linux-kernel - [PATCH v2 10/21] powerpc/iommu: return error code from .map

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Message-Id: <20210723175008.22410-11-logang@deltatee.com>
Date:   Fri, 23 Jul 2021 11:49:57 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     linux-kernel@...r.kernel.org, linux-alpha@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-ia64@...r.kernel.org,
        linux-mips@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-s390@...r.kernel.org, sparclinux@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-parisc@...r.kernel.org,
        xen-devel@...ts.xenproject.org
Cc:     Christoph Hellwig <hch@....de>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        Stephen Bates <sbates@...thlin.com>,
        Martin Oliveira <martin.oliveira@...eticom.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Geoff Levand <geoff@...radead.org>
Subject: [PATCH v2 10/21] powerpc/iommu: return error code from .map_sg() ops

From: Martin Oliveira <martin.oliveira@...eticom.com>

The .map_sg() op now expects an error code instead of zero on failure.

Propagate the error up if vio_dma_iommu_map_sg() fails.

ppc_iommu_map_sg() may fail either because of iommu_range_alloc() or
because of tbl->it_ops->set(). The former only supports returning an
error with DMA_MAPPING_ERROR and an examination of the latter indicates
that it may return arch-specific errors (for example,
tce_buildmulti_pSeriesLP()). Hence, coalesce all of those errors into
-EIO, per the documentation on dma_map_sgtable().

Signed-off-by: Martin Oliveira <martin.oliveira@...eticom.com>
Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Geoff Levand <geoff@...radead.org>
---
 arch/powerpc/kernel/iommu.c             | 4 ++--
 arch/powerpc/platforms/ps3/system-bus.c | 2 +-
 arch/powerpc/platforms/pseries/vio.c    | 5 +++--
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index 2af89a5e379f..a8ec4fe42817 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -473,7 +473,7 @@ int ppc_iommu_map_sg(struct device *dev, struct iommu_table *tbl,
 	BUG_ON(direction == DMA_NONE);
 
 	if ((nelems == 0) || !tbl)
-		return 0;
+		return -EINVAL;
 
 	outs = s = segstart = &sglist[0];
 	outcount = 1;
@@ -599,7 +599,7 @@ int ppc_iommu_map_sg(struct device *dev, struct iommu_table *tbl,
 		if (s == outs)
 			break;
 	}
-	return 0;
+	return -EIO;
 }
 
 
diff --git a/arch/powerpc/platforms/ps3/system-bus.c b/arch/powerpc/platforms/ps3/system-bus.c
index 1a5665875165..c54eb46f0cfb 100644
--- a/arch/powerpc/platforms/ps3/system-bus.c
+++ b/arch/powerpc/platforms/ps3/system-bus.c
@@ -663,7 +663,7 @@ static int ps3_ioc0_map_sg(struct device *_dev, struct scatterlist *sg,
 			   unsigned long attrs)
 {
 	BUG();
-	return 0;
+	return -EINVAL;
 }
 
 static void ps3_sb_unmap_sg(struct device *_dev, struct scatterlist *sg,
diff --git a/arch/powerpc/platforms/pseries/vio.c b/arch/powerpc/platforms/pseries/vio.c
index e00f3725ec96..e31e59c54f30 100644
--- a/arch/powerpc/platforms/pseries/vio.c
+++ b/arch/powerpc/platforms/pseries/vio.c
@@ -560,7 +560,8 @@ static int vio_dma_iommu_map_sg(struct device *dev, struct scatterlist *sglist,
 	for_each_sg(sglist, sgl, nelems, count)
 		alloc_size += roundup(sgl->length, IOMMU_PAGE_SIZE(tbl));
 
-	if (vio_cmo_alloc(viodev, alloc_size))
+	ret = vio_cmo_alloc(viodev, alloc_size);
+	if (ret)
 		goto out_fail;
 	ret = ppc_iommu_map_sg(dev, tbl, sglist, nelems, dma_get_mask(dev),
 			direction, attrs);
@@ -577,7 +578,7 @@ static int vio_dma_iommu_map_sg(struct device *dev, struct scatterlist *sglist,
 	vio_cmo_dealloc(viodev, alloc_size);
 out_fail:
 	atomic_inc(&viodev->cmo.allocs_failed);
-	return 0;
+	return ret;
 }
 
 static void vio_dma_iommu_unmap_sg(struct device *dev,
-- 
2.20.1