[PATCH 6/9] iommu: Fix iommu_probe_device() to attach the right domain

[Jason Gunthorpe <jgg@nvidia.com>]

The general invariant is that all devices in an iommu_group are attached
to group->domain. We missed some cases here where an owned group would not
get the device attached.

Rework this logic so it follows the default domain flow of the
bus_iommu_probe() - call iommu_alloc_default_domain(), then use
__iommu_group_set_domain_internal() to set up all the devices.

Finally always attach the device to the current domain if it is already
set.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 drivers/iommu/iommu.c | 45 ++++++++++++++++++++++++-------------------
 1 file changed, 25 insertions(+), 20 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index ea7700bbcf3399..d58570f361bb92 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -429,27 +429,32 @@ int iommu_probe_device(struct device *dev)
 		goto err_release;
 	}
 
-	/*
-	 * Try to allocate a default domain - needs support from the
-	 * IOMMU driver. There are still some drivers which don't
-	 * support default domains, so the return value is not yet
-	 * checked.
-	 */
 	mutex_lock(&group->mutex);
-	iommu_alloc_default_domain(group, dev);
 
-	/*
-	 * If device joined an existing group which has been claimed, don't
-	 * attach the default domain.
-	 */
-	if (group->default_domain && !group->owner) {
+	if (group->domain) {
 		ret = iommu_group_do_dma_first_attach(group, dev);
-		if (ret) {
-			mutex_unlock(&group->mutex);
-			iommu_group_put(group);
-			goto err_release;
-		}
+	} else if (!group->default_domain) {
+		/*
+		 * Try to allocate a default domain - needs support from the
+		 * IOMMU driver. There are still some drivers which don't
+		 * support default domains, so the return value is not yet
+		 * checked.
+		 */
+		iommu_alloc_default_domain(group, dev);
+		group->domain = NULL;
+		if (group->default_domain)
+			ret = __iommu_group_set_domain_internal(
+				group, group->default_domain,
+				IOMMU_SET_DOMAIN_WITH_DEFERRED);
+
+		/*
+		 * We assume that the iommu driver starts up the device in
+		 * 'set_platform_dma_ops' mode if it does not support default
+		 * domains.
+		 */
 	}
+	if (ret)
+		goto err_unlock;
 
 	iommu_create_device_direct_mappings(group, dev);
 
@@ -462,6 +467,9 @@ int iommu_probe_device(struct device *dev)
 
 	return 0;
 
+err_unlock:
+	mutex_unlock(&group->mutex);
+	iommu_group_put(group);
 err_release:
 	iommu_release_device(dev);
 
@@ -1676,9 +1684,6 @@ static int iommu_alloc_default_domain(struct iommu_group *group,
 {
 	unsigned int type;
 
-	if (group->default_domain)
-		return 0;
-
 	type = iommu_get_def_domain_type(dev) ? : iommu_def_domain_type;
 
 	return iommu_group_alloc_default_domain(dev->bus, group, type);
-- 
2.40.0