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SubjectRe: [PATCH v6 12/19] swiotlb: don't assume that io_tlb_start-io_tlb_end is coherent
On Fri, Sep 27, 2013 at 05:10:00PM +0100, Stefano Stabellini wrote:
> The swiotlb code has appropriate calls to dma_mark_clean in place for
> buffers passed to swiotlb_map_page as an argument. However it assumes
> that the swiotlb bounce buffer (io_tlb_start-io_tlb_end) is already
> coherent and doesn't need any calls to dma_mark_clean.
>
> On ARM the swiotlb bounce buffer is not coherent (the memory is
> writealloc while it should be bufferable) and therefore we need to call
> dma_mark_clean appropriately on the bounce buffer code paths too.
>
> Note that most architecures have an empty dma_mark_clean implementation
> anyway.

The other architecture that uses swiotlb is IA64 and that does have
an implementation where it touches on page attributes.

Which means I have to figure out why my HP zx6000 won't boot with 3.11 now :-(

>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> ---
> lib/swiotlb.c | 13 ++++++++++---
> 1 files changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/lib/swiotlb.c b/lib/swiotlb.c
> index 4e8686c..eb45d17 100644
> --- a/lib/swiotlb.c
> +++ b/lib/swiotlb.c
> @@ -515,6 +515,7 @@ found:
> io_tlb_orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT);
> if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)
> swiotlb_bounce(orig_addr, tlb_addr, size, DMA_TO_DEVICE);
> + dma_mark_clean(phys_to_virt(tlb_addr), size);
>
> return tlb_addr;
> }
> @@ -547,7 +548,10 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
> * First, sync the memory before unmapping the entry
> */
> if (orig_addr && ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
> + {
> + dma_mark_clean(phys_to_virt(tlb_addr), size);
> swiotlb_bounce(orig_addr, tlb_addr, size, DMA_FROM_DEVICE);
> + }
>
> /*
> * Return the buffer to the free list by setting the corresponding
> @@ -587,17 +591,20 @@ void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr,
>
> switch (target) {
> case SYNC_FOR_CPU:
> - if (likely(dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL))
> + if (likely(dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL)) {
> + dma_mark_clean(phys_to_virt(tlb_addr), size);
> swiotlb_bounce(orig_addr, tlb_addr,
> size, DMA_FROM_DEVICE);
> + }
> else
> BUG_ON(dir != DMA_TO_DEVICE);
> break;
> case SYNC_FOR_DEVICE:
> - if (likely(dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
> + if (likely(dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)) {
> swiotlb_bounce(orig_addr, tlb_addr,
> size, DMA_TO_DEVICE);
> - else
> + dma_mark_clean(phys_to_virt(tlb_addr), size);
> + } else
> BUG_ON(dir != DMA_FROM_DEVICE);
> break;
> default:
> --
> 1.7.2.5
>


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