iommu/dma: return error code from iommu_dma_map_sg()

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@deltatee.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

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 +1066,10 @@ 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 -EINVAL;
+	return ret;
 }
 
 static void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg,