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: 381ceda88c4c ("powerpc/pseries/iommu: Make use of DDW for indirect mapping")
Cc: [e-mail] # v5.15+
Signed-off-by: Gaurav Batra <[e-mail]>
Reviewed-by: Brian King <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>
Link: https://msgid.link/[e-mail]

arch/powerpc/kernel/dma-iommu.c

···
 /* 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)) {
 		/*
···
 			dev_dbg(dev, "iommu: 64-bit OK, using fixed ops\n");
 		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);

arch/powerpc/platforms/pseries/iommu.c

···
 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);
 }