iommu/dma: Fix IOVA reserve dma ranges

Fix IOVA reserve failure in the case when address of first memory region
listed in dma-ranges is equal to 0x0.

Fixes: aadad09 ("iommu/dma: Reserve IOVA for PCIe inaccessible DMA address")
Signed-off-by: Srinath Mannam <srinath.mannam@broadcom.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Sven Peter <sven@svenpeter.dev>
Link: https://lore.kernel.org/r/20200914072319.6091-1-srinath.mannam@broadcom.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/dma-iommu.c

@@ -243,9 +243,11 @@ static int iova_reserve_pci_windows(struct pci_dev *dev,
 			lo = iova_pfn(iovad, start);
 			hi = iova_pfn(iovad, end);
 			reserve_iova(iovad, lo, hi);
-		} else {
+		} else if (end < start) {
 			/* dma_ranges list should be sorted */
-			dev_err(&dev->dev, "Failed to reserve IOVA\n");
+			dev_err(&dev->dev,
+				"Failed to reserve IOVA [%#010llx-%#010llx]\n",
+				start, end);
 			return -EINVAL;
 		}