Revert "iommu: Fix false ownership failure on AMD systems with PASID activated"

This reverts commit 2380f1e.

Previous patch removed AMD iommu_v2 module. Hence its safe to revert this
workaround.

Suggested-by: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Link: https://lore.kernel.org/r/20231006095706.5694-6-vasant.hegde@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: hegdevasant

drivers/iommu/iommu.c

@@ -3113,24 +3113,6 @@ static ssize_t iommu_group_store_type(struct iommu_group *group,
 	return ret ?: count;
 }
 
-static bool iommu_is_default_domain(struct iommu_group *group)
-{
-	if (group->domain == group->default_domain)
-		return true;
-
-	/*
-	 * If the default domain was set to identity and it is still an identity
-	 * domain then we consider this a pass. This happens because of
-	 * amd_iommu_init_device() replacing the default idenytity domain with an
-	 * identity domain that has a different configuration for AMDGPU.
-	 */
-	if (group->default_domain &&
-	    group->default_domain->type == IOMMU_DOMAIN_IDENTITY &&
-	    group->domain && group->domain->type == IOMMU_DOMAIN_IDENTITY)
-		return true;
-	return false;
-}
-
 /**
  * iommu_device_use_default_domain() - Device driver wants to handle device
  *                                     DMA through the kernel DMA API.
@@ -3149,7 +3131,7 @@ int iommu_device_use_default_domain(struct device *dev)
 
 	mutex_lock(&group->mutex);
 	if (group->owner_cnt) {
-		if (group->owner || !iommu_is_default_domain(group) ||
+		if (group->domain != group->default_domain || group->owner ||
 		    !xa_empty(&group->pasid_array)) {
 			ret = -EBUSY;
 			goto unlock_out;