From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [PATCH qemu-kvm] device assignment: default requires IOMMU Date: Thu, 24 Dec 2009 09:35:45 -0200 Message-ID: <20091224113545.GB4781@amt.cnet> References: <20091223224020.GB3305@sequoia.sous-sol.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , kvm@vger.kernel.org, Alexander Graf , Dmitri Seletski , Sheng Yang To: Chris Wright Return-path: Received: from mx1.redhat.com ([209.132.183.28]:17225 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753442AbZLXLg7 (ORCPT ); Thu, 24 Dec 2009 06:36:59 -0500 Content-Disposition: inline In-Reply-To: <20091223224020.GB3305@sequoia.sous-sol.org> Sender: kvm-owner@vger.kernel.org List-ID: On Wed, Dec 23, 2009 at 02:40:20PM -0800, Chris Wright wrote: > [ resend, fixing email header, sorry for duplicate ] > > The default mode for device assignment is to rely on an IOMMU for > proper translations and a functioning device in the guest. The current > logic makes this requirement advisory, and simply disables the request > for IOMMU if one is not found on the host. This makes for a confused > user when the device assignment appears to work, but the device in the > guest is not functioning (I've seen about a half-dozen reports with > this failure mode). > > Change the logic such that the default requires the IOMMU. Period. > If the host does not have an IOMMU, device assignment will fail. > > This is a user visible change, however I think the current situation is > simply broken. > > And, of course, disabling the IOMMU requirement using the old: > > -pcidevice host=[addr],dma=none > > or the newer: > > -device pci-assign,host=[addr],iommu=0 > > will do what it always did (not require an IOMMU, and fail to work > properly). Applied, thanks.