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powerpc/dma: untangle vio_dma_mapping_ops from dma_iommu_ops
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vio_dma_mapping_ops currently does a lot of indirect calls through
dma_iommu_ops, which not only make the code harder to follow but are
also expensive in the post-spectre world.  Unwind the indirect calls
by calling the ppc_iommu_* or iommu_* APIs directly applicable, or
just use the dma_iommu_* methods directly where we can.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Christoph Hellwig authored and Michael Ellerman committed Feb 18, 2019
1 parent fbce251 commit a20f507
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Showing 3 changed files with 38 additions and 52 deletions.
1 change: 1 addition & 0 deletions arch/powerpc/include/asm/iommu.h
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Original file line number Diff line number Diff line change
Expand Up @@ -237,6 +237,7 @@ static inline void iommu_del_device(struct device *dev)
}
#endif /* !CONFIG_IOMMU_API */

u64 dma_iommu_get_required_mask(struct device *dev);
#else

static inline void *get_iommu_table_base(struct device *dev)
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2 changes: 1 addition & 1 deletion arch/powerpc/kernel/dma-iommu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -92,7 +92,7 @@ int dma_iommu_dma_supported(struct device *dev, u64 mask)
return 1;
}

static u64 dma_iommu_get_required_mask(struct device *dev)
u64 dma_iommu_get_required_mask(struct device *dev)
{
struct iommu_table *tbl = get_iommu_table_base(dev);
u64 mask;
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87 changes: 36 additions & 51 deletions arch/powerpc/platforms/pseries/vio.c
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Original file line number Diff line number Diff line change
Expand Up @@ -492,7 +492,9 @@ static void *vio_dma_iommu_alloc_coherent(struct device *dev, size_t size,
return NULL;
}

ret = dma_iommu_ops.alloc(dev, size, dma_handle, flag, attrs);
ret = iommu_alloc_coherent(dev, get_iommu_table_base(dev), size,
dma_handle, dev->coherent_dma_mask, flag,
dev_to_node(dev));
if (unlikely(ret == NULL)) {
vio_cmo_dealloc(viodev, roundup(size, PAGE_SIZE));
atomic_inc(&viodev->cmo.allocs_failed);
Expand All @@ -507,8 +509,7 @@ static void vio_dma_iommu_free_coherent(struct device *dev, size_t size,
{
struct vio_dev *viodev = to_vio_dev(dev);

dma_iommu_ops.free(dev, size, vaddr, dma_handle, attrs);

iommu_free_coherent(get_iommu_table_base(dev), size, vaddr, dma_handle);
vio_cmo_dealloc(viodev, roundup(size, PAGE_SIZE));
}

Expand All @@ -518,22 +519,22 @@ static dma_addr_t vio_dma_iommu_map_page(struct device *dev, struct page *page,
unsigned long attrs)
{
struct vio_dev *viodev = to_vio_dev(dev);
struct iommu_table *tbl;
struct iommu_table *tbl = get_iommu_table_base(dev);
dma_addr_t ret = DMA_MAPPING_ERROR;

tbl = get_iommu_table_base(dev);
if (vio_cmo_alloc(viodev, roundup(size, IOMMU_PAGE_SIZE(tbl)))) {
atomic_inc(&viodev->cmo.allocs_failed);
return ret;
}

ret = dma_iommu_ops.map_page(dev, page, offset, size, direction, attrs);
if (unlikely(dma_mapping_error(dev, ret))) {
vio_cmo_dealloc(viodev, roundup(size, IOMMU_PAGE_SIZE(tbl)));
atomic_inc(&viodev->cmo.allocs_failed);
}

if (vio_cmo_alloc(viodev, roundup(size, IOMMU_PAGE_SIZE(tbl))))
goto out_fail;
ret = iommu_map_page(dev, tbl, page, offset, size, device_to_mask(dev),
direction, attrs);
if (unlikely(ret == DMA_MAPPING_ERROR))
goto out_deallocate;
return ret;

out_deallocate:
vio_cmo_dealloc(viodev, roundup(size, IOMMU_PAGE_SIZE(tbl)));
out_fail:
atomic_inc(&viodev->cmo.allocs_failed);
return DMA_MAPPING_ERROR;
}

static void vio_dma_iommu_unmap_page(struct device *dev, dma_addr_t dma_handle,
Expand All @@ -542,11 +543,9 @@ static void vio_dma_iommu_unmap_page(struct device *dev, dma_addr_t dma_handle,
unsigned long attrs)
{
struct vio_dev *viodev = to_vio_dev(dev);
struct iommu_table *tbl;

tbl = get_iommu_table_base(dev);
dma_iommu_ops.unmap_page(dev, dma_handle, size, direction, attrs);
struct iommu_table *tbl = get_iommu_table_base(dev);

iommu_unmap_page(tbl, dma_handle, size, direction, attrs);
vio_cmo_dealloc(viodev, roundup(size, IOMMU_PAGE_SIZE(tbl)));
}

Expand All @@ -555,34 +554,32 @@ static int vio_dma_iommu_map_sg(struct device *dev, struct scatterlist *sglist,
unsigned long attrs)
{
struct vio_dev *viodev = to_vio_dev(dev);
struct iommu_table *tbl;
struct iommu_table *tbl = get_iommu_table_base(dev);
struct scatterlist *sgl;
int ret, count;
size_t alloc_size = 0;

tbl = get_iommu_table_base(dev);
for_each_sg(sglist, sgl, nelems, count)
alloc_size += roundup(sgl->length, IOMMU_PAGE_SIZE(tbl));

if (vio_cmo_alloc(viodev, alloc_size)) {
atomic_inc(&viodev->cmo.allocs_failed);
return 0;
}

ret = dma_iommu_ops.map_sg(dev, sglist, nelems, direction, attrs);

if (unlikely(!ret)) {
vio_cmo_dealloc(viodev, alloc_size);
atomic_inc(&viodev->cmo.allocs_failed);
return ret;
}
if (vio_cmo_alloc(viodev, alloc_size))
goto out_fail;
ret = ppc_iommu_map_sg(dev, tbl, sglist, nelems, device_to_mask(dev),
direction, attrs);
if (unlikely(!ret))
goto out_deallocate;

for_each_sg(sglist, sgl, ret, count)
alloc_size -= roundup(sgl->dma_length, IOMMU_PAGE_SIZE(tbl));
if (alloc_size)
vio_cmo_dealloc(viodev, alloc_size);

return ret;

out_deallocate:
vio_cmo_dealloc(viodev, alloc_size);
out_fail:
atomic_inc(&viodev->cmo.allocs_failed);
return 0;
}

static void vio_dma_iommu_unmap_sg(struct device *dev,
Expand All @@ -591,30 +588,18 @@ static void vio_dma_iommu_unmap_sg(struct device *dev,
unsigned long attrs)
{
struct vio_dev *viodev = to_vio_dev(dev);
struct iommu_table *tbl;
struct iommu_table *tbl = get_iommu_table_base(dev);
struct scatterlist *sgl;
size_t alloc_size = 0;
int count;

tbl = get_iommu_table_base(dev);
for_each_sg(sglist, sgl, nelems, count)
alloc_size += roundup(sgl->dma_length, IOMMU_PAGE_SIZE(tbl));

dma_iommu_ops.unmap_sg(dev, sglist, nelems, direction, attrs);

ppc_iommu_unmap_sg(tbl, sglist, nelems, direction, attrs);
vio_cmo_dealloc(viodev, alloc_size);
}

static int vio_dma_iommu_dma_supported(struct device *dev, u64 mask)
{
return dma_iommu_ops.dma_supported(dev, mask);
}

static u64 vio_dma_get_required_mask(struct device *dev)
{
return dma_iommu_ops.get_required_mask(dev);
}

static const struct dma_map_ops vio_dma_mapping_ops = {
.alloc = vio_dma_iommu_alloc_coherent,
.free = vio_dma_iommu_free_coherent,
Expand All @@ -623,8 +608,8 @@ static const struct dma_map_ops vio_dma_mapping_ops = {
.unmap_sg = vio_dma_iommu_unmap_sg,
.map_page = vio_dma_iommu_map_page,
.unmap_page = vio_dma_iommu_unmap_page,
.dma_supported = vio_dma_iommu_dma_supported,
.get_required_mask = vio_dma_get_required_mask,
.dma_supported = dma_iommu_dma_supported,
.get_required_mask = dma_iommu_get_required_mask,
};

/**
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