From: "Tian, Kevin" Subject: RE: [RFC PATCH 2/7] iommu: Add share domain interface in iommu for spimdev Date: Thu, 2 Aug 2018 03:17:03 +0000 Message-ID: References: <20180801102221.5308-1-nek.in.cn@gmail.com> <20180801102221.5308-3-nek.in.cn@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: "linuxarm-hv44wF8Li93QT0dZR+AlfA@public.gmane.org" To: Kenneth Lee , Jonathan Corbet , Herbert Xu , "David S . Miller" , Joerg Roedel , Alex Williamson , Kenneth Lee , Hao Fang , Zhou Wang , Zaibo Xu , Philippe Ombredanne , "Greg Kroah-Hartman" , Thomas Gleixner , "linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-crypto-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" , "kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-accelerators-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org" , Lu Return-path: In-Reply-To: <20180801102221.5308-3-nek.in.cn-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org List-Id: linux-crypto.vger.kernel.org > From: Kenneth Lee > Sent: Wednesday, August 1, 2018 6:22 PM > > From: Kenneth Lee > > This patch add sharing interface for a iommu_group. The new interface: > > iommu_group_share_domain() > iommu_group_unshare_domain() > > can be used by some virtual iommu_group (such as iommu_group for > spimdev) > to share their parent's iommu_group. > > When the domain of the group is shared, it cannot be changed before > unshared. In the future, notification can be added if update is required. Is it necessary or just asking VFIO to use parent domain directly? > > Signed-off-by: Kenneth Lee > --- > drivers/iommu/iommu.c | 28 +++++++++++++++++++++++++++- > include/linux/iommu.h | 2 ++ > 2 files changed, 29 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 63b37563db7e..a832aafe660d 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -54,6 +54,9 @@ struct iommu_group { > int id; > struct iommu_domain *default_domain; > struct iommu_domain *domain; > + atomic_t domain_shared_ref; /* Number of user of current domain. > + * The domain cannot be modified if ref > > 0 > + */ > }; > > struct group_device { > @@ -353,6 +356,7 @@ struct iommu_group *iommu_group_alloc(void) > return ERR_PTR(ret); > } > group->id = ret; > + atomic_set(&group->domain_shared_ref, 0); > > ret = kobject_init_and_add(&group->kobj, &iommu_group_ktype, > NULL, "%d", group->id); > @@ -482,6 +486,25 @@ int iommu_group_set_name(struct iommu_group > *group, const char *name) > } > EXPORT_SYMBOL_GPL(iommu_group_set_name); > > +struct iommu_domain *iommu_group_share_domain(struct > iommu_group *group) > +{ > + /* the domain can be shared only when the default domain is used > */ > + /* todo: more shareable check */ > + if (group->domain != group->default_domain) > + return ERR_PTR(-EINVAL); > + > + atomic_inc(&group->domain_shared_ref); > + return group->domain; > +} > +EXPORT_SYMBOL_GPL(iommu_group_share_domain); > + > +void iommu_group_unshare_domain(struct iommu_group *group) > +{ > + atomic_dec(&group->domain_shared_ref); > + WARN_ON(atomic_read(&group->domain_shared_ref) < 0); > +} > +EXPORT_SYMBOL_GPL(iommu_group_unshare_domain); > + > static int iommu_group_create_direct_mappings(struct iommu_group > *group, > struct device *dev) > { > @@ -1401,7 +1424,8 @@ static int __iommu_attach_group(struct > iommu_domain *domain, > { > int ret; > > - if (group->default_domain && group->domain != group- > >default_domain) > + if ((group->default_domain && group->domain != group- > >default_domain) || > + atomic_read(&group->domain_shared_ref) > 0) > return -EBUSY; > > ret = __iommu_group_for_each_dev(group, domain, > @@ -1438,6 +1462,8 @@ static void __iommu_detach_group(struct > iommu_domain *domain, > { > int ret; > > + WARN_ON(atomic_read(&group->domain_shared_ref) > 0); > + > if (!group->default_domain) { > __iommu_group_for_each_dev(group, domain, > iommu_group_do_detach_device); > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index 19938ee6eb31..278d60e3ec39 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -349,6 +349,8 @@ extern int iommu_domain_get_attr(struct > iommu_domain *domain, enum iommu_attr, > void *data); > extern int iommu_domain_set_attr(struct iommu_domain *domain, enum > iommu_attr, > void *data); > +extern struct iommu_domain *iommu_group_share_domain(struct > iommu_group *group); > +extern void iommu_group_unshare_domain(struct iommu_group *group); > > /* Window handling function prototypes */ > extern int iommu_domain_window_enable(struct iommu_domain > *domain, u32 wnd_nr, > -- > 2.17.1