[PATCH v1 13/18] vfio/mdev: Consolidate all the device_api sysfs into the core code

[Eric Farman <farman@linux.ibm.com>]

From: Jason Gunthorpe <jgg@nvidia.com>

Every driver just emits a static string, simply feed it through the ops
and provide a standard sysfs show function.

Cc: Kirti Wankhede <kwankhede@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Tony Krowiak <akrowiak@linux.ibm.com>
Cc: Jason Herne <jjherne@linux.ibm.com>
Cc: intel-gvt-dev@lists.freedesktop.org
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/6-v3-57c1502c62fd+2190-ccw_mdev_jgg@nvidia.com/
[farman: added Cc: tags]
Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
 .../driver-api/vfio-mediated-device.rst       |  4 ++-
 drivers/gpu/drm/i915/gvt/kvmgt.c              |  9 +------
 drivers/s390/cio/vfio_ccw_ops.c               |  9 +------
 drivers/s390/crypto/vfio_ap_ops.c             |  9 +------
 drivers/vfio/mdev/mdev_core.c                 |  2 +-
 drivers/vfio/mdev/mdev_sysfs.c                | 27 ++++++++++++++++---
 include/linux/mdev.h                          |  7 ++---
 samples/vfio-mdev/mbochs.c                    |  9 +------
 samples/vfio-mdev/mdpy.c                      |  9 +------
 samples/vfio-mdev/mtty.c                      | 10 +------
 10 files changed, 36 insertions(+), 59 deletions(-)

diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst
index 9f26079cacae..f410a1cd98bb 100644
--- a/Documentation/driver-api/vfio-mediated-device.rst
+++ b/Documentation/driver-api/vfio-mediated-device.rst
@@ -137,6 +137,7 @@ The structures in the mdev_parent_ops structure are as follows:
 * mdev_attr_groups: attributes of the mediated device
 * supported_config: attributes to define supported configurations
 * device_driver: device driver to bind for mediated device instances
+* device_api: String to pass through the sysfs file below
 
 The mdev_parent_ops also still has various functions pointers.  Theses exist
 for historical reasons only and shall not be used for new drivers.
@@ -225,7 +226,8 @@ Directories and files under the sysfs for Each Physical Device
 * device_api
 
   This attribute should show which device API is being created, for example,
-  "vfio-pci" for a PCI device.
+  "vfio-pci" for a PCI device. The core code maintins this sysfs using the
+  device_api member of mdev_parent_ops.
 
 * available_instances
 
diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 057ec4490104..752d7a1211e6 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -163,12 +163,6 @@ static ssize_t available_instances_show(struct mdev_type *mtype,
 	return sprintf(buf, "%u\n", num);
 }
 
-static ssize_t device_api_show(struct mdev_type *mtype,
-			       struct mdev_type_attribute *attr, char *buf)
-{
-	return sprintf(buf, "%s\n", VFIO_DEVICE_API_PCI_STRING);
-}
-
 static ssize_t description_show(struct mdev_type *mtype,
 				struct mdev_type_attribute *attr, char *buf)
 {
@@ -202,13 +196,11 @@ static ssize_t name_show(struct mdev_type *mtype,
 }
 
 static MDEV_TYPE_ATTR_RO(available_instances);
-static MDEV_TYPE_ATTR_RO(device_api);
 static MDEV_TYPE_ATTR_RO(description);
 static MDEV_TYPE_ATTR_RO(name);
 
 static struct attribute *gvt_type_attrs[] = {
 	&mdev_type_attr_available_instances.attr,
-	&mdev_type_attr_device_api.attr,
 	&mdev_type_attr_description.attr,
 	&mdev_type_attr_name.attr,
 	NULL,
@@ -1767,6 +1759,7 @@ static const struct attribute_group *intel_vgpu_groups[] = {
 
 static struct mdev_parent_ops intel_vgpu_ops = {
 	.mdev_attr_groups       = intel_vgpu_groups,
+	.device_api		= VFIO_DEVICE_API_PCI_STRING,
 	.create			= intel_vgpu_create,
 	.remove			= intel_vgpu_remove,
 
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index 2afb8f13739f..6793c8b3c58b 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -66,13 +66,6 @@ static ssize_t name_show(struct mdev_type *mtype,
 }
 static MDEV_TYPE_ATTR_RO(name);
 
-static ssize_t device_api_show(struct mdev_type *mtype,
-			       struct mdev_type_attribute *attr, char *buf)
-{
-	return sprintf(buf, "%s\n", VFIO_DEVICE_API_CCW_STRING);
-}
-static MDEV_TYPE_ATTR_RO(device_api);
-
 static ssize_t available_instances_show(struct mdev_type *mtype,
 					struct mdev_type_attribute *attr,
 					char *buf)
@@ -86,7 +79,6 @@ static MDEV_TYPE_ATTR_RO(available_instances);
 
 static struct attribute *mdev_types_attrs[] = {
 	&mdev_type_attr_name.attr,
-	&mdev_type_attr_device_api.attr,
 	&mdev_type_attr_available_instances.attr,
 	NULL,
 };
@@ -644,5 +636,6 @@ struct mdev_driver vfio_ccw_mdev_driver = {
 const struct mdev_parent_ops vfio_ccw_mdev_ops = {
 	.owner			= THIS_MODULE,
 	.device_driver		= &vfio_ccw_mdev_driver,
+	.device_api		= VFIO_DEVICE_API_CCW_STRING,
 	.supported_type_groups  = mdev_type_groups,
 };
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 6e08d04b605d..838b1a3eac8a 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -530,17 +530,9 @@ static ssize_t available_instances_show(struct mdev_type *mtype,
 
 static MDEV_TYPE_ATTR_RO(available_instances);
 
-static ssize_t device_api_show(struct mdev_type *mtype,
-			       struct mdev_type_attribute *attr, char *buf)
-{
-	return sprintf(buf, "%s\n", VFIO_DEVICE_API_AP_STRING);
-}
-
-static MDEV_TYPE_ATTR_RO(device_api);
 
 static struct attribute *vfio_ap_mdev_type_attrs[] = {
 	&mdev_type_attr_name.attr,
-	&mdev_type_attr_device_api.attr,
 	&mdev_type_attr_available_instances.attr,
 	NULL,
 };
@@ -1501,6 +1493,7 @@ static struct mdev_driver vfio_ap_matrix_driver = {
 static const struct mdev_parent_ops vfio_ap_matrix_ops = {
 	.owner			= THIS_MODULE,
 	.device_driver		= &vfio_ap_matrix_driver,
+	.device_api		= VFIO_DEVICE_API_AP_STRING,
 	.supported_type_groups	= vfio_ap_mdev_type_groups,
 };
 
diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index b314101237fe..c3018e8e6d32 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -129,7 +129,7 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops)
 	char *envp[] = { env_string, NULL };
 
 	/* check for mandatory ops */
-	if (!ops || !ops->supported_type_groups)
+	if (!ops || !ops->supported_type_groups || !ops->device_api)
 		return -EINVAL;
 	if (!ops->device_driver && (!ops->create || !ops->remove))
 		return -EINVAL;
diff --git a/drivers/vfio/mdev/mdev_sysfs.c b/drivers/vfio/mdev/mdev_sysfs.c
index f5cf1931c54e..d4b99440d19e 100644
--- a/drivers/vfio/mdev/mdev_sysfs.c
+++ b/drivers/vfio/mdev/mdev_sysfs.c
@@ -74,9 +74,30 @@ static ssize_t create_store(struct mdev_type *mtype,
 
 	return count;
 }
-
 static MDEV_TYPE_ATTR_WO(create);
 
+static ssize_t device_api_show(struct mdev_type *mtype,
+			       struct mdev_type_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%s\n", mtype->parent->ops->device_api);
+}
+static MDEV_TYPE_ATTR_RO(device_api);
+
+static struct attribute *mdev_types_std_attrs[] = {
+	&mdev_type_attr_create.attr,
+	&mdev_type_attr_device_api.attr,
+	NULL,
+};
+
+static struct attribute_group mdev_type_std_group = {
+	.attrs = mdev_types_std_attrs,
+};
+
+static const struct attribute_group *mdev_type_groups[] = {
+	&mdev_type_std_group,
+	NULL,
+};
+
 static void mdev_type_release(struct kobject *kobj)
 {
 	struct mdev_type *type = to_mdev_type(kobj);
@@ -123,7 +144,7 @@ static struct mdev_type *add_mdev_supported_type(struct mdev_parent *parent,
 		return ERR_PTR(ret);
 	}
 
-	ret = sysfs_create_file(&type->kobj, &mdev_type_attr_create.attr);
+	ret = sysfs_create_groups(&type->kobj, mdev_type_groups);
 	if (ret)
 		goto attr_create_failed;
 
@@ -144,7 +165,7 @@ static struct mdev_type *add_mdev_supported_type(struct mdev_parent *parent,
 attrs_failed:
 	kobject_put(type->devices_kobj);
 attr_devices_failed:
-	sysfs_remove_file(&type->kobj, &mdev_type_attr_create.attr);
+	sysfs_remove_groups(&type->kobj, mdev_type_groups);
 attr_create_failed:
 	kobject_del(&type->kobj);
 	kobject_put(&type->kobj);
diff --git a/include/linux/mdev.h b/include/linux/mdev.h
index a5788f592817..14655215417b 100644
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -36,6 +36,7 @@ struct device *mtype_get_parent_dev(struct mdev_type *mtype);
  *
  * @owner:		The module owner.
  * @device_driver:	Which device driver to probe() on newly created devices
+ * @device_api:		String to return for the device_api sysfs
  * @dev_attr_groups:	Attributes of the parent device.
  * @mdev_attr_groups:	Attributes of the mediated device.
  * @supported_type_groups: Attributes to define supported types. It is mandatory
@@ -80,6 +81,7 @@ struct device *mtype_get_parent_dev(struct mdev_type *mtype);
 struct mdev_parent_ops {
 	struct module   *owner;
 	struct mdev_driver *device_driver;
+	const char *device_api;
 	const struct attribute_group **dev_attr_groups;
 	const struct attribute_group **mdev_attr_groups;
 	struct attribute_group **supported_type_groups;
@@ -108,11 +110,6 @@ struct mdev_type_attribute {
 			 size_t count);
 };
 
-#define MDEV_TYPE_ATTR(_name, _mode, _show, _store)		\
-struct mdev_type_attribute mdev_type_attr_##_name =		\
-	__ATTR(_name, _mode, _show, _store)
-#define MDEV_TYPE_ATTR_RW(_name) \
-	struct mdev_type_attribute mdev_type_attr_##_name = __ATTR_RW(_name)
 #define MDEV_TYPE_ATTR_RO(_name) \
 	struct mdev_type_attribute mdev_type_attr_##_name = __ATTR_RO(_name)
 #define MDEV_TYPE_ATTR_WO(_name) \
diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
index e90c8552cc31..8d3ae97d9d6e 100644
--- a/samples/vfio-mdev/mbochs.c
+++ b/samples/vfio-mdev/mbochs.c
@@ -1358,17 +1358,9 @@ static ssize_t available_instances_show(struct mdev_type *mtype,
 }
 static MDEV_TYPE_ATTR_RO(available_instances);
 
-static ssize_t device_api_show(struct mdev_type *mtype,
-			       struct mdev_type_attribute *attr, char *buf)
-{
-	return sprintf(buf, "%s\n", VFIO_DEVICE_API_PCI_STRING);
-}
-static MDEV_TYPE_ATTR_RO(device_api);
-
 static struct attribute *mdev_types_attrs[] = {
 	&mdev_type_attr_name.attr,
 	&mdev_type_attr_description.attr,
-	&mdev_type_attr_device_api.attr,
 	&mdev_type_attr_available_instances.attr,
 	NULL,
 };
@@ -1417,6 +1409,7 @@ static struct mdev_driver mbochs_driver = {
 static const struct mdev_parent_ops mdev_fops = {
 	.owner			= THIS_MODULE,
 	.device_driver		= &mbochs_driver,
+	.device_api		= VFIO_DEVICE_API_PCI_STRING,
 	.supported_type_groups	= mdev_type_groups,
 };
 
diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c
index fe5d43e797b6..402a7ebe6563 100644
--- a/samples/vfio-mdev/mdpy.c
+++ b/samples/vfio-mdev/mdpy.c
@@ -670,17 +670,9 @@ static ssize_t available_instances_show(struct mdev_type *mtype,
 }
 static MDEV_TYPE_ATTR_RO(available_instances);
 
-static ssize_t device_api_show(struct mdev_type *mtype,
-			       struct mdev_type_attribute *attr, char *buf)
-{
-	return sprintf(buf, "%s\n", VFIO_DEVICE_API_PCI_STRING);
-}
-static MDEV_TYPE_ATTR_RO(device_api);
-
 static struct attribute *mdev_types_attrs[] = {
 	&mdev_type_attr_name.attr,
 	&mdev_type_attr_description.attr,
-	&mdev_type_attr_device_api.attr,
 	&mdev_type_attr_available_instances.attr,
 	NULL,
 };
@@ -728,6 +720,7 @@ static struct mdev_driver mdpy_driver = {
 static const struct mdev_parent_ops mdev_fops = {
 	.owner			= THIS_MODULE,
 	.device_driver          = &mdpy_driver,
+	.device_api		= VFIO_DEVICE_API_PCI_STRING,
 	.supported_type_groups	= mdev_type_groups,
 };
 
diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
index a0e1a469bd47..5dc1b6a4c02c 100644
--- a/samples/vfio-mdev/mtty.c
+++ b/samples/vfio-mdev/mtty.c
@@ -1281,17 +1281,8 @@ static ssize_t available_instances_show(struct mdev_type *mtype,
 
 static MDEV_TYPE_ATTR_RO(available_instances);
 
-static ssize_t device_api_show(struct mdev_type *mtype,
-			       struct mdev_type_attribute *attr, char *buf)
-{
-	return sprintf(buf, "%s\n", VFIO_DEVICE_API_PCI_STRING);
-}
-
-static MDEV_TYPE_ATTR_RO(device_api);
-
 static struct attribute *mdev_types_attrs[] = {
 	&mdev_type_attr_name.attr,
-	&mdev_type_attr_device_api.attr,
 	&mdev_type_attr_available_instances.attr,
 	NULL,
 };
@@ -1333,6 +1324,7 @@ static struct mdev_driver mtty_driver = {
 static const struct mdev_parent_ops mdev_fops = {
 	.owner                  = THIS_MODULE,
 	.device_driver		= &mtty_driver,
+	.device_api		= VFIO_DEVICE_API_PCI_STRING,
 	.dev_attr_groups        = mtty_dev_groups,
 	.supported_type_groups  = mdev_type_groups,
 };
-- 
2.32.0