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    Subject[PATCH v4 09/28] 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.

    Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
    Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
    ---
    arch/powerpc/platforms/powernv/pci.c | 20 ++++++++++++++------
    1 file changed, 14 insertions(+), 6 deletions(-)

    diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
    index 4945e87..9ec7d68 100644
    --- a/arch/powerpc/platforms/powernv/pci.c
    +++ b/arch/powerpc/platforms/powernv/pci.c
    @@ -589,19 +589,27 @@ struct pci_ops pnv_pci_ops = {
    .write = pnv_pci_write_config,
    };

    +static unsigned long pnv_dmadir_to_flags(enum dma_data_direction direction)
    +{
    + switch (direction) {
    + case DMA_BIDIRECTIONAL:
    + case DMA_FROM_DEVICE:
    + return TCE_PCI_READ | TCE_PCI_WRITE;
    + case DMA_TO_DEVICE:
    + return TCE_PCI_READ;
    + default:
    + return 0;
    + }
    +}
    +
    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 = pnv_dmadir_to_flags(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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