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// SPDX-License-Identifier: GPL-2.0
/*
* I/O Address Space ID allocator. There is one global IOASID space, split into
* subsets. Users create a subset with DECLARE_IOASID_SET, then allocate and
* free IOASIDs with ioasid_alloc and ioasid_free.
*/
#include <linux/ioasid.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/xarray.h>
struct ioasid_data {
ioasid_t id;
struct ioasid_set *set;
void *private;
struct rcu_head rcu;
};
static DEFINE_XARRAY_ALLOC(ioasid_xa);
/**
* ioasid_set_data - Set private data for an allocated ioasid
* @ioasid: the ID to set data
* @data: the private data
*
* For IOASID that is already allocated, private data can be set
* via this API. Future lookup can be done via ioasid_find.
*/
int ioasid_set_data(ioasid_t ioasid, void *data)
{
struct ioasid_data *ioasid_data;
int ret = 0;
xa_lock(&ioasid_xa);
ioasid_data = xa_load(&ioasid_xa, ioasid);
if (ioasid_data)
rcu_assign_pointer(ioasid_data->private, data);
else
ret = -ENOENT;
xa_unlock(&ioasid_xa);
/*
* Wait for readers to stop accessing the old private data, so the
* caller can free it.
*/
if (!ret)
synchronize_rcu();
return ret;
}
EXPORT_SYMBOL_GPL(ioasid_set_data);
/**
* ioasid_alloc - Allocate an IOASID
* @set: the IOASID set
* @min: the minimum ID (inclusive)
* @max: the maximum ID (inclusive)
* @private: data private to the caller
*
* Allocate an ID between @min and @max. The @private pointer is stored
* internally and can be retrieved with ioasid_find().
*
* Return: the allocated ID on success, or %INVALID_IOASID on failure.
*/
ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, ioasid_t max,
void *private)
{
struct ioasid_data *data;
ioasid_t id;
data = kzalloc(sizeof(*data), GFP_ATOMIC);
if (!data)
return INVALID_IOASID;
data->set = set;
data->private = private;
if (xa_alloc(&ioasid_xa, &id, data, XA_LIMIT(min, max), GFP_KERNEL)) {
pr_err("Failed to alloc ioasid from %d to %d\n", min, max);
goto exit_free;
}
data->id = id;
return id;
exit_free:
kfree(data);
return INVALID_IOASID;
}
EXPORT_SYMBOL_GPL(ioasid_alloc);
/**
* ioasid_free - Free an IOASID
* @ioasid: the ID to remove
*/
void ioasid_free(ioasid_t ioasid)
{
struct ioasid_data *ioasid_data;
ioasid_data = xa_erase(&ioasid_xa, ioasid);
kfree_rcu(ioasid_data, rcu);
}
EXPORT_SYMBOL_GPL(ioasid_free);
/**
* ioasid_find - Find IOASID data
* @set: the IOASID set
* @ioasid: the IOASID to find
* @getter: function to call on the found object
*
* The optional getter function allows to take a reference to the found object
* under the rcu lock. The function can also check if the object is still valid:
* if @getter returns false, then the object is invalid and NULL is returned.
*
* If the IOASID exists, return the private pointer passed to ioasid_alloc.
* Private data can be NULL if not set. Return an error if the IOASID is not
* found, or if @set is not NULL and the IOASID does not belong to the set.
*/
void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid,
bool (*getter)(void *))
{
void *priv;
struct ioasid_data *ioasid_data;
rcu_read_lock();
ioasid_data = xa_load(&ioasid_xa, ioasid);
if (!ioasid_data) {
priv = ERR_PTR(-ENOENT);
goto unlock;
}
if (set && ioasid_data->set != set) {
/* data found but does not belong to the set */
priv = ERR_PTR(-EACCES);
goto unlock;
}
/* Now IOASID and its set is verified, we can return the private data */
priv = rcu_dereference(ioasid_data->private);
if (getter && !getter(priv))
priv = NULL;
unlock:
rcu_read_unlock();
return priv;
}
EXPORT_SYMBOL_GPL(ioasid_find);
MODULE_AUTHOR("Jean-Philippe Brucker <jean-philippe.brucker@arm.com>");
MODULE_AUTHOR("Jacob Pan <jacob.jun.pan@linux.intel.com>");
MODULE_DESCRIPTION("IO Address Space ID (IOASID) allocator");
MODULE_LICENSE("GPL");
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