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powerpc/powernv: Do not set "read" flag if direction==DMA_NONE

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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 as the old TCE value (more precisely -
the permission bits) will be used to decide whether to put the page or not.

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>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Alexey Kardashevskiy 2015-06-05 16:35:05 +10:00 committed by Michael Ellerman
parent 22af48596e
commit 10b35b2b74
3 changed files with 17 additions and 6 deletions
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1
arch/powerpc/include/asm/iommu.h
View File

@ -200,6 +200,7 @@ 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 */

15
arch/powerpc/kernel/iommu.c
View File

@ -866,6 +866,21 @@ void iommu_free_coherent(struct iommu_table *tbl, size_t size,
}
}
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);
#ifdef CONFIG_IOMMU_API
/*
* SPAPR TCE API

7
arch/powerpc/platforms/powernv/pci.c
View File

@ -576,15 +576,10 @@ 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;