[libvirt] [PATCH v3 1/6] vfio/mdev: Add new "aggregate" parameter for mdev create

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

For special mdev type which can aggregate instances for mdev device,
this extends mdev create interface by allowing extra "aggregate=xxx"
parameter, which is passed to mdev device model to be able to create
bundled number of instances for target mdev device.

v2: create new create_with_instances operator for vendor driver
v3:
- Change parameter name as "aggregate="
- Fix new interface comments.
- Parameter checking for new option, pass UUID string only to
  parse and properly end parameter for kstrtouint() conversion.

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>
---
 drivers/vfio/mdev/mdev_core.c    | 21 +++++++++++++++++----
 drivers/vfio/mdev/mdev_private.h |  4 +++-
 drivers/vfio/mdev/mdev_sysfs.c   | 32 ++++++++++++++++++++++++++++----
 include/linux/mdev.h             | 11 +++++++++++
 4 files changed, 59 insertions(+), 9 deletions(-)

diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index 0212f0ee8aea..545c52ec7618 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -104,12 +104,17 @@ static inline void mdev_put_parent(struct mdev_parent *parent)
 }
 
 static int mdev_device_create_ops(struct kobject *kobj,
-				  struct mdev_device *mdev)
+				  struct mdev_device *mdev,
+				  unsigned int instances)
 {
 	struct mdev_parent *parent = mdev->parent;
 	int ret;
 
-	ret = parent->ops->create(kobj, mdev);
+	if (instances > 1) {
+		ret = parent->ops->create_with_instances(kobj, mdev,
+							 instances);
+	} else
+		ret = parent->ops->create(kobj, mdev);
 	if (ret)
 		return ret;
 
@@ -276,7 +281,8 @@ static void mdev_device_release(struct device *dev)
 	kfree(mdev);
 }
 
-int mdev_device_create(struct kobject *kobj, struct device *dev, uuid_le uuid)
+int mdev_device_create(struct kobject *kobj, struct device *dev, uuid_le uuid,
+		       unsigned int instances)
 {
 	int ret;
 	struct mdev_device *mdev, *tmp;
@@ -287,6 +293,12 @@ int mdev_device_create(struct kobject *kobj, struct device *dev, uuid_le uuid)
 	if (!parent)
 		return -EINVAL;
 
+	if (instances > 1 &&
+	    !parent->ops->create_with_instances) {
+		ret = -EINVAL;
+		goto mdev_fail;
+	}
+
 	mutex_lock(&mdev_list_lock);
 
 	/* Check for duplicate */
@@ -316,6 +328,7 @@ int mdev_device_create(struct kobject *kobj, struct device *dev, uuid_le uuid)
 	mdev->dev.bus     = &mdev_bus_type;
 	mdev->dev.release = mdev_device_release;
 	dev_set_name(&mdev->dev, "%pUl", uuid.b);
+	mdev->type_instances = instances;
 
 	ret = device_register(&mdev->dev);
 	if (ret) {
@@ -323,7 +336,7 @@ int mdev_device_create(struct kobject *kobj, struct device *dev, uuid_le uuid)
 		goto mdev_fail;
 	}
 
-	ret = mdev_device_create_ops(kobj, mdev);
+	ret = mdev_device_create_ops(kobj, mdev, instances);
 	if (ret)
 		goto create_fail;
 
diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
index b5819b7d7ef7..e90d295d3927 100644
--- a/drivers/vfio/mdev/mdev_private.h
+++ b/drivers/vfio/mdev/mdev_private.h
@@ -33,6 +33,7 @@ struct mdev_device {
 	struct kref ref;
 	struct list_head next;
 	struct kobject *type_kobj;
+	unsigned int type_instances;
 	bool active;
 };
 
@@ -58,7 +59,8 @@ void parent_remove_sysfs_files(struct mdev_parent *parent);
 int  mdev_create_sysfs_files(struct device *dev, struct mdev_type *type);
 void mdev_remove_sysfs_files(struct device *dev, struct mdev_type *type);
 
-int  mdev_device_create(struct kobject *kobj, struct device *dev, uuid_le uuid);
+int  mdev_device_create(struct kobject *kobj, struct device *dev, uuid_le uuid,
+			unsigned int instances);
 int  mdev_device_remove(struct device *dev, bool force_remove);
 
 #endif /* MDEV_PRIVATE_H */
diff --git a/drivers/vfio/mdev/mdev_sysfs.c b/drivers/vfio/mdev/mdev_sysfs.c
index 249472f05509..aefed0c8891b 100644
--- a/drivers/vfio/mdev/mdev_sysfs.c
+++ b/drivers/vfio/mdev/mdev_sysfs.c
@@ -54,14 +54,21 @@ static const struct sysfs_ops mdev_type_sysfs_ops = {
 static ssize_t create_store(struct kobject *kobj, struct device *dev,
 			    const char *buf, size_t count)
 {
-	char *str;
+	char *str, *param, *opt = NULL;
 	uuid_le uuid;
 	int ret;
+	unsigned int instances = 1;
 
-	if ((count < UUID_STRING_LEN) || (count > UUID_STRING_LEN + 1))
+	if (count < UUID_STRING_LEN)
 		return -EINVAL;
 
-	str = kstrndup(buf, count, GFP_KERNEL);
+	if ((param = strnchr(buf, count, ',')) == NULL) {
+		if (count > UUID_STRING_LEN + 1)
+			return -EINVAL;
+	} else if (param - buf != UUID_STRING_LEN)
+		return -EINVAL;
+
+	str = kstrndup(buf, UUID_STRING_LEN, GFP_KERNEL);
 	if (!str)
 		return -ENOMEM;
 
@@ -70,7 +77,24 @@ static ssize_t create_store(struct kobject *kobj, struct device *dev,
 	if (ret)
 		return ret;
 
-	ret = mdev_device_create(kobj, dev, uuid);
+	if (param) {
+		opt = kstrndup(param + 1, count - UUID_STRING_LEN - 1,
+			       GFP_KERNEL);
+		if (!opt)
+			return -ENOMEM;
+		if (strncmp(opt, "aggregate=", 10)) {
+			kfree(opt);
+			return -EINVAL;
+		}
+		opt += 10;
+		if (kstrtouint(opt, 10, &instances)) {
+			kfree(opt);
+			return -EINVAL;
+		}
+		kfree(opt);
+	}
+
+	ret = mdev_device_create(kobj, dev, uuid, instances);
 	if (ret)
 		return ret;
 
diff --git a/include/linux/mdev.h b/include/linux/mdev.h
index b6e048e1045f..c12c0bfc5598 100644
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -31,6 +31,14 @@ struct mdev_device;
  *			@mdev: mdev_device structure on of mediated device
  *			      that is being created
  *			Returns integer: success (0) or error (< 0)
+ * @create_with_instances: Allocate aggregated instances' resources in parent device's
+ *			driver for a particular mediated device. Optional if aggregated
+ *                      resources are not supported.
+ *			@kobj: kobject of type for which 'create' is called.
+ *			@mdev: mdev_device structure on of mediated device
+ *			      that is being created
+ *                      @instances: number of instances to aggregate
+ *			Returns integer: success (0) or error (< 0)
  * @remove:		Called to free resources in parent device's driver for a
  *			a mediated device. It is mandatory to provide 'remove'
  *			ops.
@@ -71,6 +79,9 @@ struct mdev_parent_ops {
 	struct attribute_group **supported_type_groups;
 
 	int     (*create)(struct kobject *kobj, struct mdev_device *mdev);
+	int     (*create_with_instances)(struct kobject *kobj,
+					 struct mdev_device *mdev,
+					 unsigned int instances);
 	int     (*remove)(struct mdev_device *mdev);
 	int     (*open)(struct mdev_device *mdev);
 	void    (*release)(struct mdev_device *mdev);
-- 
2.19.1