ANDROID: vfio: Add vfio_file_get_device

Add a function to get struct device from a VFIO file, this is would
be used from kvm-vfio bridge for protected device assignment.

Bug: 357781595
Bug: 348382247
Change-Id: I60026744e2bd65b290cee8eb439a542946255755
Signed-off-by: Mostafa Saleh <smostafa@google.com>

drivers/vfio/vfio_main.c

@@ -479,6 +479,19 @@ void vfio_device_put_kvm(struct vfio_device *device)
 clear:
 	device->kvm = NULL;
 }
+
+static struct vfio_device *vfio_device_from_file(struct file *file);
+/**
+ * vfio_file_get_device - Return struct device from vfio device fd
+ * @file: VFIO device file
+ */
+struct device *vfio_file_get_device(struct file *file)
+{
+	struct vfio_device *device = vfio_device_from_file(file);
+
+	return device ? device->dev : NULL;
+}
+EXPORT_SYMBOL_GPL(vfio_file_get_device);
 #endif
 
 /* true if the vfio_device has open_device() called but not close_device() */

include/linux/vfio.h

@@ -316,6 +316,7 @@ static inline bool vfio_file_has_dev(struct file *file, struct vfio_device *devi
 bool vfio_file_is_valid(struct file *file);
 bool vfio_file_enforced_coherent(struct file *file);
 void vfio_file_set_kvm(struct file *file, struct kvm *kvm);
+struct device *vfio_file_get_device(struct file *file);
 
 #define VFIO_PIN_PAGES_MAX_ENTRIES	(PAGE_SIZE/sizeof(unsigned long))