powerpc/dma: Fix dma_iommu_dma_supported compare

The table offset is in entries, each of which imply a dma address of
an IOMMU page.

Also, we should check the device can reach the whole IOMMU table.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/dma-iommu.c

@@ -74,16 +74,17 @@ static int dma_iommu_dma_supported(struct device *dev, u64 mask)
 {
 	struct iommu_table *tbl = get_iommu_table_base(dev);
 
-	if (!tbl || tbl->it_offset > mask) {
-		printk(KERN_INFO
-		       "Warning: IOMMU offset too big for device mask\n");
-		if (tbl)
-			printk(KERN_INFO
-			       "mask: 0x%08llx, table offset: 0x%08lx\n",
-				mask, tbl->it_offset);
-		else
-			printk(KERN_INFO "mask: 0x%08llx, table unavailable\n",
-				mask);
+	if (!tbl) {
+		dev_info(dev, "Warning: IOMMU dma not supported: mask 0x%08llx"
+			", table unavailable\n", mask);
+		return 0;
+	}
+
+	if ((tbl->it_offset + tbl->it_size) > (mask >> IOMMU_PAGE_SHIFT)) {
+		dev_info(dev, "Warning: IOMMU window too big for device mask\n");
+		dev_info(dev, "mask: 0x%08llx, table end: 0x%08lx\n",
+				mask, (tbl->it_offset + tbl->it_size) <<
+				IOMMU_PAGE_SHIFT);
 		return 0;
 	} else
 		return 1;