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

[Gaurav Batra]

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")

Signed-off-by: Gaurav Batra <gba...@linux.vnet.ibm.com>

Reviewed-by: Brian King <brk...@linux.vnet.ibm.com>
---
 arch/powerpc/kernel/dma-iommu.c        |  4 +++-
 arch/powerpc/platforms/pseries/iommu.c | 13 +++++++++----
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kernel/dma-iommu.c b/arch/powerpc/kernel/dma-iommu.c
index 038ce8d9061d..8920862ffd79 100644
--- a/arch/powerpc/kernel/dma-iommu.c
+++ b/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;
diff --git a/arch/powerpc/platforms/pseries/iommu.c 
b/arch/powerpc/platforms/pseries/iommu.c
index c74b71d4733d..a8acd3b402d7 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -85,19 +85,24 @@ 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);
 }
--