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

v2: create new create_with_instances operator for vendor driver

Cc: Kirti Wankhede <[email protected]>
Cc: Alex Williamson <[email protected]>
Cc: Kevin Tian <[email protected]>
Signed-off-by: Zhenyu Wang <[email protected]>
---
 drivers/vfio/mdev/mdev_core.c    | 18 +++++++++++++----
 drivers/vfio/mdev/mdev_private.h |  5 ++++-
 drivers/vfio/mdev/mdev_sysfs.c   | 34 ++++++++++++++++++++++++++------
 include/linux/mdev.h             | 10 ++++++++++
 4 files changed, 56 insertions(+), 11 deletions(-)

diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index 0212f0ee8aea..e69db302a4f2 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -104,12 +104,16 @@ 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 +280,8 @@ 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 +292,11 @@ 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 */
@@ -323,7 +333,7 @@ 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..c9d3fe04e273 100644
--- a/drivers/vfio/mdev/mdev_private.h
+++ b/drivers/vfio/mdev/mdev_private.h
@@ -52,13 +52,16 @@ struct mdev_type {
 #define to_mdev_type(_kobj)            \
        container_of(_kobj, struct mdev_type, kobj)
 
+#define MDEV_CREATE_OPT_LEN 32
+
 int  parent_create_sysfs_files(struct mdev_parent *parent);
 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..a06e5b7c69d3 100644
--- a/drivers/vfio/mdev/mdev_sysfs.c
+++ b/drivers/vfio/mdev/mdev_sysfs.c
@@ -54,11 +54,15 @@ 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, *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;
+
+       if (count > UUID_STRING_LEN + 1 + MDEV_CREATE_OPT_LEN)
                return -EINVAL;
 
        str = kstrndup(buf, count, GFP_KERNEL);
@@ -66,13 +70,31 @@ static ssize_t create_store(struct kobject *kobj, struct 
device *dev,
                return -ENOMEM;
 
        ret = uuid_le_to_bin(str, &uuid);
-       kfree(str);
-       if (ret)
+       if (ret) {
+               kfree(str);
                return ret;
+       }
 
-       ret = mdev_device_create(kobj, dev, uuid);
-       if (ret)
+       if (count > UUID_STRING_LEN + 1) {
+               opt = str + UUID_STRING_LEN;
+               if (*opt++ != ',' ||
+                   strncmp(opt, "instances=", 10)) {
+                       kfree(str);
+                       return -EINVAL;
+               }
+               opt += 10;
+               if (kstrtouint(opt, 10, &instances)) {
+                       kfree(str);
+                       return -EINVAL;
+               }
+       }
+
+       ret = mdev_device_create(kobj, dev, uuid, instances);
+       if (ret) {
+               kfree(str);
                return ret;
+       }
+       kfree(str);
 
        return count;
 }
diff --git a/include/linux/mdev.h b/include/linux/mdev.h
index b6e048e1045f..cfb702600f95 100644
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -30,6 +30,13 @@ struct mdev_device;
  *                     @kobj: kobject of type for which 'create' is called.
  *                     @mdev: mdev_device structure on of mediated device
  *                           that is being created
+ * @create_with_instances: Allocate aggregated instances' resources in parent 
device's
+ *                     driver for a particular mediated device. It is optional
+ *                     if doesn't support aggregated resources.
+ *                     @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'
@@ -71,6 +78,9 @@ 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);
-- 
2.18.0

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