[PATCH v4 01/14] iommufd/viommu: Introduce IOMMUFD_OBJ_VDEVICE and its related struct

[Nicolin Chen]

Introduce a new IOMMUFD_OBJ_VDEVICE to represent a physical device, i.e.
iommufd_device (idev) object, against an iommufd_viommu (vIOMMU) object in
the VM. This vDEVICE object (and its structure) holds all the information
and attributes in a VM, regarding the device related to the vIOMMU.

As an initial patch, add a per-vIOMMU virtual ID. This can be:
 - Virtual StreamID on a nested ARM SMMUv3, an index to a Stream Table
 - Virtual DeviceID on a nested AMD IOMMU, an index to a Device Table
 - Virtual ID on a nested Intel VT-D IOMMU, an index to a Context Table
Potentially, this vDEVICE structure can hold some vData for Confidential
Compute Architecture (CCA).

Add a pair of vdevice_alloc and vdevice_free in struct iommufd_viommu_ops
to allow driver-level vDEVICE structure allocations.

Similar to iommufd_viommu_alloc, add an iommufd_vdevice_alloc helper, so
IOMMU drivers can allocate core-embedded style structures.

Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
---
 include/linux/iommufd.h | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index 5c13c35952d8..5d61a1d2947a 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -31,6 +31,7 @@ enum iommufd_object_type {
 	IOMMUFD_OBJ_ACCESS,
 	IOMMUFD_OBJ_FAULT,
 	IOMMUFD_OBJ_VIOMMU,
+	IOMMUFD_OBJ_VDEVICE,
 #ifdef CONFIG_IOMMUFD_TEST
 	IOMMUFD_OBJ_SELFTEST,
 #endif
@@ -92,6 +93,14 @@ struct iommufd_viommu {
 	unsigned int type;
 };
 
+struct iommufd_vdevice {
+	struct iommufd_object obj;
+	struct iommufd_ctx *ictx;
+	struct iommufd_device *idev;
+	struct iommufd_viommu *viommu;
+	u64 id; /* per-vIOMMU virtual ID */
+};
+
 /**
  * struct iommufd_viommu_ops - vIOMMU specific operations
  * @free: Free all driver-specific parts of an iommufd_viommu. The memory of the
@@ -101,12 +110,24 @@ struct iommufd_viommu {
  *                       must be defined in include/uapi/linux/iommufd.h.
  *                       It must fully initialize the new iommu_domain before
  *                       returning. Upon failure, ERR_PTR must be returned.
+ * @vdevice_alloc: Allocate a driver-managed iommufd_vdevice to init some driver
+ *                 specific structure or HW procedure. Note that the core-level
+ *                 structure is filled by the iommufd core after calling this op.
+ *                 It is suggested to call iommufd_vdevice_alloc() helper for
+ *                 a bundled allocation of the core and the driver structures,
+ *                 using the ictx pointer in the given @viommu.
+ * @vdevice_free: Free a driver-managed iommufd_vdevice to de-init its structure
+ *                or HW procedure. The memory of the vdevice will be free-ed by
+ *                iommufd core.
  */
 struct iommufd_viommu_ops {
 	void (*free)(struct iommufd_viommu *viommu);
 	struct iommu_domain *(*domain_alloc_nested)(
 		struct iommufd_viommu *viommu,
 		const struct iommu_user_data *user_data);
+	struct iommufd_vdevice *(*vdevice_alloc)(struct iommufd_viommu *viommu,
+						 struct device *dev, u64 id);
+	void (*vdevice_free)(struct iommufd_vdevice *vdev);
 };
 
 #if IS_ENABLED(CONFIG_IOMMUFD)
@@ -200,4 +221,15 @@ _iommufd_object_alloc(struct iommufd_ctx *ictx, size_t size,
 			ret->member.ops = viommu_ops;                          \
 		ret;                                                           \
 	})
+#define iommufd_vdevice_alloc(ictx, drv_struct, member)                        \
+	({                                                                     \
+		static_assert(                                                 \
+			__same_type(struct iommufd_vdevice,                    \
+				    ((struct drv_struct *)NULL)->member));     \
+		static_assert(offsetof(struct drv_struct, member.obj) == 0);   \
+		container_of(_iommufd_object_alloc(ictx,                       \
+						   sizeof(struct drv_struct),  \
+						   IOMMUFD_OBJ_VDEVICE),       \
+			     struct drv_struct, member.obj);                   \
+	})
 #endif
-- 
2.43.0