Commit 10b35b2b authored by Alexey Kardashevskiy's avatar Alexey Kardashevskiy Committed by Michael Ellerman
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powerpc/powernv: Do not set "read" flag if direction==DMA_NONE 



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: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
Reviewed-by: default avatarGavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 22af4859

arch/powerpc/include/asm/iommu.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

arch/powerpc/kernel/iommu.c

+15 −0
Original line number Diff line number Diff line
@@ -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

arch/powerpc/platforms/powernv/pci.c

+1 −6
Original line number Diff line number Diff line
@@ -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;

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