On Mon, Sep 28, 2020 at 02:38:32PM -0700, Jacob Pan wrote:
> ioasid_set was introduced as an arbitrary token that is shared by a
> group of IOASIDs. For example, two IOASIDs allocated via the same
> ioasid_set pointer belong to the same set.
> 
> For guest SVA usages, system-wide IOASID resources need to be
> partitioned such that each VM can have its own quota and being managed
> separately. ioasid_set is the perfect candidate for meeting such
> requirements. This patch redefines and extends ioasid_set with the
> following new fields:
> - Quota
> - Reference count
> - Storage of its namespace
> - The token is now stored in the ioasid_set with types
> 
> Basic ioasid_set level APIs are introduced that wire up these new data.
> Existing users of IOASID APIs are converted where a host IOASID set is
> allocated for bare-metal usage.
> 
> Signed-off-by: Liu Yi L <yi.l....@intel.com>
> Signed-off-by: Jacob Pan <jacob.jun....@linux.intel.com>
> ---
>  drivers/iommu/intel/iommu.c |  26 +++--
>  drivers/iommu/intel/pasid.h |   1 +
>  drivers/iommu/intel/svm.c   |  25 ++--
>  drivers/iommu/ioasid.c      | 277 
> ++++++++++++++++++++++++++++++++++++++++----
>  include/linux/ioasid.h      |  53 +++++++--
>  5 files changed, 333 insertions(+), 49 deletions(-)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index e7bcb299e51e..872391890323 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -104,6 +104,9 @@
>   */
>  #define INTEL_IOMMU_PGSIZES  (~0xFFFUL)
>  
> +/* PASIDs used by host SVM */
> +struct ioasid_set *host_pasid_set;
> +
>  static inline int agaw_to_level(int agaw)
>  {
>       return agaw + 2;
> @@ -3147,8 +3150,8 @@ static void intel_vcmd_ioasid_free(ioasid_t ioasid, 
> void *data)
>        * Sanity check the ioasid owner is done at upper layer, e.g. VFIO
>        * We can only free the PASID when all the devices are unbound.
>        */
> -     if (ioasid_find(NULL, ioasid, NULL)) {
> -             pr_alert("Cannot free active IOASID %d\n", ioasid);
> +     if (IS_ERR(ioasid_find(host_pasid_set, ioasid, NULL))) {
> +             pr_err("IOASID %d to be freed but not in system set\n", ioasid);
>               return;
>       }
>       vcmd_free_pasid(iommu, ioasid);
> @@ -3333,8 +3336,17 @@ static int __init init_dmars(void)
>               goto free_iommu;
>  
>       /* PASID is needed for scalable mode irrespective to SVM */
> -     if (intel_iommu_sm)
> +     if (intel_iommu_sm) {
>               ioasid_install_capacity(intel_pasid_max_id);
> +             /* We should not run out of IOASIDs at boot */
> +             host_pasid_set = ioasid_set_alloc(NULL, PID_MAX_DEFAULT,
> +                                               IOASID_SET_TYPE_NULL);
> +             if (IS_ERR_OR_NULL(host_pasid_set)) {
> +                     pr_err("Failed to allocate host PASID set %lu\n",

Printing a negative value as unsigned

> +                             PTR_ERR(host_pasid_set));
> +                     intel_iommu_sm = 0;
> +             }
> +     }
>  
>       /*
>        * for each drhd
> @@ -3381,7 +3393,7 @@ static int __init init_dmars(void)
>               disable_dmar_iommu(iommu);
>               free_dmar_iommu(iommu);
>       }
> -
> +     ioasid_set_put(host_pasid_set);
>       kfree(g_iommus);
>  
>  error:
> @@ -5163,7 +5175,7 @@ static void auxiliary_unlink_device(struct dmar_domain 
> *domain,
>       domain->auxd_refcnt--;
>  
>       if (!domain->auxd_refcnt && domain->default_pasid > 0)
> -             ioasid_free(domain->default_pasid);
> +             ioasid_free(host_pasid_set, domain->default_pasid);
>  }
>  
>  static int aux_domain_add_dev(struct dmar_domain *domain,
> @@ -5181,7 +5193,7 @@ static int aux_domain_add_dev(struct dmar_domain 
> *domain,
>               int pasid;
>  
>               /* No private data needed for the default pasid */
> -             pasid = ioasid_alloc(NULL, PASID_MIN,
> +             pasid = ioasid_alloc(host_pasid_set, PASID_MIN,
>                                    pci_max_pasids(to_pci_dev(dev)) - 1,
>                                    NULL);
>               if (pasid == INVALID_IOASID) {
> @@ -5224,7 +5236,7 @@ static int aux_domain_add_dev(struct dmar_domain 
> *domain,
>       spin_unlock(&iommu->lock);
>       spin_unlock_irqrestore(&device_domain_lock, flags);
>       if (!domain->auxd_refcnt && domain->default_pasid > 0)
> -             ioasid_free(domain->default_pasid);
> +             ioasid_free(host_pasid_set, domain->default_pasid);
>  
>       return ret;
>  }
> diff --git a/drivers/iommu/intel/pasid.h b/drivers/iommu/intel/pasid.h
> index c9850766c3a9..ccdc23446015 100644
> --- a/drivers/iommu/intel/pasid.h
> +++ b/drivers/iommu/intel/pasid.h
> @@ -99,6 +99,7 @@ static inline bool pasid_pte_is_present(struct pasid_entry 
> *pte)
>  }
>  
>  extern u32 intel_pasid_max_id;
> +extern struct ioasid_set *host_pasid_set;
>  int intel_pasid_alloc_id(void *ptr, int start, int end, gfp_t gfp);
>  void intel_pasid_free_id(int pasid);
>  void *intel_pasid_lookup_id(int pasid);
> diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
> index 06a16bee7b65..2e764e283469 100644
> --- a/drivers/iommu/intel/svm.c
> +++ b/drivers/iommu/intel/svm.c
> @@ -228,7 +228,9 @@ static LIST_HEAD(global_svm_list);
>       list_for_each_entry((sdev), &(svm)->devs, list) \
>               if ((d) != (sdev)->dev) {} else
>  
> -static int pasid_to_svm_sdev(struct device *dev, unsigned int pasid,
> +static int pasid_to_svm_sdev(struct device *dev,
> +                          struct ioasid_set *set,
> +                          unsigned int pasid,
>                            struct intel_svm **rsvm,
>                            struct intel_svm_dev **rsdev)
>  {
> @@ -242,7 +244,7 @@ static int pasid_to_svm_sdev(struct device *dev, unsigned 
> int pasid,
>       if (pasid == INVALID_IOASID || pasid >= PASID_MAX)
>               return -EINVAL;
>  
> -     svm = ioasid_find(NULL, pasid, NULL);
> +     svm = ioasid_find(set, pasid, NULL);
>       if (IS_ERR(svm))
>               return PTR_ERR(svm);
>  
> @@ -312,7 +314,8 @@ int intel_svm_bind_gpasid(struct iommu_domain *domain, 
> struct device *dev,
>       dmar_domain = to_dmar_domain(domain);
>  
>       mutex_lock(&pasid_mutex);
> -     ret = pasid_to_svm_sdev(dev, data->hpasid, &svm, &sdev);
> +     ret = pasid_to_svm_sdev(dev, NULL,
> +                             data->hpasid, &svm, &sdev);
>       if (ret)
>               goto out;
>  
> @@ -417,7 +420,7 @@ int intel_svm_unbind_gpasid(struct device *dev, int pasid)
>               return -EINVAL;
>  
>       mutex_lock(&pasid_mutex);
> -     ret = pasid_to_svm_sdev(dev, pasid, &svm, &sdev);
> +     ret = pasid_to_svm_sdev(dev, NULL, pasid, &svm, &sdev);
>       if (ret)
>               goto out;
>  
> @@ -555,7 +558,7 @@ intel_svm_bind_mm(struct device *dev, int flags, struct 
> svm_dev_ops *ops,
>                       pasid_max = intel_pasid_max_id;
>  
>               /* Do not use PASID 0, reserved for RID to PASID */
> -             svm->pasid = ioasid_alloc(NULL, PASID_MIN,
> +             svm->pasid = ioasid_alloc(host_pasid_set, PASID_MIN,
>                                         pasid_max - 1, svm);
>               if (svm->pasid == INVALID_IOASID) {
>                       kfree(svm);
> @@ -572,7 +575,7 @@ intel_svm_bind_mm(struct device *dev, int flags, struct 
> svm_dev_ops *ops,
>               if (mm) {
>                       ret = mmu_notifier_register(&svm->notifier, mm);
>                       if (ret) {
> -                             ioasid_free(svm->pasid);
> +                             ioasid_free(host_pasid_set, svm->pasid);
>                               kfree(svm);
>                               kfree(sdev);
>                               goto out;
> @@ -590,7 +593,7 @@ intel_svm_bind_mm(struct device *dev, int flags, struct 
> svm_dev_ops *ops,
>               if (ret) {
>                       if (mm)
>                               mmu_notifier_unregister(&svm->notifier, mm);
> -                     ioasid_free(svm->pasid);
> +                     ioasid_free(host_pasid_set, svm->pasid);
>                       kfree(svm);
>                       kfree(sdev);
>                       goto out;
> @@ -638,7 +641,8 @@ static int intel_svm_unbind_mm(struct device *dev, int 
> pasid)
>       if (!iommu)
>               goto out;
>  
> -     ret = pasid_to_svm_sdev(dev, pasid, &svm, &sdev);
> +     ret = pasid_to_svm_sdev(dev, host_pasid_set,
> +                             pasid, &svm, &sdev);
>       if (ret)
>               goto out;
>  
> @@ -659,7 +663,7 @@ static int intel_svm_unbind_mm(struct device *dev, int 
> pasid)
>                       kfree_rcu(sdev, rcu);
>  
>                       if (list_empty(&svm->devs)) {
> -                             ioasid_free(svm->pasid);
> +                             ioasid_free(host_pasid_set, svm->pasid);
>                               if (svm->mm)
>                                       mmu_notifier_unregister(&svm->notifier, 
> svm->mm);
>                               list_del(&svm->list);
> @@ -1130,7 +1134,8 @@ int intel_svm_page_response(struct device *dev,
>               goto out;
>       }
>  
> -     ret = pasid_to_svm_sdev(dev, prm->pasid, &svm, &sdev);
> +     ret = pasid_to_svm_sdev(dev, host_pasid_set,
> +                             prm->pasid, &svm, &sdev);
>       if (ret || !sdev) {
>               ret = -ENODEV;
>               goto out;
> diff --git a/drivers/iommu/ioasid.c b/drivers/iommu/ioasid.c
> index 4277cb17e15b..61e25c2375ab 100644
> --- a/drivers/iommu/ioasid.c
> +++ b/drivers/iommu/ioasid.c
> @@ -1,8 +1,8 @@
>  // 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.
> + * sets. Users create a set with ioasid_set_alloc, then allocate/free IDs
> + * with ioasid_alloc and ioasid_free.
>   */
>  #include <linux/ioasid.h>
>  #include <linux/module.h>
> @@ -14,6 +14,8 @@
>  #define PCI_PASID_MAX 0x100000
>  static ioasid_t ioasid_capacity = PCI_PASID_MAX;
>  static ioasid_t ioasid_capacity_avail = PCI_PASID_MAX;
> +static DEFINE_XARRAY_ALLOC(ioasid_sets);
> +
>  struct ioasid_data {
>       ioasid_t id;
>       struct ioasid_set *set;
> @@ -343,6 +345,114 @@ void ioasid_detach_data(ioasid_t ioasid)
>  }
>  EXPORT_SYMBOL_GPL(ioasid_detach_data);
>  
> +static inline bool ioasid_set_is_valid(struct ioasid_set *set)

'inline' isn't needed

> +{
> +     return xa_load(&ioasid_sets, set->id) == set;
> +}
> +
> +/**
> + * ioasid_set_alloc - Allocate a new IOASID set for a given token
> + *
> + * @token:   An optional arbitrary number that can be associated with the
> + *           IOASID set. @token can be NULL if the type is
> + *           IOASID_SET_TYPE_NULL
> + * @quota:   Quota allowed in this set
> + * @type:    The type of the token used to create the IOASID set
> + *
> + * IOASID is limited system-wide resource that requires quota management.
> + * Token will be stored in the ioasid_set returned. A reference will be taken
> + * on the newly created set. Subsequent IOASID allocation within the set need
> + * to use the retured ioasid_set pointer.

                 returned

> + */
> +struct ioasid_set *ioasid_set_alloc(void *token, ioasid_t quota, int type)
> +{
> +     struct ioasid_set *set;
> +     unsigned long index;
> +     ioasid_t id;
> +
> +     if (type >= IOASID_SET_TYPE_NR)
> +             return ERR_PTR(-EINVAL);
> +
> +     /* REVISIT: may support set w/o quota, use system available */

You can drop this comment, anyone wanting to pass a quota of zero can send
a patch.

> +     if (!quota)
> +             return ERR_PTR(-EINVAL);
> +
> +     /*
> +      * Need to check space available if we share system-wide quota.
> +      * TODO: we may need to support quota free sets in the future.

You can drop this too

> +      */
> +     spin_lock(&ioasid_allocator_lock);
> +     if (quota > ioasid_capacity_avail) {
> +             pr_warn("Out of IOASID capacity! ask %d, avail %d\n",
> +                     quota, ioasid_capacity_avail);
> +             set = ERR_PTR(-ENOSPC);
> +             goto exit_unlock;
> +     }
> +
> +     /*
> +      * Token is only unique within its types but right now we have only
> +      * mm type. If we have more token types, we have to match type as well.
> +      */
> +     switch (type) {
> +     case IOASID_SET_TYPE_MM:
> +             if (!token) {
> +                     set = ERR_PTR(-EINVAL);
> +                     goto exit_unlock;
> +             }
> +             /* Search existing set tokens, reject duplicates */
> +             xa_for_each(&ioasid_sets, index, set) {
> +                     if (set->token == token &&
> +                             set->type == IOASID_SET_TYPE_MM) {

misaligned

> +                             set = ERR_PTR(-EEXIST);
> +                             goto exit_unlock;
> +                     }
> +             }
> +             break;
> +     case IOASID_SET_TYPE_NULL:
> +             if (!token)
> +                     break;
> +             fallthrough;
> +     default:
> +             pr_err("Invalid token and IOASID type\n");
> +             set = ERR_PTR(-EINVAL);
> +             goto exit_unlock;
> +     }
> +
> +     set = kzalloc(sizeof(*set), GFP_ATOMIC);
> +     if (!set) {
> +             set = ERR_PTR(-ENOMEM);
> +             goto exit_unlock;
> +     }
> +
> +     if (xa_alloc(&ioasid_sets, &id, set,
> +                  XA_LIMIT(0, ioasid_capacity_avail - quota),
> +                  GFP_ATOMIC)) {
> +             kfree(set);
> +             set = ERR_PTR(-ENOSPC);
> +             goto exit_unlock;
> +     }
> +
> +     set->token = token;
> +     set->type = type;
> +     set->quota = quota;
> +     set->id = id;
> +     refcount_set(&set->ref, 1);
> +
> +     /*
> +      * Per set XA is used to store private IDs within the set, get ready

Could drop "get ready". But I think the comment on the ioasid_set struct
is sufficient, maybe you can drop this whole comment.

> +      * for ioasid_set private ID and system-wide IOASID allocation
> +      * results.
> +      */
> +     xa_init(&set->xa);
> +     ioasid_capacity_avail -= quota;
> +
> +exit_unlock:
> +     spin_unlock(&ioasid_allocator_lock);
> +
> +     return set;
> +}
> +EXPORT_SYMBOL_GPL(ioasid_set_alloc);
> +
>  /**
>   * ioasid_alloc - Allocate an IOASID
>   * @set: the IOASID set
> @@ -360,11 +470,22 @@ ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t 
> min, ioasid_t max,
>  {
>       struct ioasid_data *data;
>       void *adata;
> -     ioasid_t id;
> +     ioasid_t id = INVALID_IOASID;
> +
> +     spin_lock(&ioasid_allocator_lock);
> +     /* Check if the IOASID set has been allocated and initialized */
> +     if (WARN_ON(!ioasid_set_is_valid(set)))
> +             goto done_unlock;
> +
> +     if (set->quota <= set->nr_ioasids) {
> +             pr_err_ratelimited("IOASID set out of quota %d\n",
> +                                set->quota);
> +             goto done_unlock;
> +     }
>  
>       data = kzalloc(sizeof(*data), GFP_ATOMIC);
>       if (!data)
> -             return INVALID_IOASID;
> +             goto done_unlock;
>  
>       data->set = set;
>       data->private = private;
> @@ -373,11 +494,10 @@ ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t 
> min, ioasid_t 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);
> +             pr_err_ratelimited("Failed IOASID allocation %lu\n", 
> active_allocator->flags);
>               goto exit_free;
>       }
>  
> @@ -386,46 +506,153 @@ ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t 
> min, ioasid_t max,
>               /* 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);
> +             if (active_allocator->flags & IOASID_ALLOCATOR_CUSTOM)
> +                     xa_erase(&active_allocator->xa, id);

That doesn't look right, given we get here if the CUSTOM flag is set and
xa_alloc() fails. Should it be in the next block?

>               goto exit_free;
>       }
>       data->id = id;
>  
> -     spin_unlock(&ioasid_allocator_lock);
> -     return id;
> +     /* Store IOASID in the per set data */
> +     if (xa_err(xa_store(&set->xa, id, data, GFP_ATOMIC))) {
> +             pr_err_ratelimited("Failed to store ioasid %d in set\n", id);
> +             active_allocator->ops->free(id, active_allocator->ops->pdata);
> +             goto exit_free;

Should set id = INVALID_IOASID. I feel this function would be more
readable if we keep separate error and success paths.

> +     }
> +     set->nr_ioasids++;
> +     goto done_unlock;
>  exit_free:
> -     spin_unlock(&ioasid_allocator_lock);
>       kfree(data);
> -     return INVALID_IOASID;
> +done_unlock:
> +     spin_unlock(&ioasid_allocator_lock);
> +     return id;
>  }
>  EXPORT_SYMBOL_GPL(ioasid_alloc);
>  
> -/**
> - * ioasid_free - Free an IOASID
> - * @ioasid: the ID to remove
> - */
> -void ioasid_free(ioasid_t ioasid)
> +static void ioasid_do_free_locked(struct ioasid_data *data)
>  {
>       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);
> +     active_allocator->ops->free(data->id, 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);
> +             ioasid_data = xa_erase(&active_allocator->xa, data->id);
>               kfree_rcu(ioasid_data, rcu);
>       }
>  
> -exit_unlock:
> +     data->set->nr_ioasids--;
> +     xa_erase(&data->set->xa, data->id);
> +}
> +
> +static void ioasid_free_locked(struct ioasid_set *set, ioasid_t ioasid)
> +{
> +     struct ioasid_data *data;
> +
> +     data = xa_load(&active_allocator->xa, ioasid);
> +     if (!data) {
> +             pr_err("Trying to free unknown IOASID %u\n", ioasid);
> +             return;
> +     }
> +     if (data->set != set) {
> +             pr_warn("Cannot free IOASID %u due to set ownership\n", ioasid);
> +             return;
> +     }
> +     /* Check if the set exists */
> +     if (WARN_ON(!xa_load(&ioasid_sets, data->set->id)))
> +             return;
> +
> +     ioasid_do_free_locked(data);
> +}
> +
> +/**
> + * ioasid_free - Drop reference on an IOASID. Free if refcount drops to 0,
> + *               including free from its set and system-wide list.
> + * @set:     The ioasid_set to check permission with. If not NULL, IOASID
> + *           free will fail if the set does not match.
> + * @ioasid:  The IOASID to remove
> + */
> +void ioasid_free(struct ioasid_set *set, ioasid_t ioasid)
> +{
> +     spin_lock(&ioasid_allocator_lock);
> +     ioasid_free_locked(set, ioasid);
>       spin_unlock(&ioasid_allocator_lock);
>  }
>  EXPORT_SYMBOL_GPL(ioasid_free);
>  
> +static void ioasid_set_get_locked(struct ioasid_set *set)
> +{
> +     if (WARN_ON(!ioasid_set_is_valid(set)))
> +             return;
> +
> +     refcount_inc(&set->ref);
> +}
> +
> +void ioasid_set_get(struct ioasid_set *set)
> +{
> +     spin_lock(&ioasid_allocator_lock);
> +     ioasid_set_get_locked(set);
> +     spin_unlock(&ioasid_allocator_lock);
> +}
> +EXPORT_SYMBOL_GPL(ioasid_set_get);
> +
> +static void ioasid_set_put_locked(struct ioasid_set *set)
> +{
> +     struct ioasid_data *entry;
> +     unsigned long index;
> +
> +     if (WARN_ON(!ioasid_set_is_valid(set)))
> +             return;
> +
> +     if (!refcount_dec_and_test(&set->ref))
> +             return;
> +
> +     /* The set is already empty, we just destroy the set. */
> +     if (xa_empty(&set->xa))
> +             goto done_destroy;

Do we need this optimization, if xa_for_each() is allowed on the empty xa?
This function doesn't really need to be fast. Otherwise you can just test
nr_ioasids.

> +
> +     /*
> +      * Free all PASIDs from system-wide IOASID pool, all subscribers gets
> +      * notified and do cleanup of their own.
> +      * Note that some references of the IOASIDs within the set can still
> +      * be held after the free call. This is OK in that the IOASIDs will be
> +      * marked inactive, the only operations can be done is ioasid_put.
> +      * No need to track IOASID set states since there is no reclaim phase.
> +      */
> +     xa_for_each(&set->xa, index, entry) {
> +             ioasid_free_locked(set, index);
> +             /* Free from per set private pool */
> +             xa_erase(&set->xa, index);
> +     }
> +
> +done_destroy:
> +     /* Return the quota back to system pool */
> +     ioasid_capacity_avail += set->quota;
> +
> +     /*
> +      * Token got released right away after the ioasid_set is freed.
> +      * If a new set is created immediately with the newly released token,
> +      * it will not allocate the same IOASIDs unless they are reclaimed.
> +      */
> +     xa_erase(&ioasid_sets, set->id);
> +     kfree_rcu(set, rcu);
> +}
> +
> +/**
> + * ioasid_set_put - Drop a reference to the IOASID set. Free all IOASIDs 
> within
> + *                  the set if there are no more users.
> + *
> + * @set:     The IOASID set ID to be freed
> + *
> + * If refcount drops to zero, all IOASIDs allocated within the set will be
> + * freed.
> + */
> +void ioasid_set_put(struct ioasid_set *set)
> +{
> +     spin_lock(&ioasid_allocator_lock);
> +     ioasid_set_put_locked(set);
> +     spin_unlock(&ioasid_allocator_lock);
> +}
> +EXPORT_SYMBOL_GPL(ioasid_set_put);
> +
>  /**
>   * ioasid_find - Find IOASID data
>   * @set: the IOASID set
> diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h
> index 7fc320656be2..1ae213b660f0 100644
> --- a/include/linux/ioasid.h
> +++ b/include/linux/ioasid.h
> @@ -4,14 +4,43 @@
>  
>  #include <linux/types.h>
>  #include <linux/errno.h>
> +#include <linux/xarray.h>
> +#include <linux/refcount.h>
>  
>  #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);
>  
> +/* IOASID set types */
> +enum ioasid_set_type {
> +     IOASID_SET_TYPE_NULL = 1, /* Set token is NULL */
> +     IOASID_SET_TYPE_MM,       /* Set token is a mm_struct pointer
> +                                * i.e. associated with a process
> +                                */
> +     IOASID_SET_TYPE_NR,
> +};
> +
> +/**
> + * struct ioasid_set - Meta data about ioasid_set
> + * @xa:              XArray to store ioasid_set private IDs, can be used for
> + *           guest-host IOASID mapping, or just a private IOASID namespace.
> + * @token:   Unique to identify an IOASID set
> + * @type:    Token types
> + * @quota:   Max number of IOASIDs can be allocated within the set
> + * @nr_ioasids:      Number of IOASIDs currently allocated in the set
> + * @id:              ID of the set
> + * @ref:     Reference count of the users
> + */
>  struct ioasid_set {
> -     int dummy;
> +     struct xarray xa;
> +     void *token;
> +     int type;

Could be an 'enum ioasid_set_type'

> +     int quota;
> +     int nr_ioasids;

These could be unsigned, or ioasid_t

> +     int id;

unsigned as well

> +     refcount_t ref;
> +     struct rcu_head rcu;
>  };
>  
>  /**
> @@ -29,14 +58,16 @@ struct ioasid_allocator_ops {
>       void *pdata;
>  };
>  
> -#define DECLARE_IOASID_SET(name) struct ioasid_set name = { 0 }
> -
>  #if IS_ENABLED(CONFIG_IOASID)
>  void ioasid_install_capacity(ioasid_t total);
>  ioasid_t ioasid_get_capacity(void);
> +struct ioasid_set *ioasid_set_alloc(void *token, ioasid_t quota, int type);
> +void ioasid_set_get(struct ioasid_set *set);
> +void ioasid_set_put(struct ioasid_set *set);
> +
>  ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, ioasid_t max,
>                     void *private);
> -void ioasid_free(ioasid_t ioasid);
> +void ioasid_free(struct ioasid_set *set, 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);
> @@ -59,12 +90,20 @@ static inline ioasid_t ioasid_alloc(struct ioasid_set 
> *set, ioasid_t min,
>       return INVALID_IOASID;
>  }
>  
> -static inline void ioasid_free(ioasid_t ioasid)
> +static inline void ioasid_free(struct ioasid_set *set, ioasid_t ioasid)
> +{
> +}
> +
> +static inline struct ioasid_set *ioasid_set_alloc(void *token, ioasid_t 
> quota, int type)
> +{
> +     return ERR_PTR(-ENOTSUPP);
> +}
> +
> +static inline void ioasid_set_put(struct ioasid_set *set)
>  {
>  }

A stub is missing for ioasid_set_get()

>  
> -static inline void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid,
> -                             bool (*getter)(void *))
> +static inline void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid, 
> bool (*getter)(void *))

Spurious change?

Thanks,
Jean

>  {
>       return NULL;
>  }
> -- 
> 2.7.4
> 

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