vfio: Make vfio_container optionally compiled

Add a kconfig CONFIG_VFIO_CONTAINER that control compiling the container
code. If 'n' then only iommufd will provide the container service.

This allows a compilation check that no inappropriate dependencies between
the device/group and container have been created.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/vfio/Kconfig

@@ -3,33 +3,34 @@ menuconfig VFIO
 	tristate "VFIO Non-Privileged userspace driver framework"
 	select IOMMU_API
 	depends on IOMMUFD || !IOMMUFD
-	select VFIO_IOMMU_TYPE1 if MMU && (X86 || S390 || ARM || ARM64)
+	select VFIO_CONTAINER if IOMMUFD=n
 	help
 	  VFIO provides a framework for secure userspace device drivers.
 	  See Documentation/driver-api/vfio.rst for more details.
 
 	  If you don't know what to do here, say N.
 
 if VFIO
+config VFIO_CONTAINER
+	bool "Support for the VFIO container /dev/vfio/vfio"
+	default y
+	help
+	  The VFIO container is the classic interface to VFIO.
+	  If N is selected here then IOMMUFD will provide the
+	  character device.
+
+	  Unless testing IOMMUFD say N here.
+
+if VFIO_CONTAINER
 config VFIO_IOMMU_TYPE1
 	tristate
-	default n
+	default MMU && (X86 || S390 || ARM || ARM64)
 
 config VFIO_IOMMU_SPAPR_TCE
 	tristate
 	depends on SPAPR_TCE_IOMMU
 	default VFIO
 
-config VFIO_SPAPR_EEH
-	tristate
-	depends on EEH && VFIO_IOMMU_SPAPR_TCE
-	default VFIO
-
-config VFIO_VIRQFD
-	tristate
-	select EVENTFD
-	default n
-
 config VFIO_NOIOMMU
 	bool "VFIO No-IOMMU support"
 	help
@@ -43,6 +44,17 @@ config VFIO_NOIOMMU
 	  this mode since there is no IOMMU to provide DMA translation.
 
 	  If you don't know what to do here, say N.
+endif
+
+config VFIO_SPAPR_EEH
+	tristate
+	depends on EEH && VFIO_IOMMU_SPAPR_TCE
+	default VFIO
+
+config VFIO_VIRQFD
+	tristate
+	select EVENTFD
+	default n
 
 source "drivers/vfio/pci/Kconfig"
 source "drivers/vfio/platform/Kconfig"

drivers/vfio/Makefile

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 vfio_virqfd-y := virqfd.o
 
-vfio-y += vfio_container.o
+vfio-$(CONFIG_VFIO_CONTAINER) += vfio_container.o
 vfio-y += vfio_main.o
 vfio-$(CONFIG_IOMMUFD) += vfio_iommufd.o
 

drivers/vfio/vfio.h

@@ -49,7 +49,9 @@ struct vfio_group {
 	struct list_head		device_list;
 	struct mutex			device_lock;
 	struct list_head		vfio_next;
+#if IS_ENABLED(CONFIG_VFIO_CONTAINER)
 	struct list_head		container_next;
+#endif
 	enum vfio_group_type		type;
 	unsigned int			dev_counter;
 	struct rw_semaphore		group_rwsem;
@@ -59,6 +61,7 @@ struct vfio_group {
 	struct iommufd_ctx		*iommufd;
 };
 
+#if IS_ENABLED(CONFIG_VFIO_CONTAINER)
 /* events for the backend driver notify callback */
 enum vfio_iommu_notify_type {
 	VFIO_IOMMU_CONTAINER_CLOSE = 0,
@@ -125,6 +128,74 @@ int vfio_container_dma_rw(struct vfio_device *device, dma_addr_t iova,
 
 int __init vfio_container_init(void);
 void vfio_container_cleanup(void);
+#else
+static inline struct vfio_container *
+vfio_container_from_file(struct file *filep)
+{
+	return NULL;
+}
+
+static inline int vfio_container_use(struct vfio_group *group);
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void vfio_container_unuse(struct vfio_group *group)
+{
+}
+
+static inline int vfio_container_attach_group(struct vfio_group *group,
+					      struct vfio_container *container)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void vfio_container_detatch_group(struct vfio_group *group)
+{
+}
+
+static inline void vfio_container_register_device(struct vfio_device *device)
+{
+}
+
+static inline void vfio_container_unregister_device(struct vfio_device *device)
+{
+}
+
+static inline long
+vfio_container_ioctl_check_extension(struct vfio_container *container,
+				     unsigned long arg)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int vfio_container_pin_pages(struct vfio_device *device,
+					   dma_addr_t iova, int npage, int prot,
+					   struct page **pages)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void vfio_container_unpin_pages(struct vfio_device *device,
+					      dma_addr_t iova, int npage)
+{
+}
+
+static inline int vfio_container_dma_rw(struct vfio_device *device,
+					dma_addr_t iova, void *data, size_t len,
+					bool write)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int vfio_container_init(void)
+{
+	return 0;
+}
+static inline void vfio_container_cleanup(void)
+{
+}
+#endif
 
 #if IS_ENABLED(CONFIG_IOMMUFD)
 int vfio_iommufd_bind(struct vfio_device *device, struct iommufd_ctx *ictx);