Hi Jacob,

On 8/22/20 12:35 PM, Jacob Pan wrote:
ioasid_set was introduced as an arbitrary token that are shared by a
group of IOASIDs. For example, if IOASID #1 and #2 are allocated via the
same ioasid_set*, they are viewed as to belong to the same set.

For guest SVA usages, system-wide IOASID resources need to be
partitioned such that VMs 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 stored in the new ioasid_set but with optional types

ioasid_set level APIs are introduced that wires 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 |  27 ++-
  drivers/iommu/intel/pasid.h |   1 +
  drivers/iommu/intel/svm.c   |   8 +-
  drivers/iommu/ioasid.c      | 390 +++++++++++++++++++++++++++++++++++++++++---
  include/linux/ioasid.h      |  82 ++++++++--
  5 files changed, 465 insertions(+), 43 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index a3a0b5c8921d..5813eeaa5edb 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -42,6 +42,7 @@
  #include <linux/crash_dump.h>
  #include <linux/numa.h>
  #include <linux/swiotlb.h>
+#include <linux/ioasid.h>
  #include <asm/irq_remapping.h>
  #include <asm/cacheflush.h>
  #include <asm/iommu.h>
@@ -103,6 +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;
@@ -3103,8 +3107,8 @@ 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("Cannot free IOASID %d, not in system set\n", ioasid);
                return;
        }
        vcmd_free_pasid(iommu, ioasid);
@@ -3288,6 +3292,19 @@ static int __init init_dmars(void)
        if (ret)
                goto free_iommu;
+ /* PASID is needed for scalable mode irrespective to SVM */
+       if (intel_iommu_sm) {
+               ioasid_install_capacity(intel_pasid_max_id);
+               /* We should not run out of IOASIDs at boot */
+               host_pasid_set = ioasid_alloc_set(NULL, PID_MAX_DEFAULT,
+                                               IOASID_SET_TYPE_NULL);
+               if (IS_ERR_OR_NULL(host_pasid_set)) {
+                       pr_err("Failed to enable host PASID allocator %lu\n",
+                               PTR_ERR(host_pasid_set));
+                       intel_iommu_sm = 0;
+               }
+       }
+
        /*
         * for each drhd
         *   enable fault log
@@ -5149,7 +5166,7 @@ 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,
@@ -5167,7 +5184,7 @@ 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) {
@@ -5210,7 +5227,7 @@ 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 37a9beabc0ca..634e191ca2c3 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -551,7 +551,7 @@ 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);
@@ -568,7 +568,7 @@ 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;
@@ -586,7 +586,7 @@ 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;
@@ -655,7 +655,7 @@ 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);
diff --git a/drivers/iommu/ioasid.c b/drivers/iommu/ioasid.c
index 5f63af07acd5..f73b3dbfc37a 100644
--- a/drivers/iommu/ioasid.c
+++ b/drivers/iommu/ioasid.c
@@ -1,22 +1,58 @@
  // 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.
+ * subsets. Users create a subset with ioasid_alloc_set, then allocate/free IDs
+ * 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>
+#include <linux/ioasid.h>
+
+static DEFINE_XARRAY_ALLOC(ioasid_sets);
+enum ioasid_state {
+       IOASID_STATE_INACTIVE,
+       IOASID_STATE_ACTIVE,
+       IOASID_STATE_FREE_PENDING,
+};
+/**
+ * struct ioasid_data - Meta data about ioasid
+ *
+ * @id:                Unique ID
+ * @users      Number of active users
+ * @state      Track state of the IOASID
+ * @set                Meta data of the set this IOASID belongs to
+ * @private    Private data associated with the IOASID
+ * @rcu                For free after RCU grace period
+ */
  struct ioasid_data {
        ioasid_t id;
        struct ioasid_set *set;
+       refcount_t users;
+       enum ioasid_state state;
        void *private;
        struct rcu_head rcu;
  };
+/* Default to PCIe standard 20 bit PASID */
+#define PCI_PASID_MAX 0x100000
+static ioasid_t ioasid_capacity = PCI_PASID_MAX;
+static ioasid_t ioasid_capacity_avail = PCI_PASID_MAX;
+
+void ioasid_install_capacity(ioasid_t total)
+{
+       ioasid_capacity = ioasid_capacity_avail = total;

Need any check for multiple settings or setting after used?

+}
+EXPORT_SYMBOL_GPL(ioasid_install_capacity);
+
+ioasid_t ioasid_get_capacity()
+{
+       return ioasid_capacity;
+}
+EXPORT_SYMBOL_GPL(ioasid_get_capacity);
+
  /*
   * struct ioasid_allocator_data - Internal data structure to hold information
   * about an allocator. There are two types of allocators:
@@ -306,11 +342,23 @@ 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(xa_load(&ioasid_sets, set->sid) != set)) {
+               pr_warn("Invalid set\n");
+               goto done_unlock;
+       }
+
+       if (set->quota <= set->nr_ioasids) {
+               pr_err("IOASID set %d out of quota %d\n", set->sid, 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;
@@ -319,7 +367,6 @@ 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) {
@@ -335,42 +382,339 @@ ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t 
min, ioasid_t max,
                goto exit_free;
        }
        data->id = id;
+       data->state = IOASID_STATE_ACTIVE;
+       refcount_set(&data->users, 1);
+
+       /* Store IOASID in the per set data */
+       if (xa_err(xa_store(&set->xa, id, data, GFP_ATOMIC))) {
+               pr_err("Failed to ioasid %d in set %d\n", id, set->sid);
+               goto exit_free;
+       }
+       set->nr_ioasids++;
+       goto done_unlock;
- spin_unlock(&ioasid_allocator_lock);
-       return id;
  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);
+static void ioasid_do_free(struct ioasid_data *data)
+{
+       struct ioasid_data *ioasid_data;
+       struct ioasid_set *sdata;
+
+       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, data->id);
+               kfree_rcu(ioasid_data, rcu);
+       }
+
+       sdata = xa_load(&ioasid_sets, data->set->sid);
+       if (!sdata) {
+               pr_err("No set %d for IOASID %d\n", data->set->sid,
+                      data->id);
+               return;
+       }
+       xa_erase(&sdata->xa, data->id);
+       sdata->nr_ioasids--;
+}
+
+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;
+       }
+       data->state = IOASID_STATE_FREE_PENDING;
+
+       if (!refcount_dec_and_test(&data->users))
+               return;
+
+       ioasid_do_free(data);
+}
+
  /**
- * ioasid_free - Free an IOASID
- * @ioasid: the ID to remove
+ * 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(ioasid_t ioasid)
+void ioasid_free(struct ioasid_set *set, ioasid_t ioasid)
  {
-       struct ioasid_data *ioasid_data;
+       spin_lock(&ioasid_allocator_lock);
+       ioasid_free_locked(set, ioasid);
+       spin_unlock(&ioasid_allocator_lock);
+}
+EXPORT_SYMBOL_GPL(ioasid_free);
+/**
+ * ioasid_alloc_set - Allocate a new IOASID set for a given token
+ *
+ * @token:     Unique token of the IOASID set, cannot be NULL

What's the use of @token? I might be able to find the answer in the
code, but i have no idea when i comes here first time. :-)

This line of comment says that token cannot be NULL. It seems not to
match the real code, where token could be NULL if type is
IOASID_SET_TYPE_NULL.

+ * @quota:     Quota allowed in this set. Only for new set creation
+ * @flags:     Special requirements
+ *
+ * IOASID can be limited system-wide resource that requires quota management.
+ * If caller does not wish to enforce quota, use IOASID_SET_NO_QUOTA flag.

If you are not going to add NO_QUOTA support this time, I'd suggest you
to remove above comment.

+ *
+ * Token will be stored in the ioasid_set returned. A reference will be taken
+ * upon finding a matching set or newly created set.
+ * IOASID allocation within the set and other per set operations will use
+ * the retured ioasid_set *.

nit: remove *, or you mean the ioasid_set pointer?

+ *
+ */
+struct ioasid_set *ioasid_alloc_set(void *token, ioasid_t quota, int type)
+{
+       struct ioasid_set *sdata;
+       unsigned long index;
+       ioasid_t id;
+
+       if (type >= IOASID_SET_TYPE_NR)
+               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.
+        */
        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);
+       if (quota > ioasid_capacity_avail) {

Thinking that ioasid_set itself needs an ioasid, so the check might be

        (quota + 1 > ioasid_capacity_avail)?

+               pr_warn("Out of IOASID capacity! ask %d, avail %d\n",
+                       quota, ioasid_capacity_avail);
+               sdata = ERR_PTR(-ENOSPC);
                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);
+       /*
+        * 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:
+               /* Search existing set tokens, reject duplicates */
+               xa_for_each(&ioasid_sets, index, sdata) {
+                       if (sdata->token == token &&
+                               sdata->type == IOASID_SET_TYPE_MM) {
+                               sdata = ERR_PTR(-EEXIST);
+                               goto exit_unlock;
+                       }
+               }

Do you need to enforce non-NULL token policy here?

+               break;
+       case IOASID_SET_TYPE_NULL:
+               if (!token)
+                       break;
+               fallthrough;
+       default:
+               pr_err("Invalid token and IOASID type\n");
+               sdata = ERR_PTR(-EINVAL);
+               goto exit_unlock;
        }
+ /* REVISIT: may support set w/o quota, use system available */
+       if (!quota) {
+               sdata = ERR_PTR(-EINVAL);
+               goto exit_unlock;
+       }
+
+       sdata = kzalloc(sizeof(*sdata), GFP_ATOMIC);
+       if (!sdata) {
+               sdata = ERR_PTR(-ENOMEM);
+               goto exit_unlock;
+       }
+
+       if (xa_alloc(&ioasid_sets, &id, sdata,
+                       XA_LIMIT(0, ioasid_capacity_avail - quota),
+                       GFP_ATOMIC)) {
+               kfree(sdata);
+               sdata = ERR_PTR(-ENOSPC);
+               goto exit_unlock;
+       }
+
+       sdata->token = token;
+       sdata->type = type;
+       sdata->quota = quota;
+       sdata->sid = id;
+       refcount_set(&sdata->ref, 1);
+
+       /*
+        * Per set XA is used to store private IDs within the set, get ready
+        * for ioasid_set private ID and system-wide IOASID allocation
+        * results.
+        */

I'm not sure that I understood the per-set XA correctly. Is it used to
save both private ID and real ID allocated from the system-wide pool? If
so, isn't private id might be equal to real ID?

+       xa_init_flags(&sdata->xa, XA_FLAGS_ALLOC);
+       ioasid_capacity_avail -= quota;

As mentioned above, the ioasid_set consumed one extra ioasid, so

        ioasid_capacity_avail -= (quota + 1);

?

+
  exit_unlock:
        spin_unlock(&ioasid_allocator_lock);
+
+       return sdata;
  }
-EXPORT_SYMBOL_GPL(ioasid_free);
+EXPORT_SYMBOL_GPL(ioasid_alloc_set);
+
+void ioasid_set_get_locked(struct ioasid_set *set)
+{
+       if (WARN_ON(xa_load(&ioasid_sets, set->sid) != set)) {
+               pr_warn("Invalid set data\n");
+               return;
+       }
+
+       refcount_inc(&set->ref);
+}
+EXPORT_SYMBOL_GPL(ioasid_set_get_locked);
+
+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);
+
+void ioasid_set_put_locked(struct ioasid_set *set)
+{
+       struct ioasid_data *entry;
+       unsigned long index;
+
+       if (WARN_ON(xa_load(&ioasid_sets, set->sid) != set)) {

There are multiple occurences of this line of code, how about defining
it as a inline helper?

static inline bool ioasid_is_valid(struct ioasid_set *set)
{
        return xa_load(&ioasid_sets, set->sid) == set;
}

+               pr_warn("Invalid set data\n");
+               return;
+       }
+
+       if (!refcount_dec_and_test(&set->ref)) {
+               pr_debug("%s: IOASID set %d has %d users\n",
+                       __func__, set->sid, refcount_read(&set->ref));
+               return;
+       }
+
+       /* The set is already empty, we just destroy the set. */
+       if (xa_empty(&set->xa))
+               goto done_destroy;
+
+       /*
+        * 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;
+       kfree_rcu(set, rcu);
+
+       /*
+        * 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->sid);

No. pointer is used after free.

+}
+EXPORT_SYMBOL_GPL(ioasid_set_put_locked);
+
+/**
+ * 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_adjust_set - Adjust the quota of an IOASID set
+ * @set:       IOASID set to be assigned
+ * @quota:     Quota allowed in this set
+ *
+ * Return 0 on success. If the new quota is smaller than the number of
+ * IOASIDs already allocated, -EINVAL will be returned. No change will be
+ * made to the existing quota.
+ */
+int ioasid_adjust_set(struct ioasid_set *set, int quota)
+{
+       int ret = 0;
+
+       spin_lock(&ioasid_allocator_lock);
+       if (set->nr_ioasids > quota) {
+               pr_err("New quota %d is smaller than outstanding IOASIDs %d\n",
+                       quota, set->nr_ioasids);
+               ret = -EINVAL;
+               goto done_unlock;
+       }
+
+       if (quota >= ioasid_capacity_avail) {

This check doesn't make sense since you are updating (not asking for) a
quota.

if ((quota > set->quota) &&
    (quota - set->quota > ioasid_capacity_avail))

+               ret = -ENOSPC;
+               goto done_unlock;
+       }
+
+       /* Return the delta back to system pool */
+       ioasid_capacity_avail += set->quota - quota;

ioasid_capacity_avail is defined as a unsigned int, hence this always
increase the available capacity value even the caller is asking for a
bigger quota?

+
+       /*
+        * May have a policy to prevent giving all available IOASIDs
+        * to one set. But we don't enforce here, it should be in the
+        * upper layers.
+        */
+       set->quota = quota;
+
+done_unlock:
+       spin_unlock(&ioasid_allocator_lock);
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(ioasid_adjust_set);
+
+/**
+ * ioasid_set_for_each_ioasid - Iterate over all the IOASIDs within the set
+ *
+ * Caller must hold a reference of the set and handles its own locking.

Do you need to hold ioasid_allocator_lock here?

+ */
+int ioasid_set_for_each_ioasid(struct ioasid_set *set,
+                              void (*fn)(ioasid_t id, void *data),
+                              void *data)
+{
+       struct ioasid_data *entry;
+       unsigned long index;
+       int ret = 0;
+
+       if (xa_empty(&set->xa)) {
+               pr_warn("No IOASIDs in the set %d\n", set->sid);
+               return -ENOENT;
+       }
+
+       xa_for_each(&set->xa, index, entry) {
+               fn(index, data);
+       }
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(ioasid_set_for_each_ioasid);
/**
   * ioasid_find - Find IOASID data
diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h
index 9c44947a68c8..412d025d440e 100644
--- a/include/linux/ioasid.h
+++ b/include/linux/ioasid.h
@@ -10,8 +10,35 @@ 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,
+                                  * i.e. associated with a process
+                                  */
+       IOASID_SET_TYPE_NR,
+};
+
+/**
+ * struct ioasid_set - Meta data about ioasid_set
+ * @type:      Token types and other features
+ * @token:     Unique to identify an IOASID 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
+ * @nr_ioasids Number of IOASIDs currently allocated in the set
+ * @sid:       ID of the set
+ * @ref:       Reference count of the users
+ */
  struct ioasid_set {
-       int dummy;
+       void *token;
+       struct xarray xa;
+       int type;
+       int quota;
+       int nr_ioasids;
+       int sid;
+       refcount_t ref;
+       struct rcu_head rcu;
  };
/**
@@ -29,31 +56,64 @@ 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_alloc_set(void *token, ioasid_t quota, int type);
+int ioasid_adjust_set(struct ioasid_set *set, int quota);
+void ioasid_set_get_locked(struct ioasid_set *set);
+void ioasid_set_put_locked(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_find(struct ioasid_set *set, ioasid_t ioasid,
-                 bool (*getter)(void *));
+void ioasid_free(struct ioasid_set *set, ioasid_t ioasid);
+
+bool ioasid_is_active(ioasid_t ioasid);
+
+void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid, bool (*getter)(void 
*));
+int ioasid_attach_data(ioasid_t ioasid, void *data);
  int ioasid_register_allocator(struct ioasid_allocator_ops *allocator);
  void ioasid_unregister_allocator(struct ioasid_allocator_ops *allocator);
-int ioasid_attach_data(ioasid_t ioasid, void *data);
-
+void ioasid_is_in_set(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);
  #else /* !CONFIG_IOASID */
+static inline void ioasid_install_capacity(ioasid_t total)
+{
+}
+
+static inline ioasid_t ioasid_get_capacity(void)
+{
+       return 0;
+}
+
  static inline ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min,
                                    ioasid_t max, void *private)
  {
        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 bool ioasid_is_active(ioasid_t ioasid)
+{
+       return false;
+}
+
+static inline struct ioasid_set *ioasid_alloc_set(void *token, ioasid_t quota, 
int type)
+{
+       return ERR_PTR(-ENOTSUPP);
+}
+
+static inline void ioasid_set_put(struct ioasid_set *set)
  {
  }
-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 *))
  {
        return NULL;
  }


Best regards,
baolu
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