IOASID set is allocated with an initial quota, at runtime there may be
needs to balance IOASID resources among different VMs/sets.

This patch adds a new API to adjust per set quota.

Signed-off-by: Jacob Pan <jacob.jun....@linux.intel.com>
---
 drivers/iommu/ioasid.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/ioasid.h |  6 ++++++
 2 files changed, 50 insertions(+)

diff --git a/drivers/iommu/ioasid.c b/drivers/iommu/ioasid.c
index 27dce2cb5af2..5ac28862a1db 100644
--- a/drivers/iommu/ioasid.c
+++ b/drivers/iommu/ioasid.c
@@ -578,6 +578,50 @@ void ioasid_free_set(int sid, bool destroy_set)
 }
 EXPORT_SYMBOL_GPL(ioasid_free_set);
 
+/**
+ * ioasid_adjust_set - Adjust the quota of an IOASID set
+ * @quota:     Quota allowed in this set
+ * @sid:       IOASID set ID to be assigned
+ *
+ * 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(int sid, int quota)
+{
+       struct ioasid_set_data *sdata;
+       int ret = 0;
+
+       mutex_lock(&ioasid_allocator_lock);
+       sdata = xa_load(&ioasid_sets, sid);
+       if (!sdata || sdata->nr_ioasids > quota) {
+               pr_err("Failed to adjust IOASID set %d quota %d\n",
+                       sid, quota);
+               ret = -EINVAL;
+               goto done_unlock;
+       }
+
+       if (quota >= ioasid_capacity_avail) {
+               ret = -ENOSPC;
+               goto done_unlock;
+       }
+
+       /* Return the delta back to system pool */
+       ioasid_capacity_avail += sdata->size - 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.
+        */
+       sdata->size = quota;
+
+done_unlock:
+       mutex_unlock(&ioasid_allocator_lock);
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(ioasid_adjust_set);
 
 /**
  * ioasid_find - Find IOASID data
diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h
index 32d032913828..6e7de6fb91bf 100644
--- a/include/linux/ioasid.h
+++ b/include/linux/ioasid.h
@@ -73,6 +73,7 @@ int ioasid_alloc_set(struct ioasid_set *token, ioasid_t 
quota, int *sid);
 void ioasid_free_set(int sid, bool destroy_set);
 int ioasid_find_sid(ioasid_t ioasid);
 int ioasid_notify(ioasid_t id, enum ioasid_notify_val cmd);
+int ioasid_adjust_set(int sid, int quota);
 
 #else /* !CONFIG_IOASID */
 static inline ioasid_t ioasid_alloc(int sid, ioasid_t min,
@@ -136,5 +137,10 @@ static inline int ioasid_alloc_system_set(int quota)
        return -ENOTSUPP;
 }
 
+static inline int ioasid_adjust_set(int sid, int quota)
+{
+       return -ENOTSUPP;
+}
+
 #endif /* CONFIG_IOASID */
 #endif /* __LINUX_IOASID_H */
-- 
2.7.4

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