From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759202AbbA1U2K (ORCPT ); Wed, 28 Jan 2015 15:28:10 -0500 Received: from foss-mx-na.foss.arm.com ([217.140.108.86]:45504 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755769AbbA1U2H (ORCPT ); Wed, 28 Jan 2015 15:28:07 -0500 Date: Wed, 28 Jan 2015 14:30:06 +0000 From: Will Deacon To: Joerg Roedel Cc: "iommu@lists.linux-foundation.org" , Kukjin Kim , David Woodhouse , Heiko Stuebner , Hiroshi Doyu , Thierry Reding , Alex Williamson , Arnd Bergmann , "linux-kernel@vger.kernel.org" , Robin Murphy , Laurent Pinchart , "jroedel@suse.de" Subject: Re: [PATCH 2/5] iommu: Allocate a default domain for iommu groups Message-ID: <20150128143006.GQ1569@arm.com> References: <1422317339-22620-1-git-send-email-joro@8bytes.org> <1422317339-22620-3-git-send-email-joro@8bytes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1422317339-22620-3-git-send-email-joro@8bytes.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 27, 2015 at 12:08:56AM +0000, Joerg Roedel wrote: > From: Joerg Roedel > > The default domain will be used (if supported by the iommu > driver) when the devices in the iommu group are not attached > to any other domain. > > Signed-off-by: Joerg Roedel > --- > drivers/iommu/iommu.c | 26 +++++++++++++++++++++++--- > 1 file changed, 23 insertions(+), 3 deletions(-) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 34636eb..8f33ddd3 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -76,6 +76,9 @@ struct iommu_group_attribute iommu_group_attr_##_name = \ > #define to_iommu_group(_kobj) \ > container_of(_kobj, struct iommu_group, kobj) > > +static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus, > + enum iommu_domain_type type); > + > static ssize_t iommu_group_attr_show(struct kobject *kobj, > struct attribute *__attr, char *buf) > { > @@ -362,6 +365,17 @@ rename: > > kobject_get(group->devices_kobj); > > + /* > + * Try to allocate a default domain for the group, if this > + * hasn't happened yet. This is not the best place to do that, > + * it should happen in iommu_group_alloc(). But we have no > + * iommu_ops there yet, so the allocation has to happen here for > + * now. > + */ > + if (group->default_domain == NULL) > + group->default_domain = __iommu_domain_alloc(dev->bus, > + IOMMU_DOMAIN_DMA); Having a per-group domain is wasteful for IOMMUs that only support a modest number of concurrent domains, so in reality I think we need to have one domain per IOMMU instance. Is that possible? One problem with the current per-bus approach is that __iommu_domain_alloc can't figure out which IOMMU instance corresponds to the group. Will