Hi Jacob, On 8/22/20 6:35 AM, Jacob Pan wrote: > Relations among IOASID users largely follow a publisher-subscriber > pattern. E.g. to support guest SVA on Intel Scalable I/O Virtualization > (SIOV) enabled platforms, VFIO, IOMMU, device drivers, KVM are all users > of IOASIDs. When a state change occurs, VFIO publishes the change event > that needs to be processed by other users/subscribers. > > This patch introduced two types of notifications: global and per > ioasid_set. The latter is intended for users who only needs to handle > events related to the IOASID of a given set. > For more information, refer to the kernel documentation at > Documentation/ioasid.rst. > > Signed-off-by: Liu Yi L <yi.l....@intel.com> > Signed-off-by: Wu Hao <hao...@intel.com> > Signed-off-by: Jacob Pan <jacob.jun....@linux.intel.com> > --- > drivers/iommu/ioasid.c | 280 > ++++++++++++++++++++++++++++++++++++++++++++++++- > include/linux/ioasid.h | 70 +++++++++++++ > 2 files changed, 348 insertions(+), 2 deletions(-) > > diff --git a/drivers/iommu/ioasid.c b/drivers/iommu/ioasid.c > index c0aef38a4fde..6ddc09a7fe74 100644 > --- a/drivers/iommu/ioasid.c > +++ b/drivers/iommu/ioasid.c > @@ -9,8 +9,35 @@ > #include <linux/spinlock.h> > #include <linux/xarray.h> > #include <linux/ioasid.h> > +#include <linux/sched/mm.h> > > static DEFINE_XARRAY_ALLOC(ioasid_sets); > +/* > + * An IOASID could have multiple consumers where each consumeer may have can have multiple consumers > + * hardware contexts associated with IOASIDs. > + * When a status change occurs, such as IOASID is being freed, notifier > chains s/such as IOASID is being freed/, like on IOASID deallocation, > + * are used to keep the consumers in sync. > + * This is a publisher-subscriber pattern where publisher can change the > + * state of each IOASID, e.g. alloc/free, bind IOASID to a device and mm. > + * On the other hand, subscribers gets notified for the state change and > + * keep local states in sync. > + * > + * Currently, the notifier is global. A further optimization could be per > + * IOASID set notifier chain. > + */ > +static ATOMIC_NOTIFIER_HEAD(ioasid_chain); > + > +/* List to hold pending notification block registrations */ > +static LIST_HEAD(ioasid_nb_pending_list); > +static DEFINE_SPINLOCK(ioasid_nb_lock); > +struct ioasid_set_nb { > + struct list_head list; > + struct notifier_block *nb; > + void *token; > + struct ioasid_set *set; > + bool active; > +}; > + > enum ioasid_state { > IOASID_STATE_INACTIVE, > IOASID_STATE_ACTIVE, > @@ -394,6 +421,7 @@ EXPORT_SYMBOL_GPL(ioasid_find_by_spid); > ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, ioasid_t max, > void *private) > { > + struct ioasid_nb_args args; > struct ioasid_data *data; > void *adata; > ioasid_t id = INVALID_IOASID; > @@ -445,8 +473,14 @@ ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t > min, ioasid_t max, > goto exit_free; > } > set->nr_ioasids++; > - goto done_unlock; > + args.id = id; > + /* Set private ID is not attached during allocation */ > + args.spid = INVALID_IOASID; > + args.set = set; > + atomic_notifier_call_chain(&set->nh, IOASID_ALLOC, &args); > > + spin_unlock(&ioasid_allocator_lock); > + return id; spurious change > exit_free: > kfree(data); > done_unlock: > @@ -479,6 +513,7 @@ static void ioasid_do_free(struct ioasid_data *data) > > static void ioasid_free_locked(struct ioasid_set *set, ioasid_t ioasid) > { > + struct ioasid_nb_args args; > struct ioasid_data *data; > > data = xa_load(&active_allocator->xa, ioasid); > @@ -491,7 +526,16 @@ static void ioasid_free_locked(struct ioasid_set *set, > ioasid_t ioasid) > pr_warn("Cannot free IOASID %u due to set ownership\n", ioasid); > return; > } > + spurious new line > data->state = IOASID_STATE_FREE_PENDING; > + /* Notify all users that this IOASID is being freed */ > + args.id = ioasid; > + args.spid = data->spid; > + args.pdata = data->private; > + args.set = data->set; > + atomic_notifier_call_chain(&ioasid_chain, IOASID_FREE, &args); > + /* Notify the ioasid_set for per set users */ > + atomic_notifier_call_chain(&set->nh, IOASID_FREE, &args); > > if (!refcount_dec_and_test(&data->users)) > return; Shouldn't we call the notifier only when ref count == 0? > @@ -514,6 +558,28 @@ void ioasid_free(struct ioasid_set *set, ioasid_t ioasid) > } > EXPORT_SYMBOL_GPL(ioasid_free); > > +static void ioasid_add_pending_nb(struct ioasid_set *set) > +{ > + struct ioasid_set_nb *curr; > + > + if (set->type != IOASID_SET_TYPE_MM) > + return; > + > + /* > + * Check if there are any pending nb requests for the given token, if so > + * add them to the notifier chain. > + */ > + spin_lock(&ioasid_nb_lock); > + list_for_each_entry(curr, &ioasid_nb_pending_list, list) { > + if (curr->token == set->token && !curr->active) { > + atomic_notifier_chain_register(&set->nh, curr->nb); > + curr->set = set; > + curr->active = true; > + } > + } > + spin_unlock(&ioasid_nb_lock); > +} > + > /** > * ioasid_alloc_set - Allocate a new IOASID set for a given token > * > @@ -601,6 +667,13 @@ struct ioasid_set *ioasid_alloc_set(void *token, > ioasid_t quota, int type) > sdata->quota = quota; > sdata->sid = id; > refcount_set(&sdata->ref, 1); > + ATOMIC_INIT_NOTIFIER_HEAD(&sdata->nh); > + > + /* > + * Check if there are any pending nb requests for the given token, if so > + * add them to the notifier chain. > + */ > + ioasid_add_pending_nb(sdata); > > /* > * Per set XA is used to store private IDs within the set, get ready > @@ -617,6 +690,30 @@ struct ioasid_set *ioasid_alloc_set(void *token, > ioasid_t quota, int type) > } > EXPORT_SYMBOL_GPL(ioasid_alloc_set); > > + > +/* > + * ioasid_find_mm_set - Retrieve IOASID set with mm token > + * Take a reference of the set if found. > + */ > +static struct ioasid_set *ioasid_find_mm_set(struct mm_struct *token) > +{ > + struct ioasid_set *sdata, *set = NULL; > + unsigned long index; > + > + spin_lock(&ioasid_allocator_lock); > + > + xa_for_each(&ioasid_sets, index, sdata) { > + if (sdata->type == IOASID_SET_TYPE_MM && sdata->token == token) > { > + refcount_inc(&sdata->ref); > + set = sdata; > + goto exit_unlock; > + } > + } > +exit_unlock: > + spin_unlock(&ioasid_allocator_lock); > + return set; > +} > + > void ioasid_set_get_locked(struct ioasid_set *set) > { > if (WARN_ON(xa_load(&ioasid_sets, set->sid) != set)) { > @@ -638,6 +735,8 @@ EXPORT_SYMBOL_GPL(ioasid_set_get); > > void ioasid_set_put_locked(struct ioasid_set *set) > { > + struct ioasid_nb_args args = { 0 }; > + struct ioasid_set_nb *curr; > struct ioasid_data *entry; > unsigned long index; > > @@ -673,8 +772,24 @@ void ioasid_set_put_locked(struct ioasid_set *set) > done_destroy: > /* Return the quota back to system pool */ > ioasid_capacity_avail += set->quota; > - kfree_rcu(set, rcu); > > + /* Restore pending status of the set NBs */ > + spin_lock(&ioasid_nb_lock); > + list_for_each_entry(curr, &ioasid_nb_pending_list, list) { > + if (curr->token == set->token) { > + if (curr->active) > + curr->active = false; > + else > + pr_warn("Set token exists but not active!\n"); > + } > + } > + spin_unlock(&ioasid_nb_lock); > + > + args.set = set; > + atomic_notifier_call_chain(&ioasid_chain, IOASID_SET_FREE, &args); > + > + kfree_rcu(set, rcu); > + pr_debug("Set freed %d\n", set->sid); > /* > * Token got released right away after the ioasid_set is freed. > * If a new set is created immediately with the newly released token, > @@ -927,6 +1042,167 @@ void *ioasid_find(struct ioasid_set *set, ioasid_t > ioasid, > } > EXPORT_SYMBOL_GPL(ioasid_find); > > +int ioasid_register_notifier(struct ioasid_set *set, struct notifier_block > *nb) > +{ > + if (set) > + return atomic_notifier_chain_register(&set->nh, nb); > + else > + return atomic_notifier_chain_register(&ioasid_chain, nb); > +} > +EXPORT_SYMBOL_GPL(ioasid_register_notifier); > + > +void ioasid_unregister_notifier(struct ioasid_set *set, > + struct notifier_block *nb) > +{ > + struct ioasid_set_nb *curr; > + > + spin_lock(&ioasid_nb_lock); > + /* > + * Pending list is registered with a token without an ioasid_set, > + * therefore should not be unregistered directly. > + */ > + list_for_each_entry(curr, &ioasid_nb_pending_list, list) { > + if (curr->nb == nb) { > + pr_warn("Cannot unregister NB from pending list\n"); > + spin_unlock(&ioasid_nb_lock); > + return; > + } > + } > + spin_unlock(&ioasid_nb_lock); is it safe to release the lock here? What does prevent another NB to be added to ioasid_nb_pending_list after that? > + > + if (set) > + atomic_notifier_chain_unregister(&set->nh, nb); > + else > + atomic_notifier_chain_unregister(&ioasid_chain, nb); > +} > +EXPORT_SYMBOL_GPL(ioasid_unregister_notifier); > + > +int ioasid_register_notifier_mm(struct mm_struct *mm, struct notifier_block > *nb) > +{ > + struct ioasid_set_nb *curr; > + struct ioasid_set *set; > + int ret = 0; > + > + if (!mm) > + return -EINVAL; > + > + spin_lock(&ioasid_nb_lock); > + > + /* Check for duplicates, nb is unique per set */ > + list_for_each_entry(curr, &ioasid_nb_pending_list, list) { > + if (curr->token == mm && curr->nb == nb) { > + ret = -EBUSY; > + goto exit_unlock; > + } > + } > + > + /* Check if the token has an existing set */ > + set = ioasid_find_mm_set(mm); > + if (IS_ERR_OR_NULL(set)) { > + /* Add to the rsvd list as inactive */ > + curr->active = false; > + } else { > + /* REVISIT: Only register empty set for now. Can add an option > + * in the future to playback existing PASIDs. > + */ > + if (set->nr_ioasids) { > + pr_warn("IOASID set %d not empty\n", set->sid); > + ret = -EBUSY; > + goto exit_unlock; > + } > + curr = kzalloc(sizeof(*curr), GFP_ATOMIC); > + if (!curr) { > + ret = -ENOMEM; > + goto exit_unlock; > + } > + curr->token = mm; > + curr->nb = nb; > + curr->active = true; > + curr->set = set; > + > + /* Set already created, add to the notifier chain */ > + atomic_notifier_chain_register(&set->nh, nb); > + /* > + * Do not hold a reference, if the set gets destroyed, the nb > + * entry will be marked inactive. > + */ > + ioasid_set_put(set); > + } > + > + list_add(&curr->list, &ioasid_nb_pending_list); > + > +exit_unlock: > + spin_unlock(&ioasid_nb_lock); > + return ret; > +} > +EXPORT_SYMBOL_GPL(ioasid_register_notifier_mm); > + > +void ioasid_unregister_notifier_mm(struct mm_struct *mm, struct > notifier_block *nb) > +{ > + struct ioasid_set_nb *curr; > + > + spin_lock(&ioasid_nb_lock); > + list_for_each_entry(curr, &ioasid_nb_pending_list, list) { > + if (curr->token == mm && curr->nb == nb) { > + list_del(&curr->list); > + goto exit_free; > + } > + } > + pr_warn("No ioasid set found for mm token %llx\n", (u64)mm); > + goto done_unlock; > + > +exit_free: > + if (curr->active) { > + pr_debug("mm set active, unregister %llx\n", > + (u64)mm); > + atomic_notifier_chain_unregister(&curr->set->nh, nb); > + } > + kfree(curr); > +done_unlock: > + spin_unlock(&ioasid_nb_lock); > + return; > +} > +EXPORT_SYMBOL_GPL(ioasid_unregister_notifier_mm); > + > +/** > + * ioasid_notify - Send notification on a given IOASID for status change. > + * Used by publishers when the status change may affect > + * subscriber's internal state. > + * > + * @ioasid: The IOASID to which the notification will send > + * @cmd: The notification event > + * @flags: Special instructions, e.g. notify with a set or global > + */ > +int ioasid_notify(ioasid_t ioasid, enum ioasid_notify_val cmd, unsigned int > flags) > +{ > + struct ioasid_data *ioasid_data; > + struct ioasid_nb_args args = { 0 }; > + int ret = 0; > + > + spin_lock(&ioasid_allocator_lock); > + ioasid_data = xa_load(&active_allocator->xa, ioasid); > + if (!ioasid_data) { > + pr_err("Trying to notify unknown IOASID %u\n", ioasid); > + spin_unlock(&ioasid_allocator_lock); > + return -EINVAL; > + } > + > + args.id = ioasid; > + args.set = ioasid_data->set; > + args.pdata = ioasid_data->private; > + args.spid = ioasid_data->spid; > + if (flags & IOASID_NOTIFY_ALL) { > + ret = atomic_notifier_call_chain(&ioasid_chain, cmd, &args); > + } else if (flags & IOASID_NOTIFY_SET) { > + ret = atomic_notifier_call_chain(&ioasid_data->set->nh, > + cmd, &args); > + } > + spin_unlock(&ioasid_allocator_lock); > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(ioasid_notify); > + > MODULE_AUTHOR("Jean-Philippe Brucker <jean-philippe.bruc...@arm.com>"); > MODULE_AUTHOR("Jacob Pan <jacob.jun....@linux.intel.com>"); > MODULE_DESCRIPTION("IO Address Space ID (IOASID) allocator"); > diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h > index d4b3e83672f6..572111cd3b4b 100644 > --- a/include/linux/ioasid.h > +++ b/include/linux/ioasid.h > @@ -23,6 +23,7 @@ enum ioasid_set_type { > * struct ioasid_set - Meta data about ioasid_set > * @type: Token types and other features > * @token: Unique to identify an IOASID set > + * @nh: Notifier for IOASID events within the set list of notifiers private to that set? > * @xa: XArray to store ioasid_set private IDs, can be used for > * guest-host IOASID mapping, or just a private IOASID namespace. > * @quota: Max number of IOASIDs can be allocated within the set > @@ -32,6 +33,7 @@ enum ioasid_set_type { > */ > struct ioasid_set { > void *token; > + struct atomic_notifier_head nh; > struct xarray xa; > int type; > int quota; > @@ -56,6 +58,49 @@ struct ioasid_allocator_ops { > void *pdata; > }; > > +/* Notification data when IOASID status changed */ > +enum ioasid_notify_val { > + IOASID_ALLOC = 1, > + IOASID_FREE, > + IOASID_BIND, > + IOASID_UNBIND, > + IOASID_SET_ALLOC, > + IOASID_SET_FREE, > +}; > + > +#define IOASID_NOTIFY_ALL BIT(0) > +#define IOASID_NOTIFY_SET BIT(1) > +/** > + * enum ioasid_notifier_prios - IOASID event notification order > + * > + * When status of an IOASID changes, users might need to take actions to > + * reflect the new state. For example, when an IOASID is freed due to > + * exception, the hardware context in virtual CPU, DMA device, and IOMMU > + * shall be cleared and drained. Order is required to prevent life cycle > + * problems. > + */ > +enum ioasid_notifier_prios { > + IOASID_PRIO_LAST, > + IOASID_PRIO_DEVICE, > + IOASID_PRIO_IOMMU, > + IOASID_PRIO_CPU, > +}; > + > +/** > + * struct ioasid_nb_args - Argument provided by IOASID core when notifier > + * is called. > + * @id: The IOASID being notified > + * @spid: The set private ID associated with the IOASID > + * @set: The IOASID set of @id > + * @pdata: The private data attached to the IOASID > + */ > +struct ioasid_nb_args { > + ioasid_t id; > + ioasid_t spid; > + struct ioasid_set *set; > + void *pdata; > +}; > + > #if IS_ENABLED(CONFIG_IOASID) > void ioasid_install_capacity(ioasid_t total); > ioasid_t ioasid_get_capacity(void); > @@ -75,8 +120,16 @@ void *ioasid_find(struct ioasid_set *set, ioasid_t > ioasid, bool (*getter)(void * > int ioasid_attach_data(ioasid_t ioasid, void *data); > int ioasid_attach_spid(ioasid_t ioasid, ioasid_t spid); > ioasid_t ioasid_find_by_spid(struct ioasid_set *set, ioasid_t spid); > + > +int ioasid_register_notifier(struct ioasid_set *set, > + struct notifier_block *nb); > +void ioasid_unregister_notifier(struct ioasid_set *set, > + struct notifier_block *nb); > + > int ioasid_register_allocator(struct ioasid_allocator_ops *allocator); > void ioasid_unregister_allocator(struct ioasid_allocator_ops *allocator); > + > +int ioasid_notify(ioasid_t ioasid, enum ioasid_notify_val cmd, unsigned int > flags); > void ioasid_is_in_set(struct ioasid_set *set, ioasid_t ioasid); > int ioasid_get(struct ioasid_set *set, ioasid_t ioasid); > int ioasid_get_locked(struct ioasid_set *set, ioasid_t ioasid); > @@ -85,6 +138,9 @@ void ioasid_put_locked(struct ioasid_set *set, ioasid_t > ioasid); > int ioasid_set_for_each_ioasid(struct ioasid_set *sdata, > void (*fn)(ioasid_t id, void *data), > void *data); > +int ioasid_register_notifier_mm(struct mm_struct *mm, struct notifier_block > *nb); > +void ioasid_unregister_notifier_mm(struct mm_struct *mm, struct > notifier_block *nb); > + > #else /* !CONFIG_IOASID */ > static inline void ioasid_install_capacity(ioasid_t total) > { > @@ -124,6 +180,20 @@ static inline void *ioasid_find(struct ioasid_set *set, > ioasid_t ioasid, bool (* > return NULL; > } > > +static inline int ioasid_register_notifier(struct notifier_block *nb) > +{ > + return -ENOTSUPP; > +} > + > +static inline void ioasid_unregister_notifier(struct notifier_block *nb) > +{ > +} > + > +static inline int ioasid_notify(ioasid_t ioasid, enum ioasid_notify_val cmd, > unsigned int flags) > +{ > + return -ENOTSUPP; > +} > + > static inline int ioasid_register_allocator(struct ioasid_allocator_ops > *allocator) > { > return -ENOTSUPP; > Thanks
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