iommu/ioasid: Introduce ioasid_set private ID

When an IOASID set is used for guest SVA, each VM will acquire its
ioasid_set for IOASID allocations. IOASIDs within the VM must have a
host/physical IOASID backing, mapping between guest and host IOASIDs can
be non-identical. IOASID set private ID (SPID) is introduced in this
patch to be used as guest IOASID. However, the concept of ioasid_set
specific namespace is generic, thus named SPID.

As SPID namespace is within the IOASID set, the IOASID core can provide
lookup services at both directions. SPIDs may not be allocated when its
IOASID is allocated, the mapping between SPID and IOASID is usually
established when a guest page table is bound to a host PASID.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>

drivers/iommu/ioasid.c

@@ -21,6 +21,7 @@ enum ioasid_state {
  * struct ioasid_data - Meta data about ioasid
  *
  * @id:		Unique ID
+ * @spid:	Private ID unique within a set
  * @users	Number of active users
  * @state	Track state of the IOASID
  * @set		Meta data of the set this IOASID belongs to
@@ -29,6 +30,7 @@ enum ioasid_state {
  */
 struct ioasid_data {
 	ioasid_t id;
+	ioasid_t spid;
 	struct ioasid_set *set;
 	refcount_t users;
 	enum ioasid_state state;
@@ -325,6 +327,58 @@ int ioasid_attach_data(ioasid_t ioasid, void *data)
 }
 EXPORT_SYMBOL_GPL(ioasid_attach_data);
 
+/**
+ * ioasid_attach_spid - Attach ioasid_set private ID to an IOASID
+ *
+ * @ioasid: the ID to attach
+ * @spid:   the ioasid_set private ID of @ioasid
+ *
+ * For IOASID that is already allocated, private ID within the set can be
+ * attached via this API. Future lookup can be done via ioasid_find.
+ */
+int ioasid_attach_spid(ioasid_t ioasid, ioasid_t spid)
+{
+	struct ioasid_data *ioasid_data;
+	int ret = 0;
+
+	spin_lock(&ioasid_allocator_lock);
+	ioasid_data = xa_load(&active_allocator->xa, ioasid);
+
+	if (!ioasid_data) {
+		pr_err("No IOASID entry %d to attach SPID %d\n",
+			ioasid, spid);
+		ret = -ENOENT;
+		goto done_unlock;
+	}
+	ioasid_data->spid = spid;
+
+done_unlock:
+	spin_unlock(&ioasid_allocator_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(ioasid_attach_spid);
+
+ioasid_t ioasid_find_by_spid(struct ioasid_set *set, ioasid_t spid)
+{
+	struct ioasid_data *entry;
+	unsigned long index;
+
+	if (!xa_load(&ioasid_sets, set->sid)) {
+		pr_warn("Invalid set\n");
+		return INVALID_IOASID;
+	}
+
+	xa_for_each(&set->xa, index, entry) {
+		if (spid == entry->spid) {
+			pr_debug("Found ioasid %lu by spid %u\n", index, spid);
+			refcount_inc(&entry->users);
+			return index;
+		}
+	}
+	return INVALID_IOASID;
+}
+EXPORT_SYMBOL_GPL(ioasid_find_by_spid);
+
 /**
  * ioasid_alloc - Allocate an IOASID
  * @set: the IOASID set

include/linux/ioasid.h

@@ -73,6 +73,8 @@ 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_attach_spid(ioasid_t ioasid, ioasid_t spid);
+ioasid_t ioasid_find_by_spid(struct ioasid_set *set, ioasid_t spid);
 int ioasid_register_allocator(struct ioasid_allocator_ops *allocator);
 void ioasid_unregister_allocator(struct ioasid_allocator_ops *allocator);
 void ioasid_is_in_set(struct ioasid_set *set, ioasid_t ioasid);
@@ -136,5 +138,15 @@ static inline int ioasid_attach_data(ioasid_t ioasid, void *data)
 	return -ENOTSUPP;
 }
 
+staic inline int ioasid_attach_spid(ioasid_t ioasid, ioasid_t spid)
+{
+	return -ENOTSUPP;
+}
+
+static inline ioasid_t ioasid_find_by_spid(struct ioasid_set *set, ioasid_t spid)
+{
+	return -ENOTSUPP;
+}
+
 #endif /* CONFIG_IOASID */
 #endif /* __LINUX_IOASID_H */