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Subject[PATCH kernel v6 10/29] powerpc/powernv: Do not set "read" flag if direction==DMA_NONE
Date
Normally a bitmap from the iommu_table is used to track what TCE entry
is in use. Since we are going to use iommu_table without its locks and
do xchg() instead, it becomes essential not to put bits which are not
implied in the direction flag.

This adds iommu_direction_to_tce_perm() (its counterpart is there already)
and uses it for powernv's pnv_tce_build().

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
arch/powerpc/include/asm/iommu.h | 1 +
arch/powerpc/kernel/iommu.c | 15 +++++++++++++++
arch/powerpc/platforms/powernv/pci.c | 7 +------
3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
index ed69b7d..2af2d70 100644
--- a/arch/powerpc/include/asm/iommu.h
+++ b/arch/powerpc/include/asm/iommu.h
@@ -203,6 +203,7 @@ extern int iommu_take_ownership(struct iommu_table *tbl);
extern void iommu_release_ownership(struct iommu_table *tbl);

extern enum dma_data_direction iommu_tce_direction(unsigned long tce);
+extern unsigned long iommu_direction_to_tce_perm(enum dma_data_direction dir);

#endif /* __KERNEL__ */
#endif /* _ASM_IOMMU_H */
diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index 1b4a178..865beef 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -916,6 +916,21 @@ enum dma_data_direction iommu_tce_direction(unsigned long tce)
}
EXPORT_SYMBOL_GPL(iommu_tce_direction);

+unsigned long iommu_direction_to_tce_perm(enum dma_data_direction dir)
+{
+ switch (dir) {
+ case DMA_BIDIRECTIONAL:
+ return TCE_PCI_READ | TCE_PCI_WRITE;
+ case DMA_FROM_DEVICE:
+ return TCE_PCI_WRITE;
+ case DMA_TO_DEVICE:
+ return TCE_PCI_READ;
+ default:
+ return 0;
+ }
+}
+EXPORT_SYMBOL_GPL(iommu_direction_to_tce_perm);
+
void iommu_flush_tce(struct iommu_table *tbl)
{
/* Flush/invalidate TLB caches if necessary */
diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
index 54323d6..609f5b1 100644
--- a/arch/powerpc/platforms/powernv/pci.c
+++ b/arch/powerpc/platforms/powernv/pci.c
@@ -593,15 +593,10 @@ static int pnv_tce_build(struct iommu_table *tbl, long index, long npages,
unsigned long uaddr, enum dma_data_direction direction,
struct dma_attrs *attrs, bool rm)
{
- u64 proto_tce;
+ u64 proto_tce = iommu_direction_to_tce_perm(direction);
__be64 *tcep, *tces;
u64 rpn;

- proto_tce = TCE_PCI_READ; // Read allowed
-
- if (direction != DMA_TO_DEVICE)
- proto_tce |= TCE_PCI_WRITE;
-
tces = tcep = ((__be64 *)tbl->it_base) + index - tbl->it_offset;
rpn = __pa(uaddr) >> tbl->it_page_shift;

--
2.0.0


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