vfio-mdev: Make mdev_parent private

Rather than hoping for good behavior by marking some elements
internal, enforce it by making the entire structure private and
creating an accessor function for the one useful external field.

Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Jike Song <jike.song@intel.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed by: Kirti Wankhede <kwankhede@nvidia.com>

6 files changed, 23 insertions, 15 deletions

diff --git a/Documentation/vfio-mediated-device.txt b/Documentation/vfio-mediated-device.txt
index cfee106a3679..d226c7a5ba8b 100644
--- a/Documentation/vfio-mediated-device.txt
+++ b/Documentation/vfio-mediated-device.txt
@@ -223,6 +223,9 @@ Directories and files under the sysfs for Each Physical Device
 
         sprintf(buf, "%s-%s", dev_driver_string(parent->dev), group->name);
 
+  (or using mdev_parent_dev(mdev) to arrive at the parent device outside
+   of the core mdev code)
+
 * device_api
 
   This attribute should show which device API is being created, for example,
diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 081ada238107..38500329aa92 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -396,7 +396,7 @@ static int intel_vgpu_create(struct kobject *kobj, struct mdev_device *mdev)
         struct device *pdev;
         void *gvt;
 
-        pdev = mdev->parent->dev;
+        pdev = mdev_parent_dev(mdev);
         gvt = kdev_to_i915(pdev)->gvt;
 
         type = intel_gvt_find_vgpu_type(gvt, kobject_name(kobj));
diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index bf3b3b0b3d2b..30d05304241e 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -30,6 +30,12 @@ static struct class_compat *mdev_bus_compat_class;
 static LIST_HEAD(mdev_list);
 static DEFINE_MUTEX(mdev_list_lock);
 
+struct device *mdev_parent_dev(struct mdev_device *mdev)
+{
+        return mdev->parent->dev;
+}
+EXPORT_SYMBOL(mdev_parent_dev);
+
 static int _find_mdev_device(struct device *dev, void *data)
 {
         struct mdev_device *mdev;
diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
index 0b72c2d9ee40..b05dd22fc9a6 100644
--- a/drivers/vfio/mdev/mdev_private.h
+++ b/drivers/vfio/mdev/mdev_private.h
@@ -16,6 +16,16 @@
 int  mdev_bus_register(void);
 void mdev_bus_unregister(void);
 
+struct mdev_parent {
+        struct device *dev;
+        const struct mdev_parent_ops *ops;
+        struct kref ref;
+        struct mutex lock;
+        struct list_head next;
+        struct kset *mdev_types_kset;
+        struct list_head type_list;
+};
+
 struct mdev_type {
         struct kobject kobj;
         struct kobject *devices_kobj;
diff --git a/include/linux/mdev.h b/include/linux/mdev.h
index 853bb78e5866..f586222b6c25 100644
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -13,19 +13,6 @@
 #ifndef MDEV_H
 #define MDEV_H
 
-/* Parent device */
-struct mdev_parent {
-        struct device                   *dev;
-        const struct mdev_parent_ops    *ops;
-
-        /* internal */
-        struct kref             ref;
-        struct mutex            lock;
-        struct list_head        next;
-        struct kset             *mdev_types_kset;
-        struct list_head        type_list;
-};
-
 /* Mediated device */
 struct mdev_device {
         struct device           dev;
@@ -165,4 +152,6 @@ extern void mdev_unregister_device(struct device *dev);
 extern int  mdev_register_driver(struct mdev_driver *drv, struct module *owner);
 extern void mdev_unregister_driver(struct mdev_driver *drv);
 
+extern struct device *mdev_parent_dev(struct mdev_device *mdev);
+
 #endif /* MDEV_H */
diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
index 1a74f0e488da..5e13efc62bad 100644
--- a/samples/vfio-mdev/mtty.c
+++ b/samples/vfio-mdev/mtty.c
@@ -734,7 +734,7 @@ int mtty_create(struct kobject *kobj, struct mdev_device *mdev)
 
         for (i = 0; i < 2; i++) {
                 snprintf(name, MTTY_STRING_LEN, "%s-%d",
-                        dev_driver_string(mdev->parent->dev), i + 1);
+                        dev_driver_string(mdev_parent_dev(mdev)), i + 1);
                 if (!strcmp(kobj->name, name)) {
                         nr_ports = i + 1;
                         break;