From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51672) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1afixw-0003iU-Cc for qemu-devel@nongnu.org; Tue, 15 Mar 2016 03:00:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1afixq-0004Qr-GJ for qemu-devel@nongnu.org; Tue, 15 Mar 2016 03:00:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33373) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1afixq-0004Qf-B6 for qemu-devel@nongnu.org; Tue, 15 Mar 2016 03:00:22 -0400 Date: Tue, 15 Mar 2016 09:00:17 +0200 From: "Michael S. Tsirkin" Message-ID: <20160315085849-mutt-send-email-mst@redhat.com> References: <56E70871.3050305@gmail.com> <56E709CF.1060109@siemens.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56E709CF.1060109@siemens.com> Subject: Re: [Qemu-devel] [PATCH][RFC] IOMMU: Add Support to VFIO devices with vIOMMU present List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: marcel@redhat.com, "Aviv B.D." , Alex Williamson , qemu-devel@nongnu.org, Peter Xu On Mon, Mar 14, 2016 at 07:58:23PM +0100, Jan Kiszka wrote: > On 2016-03-14 19:52, Marcel Apfelbaum wrote: > > On 03/12/2016 06:13 PM, Aviv B.D. wrote: > >> From: "Aviv B.D." > > >> > >> * Fix bug that prevent qemu from starting up when vIOMMU and VFIO > >> device are present. > >> * Advertise Cache Mode capability in iommu cap register. > > For the final version: Please keep that feature optional, for the sake > of emulation accuracy (no modern hw exposes it any more). Maybe turn it > one once a vfio device is in the scope of the IOMMU? That would be hard to implement: VFIO supports hotplug and there's no way to change this on the fly. I would say - make the feature an optional flag - deny adding a VFIO device if the flag is not set > >> * Register every VFIO device with IOMMU state. > >> * On page cache invalidation in vIOMMU, check if the domain belong to > >> VFIO device and mirror the guest requests to host. > >> > >> Not working (Yet!): > >> * Tested only with network interface card (ixgbevf) and > >> intel_iommu=strict in guest's kernel command line. > >> * Lock up under high load. > >> * Errors on guest poweroff. > >> * High relative latency compare to VFIO without IOMMU. > > > > Adding (possibly) interested developers to the thread. > > Thanks, > Jan > > -- > Siemens AG, Corporate Technology, CT RDA ITP SES-DE > Corporate Competence Center Embedded Linux