+++ /dev/null
-// 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;
-};
-
-/*
- * struct ioasid_allocator_data - Internal data structure to hold information
- * about an allocator. There are two types of allocators:
- *
- * - Default allocator always has its own XArray to track the IOASIDs allocated.
- * - Custom allocators may share allocation helpers with different private data.
- * Custom allocators that share the same helper functions also share the same
- * XArray.
- * Rules:
- * 1. Default allocator is always available, not dynamically registered. This is
- * to prevent race conditions with early boot code that want to register
- * custom allocators or allocate IOASIDs.
- * 2. Custom allocators take precedence over the default allocator.
- * 3. When all custom allocators sharing the same helper functions are
- * unregistered (e.g. due to hotplug), all outstanding IOASIDs must be
- * freed. Otherwise, outstanding IOASIDs will be lost and orphaned.
- * 4. When switching between custom allocators sharing the same helper
- * functions, outstanding IOASIDs are preserved.
- * 5. When switching between custom allocator and default allocator, all IOASIDs
- * must be freed to ensure unadulterated space for the new allocator.
- *
- * @ops: allocator helper functions and its data
- * @list: registered custom allocators
- * @slist: allocators share the same ops but different data
- * @flags: attributes of the allocator
- * @xa: xarray holds the IOASID space
- * @rcu: used for kfree_rcu when unregistering allocator
- */
-struct ioasid_allocator_data {
- struct ioasid_allocator_ops *ops;
- struct list_head list;
- struct list_head slist;
-#define IOASID_ALLOCATOR_CUSTOM BIT(0) /* Needs framework to track results */
- unsigned long flags;
- struct xarray xa;
- struct rcu_head rcu;
-};
-
-static DEFINE_SPINLOCK(ioasid_allocator_lock);
-static LIST_HEAD(allocators_list);
-
-static ioasid_t default_alloc(ioasid_t min, ioasid_t max, void *opaque);
-static void default_free(ioasid_t ioasid, void *opaque);
-
-static struct ioasid_allocator_ops default_ops = {
- .alloc = default_alloc,
- .free = default_free,
-};
-
-static struct ioasid_allocator_data default_allocator = {
- .ops = &default_ops,
- .flags = 0,
- .xa = XARRAY_INIT(ioasid_xa, XA_FLAGS_ALLOC),
-};
-
-static struct ioasid_allocator_data *active_allocator = &default_allocator;
-
-static ioasid_t default_alloc(ioasid_t min, ioasid_t max, void *opaque)
-{
- ioasid_t id;
-
- if (xa_alloc(&default_allocator.xa, &id, opaque, XA_LIMIT(min, max), GFP_ATOMIC)) {
- pr_err("Failed to alloc ioasid from %d to %d\n", min, max);
- return INVALID_IOASID;
- }
-
- return id;
-}
-
-static void default_free(ioasid_t ioasid, void *opaque)
-{
- struct ioasid_data *ioasid_data;
-
- ioasid_data = xa_erase(&default_allocator.xa, ioasid);
- kfree_rcu(ioasid_data, rcu);
-}
-
-/* Allocate and initialize a new custom allocator with its helper functions */
-static struct ioasid_allocator_data *ioasid_alloc_allocator(struct ioasid_allocator_ops *ops)
-{
- struct ioasid_allocator_data *ia_data;
-
- ia_data = kzalloc(sizeof(*ia_data), GFP_ATOMIC);
- if (!ia_data)
- return NULL;
-
- xa_init_flags(&ia_data->xa, XA_FLAGS_ALLOC);
- INIT_LIST_HEAD(&ia_data->slist);
- ia_data->flags |= IOASID_ALLOCATOR_CUSTOM;
- ia_data->ops = ops;
-
- /* For tracking custom allocators that share the same ops */
- list_add_tail(&ops->list, &ia_data->slist);
-
- return ia_data;
-}
-
-static bool use_same_ops(struct ioasid_allocator_ops *a, struct ioasid_allocator_ops *b)
-{
- return (a->free == b->free) && (a->alloc == b->alloc);
-}
-
-/**
- * ioasid_register_allocator - register a custom allocator
- * @ops: the custom allocator ops to be registered
- *
- * Custom allocators take precedence over the default xarray based allocator.
- * Private data associated with the IOASID allocated by the custom allocators
- * are managed by IOASID framework similar to data stored in xa by default
- * allocator.
- *
- * There can be multiple allocators registered but only one is active. In case
- * of runtime removal of a custom allocator, the next one is activated based
- * on the registration ordering.
- *
- * Multiple allocators can share the same alloc() function, in this case the
- * IOASID space is shared.
- */
-int ioasid_register_allocator(struct ioasid_allocator_ops *ops)
-{
- struct ioasid_allocator_data *ia_data;
- struct ioasid_allocator_data *pallocator;
- int ret = 0;
-
- spin_lock(&ioasid_allocator_lock);
-
- ia_data = ioasid_alloc_allocator(ops);
- if (!ia_data) {
- ret = -ENOMEM;
- goto out_unlock;
- }
-
- /*
- * No particular preference, we activate the first one and keep
- * the later registered allocators in a list in case the first one gets
- * removed due to hotplug.
- */
- if (list_empty(&allocators_list)) {
- WARN_ON(active_allocator != &default_allocator);
- /* Use this new allocator if default is not active */
- if (xa_empty(&active_allocator->xa)) {
- rcu_assign_pointer(active_allocator, ia_data);
- list_add_tail(&ia_data->list, &allocators_list);
- goto out_unlock;
- }
- pr_warn("Default allocator active with outstanding IOASID\n");
- ret = -EAGAIN;
- goto out_free;
- }
-
- /* Check if the allocator is already registered */
- list_for_each_entry(pallocator, &allocators_list, list) {
- if (pallocator->ops == ops) {
- pr_err("IOASID allocator already registered\n");
- ret = -EEXIST;
- goto out_free;
- } else if (use_same_ops(pallocator->ops, ops)) {
- /*
- * If the new allocator shares the same ops,
- * then they will share the same IOASID space.
- * We should put them under the same xarray.
- */
- list_add_tail(&ops->list, &pallocator->slist);
- goto out_free;
- }
- }
- list_add_tail(&ia_data->list, &allocators_list);
-
- spin_unlock(&ioasid_allocator_lock);
- return 0;
-out_free:
- kfree(ia_data);
-out_unlock:
- spin_unlock(&ioasid_allocator_lock);
- return ret;
-}
-EXPORT_SYMBOL_GPL(ioasid_register_allocator);
-
-/**
- * ioasid_unregister_allocator - Remove a custom IOASID allocator ops
- * @ops: the custom allocator to be removed
- *
- * Remove an allocator from the list, activate the next allocator in
- * the order it was registered. Or revert to default allocator if all
- * custom allocators are unregistered without outstanding IOASIDs.
- */
-void ioasid_unregister_allocator(struct ioasid_allocator_ops *ops)
-{
- struct ioasid_allocator_data *pallocator;
- struct ioasid_allocator_ops *sops;
-
- spin_lock(&ioasid_allocator_lock);
- if (list_empty(&allocators_list)) {
- pr_warn("No custom IOASID allocators active!\n");
- goto exit_unlock;
- }
-
- list_for_each_entry(pallocator, &allocators_list, list) {
- if (!use_same_ops(pallocator->ops, ops))
- continue;
-
- if (list_is_singular(&pallocator->slist)) {
- /* No shared helper functions */
- list_del(&pallocator->list);
- /*
- * All IOASIDs should have been freed before
- * the last allocator that shares the same ops
- * is unregistered.
- */
- WARN_ON(!xa_empty(&pallocator->xa));
- if (list_empty(&allocators_list)) {
- pr_info("No custom IOASID allocators, switch to default.\n");
- rcu_assign_pointer(active_allocator, &default_allocator);
- } else if (pallocator == active_allocator) {
- rcu_assign_pointer(active_allocator,
- list_first_entry(&allocators_list,
- struct ioasid_allocator_data, list));
- pr_info("IOASID allocator changed");
- }
- kfree_rcu(pallocator, rcu);
- break;
- }
- /*
- * Find the matching shared ops to delete,
- * but keep outstanding IOASIDs
- */
- list_for_each_entry(sops, &pallocator->slist, list) {
- if (sops == ops) {
- list_del(&ops->list);
- break;
- }
- }
- break;
- }
-
-exit_unlock:
- spin_unlock(&ioasid_allocator_lock);
-}
-EXPORT_SYMBOL_GPL(ioasid_unregister_allocator);
-
-/**
- * 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;
-
- spin_lock(&ioasid_allocator_lock);
- ioasid_data = xa_load(&active_allocator->xa, ioasid);
- if (ioasid_data)
- rcu_assign_pointer(ioasid_data->private, data);
- else
- ret = -ENOENT;
- spin_unlock(&ioasid_allocator_lock);
-
- /*
- * 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;
- void *adata;
- ioasid_t id;
-
- data = kzalloc(sizeof(*data), GFP_ATOMIC);
- if (!data)
- return INVALID_IOASID;
-
- data->set = set;
- data->private = private;
-
- /*
- * Custom allocator needs allocator data to perform platform specific
- * operations.
- */
- spin_lock(&ioasid_allocator_lock);
- adata = active_allocator->flags & IOASID_ALLOCATOR_CUSTOM ? active_allocator->ops->pdata : data;
- id = active_allocator->ops->alloc(min, max, adata);
- if (id == INVALID_IOASID) {
- pr_err("Failed ASID allocation %lu\n", active_allocator->flags);
- goto exit_free;
- }
-
- if ((active_allocator->flags & IOASID_ALLOCATOR_CUSTOM) &&
- xa_alloc(&active_allocator->xa, &id, data, XA_LIMIT(id, id), GFP_ATOMIC)) {
- /* Custom allocator needs framework to store and track allocation results */
- pr_err("Failed to alloc ioasid from %d\n", id);
- active_allocator->ops->free(id, active_allocator->ops->pdata);
- goto exit_free;
- }
- data->id = id;
-
- spin_unlock(&ioasid_allocator_lock);
- return id;
-exit_free:
- spin_unlock(&ioasid_allocator_lock);
- 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;
-
- spin_lock(&ioasid_allocator_lock);
- ioasid_data = xa_load(&active_allocator->xa, ioasid);
- if (!ioasid_data) {
- pr_err("Trying to free unknown IOASID %u\n", ioasid);
- goto exit_unlock;
- }
-
- active_allocator->ops->free(ioasid, active_allocator->ops->pdata);
- /* Custom allocator needs additional steps to free the xa element */
- if (active_allocator->flags & IOASID_ALLOCATOR_CUSTOM) {
- ioasid_data = xa_erase(&active_allocator->xa, ioasid);
- kfree_rcu(ioasid_data, rcu);
- }
-
-exit_unlock:
- spin_unlock(&ioasid_allocator_lock);
-}
-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;
- struct ioasid_allocator_data *idata;
-
- rcu_read_lock();
- idata = rcu_dereference(active_allocator);
- ioasid_data = xa_load(&idata->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");
projects / platform / kernel / linux-rpi.git / commitdiff