy Lutomirski , Paolo Bonzini , Linux Virtualization , Christoph Hellwig , Martin Schwidefsky Subject: Re: [PATCH v3 0/3] virtio DMA API core stuff Message-ID: <20151123000329-mutt-send-email-mst@redhat.com> References: <20151028161424-mutt-send-email-mst@redhat.com> <1446042754.3405.237.camel@infradead.org> <20151028175136-mutt-send-email-mst@redhat.com> <20151029104301-mutt-send-email-mst@redhat.com> <1446135536.3405.279.camel@infradead.org> <20151108120627-mutt-send-email-mst@redhat.com> <20151108114946.GG2255@suse.de> <5651BDC0.2040206@gmail.com> <1448207661.89124.50.camel@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1448207661.89124.50.camel@infradead.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1359 Lines: 39 On Sun, Nov 22, 2015 at 03:54:21PM +0000, David Woodhouse wrote: > On Sun, 2015-11-22 at 15:06 +0200, Marcel Apfelbaum wrote: > > > > > > I tried to generate a DMAR table that excludes some devices from > > IOMMU translation, however it does not help. > > > > The reason is, as far as I understand, that Linux kernel does > > not allow any device being outside an IOMMU scope if the > > iommu kernel option is activated. > > > > Does anybody know if it is "by design" or is simply an uncommon > > configuration? > > (some devices in an IOMMU scope, while others outside *any* IOMMU > > scope) > > That's a kernel bug in the way it handles per-device DMA operations. Or > more to the point, in the way it doesn't — the non-translated devices > end up being pointed to the intel_dma_ops despite the fact they > shouldn't be. I'm working on that... > > -- > dwmw2 > Interesting. This seems to imply such configurations aren't common, so I wonder whether other guest OS-es treat them correctly. If many of them are, we probably shouldn't use this in QEMU: we care about guests actually working :) -- MST -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/