[PATCH] ppc64: create iommu_free_table()

This patch is from John Rose <johnrose@austin.ibm.com>.

The patch below creates iommu_free_table().  Iommu tables are not currently
freed in PPC64.  This could cause a memory leak for DLPAR of an EADS slot. 
The function verifies that there are no outstanding TCE entries for the
range of the table before freeing it.  I added a call to iommu_free_table()
to the code that dynamically removes a device node.  This should be fairly
symmetrical with the table allocation, which happens during dynamic
addition of a device node.
Signed-off-by: John Rose <johnrose@austin.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/ppc64/kernel/pSeries_iommu.c

@@ -412,6 +412,38 @@ void iommu_devnode_init(struct device_node *dn)
 	dn->iommu_table = iommu_init_table(tbl);
 }
 
+void iommu_free_table(struct device_node *dn)
+{
+	struct iommu_table *tbl = dn->iommu_table;
+	unsigned long bitmap_sz, i;
+	unsigned int order;
+
+	if (!tbl || !tbl->it_map) {
+		printk(KERN_ERR "%s: expected TCE map for %s\n", __FUNCTION__,
+				dn->full_name);
+		return;
+	}
+
+	/* verify that table contains no entries */
+	/* it_mapsize is in entries, and we're examining 64 at a time */
+	for (i = 0; i < (tbl->it_mapsize/64); i++) {
+		if (tbl->it_map[i] != 0) {
+			printk(KERN_WARNING "%s: Unexpected TCEs for %s\n",
+				__FUNCTION__, dn->full_name);
+			break;
+		}
+	}
+
+	/* calculate bitmap size in bytes */
+	bitmap_sz = (tbl->it_mapsize + 7) / 8;
+
+	/* free bitmap */
+	order = get_order(bitmap_sz);
+	free_pages((unsigned long) tbl->it_map, order);
+
+	/* free table */
+	kfree(tbl);
+}
 
 void iommu_setup_pSeries(void)
 {

arch/ppc64/kernel/prom.c

@@ -1818,6 +1818,9 @@ int of_remove_node(struct device_node *np)
 		return -EBUSY;
 	}
 
+	if (np->iommu_table)
+		iommu_free_table(np);
+
 	write_lock(&devtree_lock);
 	OF_MARK_STALE(np);
 	remove_node_proc_entries(np);

include/asm-ppc64/iommu.h

@@ -113,6 +113,9 @@ extern void iommu_setup_u3(void);
 /* Creates table for an individual device node */
 extern void iommu_devnode_init(struct device_node *dn);
 
+/* Frees table for an individual device node */
+extern void iommu_free_table(struct device_node *dn);
+
 #endif /* CONFIG_PPC_MULTIPLATFORM */
 
 #ifdef CONFIG_PPC_ISERIES