iommufd: Add kAPI toward external drivers for physical devices

Add the four functions external drivers need to connect physical DMA to
the IOMMUFD:

iommufd_device_bind() / iommufd_device_unbind()
  Register the device with iommufd and establish security isolation.

iommufd_device_attach() / iommufd_device_detach()
  Connect a bound device to a page table

Binding a device creates a device object ID in the uAPI, however the
generic API does not yet provide any IOCTLs to manipulate them.

Link: https://lore.kernel.org/r/13-v6-a196d26f289e+11787-iommufd_jgg@nvidia.comReviewed-by: Kevin Tian <kevin.tian@intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Yi Liu <yi.l.liu@intel.com>
Tested-by: Lixiao Yang <lixiao.yang@intel.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/iommu/iommufd/Makefile

 # SPDX-License-Identifier: GPL-2.0-only
 iommufd-y := \
+	device.o \
 	hw_pagetable.o \
 	io_pagetable.o \
 	ioas.o \

drivers/iommu/iommufd/iommufd_private.h

@@ -103,6 +103,7 @@ static inline int iommufd_ucmd_respond(struct iommufd_ucmd *ucmd,
 enum iommufd_object_type {
 	IOMMUFD_OBJ_NONE,
 	IOMMUFD_OBJ_ANY = IOMMUFD_OBJ_NONE,
+	IOMMUFD_OBJ_DEVICE,
 	IOMMUFD_OBJ_HW_PAGETABLE,
 	IOMMUFD_OBJ_IOAS,
 };
@@ -229,6 +230,8 @@ struct iommufd_hw_pagetable {
 	struct iommufd_ioas *ioas;
 	struct iommu_domain *domain;
 	bool auto_domain : 1;
+	bool enforce_cache_coherency : 1;
+	bool msi_cookie : 1;
 	/* Head at iommufd_ioas::hwpt_list */
 	struct list_head hwpt_item;
 	struct mutex devices_lock;
@@ -240,6 +243,8 @@ iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
 			   struct device *dev);
 void iommufd_hw_pagetable_destroy(struct iommufd_object *obj);
 
+void iommufd_device_destroy(struct iommufd_object *obj);
+
 struct iommufd_access {
 	unsigned long iova_alignment;
 	u32 iopt_access_list_id;

drivers/iommu/iommufd/main.c

@@ -357,6 +357,9 @@ void iommufd_ctx_put(struct iommufd_ctx *ictx)
 EXPORT_SYMBOL_NS_GPL(iommufd_ctx_put, IOMMUFD);
 
 static const struct iommufd_object_ops iommufd_object_ops[] = {
+	[IOMMUFD_OBJ_DEVICE] = {
+		.destroy = iommufd_device_destroy,
+	},
 	[IOMMUFD_OBJ_IOAS] = {
 		.destroy = iommufd_ioas_destroy,
 	},

include/linux/iommufd.h

@@ -9,10 +9,19 @@
 #include <linux/types.h>
 #include <linux/errno.h>
 #include <linux/err.h>
+#include <linux/device.h>
 
+struct iommufd_device;
 struct iommufd_ctx;
 struct file;
 
+struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx,
+					   struct device *dev, u32 *id);
+void iommufd_device_unbind(struct iommufd_device *idev);
+
+int iommufd_device_attach(struct iommufd_device *idev, u32 *pt_id);
+void iommufd_device_detach(struct iommufd_device *idev);
+
 enum {
 	IOMMUFD_ACCESS_RW_READ = 0,
 	IOMMUFD_ACCESS_RW_WRITE = 1 << 0,