[PATCH 3/6] vfio/mdev: Add "aggregated_instances" attribute for supported mdev device

[Zhenyu Wang <zhenyuw@linux.intel.com>]

For mdev device created by "aggregate" parameter, this creates new mdev
device attribute "aggregated_instances" to show number of aggregated
instances allocated.

Cc: Kirti Wankhede <kwankhede@nvidia.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Cc: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
---
v2:
- change attribute name as "aggregated_instances"
v3:
- create only for aggregated allocation
v4:
- fix remove

 drivers/vfio/mdev/mdev_sysfs.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/vfio/mdev/mdev_sysfs.c b/drivers/vfio/mdev/mdev_sysfs.c
index acd3ec2900b5..f131480a767a 100644
--- a/drivers/vfio/mdev/mdev_sysfs.c
+++ b/drivers/vfio/mdev/mdev_sysfs.c
@@ -289,6 +289,17 @@ static ssize_t remove_store(struct device *dev, struct device_attribute *attr,
 
 static DEVICE_ATTR_WO(remove);
 
+static ssize_t
+aggregated_instances_show(struct device *dev,
+			  struct device_attribute *attr,
+			  char *buf)
+{
+	struct mdev_device *mdev = to_mdev_device(dev);
+	return sprintf(buf, "%u\n", mdev->type_instances);
+}
+
+static DEVICE_ATTR_RO(aggregated_instances);
+
 static const struct attribute *mdev_device_attrs[] = {
 	&dev_attr_remove.attr,
 	NULL,
@@ -296,6 +307,7 @@ static const struct attribute *mdev_device_attrs[] = {
 
 int  mdev_create_sysfs_files(struct device *dev, struct mdev_type *type)
 {
+	struct mdev_device *mdev = to_mdev_device(dev);
 	int ret;
 
 	ret = sysfs_create_link(type->devices_kobj, &dev->kobj, dev_name(dev));
@@ -310,8 +322,17 @@ int  mdev_create_sysfs_files(struct device *dev, struct mdev_type *type)
 	if (ret)
 		goto create_files_failed;
 
+	if (mdev->type_instances > 1) {
+		ret = sysfs_create_file(&dev->kobj,
+					&dev_attr_aggregated_instances.attr);
+		if (ret)
+			goto create_aggregated_failed;
+	}
+
 	return ret;
 
+create_aggregated_failed:
+	sysfs_remove_files(&dev->kobj, mdev_device_attrs);
 create_files_failed:
 	sysfs_remove_link(&dev->kobj, "mdev_type");
 type_link_failed:
@@ -321,6 +342,10 @@ int  mdev_create_sysfs_files(struct device *dev, struct mdev_type *type)
 
 void mdev_remove_sysfs_files(struct device *dev, struct mdev_type *type)
 {
+	struct mdev_device *mdev = to_mdev_device(dev);
+	if (mdev->type_instances > 1)
+		sysfs_remove_file(&dev->kobj,
+				  &dev_attr_aggregated_instances.attr);
 	sysfs_remove_files(&dev->kobj, mdev_device_attrs);
 	sysfs_remove_link(&dev->kobj, "mdev_type");
 	sysfs_remove_link(type->devices_kobj, dev_name(dev));
-- 
2.24.0.rc0