vfio/mdev: add mdev available instance checking to the core

Many of the mdev drivers use a simple counter for keeping track of the
available instances. Move this code to the core code and store the counter
in the mdev_parent. Implement it using correct locking, fixing mdpy.

Drivers just provide the value in the mdev_driver at registration time
and the core code takes care of maintaining it and exposing the value in
sysfs.

[hch: count instances per-parent instead of per-type, use an atomic_t
 to avoid taking mdev_list_lock in the show method]

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Link: https://lore.kernel.org/r/20220923092652.100656-15-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Jason Gunthorpe
2022-09-23 11:26:52 +02:00
committed by Alex Williamson
parent 685a1537f4
commit 9c799c224d
9 changed files with 32 additions and 53 deletions

View File

@@ -45,6 +45,7 @@ struct mdev_parent {
struct rw_semaphore unreg_sem;
struct mdev_type **types;
unsigned int nr_types;
atomic_t available_instances;
};
static inline struct mdev_device *to_mdev_device(struct device *dev)
@@ -55,6 +56,7 @@ static inline struct mdev_device *to_mdev_device(struct device *dev)
/**
* struct mdev_driver - Mediated device driver
* @device_api: string to return for the device_api sysfs
* @max_instances: maximum number of instances supported (optional)
* @probe: called when new device created
* @remove: called when device removed
* @get_available: Return the max number of instances that can be created
@@ -63,6 +65,7 @@ static inline struct mdev_device *to_mdev_device(struct device *dev)
**/
struct mdev_driver {
const char *device_api;
unsigned int max_instances;
int (*probe)(struct mdev_device *dev);
void (*remove)(struct mdev_device *dev);
unsigned int (*get_available)(struct mdev_type *mtype);