diff options
| -rw-r--r-- | drivers/iommu/ioasid.c | 289 | ||||
| -rw-r--r-- | include/linux/ioasid.h | 28 |
2 files changed, 308 insertions, 9 deletions
diff --git a/drivers/iommu/ioasid.c b/drivers/iommu/ioasid.c index aadf500c281c..0f8dd377aada 100644 --- a/drivers/iommu/ioasid.c +++ b/drivers/iommu/ioasid.c @@ -17,7 +17,245 @@ struct ioasid_data { struct rcu_head rcu; }; -static DEFINE_XARRAY_ALLOC(ioasid_xa); +/* + * 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 @@ -32,13 +270,13 @@ 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); + 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; - xa_unlock(&ioasid_xa); + spin_unlock(&ioasid_allocator_lock); /* * Wait for readers to stop accessing the old private data, so the @@ -67,6 +305,7 @@ 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); @@ -76,14 +315,31 @@ ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, ioasid_t max, 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); + /* + * 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; } @@ -97,9 +353,22 @@ void ioasid_free(ioasid_t ioasid) { struct ioasid_data *ioasid_data; - ioasid_data = xa_erase(&ioasid_xa, ioasid); + 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; + } - kfree_rcu(ioasid_data, rcu); + 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); @@ -122,9 +391,11 @@ void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid, { void *priv; struct ioasid_data *ioasid_data; + struct ioasid_allocator_data *idata; rcu_read_lock(); - ioasid_data = xa_load(&ioasid_xa, ioasid); + idata = rcu_dereference(active_allocator); + ioasid_data = xa_load(&idata->xa, ioasid); if (!ioasid_data) { priv = ERR_PTR(-ENOENT); goto unlock; diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h index 17337a13f06e..6f000d7a0ddc 100644 --- a/include/linux/ioasid.h +++ b/include/linux/ioasid.h @@ -7,11 +7,28 @@ #define INVALID_IOASID ((ioasid_t)-1) typedef unsigned int ioasid_t; +typedef ioasid_t (*ioasid_alloc_fn_t)(ioasid_t min, ioasid_t max, void *data); +typedef void (*ioasid_free_fn_t)(ioasid_t ioasid, void *data); struct ioasid_set { int dummy; }; +/** + * struct ioasid_allocator_ops - IOASID allocator helper functions and data + * + * @alloc: helper function to allocate IOASID + * @free: helper function to free IOASID + * @list: for tracking ops that share helper functions but not data + * @pdata: data belong to the allocator, provided when calling alloc() + */ +struct ioasid_allocator_ops { + ioasid_alloc_fn_t alloc; + ioasid_free_fn_t free; + struct list_head list; + void *pdata; +}; + #define DECLARE_IOASID_SET(name) struct ioasid_set name = { 0 } #if IS_ENABLED(CONFIG_IOASID) @@ -20,6 +37,8 @@ ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, ioasid_t max, void ioasid_free(ioasid_t ioasid); void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid, bool (*getter)(void *)); +int ioasid_register_allocator(struct ioasid_allocator_ops *allocator); +void ioasid_unregister_allocator(struct ioasid_allocator_ops *allocator); int ioasid_set_data(ioasid_t ioasid, void *data); #else /* !CONFIG_IOASID */ @@ -39,6 +58,15 @@ static inline void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid, return NULL; } +static inline int ioasid_register_allocator(struct ioasid_allocator_ops *allocator) +{ + return -ENOTSUPP; +} + +static inline void ioasid_unregister_allocator(struct ioasid_allocator_ops *allocator) +{ +} + static inline int ioasid_set_data(ioasid_t ioasid, void *data) { return -ENOTSUPP; |