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