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Subject[PATCH 08/34] powerpc/dma: untangle vio_dma_mapping_ops from dma_iommu_ops
Date
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>
---
arch/powerpc/include/asm/iommu.h | 1 +
arch/powerpc/kernel/dma-iommu.c | 2 +-
arch/powerpc/platforms/pseries/vio.c | 87 ++++++++++++----------------
3 files changed, 38 insertions(+), 52 deletions(-)

diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
index 35db0cbc9222..75daa10f31a4 100644
--- a/arch/powerpc/include/asm/iommu.h
+++ b/arch/powerpc/include/asm/iommu.h
@@ -242,6 +242,7 @@ static inline int __init tce_iommu_bus_notifier_init(void)
}
#endif /* !CONFIG_IOMMU_API */

+u64 dma_iommu_get_required_mask(struct device *dev);
int dma_iommu_mapping_error(struct device *dev, dma_addr_t dma_addr);

#else
diff --git a/arch/powerpc/kernel/dma-iommu.c b/arch/powerpc/kernel/dma-iommu.c
index 2ca6cfaebf65..0613278abf9f 100644
--- a/arch/powerpc/kernel/dma-iommu.c
+++ b/arch/powerpc/kernel/dma-iommu.c
@@ -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;
diff --git a/arch/powerpc/platforms/pseries/vio.c b/arch/powerpc/platforms/pseries/vio.c
index 88f1ad1d6309..ea3a9745c812 100644
--- a/arch/powerpc/platforms/pseries/vio.c
+++ b/arch/powerpc/platforms/pseries/vio.c
@@ -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);
@@ -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));
}

@@ -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 = IOMMU_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 == IOMMU_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 IOMMU_MAPPING_ERROR;
}

static void vio_dma_iommu_unmap_page(struct device *dev, dma_addr_t dma_handle,
@@ -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)));
}

@@ -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,
@@ -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,
@@ -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_mapping_error,
+ .get_required_mask = dma_iommu_get_required_mask,
.mapping_error = dma_iommu_mapping_error,
};

--
2.19.1
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