[PATCH 1/2] iommu: Store either domain or handle in group->pasid_array

[Yi Liu <yi.l.liu@intel.com>]

iommu_attach_device_pasid() only stores handle to group->pasid_array
when there is a valid handle input. However, it makes the
iommu_attach_device_pasid() unable to detect if the pasid has been
attached or not. To be complete, let the iommu_attach_device_pasid()
store the domain to group->pasid_array if no valid handle.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
 drivers/iommu/iommu.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 28ffd836592b..278c4eb8f225 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -45,6 +45,8 @@ static unsigned int iommu_def_domain_type __read_mostly;
 static bool iommu_dma_strict __read_mostly = IS_ENABLED(CONFIG_IOMMU_DEFAULT_DMA_STRICT);
 static u32 iommu_cmd_line __read_mostly;
 
+enum { IOMMU_PASID_ARRAY_DOMAIN, IOMMU_PASID_ARRAY_HANDLE };
+
 struct iommu_group {
 	struct kobject kobj;
 	struct kobject *devices_kobj;
@@ -3374,6 +3376,7 @@ int iommu_attach_device_pasid(struct iommu_domain *domain,
 	struct iommu_group *group = dev->iommu_group;
 	struct group_device *device;
 	const struct iommu_ops *ops;
+	void *xa_entry;
 	int ret;
 
 	if (!group)
@@ -3397,10 +3400,14 @@ int iommu_attach_device_pasid(struct iommu_domain *domain,
 		}
 	}
 
-	if (handle)
+	if (handle) {
 		handle->domain = domain;
+		xa_entry = xa_tag_pointer(handle, IOMMU_PASID_ARRAY_HANDLE);
+	} else {
+		xa_entry = xa_tag_pointer(domain, IOMMU_PASID_ARRAY_DOMAIN);
+	}
 
-	ret = xa_insert(&group->pasid_array, pasid, handle, GFP_KERNEL);
+	ret = xa_insert(&group->pasid_array, pasid, xa_entry, GFP_KERNEL);
 	if (ret)
 		goto out_unlock;
 
@@ -3480,13 +3487,17 @@ struct iommu_attach_handle *
 iommu_attach_handle_get(struct iommu_group *group, ioasid_t pasid, unsigned int type)
 {
 	struct iommu_attach_handle *handle;
+	void *xa_entry;
 
 	xa_lock(&group->pasid_array);
-	handle = xa_load(&group->pasid_array, pasid);
-	if (!handle)
+	xa_entry = xa_load(&group->pasid_array, pasid);
+	if (xa_pointer_tag(xa_entry) == IOMMU_PASID_ARRAY_HANDLE) {
+		handle = xa_untag_pointer(xa_entry);
+		if (type && handle->domain->type != type)
+			handle = ERR_PTR(-EBUSY);
+	} else {
 		handle = ERR_PTR(-ENOENT);
-	else if (type && handle->domain->type != type)
-		handle = ERR_PTR(-EBUSY);
+	}
 	xa_unlock(&group->pasid_array);
 
 	return handle;
-- 
2.34.1