This adds an optional ops entry to query the default domain
types supported by the iommu driver for  a specific device.
This is necessary in cases where the iommu driver can only
support a specific type of default domain for a device. In
normal cases, this ops will return IOMMU_DOMAIN_ANY which
indicates that the iommu driver supports both IOMMU_DOMAIN_DMA
and IOMMU_DOMAIN_IDENTITY, hence the static default domain
type will be used.

Signed-off-by: Lu Baolu <[email protected]>
---
 drivers/iommu/iommu.c | 13 ++++++++++---
 include/linux/iommu.h | 11 +++++++++++
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index acd6830e6e9b..1ad9a1f2e078 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1097,15 +1097,22 @@ struct iommu_group *iommu_group_get_for_dev(struct 
device *dev)
         * IOMMU driver.
         */
        if (!group->default_domain) {
+               unsigned int domain_type = IOMMU_DOMAIN_ANY;
                struct iommu_domain *dom;
 
-               dom = __iommu_domain_alloc(dev->bus, iommu_def_domain_type);
-               if (!dom && iommu_def_domain_type != IOMMU_DOMAIN_DMA) {
+               if (ops->def_domain_type)
+                       domain_type = ops->def_domain_type(dev);
+
+               if (domain_type == IOMMU_DOMAIN_ANY)
+                       domain_type = iommu_def_domain_type;
+
+               dom = __iommu_domain_alloc(dev->bus, domain_type);
+               if (!dom && domain_type != IOMMU_DOMAIN_DMA) {
                        dom = __iommu_domain_alloc(dev->bus, IOMMU_DOMAIN_DMA);
                        if (dom) {
                                dev_warn(dev,
                                         "failed to allocate default IOMMU 
domain of type %u; falling back to IOMMU_DOMAIN_DMA",
-                                        iommu_def_domain_type);
+                                        domain_type);
                        }
                }
 
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 8239ece9fdfc..ba9a5b996a63 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -79,12 +79,16 @@ struct iommu_domain_geometry {
  *     IOMMU_DOMAIN_DMA        - Internally used for DMA-API implementations.
  *                               This flag allows IOMMU drivers to implement
  *                               certain optimizations for these domains
+ *     IOMMU_DOMAIN_ANY        - All domain types defined here
  */
 #define IOMMU_DOMAIN_BLOCKED   (0U)
 #define IOMMU_DOMAIN_IDENTITY  (__IOMMU_DOMAIN_PT)
 #define IOMMU_DOMAIN_UNMANAGED (__IOMMU_DOMAIN_PAGING)
 #define IOMMU_DOMAIN_DMA       (__IOMMU_DOMAIN_PAGING |        \
                                 __IOMMU_DOMAIN_DMA_API)
+#define IOMMU_DOMAIN_ANY       (IOMMU_DOMAIN_IDENTITY |        \
+                                IOMMU_DOMAIN_UNMANAGED |       \
+                                IOMMU_DOMAIN_DMA)
 
 struct iommu_domain {
        unsigned type;
@@ -196,6 +200,11 @@ enum iommu_dev_features {
  * @dev_feat_enabled: check enabled feature
  * @aux_attach/detach_dev: aux-domain specific attach/detach entries.
  * @aux_get_pasid: get the pasid given an aux-domain
+ * @def_domain_type: get per-device default domain type that the IOMMU
+ *             driver is able to support. Valid returns values:
+ *             - IOMMU_DOMAIN_DMA: only suports non-identity domain
+ *             - IOMMU_DOMAIN_IDENTITY: only supports identity domain
+ *             - IOMMU_DOMAIN_ANY: supports all
  * @pgsize_bitmap: bitmap of all possible supported page sizes
  */
 struct iommu_ops {
@@ -251,6 +260,8 @@ struct iommu_ops {
        void (*aux_detach_dev)(struct iommu_domain *domain, struct device *dev);
        int (*aux_get_pasid)(struct iommu_domain *domain, struct device *dev);
 
+       int (*def_domain_type)(struct device *dev);
+
        unsigned long pgsize_bitmap;
 };
 
-- 
2.17.1

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