vhost_iotlb: split out IOTLB initialization

mainline inclusion
from mainline-v5.19-rc1
commit 1cb10899
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5WXCZ
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1cb108994c6830cc6a6e066ad7d9a22ef59fa167

----------------------------------------------------------------------

This patch splits out IOTLB initialization to make sure it could be
reused by external modules.
Signed-off-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NGautam Dawar <gdawar@xilinx.com>
Message-Id: <20220330180436.24644-9-gdawar@xilinx.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NPengyuan Zhao <zhaopengyuan@hisilicon.com>

drivers/vhost/iotlb.c

@@ -125,6 +125,23 @@ void vhost_iotlb_del_range(struct vhost_iotlb *iotlb, u64 start, u64 last)
 }
 EXPORT_SYMBOL_GPL(vhost_iotlb_del_range);
 
+/**
+ * vhost_iotlb_init - initialize a vhost IOTLB
+ * @iotlb: the IOTLB that needs to be initialized
+ * @limit: maximum number of IOTLB entries
+ * @flags: VHOST_IOTLB_FLAG_XXX
+ */
+void vhost_iotlb_init(struct vhost_iotlb *iotlb, unsigned int limit,
+		      unsigned int flags)
+{
+	iotlb->root = RB_ROOT_CACHED;
+	iotlb->limit = limit;
+	iotlb->nmaps = 0;
+	iotlb->flags = flags;
+	INIT_LIST_HEAD(&iotlb->list);
+}
+EXPORT_SYMBOL_GPL(vhost_iotlb_init);
+
 /**
  * vhost_iotlb_alloc - add a new vhost IOTLB
  * @limit: maximum number of IOTLB entries
@@ -139,11 +156,7 @@ struct vhost_iotlb *vhost_iotlb_alloc(unsigned int limit, unsigned int flags)
 	if (!iotlb)
 		return NULL;
 
-	iotlb->root = RB_ROOT_CACHED;
-	iotlb->limit = limit;
-	iotlb->nmaps = 0;
-	iotlb->flags = flags;
-	INIT_LIST_HEAD(&iotlb->list);
+	vhost_iotlb_init(iotlb, limit, flags);
 
 	return iotlb;
 }

include/linux/vhost_iotlb.h

@@ -36,6 +36,8 @@ int vhost_iotlb_add_range(struct vhost_iotlb *iotlb, u64 start, u64 last,
 			  u64 addr, unsigned int perm);
 void vhost_iotlb_del_range(struct vhost_iotlb *iotlb, u64 start, u64 last);
 
+void vhost_iotlb_init(struct vhost_iotlb *iotlb, unsigned int limit,
+		      unsigned int flags);
 struct vhost_iotlb *vhost_iotlb_alloc(unsigned int limit, unsigned int flags);
 void vhost_iotlb_free(struct vhost_iotlb *iotlb);
 void vhost_iotlb_reset(struct vhost_iotlb *iotlb);