[PATCH RFCv1 11/14] iommufd: Add struct iommufd_vqueue and its related viommu ops

[Nicolin Chen <nicolinc@xxxxxxxxxx>]

Inroduce a new core structure and its allocator iommufd_vqueue_alloc().

This can be used for a viommu to allocate a HW-accelerated queue, e.g.
NVIDIA's virtual command queue and AMD vIOMMU's command buffer.

Also add a pair of viommu ops for iommufd to forward user space ioctls
to IOMMU drivers.

Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
---
 drivers/iommu/iommufd/viommu.c |  1 +
 include/linux/iommu.h          |  1 +
 include/linux/iommufd.h        | 27 +++++++++++++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/drivers/iommu/iommufd/viommu.c b/drivers/iommu/iommufd/viommu.c
index 71baca0c75de..8894878c1e73 100644
--- a/drivers/iommu/iommufd/viommu.c
+++ b/drivers/iommu/iommufd/viommu.c
@@ -19,6 +19,7 @@
 	}
 
 viommu_struct_alloc(viommu);
+viommu_struct_alloc(vqueue);
 
 void iommufd_viommu_destroy(struct iommufd_object *obj)
 {
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 4d4461146288..475f41f2d41f 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -146,6 +146,7 @@ struct iopf_queue {
 };
 
 struct iommufd_viommu;
+struct iommufd_vqueue;
 
 /* iommu fault flags */
 #define IOMMU_FAULT_READ	0x0
diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index 2be302b82f47..5b97b04aa145 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -20,6 +20,7 @@ struct iommufd_access;
 struct iommufd_hwpt_paging;
 struct file;
 struct iommu_group;
+struct iommu_user_data;
 
 enum iommufd_object_type {
 	IOMMUFD_OBJ_NONE,
@@ -97,12 +98,27 @@ struct iommufd_viommu {
  * @free: Free all driver-specific parts of an iommufd_viommu. The memory
  *        of the entire viommu will be free-ed by iommufd core
  * @set/unset_dev_id: set/unset a user space virtual id for a device
+ * @vqueue_alloc: Allocate an iommufd_vqueue as a user space command queue for a
+ *                @viommu instance. Queue specific @user_data must be defined in
+ *                the include/uapi/linux/iommufd.h header.
+ * @vqueue_free: Free all driver-specific parts of an iommufd_vqueue. The memory
+ *               of the iommufd_vqueue will be free-ed by iommufd core
  */
 struct iommufd_viommu_ops {
 	void (*free)(struct iommufd_viommu *viommu);
 	int (*set_dev_id)(struct iommufd_viommu *viommu,
 			  struct device *dev, u64 dev_id);
 	void (*unset_dev_id)(struct iommufd_viommu *viommu, struct device *dev);
+	struct iommufd_vqueue *(*vqueue_alloc)(
+		struct iommufd_viommu *viommu,
+		const struct iommu_user_data *user_data);
+	void (*vqueue_free)(struct iommufd_vqueue *vqueue);
+};
+
+struct iommufd_vqueue {
+	struct iommufd_object obj;
+	struct iommufd_ctx *ictx;
+	struct iommufd_viommu *viommu;
 };
 
 #if IS_ENABLED(CONFIG_IOMMUFD)
@@ -123,6 +139,7 @@ int iommufd_vfio_compat_ioas_create(struct iommufd_ctx *ictx);
 int iommufd_vfio_compat_set_no_iommu(struct iommufd_ctx *ictx);
 
 struct iommufd_viommu *_iommufd_viommu_alloc(size_t size);
+struct iommufd_vqueue *_iommufd_vqueue_alloc(size_t size);
 #else /* !CONFIG_IOMMUFD */
 static inline struct iommufd_ctx *iommufd_ctx_from_file(struct file *file)
 {
@@ -168,6 +185,11 @@ static inline struct iommufd_viommu *_iommufd_viommu_alloc(size_t size)
 {
 	return NULL;
 }
+
+static inline struct iommufd_vqueue *_iommufd_vqueue_alloc(size_t size)
+{
+	return NULL;
+}
 #endif /* CONFIG_IOMMUFD */
 
 /*
@@ -179,4 +201,9 @@ static inline struct iommufd_viommu *_iommufd_viommu_alloc(size_t size)
 					   BUILD_BUG_ON_ZERO(offsetof(        \
 						struct drv_struct, member))), \
 		     struct drv_struct, member)
+#define iommufd_vqueue_alloc(drv_struct, member) \
+	container_of(_iommufd_vqueue_alloc(sizeof(struct drv_struct) +        \
+					   BUILD_BUG_ON_ZERO(offsetof(        \
+						struct drv_struct, member))), \
+		     struct drv_struct, member)
 #endif
-- 
2.43.0