From: Kenneth Lee Subject: [RFC PATCH 2/7] iommu: Add share domain interface in iommu for spimdev Date: Wed, 1 Aug 2018 18:22:16 +0800 Message-ID: <20180801102221.5308-3-nek.in.cn@gmail.com> References: <20180801102221.5308-1-nek.in.cn@gmail.com> Cc: linuxarm@huawei.com To: 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@vger.kernel.org, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, iommu@lists.linux-foundation.org, kvm@vger.kernel.org, linux-accelerators@lists.ozlabs.org, Lu Baolu , Sanjay Kumar Return-path: In-Reply-To: <20180801102221.5308-1-nek.in.cn@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org 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. 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