[PATCH 5.15 681/917] iommu/dma: Fix incorrect error return on iommu deferred attach

[Greg Kroah-Hartman]

From: Logan Gunthorpe <logang@xxxxxxxxxxxx>

[ Upstream commit ac315f96b3bd6f6b8f18f387816c7c2cc6b32e02 ]

scsi_dma_map() was reporting a failure during boot on an AMD machine
with the IOMMU enabled.

  scsi_dma_map failed: request for 36 bytes!

The issue was tracked down to a mistake in logic: should not return
an error if iommu_deferred_attach() returns zero.

Reported-by: Marshall Midden <marshallmidden@xxxxxxxxx>
Fixes: dabb16f67215 ("iommu/dma: return error code from iommu_dma_map_sg()")
Link: https://lore.kernel.org/all/CAD2CkAWjS8=kKwEEN4cgVNjyFORUibzEiCUA-X+SMtbo0JoMmA@xxxxxxxxxxxxxx
Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20211027174757.119755-1-logang@xxxxxxxxxxxx
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/iommu/dma-iommu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 19bebacbf1780..2d60216440009 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1007,7 +1007,8 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
 
 	if (static_branch_unlikely(&iommu_deferred_attach_enabled)) {
 		ret = iommu_deferred_attach(dev, domain);
-		goto out;
+		if (ret)
+			goto out;
 	}
 
 	if (dev_is_untrusted(dev))
-- 
2.33.0