powerpc/iommu: Incorrect DDW Table is referenced for SR-IOV device

For an SR-IOV device, while enabling DDW, a new table is created and
added at index 1 in the group. In the below 2 scenarios, the table is
incorrectly referenced at index 0 (which is where the table is for
default DMA window).

1. When adding DDW

   This issue is exposed with "slub_debug". Error thrown out from
   dma_iommu_dma_supported()

   Warning: IOMMU offset too big for device mask
   mask: 0xffffffff, table offset: 0x800000000000000

2. During Dynamic removal of the PCI device.

   Error is from iommu_tce_table_put() since a NULL table pointer is
   passed in.

Fixes: 381ceda ("powerpc/pseries/iommu: Make use of DDW for indirect mapping")
Cc: stable@vger.kernel.org # v5.15+
Signed-off-by: Gaurav Batra <gbatra@linux.vnet.ibm.com>
Reviewed-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230505184701.91613-1-gbatra@linux.vnet.ibm.com

Author: Gaurav Batra

arch/powerpc/kernel/dma-iommu.c

@@ -144,7 +144,7 @@ static bool dma_iommu_bypass_supported(struct device *dev, u64 mask)
 /* We support DMA to/from any memory page via the iommu */
 int dma_iommu_dma_supported(struct device *dev, u64 mask)
 {
-	struct iommu_table *tbl = get_iommu_table_base(dev);
+	struct iommu_table *tbl;
 
 	if (dev_is_pci(dev) && dma_iommu_bypass_supported(dev, mask)) {
 		/*
@@ -162,6 +162,8 @@ int dma_iommu_dma_supported(struct device *dev, u64 mask)
 		return 1;
 	}
 
+	tbl = get_iommu_table_base(dev);
+
 	if (!tbl) {
 		dev_err(dev, "Warning: IOMMU dma not supported: mask 0x%08llx, table unavailable\n", mask);
 		return 0;

arch/powerpc/platforms/pseries/iommu.c

@@ -91,19 +91,24 @@ static struct iommu_table_group *iommu_pseries_alloc_group(int node)
 static void iommu_pseries_free_group(struct iommu_table_group *table_group,
 		const char *node_name)
 {
-	struct iommu_table *tbl;
-
 	if (!table_group)
 		return;
 
-	tbl = table_group->tables[0];
 #ifdef CONFIG_IOMMU_API
 	if (table_group->group) {
 		iommu_group_put(table_group->group);
 		BUG_ON(table_group->group);
 	}
 #endif
-	iommu_tce_table_put(tbl);
+
+	/* Default DMA window table is at index 0, while DDW at 1. SR-IOV
+	 * adapters only have table on index 1.
+	 */
+	if (table_group->tables[0])
+		iommu_tce_table_put(table_group->tables[0]);
+
+	if (table_group->tables[1])
+		iommu_tce_table_put(table_group->tables[1]);
 
 	kfree(table_group);
 }