vfio/mdev: consolidate all the description sysfs into the core code

Every driver just emits a string, simply add a method to the mdev_driver
to return it and provide a standard sysfs show function.

Remove the now unused types_attrs field in struct mdev_driver and the
support code for it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>
Link: https://lore.kernel.org/r/20220923092652.100656-14-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

2 files changed, 33 insertions, 9 deletions

diff --git a/drivers/vfio/mdev/mdev_driver.c b/drivers/vfio/mdev/mdev_driver.c
index 60e8b9f6474e..7825d83a55f8 100644
--- a/drivers/vfio/mdev/mdev_driver.c
+++ b/drivers/vfio/mdev/mdev_driver.c
@@ -55,7 +55,7 @@ struct bus_type mdev_bus_type = {
  **/
 int mdev_register_driver(struct mdev_driver *drv)
 {
-	if (!drv->types_attrs || !drv->device_api)
+	if (!drv->device_api)
 		return -EINVAL;
 
 	/* initialize common driver fields */
diff --git a/drivers/vfio/mdev/mdev_sysfs.c b/drivers/vfio/mdev/mdev_sysfs.c
index b7f87c3eda5e..658b3bf5ed0b 100644
--- a/drivers/vfio/mdev/mdev_sysfs.c
+++ b/drivers/vfio/mdev/mdev_sysfs.c
@@ -14,7 +14,19 @@
 
 #include "mdev_private.h"
 
-/* Static functions */
+struct mdev_type_attribute {
+	struct attribute attr;
+	ssize_t (*show)(struct mdev_type *mtype,
+			struct mdev_type_attribute *attr, char *buf);
+	ssize_t (*store)(struct mdev_type *mtype,
+			 struct mdev_type_attribute *attr, const char *buf,
+			 size_t count);
+};
+
+#define MDEV_TYPE_ATTR_RO(_name) \
+	struct mdev_type_attribute mdev_type_attr_##_name = __ATTR_RO(_name)
+#define MDEV_TYPE_ATTR_WO(_name) \
+	struct mdev_type_attribute mdev_type_attr_##_name = __ATTR_WO(_name)
 
 static ssize_t mdev_type_attr_show(struct kobject *kobj,
 				     struct attribute *__attr, char *buf)
@@ -100,16 +112,35 @@ static ssize_t available_instances_show(struct mdev_type *mtype,
 }
 static MDEV_TYPE_ATTR_RO(available_instances);
 
+static ssize_t description_show(struct mdev_type *mtype,
+				struct mdev_type_attribute *attr,
+				char *buf)
+{
+	return mtype->parent->mdev_driver->show_description(mtype, buf);
+}
+static MDEV_TYPE_ATTR_RO(description);
+
 static struct attribute *mdev_types_core_attrs[] = {
 	&mdev_type_attr_create.attr,
 	&mdev_type_attr_device_api.attr,
 	&mdev_type_attr_name.attr,
 	&mdev_type_attr_available_instances.attr,
+	&mdev_type_attr_description.attr,
 	NULL,
 };
 
+static umode_t mdev_types_core_is_visible(struct kobject *kobj,
+					  struct attribute *attr, int n)
+{
+	if (attr == &mdev_type_attr_description.attr &&
+	    !to_mdev_type(kobj)->parent->mdev_driver->show_description)
+		return 0;
+	return attr->mode;
+}
+
 static struct attribute_group mdev_type_core_group = {
 	.attrs = mdev_types_core_attrs,
+	.is_visible = mdev_types_core_is_visible,
 };
 
 static const struct attribute_group *mdev_type_groups[] = {
@@ -155,13 +186,8 @@ static int mdev_type_add(struct mdev_parent *parent, struct mdev_type *type)
 		goto attr_devices_failed;
 	}
 
-	ret = sysfs_create_files(&type->kobj, parent->mdev_driver->types_attrs);
-	if (ret)
-		goto attrs_failed;
 	return 0;
 
-attrs_failed:
-	kobject_put(type->devices_kobj);
 attr_devices_failed:
 	kobject_del(&type->kobj);
 	kobject_put(&type->kobj);
@@ -170,8 +196,6 @@ attr_devices_failed:
 
 static void mdev_type_remove(struct mdev_type *type)
 {
-	sysfs_remove_files(&type->kobj, type->parent->mdev_driver->types_attrs);
-
 	kobject_put(type->devices_kobj);
 	kobject_del(&type->kobj);
 	kobject_put(&type->kobj);