[PATCH v2 04/21] dma-iommu: Return error code from iommu_dma_map_sg()

From: Logan Gunthorpe (logang@xxxxxxxxxxxx)
Date: Fri Jul 23 2021 - 13:50:57 EST


Return appropriate error codes EINVAL or ENOMEM from
iommup_dma_map_sg(). If lower level code returns ENOMEM, then we
return it, other errors are coalesced into EINVAL.

iommu_dma_map_sg_swiotlb() returns -EIO as its an unknown error
from a call that returns DMA_MAPPING_ERROR.

Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
---
drivers/iommu/dma-iommu.c | 23 ++++++++++++++++-------
1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 98ba927aee1a..d9aaed080e68 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -972,7 +972,7 @@ static int iommu_dma_map_sg_swiotlb(struct device *dev, struct scatterlist *sg,

out_unmap:
iommu_dma_unmap_sg_swiotlb(dev, sg, i, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC);
- return 0;
+ return -EIO;
}

/*
@@ -993,11 +993,13 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
dma_addr_t iova;
size_t iova_len = 0;
unsigned long mask = dma_get_seg_boundary(dev);
+ ssize_t ret;
int i;

- if (static_branch_unlikely(&iommu_deferred_attach_enabled) &&
- iommu_deferred_attach(dev, domain))
- return 0;
+ if (static_branch_unlikely(&iommu_deferred_attach_enabled)) {
+ ret = iommu_deferred_attach(dev, domain);
+ goto out;
+ }

if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
iommu_dma_sync_sg_for_device(dev, sg, nents, dir);
@@ -1045,14 +1047,17 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
}

iova = iommu_dma_alloc_iova(domain, iova_len, dma_get_mask(dev), dev);
- if (!iova)
+ if (!iova) {
+ ret = -ENOMEM;
goto out_restore_sg;
+ }

/*
* We'll leave any physical concatenation to the IOMMU driver's
* implementation - it knows better than we do.
*/
- if (iommu_map_sg_atomic(domain, iova, sg, nents, prot) < iova_len)
+ ret = iommu_map_sg_atomic(domain, iova, sg, nents, prot);
+ if (ret < iova_len)
goto out_free_iova;

return __finalise_sg(dev, sg, nents, iova);
@@ -1061,7 +1066,11 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
iommu_dma_free_iova(cookie, iova, iova_len, NULL);
out_restore_sg:
__invalidate_sg(sg, nents);
- return 0;
+out:
+ if (ret == -ENOMEM)
+ return ret;
+ else
+ return -EINVAL;
}

static void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
--
2.20.1