[PATCH] iommu/dma-iommu: Fix wrong scatterlist length assignment in P2PDMA path

[lirongqing]

From: Li RongQing <lirongqing@xxxxxxxxx>

In iommu_dma_map_sg(), when handling PCI P2PDMA cases, the DMA length
of the current scatterlist segment `s` is incorrectly assigned from the
head entry `sg->length` instead of the current entry `s->length`.

This typo causes all P2PDMA segments in the scatterlist to inherit the
length of the first segment, leading to corrupted DMA lengths for multi-
segment scatterlists.

Fix this by using `s->length` instead of `sg->length`.

Fixes: a25e7962db ("PCI/P2PDMA: Refactor the p2pdma mapping helpers")
Signed-off-by: Li RongQing <lirongqing@xxxxxxxxx>
---
 drivers/iommu/dma-iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 54d96e8..e8d4c2d 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1465,7 +1465,7 @@ int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 			 */
 			s->dma_address = pci_p2pdma_bus_addr_map(
 				p2pdma_state.mem, sg_phys(s));
-			sg_dma_len(s) = sg->length;
+			sg_dma_len(s) = s->length;
 			sg_dma_mark_bus_address(s);
 			continue;
 		default:
-- 
2.9.4