From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:45096) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SSzlR-00064j-79 for qemu-devel@nongnu.org; Fri, 11 May 2012 20:00:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SSzlP-00042X-4S for qemu-devel@nongnu.org; Fri, 11 May 2012 20:00:48 -0400 Received: from mail-pz0-f45.google.com ([209.85.210.45]:56180) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SSzlO-00042F-Qs for qemu-devel@nongnu.org; Fri, 11 May 2012 20:00:47 -0400 Received: by dadv2 with SMTP id v2so5062664dad.4 for ; Fri, 11 May 2012 17:00:44 -0700 (PDT) Date: Fri, 11 May 2012 17:00:40 -0700 From: Greg KH Message-ID: <20120512000040.GA17559@kroah.com> References: <20120511222148.30496.68571.stgit@bling.home> <20120511225534.30496.54563.stgit@bling.home> <20120511233821.GA9335@kroah.com> <1336780681.12477.198.camel@bling.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1336780681.12477.198.camel@bling.home> Subject: Re: [Qemu-devel] [PATCH 01/13] driver core: Add iommu_group tracking to struct device List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alex Williamson Cc: aafabbri@cisco.com, kvm@vger.kernel.org, B07421@freescale.com, aik@ozlabs.ru, konrad.wilk@oracle.com, linux-pci@vger.kernel.org, agraf@suse.de, qemu-devel@nongnu.org, chrisw@sous-sol.org, B08248@freescale.com, iommu@lists.linux-foundation.org, avi@redhat.com, joerg.roedel@amd.com, bhelgaas@google.com, benve@cisco.com, dwmw2@infradead.org, linux-kernel@vger.kernel.org, david@gibson.dropbear.id.au On Fri, May 11, 2012 at 05:58:01PM -0600, Alex Williamson wrote: > On Fri, 2012-05-11 at 16:38 -0700, Greg KH wrote: > > On Fri, May 11, 2012 at 04:55:35PM -0600, Alex Williamson wrote: > > > IOMMU groups allow IOMMU drivers to represent DMA visibility > > > and isolation of devices. Multiple devices may be grouped > > > together for the purposes of DMA. Placing a pointer on > > > struct device enable easy access for things like streaming > > > DMA programming and drivers like VFIO. > > > > > > Signed-off-by: Alex Williamson > > > > Can't you get this today from the iommu_ops pointer that is on the bus > > that the device is associated with? Or can devices on a bus have > > different iommu_group pointers? > > The latter, each device on a bus might be it's own group. This is often > the case on x86 unless PCIe-to-PCI bridges obscure the device > visibility. Thanks, Ah, ok, then I have no objection to add this to struct device: Acked-by: Greg Kroah-Hartman