From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:59808) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QoR5H-0008OU-Av for qemu-devel@nongnu.org; Tue, 02 Aug 2011 22:21:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QoR5E-0007TQ-S9 for qemu-devel@nongnu.org; Tue, 02 Aug 2011 22:21:23 -0400 Received: from e23smtp03.au.ibm.com ([202.81.31.145]:38353) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QoR5E-0007Sc-5R for qemu-devel@nongnu.org; Tue, 02 Aug 2011 22:21:20 -0400 Received: from d23relay03.au.ibm.com (d23relay03.au.ibm.com [202.81.31.245]) by e23smtp03.au.ibm.com (8.14.4/8.13.1) with ESMTP id p732FlNS007173 for ; Wed, 3 Aug 2011 12:15:47 +1000 Received: from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.235.139]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p732L2NO864486 for ; Wed, 3 Aug 2011 12:21:02 +1000 Received: from d23av04.au.ibm.com (loopback [127.0.0.1]) by d23av04.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p732L0Nw009393 for ; Wed, 3 Aug 2011 12:21:02 +1000 Date: Wed, 3 Aug 2011 12:04:22 +1000 From: David Gibson Message-ID: <20110803020422.GF29719@yookeroo.fritz.box> References: <1311983933.8793.42.camel@pasglop> <1312050011.2265.185.camel@x201.home> <20110802082848.GD29719@yookeroo.fritz.box> <1312308847.2653.467.camel@bling.home> <1312310121.2653.470.camel@bling.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1312310121.2653.470.camel@bling.home> Subject: Re: [Qemu-devel] kvm PCI assignment & VFIO ramblings List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alex Williamson Cc: chrisw , Alexey Kardashevskiy , kvm@vger.kernel.org, Paul Mackerras , "linux-pci@vger.kernel.org" , qemu-devel , aafabbri , iommu , linuxppc-dev , benve@cisco.com On Tue, Aug 02, 2011 at 12:35:19PM -0600, Alex Williamson wrote: > On Tue, 2011-08-02 at 12:14 -0600, Alex Williamson wrote: > > On Tue, 2011-08-02 at 18:28 +1000, David Gibson wrote: > > > On Sat, Jul 30, 2011 at 12:20:08PM -0600, Alex Williamson wrote: > > > > On Sat, 2011-07-30 at 09:58 +1000, Benjamin Herrenschmidt wrote: > > > [snip] > > > > On x86, the USB controllers don't typically live behind a PCIe-to-PCI > > > > bridge, so don't suffer the source identifier problem, but they do often > > > > share an interrupt. But even then, we can count on most modern devices > > > > supporting PCI2.3, and thus the DisINTx feature, which allows us to > > > > share interrupts. In any case, yes, it's more rare but we need to know > > > > how to handle devices behind PCI bridges. However I disagree that we > > > > need to assign all the devices behind such a bridge to the guest. > > > > There's a difference between removing the device from the host and > > > > exposing the device to the guest. > > > > > > I think you're arguing only over details of what words to use for > > > what, rather than anything of substance here. The point is that an > > > entire partitionable group must be assigned to "host" (in which case > > > kernel drivers may bind to it) or to a particular guest partition (or > > > at least to a single UID on the host). Which of the assigned devices > > > the partition actually uses is another matter of course, as is at > > > exactly which level they become "de-exposed" if you don't want to use > > > all of then. > > > > Well first we need to define what a partitionable group is, whether it's > > based on hardware requirements or user policy. And while I agree that > > we need unique ownership of a partition, I disagree that qemu is > > necessarily the owner of the entire partition vs individual devices. > > Sorry, I didn't intend to have such circular logic. "... I disagree > that qemu is necessarily the owner of the entire partition vs granted > access to devices within the partition". Thanks, I still don't understand the distinction you're making. We're saying the group is "owned" by a given user or guest in the sense that no-one else may use anything in the group (including host drivers). At that point none, some or all of the devices in the group may actually be used by the guest. You seem to be making a distinction between "owned by" and "assigned to" and "used by" and I really don't see what it is. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson