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authorJason Gunthorpe <jgg@nvidia.com>2022-09-23 11:26:52 +0200
committerAlex Williamson <alex.williamson@redhat.com>2022-10-04 12:06:58 -0600
commit9c799c224d6ebc5be51065bd3217a2d7eea23b8f (patch)
treed09166f170afc9fc32ecfe8205964a6257b81990 /drivers/vfio/mdev
parent685a1537f4c603cfcaf4b9be56ff6a571f7ddd08 (diff)
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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>
Diffstat (limited to 'drivers/vfio/mdev')
-rw-r--r--drivers/vfio/mdev/mdev_core.c22
-rw-r--r--drivers/vfio/mdev/mdev_sysfs.c5
2 files changed, 23 insertions, 4 deletions
diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index 93f8caf2e5f7..58f91b3bd670 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -70,6 +70,7 @@ int mdev_register_parent(struct mdev_parent *parent, struct device *dev,
parent->mdev_driver = mdev_driver;
parent->types = types;
parent->nr_types = nr_types;
+ atomic_set(&parent->available_instances, mdev_driver->max_instances);
if (!mdev_bus_compat_class) {
mdev_bus_compat_class = class_compat_register("mdev_bus");
@@ -115,14 +116,17 @@ EXPORT_SYMBOL(mdev_unregister_parent);
static void mdev_device_release(struct device *dev)
{
struct mdev_device *mdev = to_mdev_device(dev);
-
- /* Pairs with the get in mdev_device_create() */
- kobject_put(&mdev->type->kobj);
+ struct mdev_parent *parent = mdev->type->parent;
mutex_lock(&mdev_list_lock);
list_del(&mdev->next);
+ if (!parent->mdev_driver->get_available)
+ atomic_inc(&parent->available_instances);
mutex_unlock(&mdev_list_lock);
+ /* Pairs with the get in mdev_device_create() */
+ kobject_put(&mdev->type->kobj);
+
dev_dbg(&mdev->dev, "MDEV: destroying\n");
kfree(mdev);
}
@@ -144,6 +148,18 @@ int mdev_device_create(struct mdev_type *type, const guid_t *uuid)
}
}
+ if (!drv->get_available) {
+ /*
+ * Note: that non-atomic read and dec is fine here because
+ * all modifications are under mdev_list_lock.
+ */
+ if (!atomic_read(&parent->available_instances)) {
+ mutex_unlock(&mdev_list_lock);
+ return -EUSERS;
+ }
+ atomic_dec(&parent->available_instances);
+ }
+
mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
if (!mdev) {
mutex_unlock(&mdev_list_lock);
diff --git a/drivers/vfio/mdev/mdev_sysfs.c b/drivers/vfio/mdev/mdev_sysfs.c
index 658b3bf5ed0b..abe3359dd477 100644
--- a/drivers/vfio/mdev/mdev_sysfs.c
+++ b/drivers/vfio/mdev/mdev_sysfs.c
@@ -108,7 +108,10 @@ static ssize_t available_instances_show(struct mdev_type *mtype,
{
struct mdev_driver *drv = mtype->parent->mdev_driver;
- return sysfs_emit(buf, "%u\n", drv->get_available(mtype));
+ if (drv->get_available)
+ return sysfs_emit(buf, "%u\n", drv->get_available(mtype));
+ return sysfs_emit(buf, "%u\n",
+ atomic_read(&mtype->parent->available_instances));
}
static MDEV_TYPE_ATTR_RO(available_instances);