[PATCH] powerpc/iommu: DMA address offset is incorrectly calculated with 2MB TCEs

[Gaurav Batra]

When DMA window is backed by 2MB TCEs, the DMA address for the mapped
page should be the offset of the page relative to the 2MB TCE. The code
was incorrectly setting the DMA address to the beginning of the TCE
range.

Mellanox driver is reporting timeout trying to ENABLE_HCA for an SR-IOV
ethernet port, when DMA window is backed by 2MB TCEs.

Signed-off-by: Gaurav Batra <gbatra at linux.vnet.ibm.com>

Reviewed-by: Greg Joyce <gjoyce at linux.vnet.ibm.com>
Reviewed-by: Brian King <brking at linux.vnet.ibm.com>
---
 arch/powerpc/kernel/iommu.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index ee95937bdaf1..ca57526ce47a 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -517,7 +517,7 @@ int ppc_iommu_map_sg(struct device *dev, struct iommu_table *tbl,
 		/* Convert entry to a dma_addr_t */
 		entry += tbl->it_offset;
 		dma_addr = entry << tbl->it_page_shift;
-		dma_addr |= (s->offset & ~IOMMU_PAGE_MASK(tbl));
+		dma_addr |= (vaddr & ~IOMMU_PAGE_MASK(tbl));
 
 		DBG("  - %lu pages, entry: %lx, dma_addr: %lx\n",
 			    npages, entry, dma_addr);
@@ -904,6 +904,7 @@ void *iommu_alloc_coherent(struct device *dev, struct iommu_table *tbl,
 	unsigned int order;
 	unsigned int nio_pages, io_order;
 	struct page *page;
+	int tcesize = (1 << tbl->it_page_shift);
 
 	size = PAGE_ALIGN(size);
 	order = get_order(size);
@@ -930,7 +931,8 @@ void *iommu_alloc_coherent(struct device *dev, struct iommu_table *tbl,
 	memset(ret, 0, size);
 
 	/* Set up tces to cover the allocated range */
-	nio_pages = size >> tbl->it_page_shift;
+	nio_pages = IOMMU_PAGE_ALIGN(size, tbl) >> tbl->it_page_shift;
+
 	io_order = get_iommu_order(size, tbl);
 	mapping = iommu_alloc(dev, tbl, ret, nio_pages, DMA_BIDIRECTIONAL,
 			      mask >> tbl->it_page_shift, io_order, 0);
@@ -938,7 +940,8 @@ void *iommu_alloc_coherent(struct device *dev, struct iommu_table *tbl,
 		free_pages((unsigned long)ret, order);
 		return NULL;
 	}
-	*dma_handle = mapping;
+
+	*dma_handle = mapping | ((u64)ret & (tcesize - 1));
 	return ret;
 }
 
--