[Xen-devel] [PATCH v5 13/13] swiotlb: don't assume that io_tlb_start-io_tlb_end is coherent

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

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.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
 lib/swiotlb.c |   12 +++++++++---
 1 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 4e8686c..b1f43f6 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -547,7 +547,10 @@ 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 +590,20 @@ 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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