From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ch1outboundpool.messaging.microsoft.com (ch1ehsobe001.messaging.microsoft.com [216.32.181.181]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "Microsoft Secure Server Authority" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id 1E688B6FAF for ; Tue, 23 Aug 2011 21:09:57 +1000 (EST) Date: Tue, 23 Aug 2011 13:09:42 +0200 From: Joerg Roedel To: Benjamin Herrenschmidt Subject: Re: kvm PCI assignment & VFIO ramblings Message-ID: <20110823110942.GL2079@amd.com> References: <1314082483.30478.43.camel@pasglop> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" In-Reply-To: <1314082483.30478.43.camel@pasglop> Cc: chrisw , Alexey Kardashevskiy , "kvm@vger.kernel.org" , Paul Mackerras , "linux-pci@vger.kernel.org" , qemu-devel , aafabbri , iommu , Avi Kivity , Anthony Liguori , linuxppc-dev , "benve@cisco.com" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, Aug 23, 2011 at 02:54:43AM -0400, Benjamin Herrenschmidt wrote: > Possibly, the question that interest me the most is what interface will > KVM end up using. I'm also not terribly fan with the (perceived) > discrepancy between using uiommu to create groups but using the group fd > to actually do the mappings, at least if that is still the plan. > > If the separate uiommu interface is kept, then anything that wants to be > able to benefit from the ability to put multiple devices (or existing > groups) into such a "meta group" would need to be explicitly modified to > deal with the uiommu APIs. > > I tend to prefer such "meta groups" as being something you create > statically using a configuration interface, either via sysfs, netlink or > ioctl's to a "control" vfio device driven by a simple command line tool > (which can have the configuration stored in /etc and re-apply it at > boot). Hmm, I don't think that these groups are static for the systems run-time. They only exist for the lifetime of a guest per default, at least on x86. Thats why I prefer to do this grouping using VFIO and not some sysfs interface (which would be the third interface beside the ioctls and netlink a VFIO user needs to be aware of). Doing this in the ioctl interface just makes things easier. Joerg -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632