From: Joerg Roedel <jroe...@suse.de>

This patch changes the behavior of the iommu_attach_device
and iommu_detach_device functions. With this change these
functions only work on devices that have their own group.
For all other devices the iommu_group_attach/detach
functions must be used.

Signed-off-by: Joerg Roedel <jroe...@suse.de>
---
 drivers/iommu/iommu.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 59 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 8f33ddd3..b63a550 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -51,6 +51,7 @@ struct iommu_group {
        void (*iommu_data_release)(void *iommu_data);
        char *name;
        int id;
+       unsigned dev_cnt;
        struct iommu_domain *default_domain;
 };
 
@@ -380,6 +381,7 @@ rename:
 
        mutex_lock(&group->mutex);
        list_add_tail(&device->list, &group->devices);
+       group->dev_cnt += 1;
        mutex_unlock(&group->mutex);
 
        /* Notify any listeners about change to group. */
@@ -408,6 +410,7 @@ void iommu_group_remove_device(struct device *dev)
                                     IOMMU_GROUP_NOTIFY_DEL_DEVICE, dev);
 
        mutex_lock(&group->mutex);
+       group->dev_cnt -= 1;
        list_for_each_entry(tmp_device, &group->devices, list) {
                if (tmp_device->dev == dev) {
                        device = tmp_device;
@@ -943,7 +946,8 @@ void iommu_domain_free(struct iommu_domain *domain)
 }
 EXPORT_SYMBOL_GPL(iommu_domain_free);
 
-int iommu_attach_device(struct iommu_domain *domain, struct device *dev)
+static int __iommu_attach_device(struct iommu_domain *domain,
+                                struct device *dev)
 {
        int ret;
        if (unlikely(domain->ops->attach_dev == NULL))
@@ -954,9 +958,38 @@ int iommu_attach_device(struct iommu_domain *domain, 
struct device *dev)
                trace_attach_device_to_domain(dev);
        return ret;
 }
+
+int iommu_attach_device(struct iommu_domain *domain, struct device *dev)
+{
+       struct iommu_group *group;
+       int ret;
+
+       group = iommu_group_get(dev);
+       /* FIXME: Remove this when groups a mandatory for iommu drivers */
+       if (group == NULL)
+               return __iommu_attach_device(domain, dev);
+
+       /*
+        * We have a group - lock it to make sure the device-count doesn't
+        * change while we are attaching
+        */
+       mutex_lock(&group->mutex);
+       ret = -EINVAL;
+       if (group->dev_cnt != 1)
+               goto out_unlock;
+
+       ret = iommu_attach_group(domain, group);
+
+out_unlock:
+       mutex_unlock(&group->mutex);
+       iommu_group_put(group);
+
+       return ret;
+}
 EXPORT_SYMBOL_GPL(iommu_attach_device);
 
-void iommu_detach_device(struct iommu_domain *domain, struct device *dev)
+static void __iommu_detach_device(struct iommu_domain *domain,
+                                 struct device *dev)
 {
        if (unlikely(domain->ops->detach_dev == NULL))
                return;
@@ -964,6 +997,28 @@ void iommu_detach_device(struct iommu_domain *domain, 
struct device *dev)
        domain->ops->detach_dev(domain, dev);
        trace_detach_device_from_domain(dev);
 }
+
+void iommu_detach_device(struct iommu_domain *domain, struct device *dev)
+{
+       struct iommu_group *group;
+
+       group = iommu_group_get(dev);
+       /* FIXME: Remove this when groups a mandatory for iommu drivers */
+       if (group == NULL)
+               return __iommu_detach_device(domain, dev);
+
+       mutex_lock(&group->mutex);
+       if (group->dev_cnt != 1) {
+               WARN_ON(1);
+               goto out_unlock;
+       }
+
+       iommu_detach_group(domain, group);
+
+out_unlock:
+       mutex_unlock(&group->mutex);
+       iommu_group_put(group);
+}
 EXPORT_SYMBOL_GPL(iommu_detach_device);
 
 /*
@@ -980,7 +1035,7 @@ static int iommu_group_do_attach_device(struct device 
*dev, void *data)
 {
        struct iommu_domain *domain = data;
 
-       return iommu_attach_device(domain, dev);
+       return __iommu_attach_device(domain, dev);
 }
 
 int iommu_attach_group(struct iommu_domain *domain, struct iommu_group *group)
@@ -994,7 +1049,7 @@ static int iommu_group_do_detach_device(struct device 
*dev, void *data)
 {
        struct iommu_domain *domain = data;
 
-       iommu_detach_device(domain, dev);
+       __iommu_detach_device(domain, dev);
 
        return 0;
 }
-- 
1.9.1

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