[Xen-changelog] [linux-2.6.18-xen] swiotlb: Allow sync on arbitrary offsets into dma-mapped region.

["Xen patchbot-linux-2.6.18-xen" <patchbot-linux-2.6.18-xen@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Date 1184008553 -3600
# Node ID 5684370b1c4d9911fd4118fdc472c3c7a9adfca3
# Parent  5a4e93508aa03799989b63f8413aeae7df87c576
swiotlb: Allow sync on arbitrary offsets into dma-mapped region.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
 arch/i386/kernel/swiotlb.c |   21 ++++++++++++++-------
 1 files changed, 14 insertions(+), 7 deletions(-)

diff -r 5a4e93508aa0 -r 5684370b1c4d arch/i386/kernel/swiotlb.c
--- a/arch/i386/kernel/swiotlb.c        Mon Jul 09 20:00:19 2007 +0100
+++ b/arch/i386/kernel/swiotlb.c        Mon Jul 09 20:15:53 2007 +0100
@@ -378,17 +378,25 @@ map_single(struct device *hwdev, struct 
         */
        slot_buf = buffer;
        for (i = 0; i < nslots; i++) {
+               slot_buf.page += slot_buf.offset >> PAGE_SHIFT;
+               slot_buf.offset &= PAGE_SIZE - 1;
                io_tlb_orig_addr[index+i] = slot_buf;
                slot_buf.offset += 1 << IO_TLB_SHIFT;
-               if (slot_buf.offset >= PAGE_SIZE) {
-                       slot_buf.page++;
-                       slot_buf.offset -= PAGE_SIZE;
-               }
        }
        if ((dir == DMA_TO_DEVICE) || (dir == DMA_BIDIRECTIONAL))
                __sync_single(buffer, dma_addr, size, DMA_TO_DEVICE);
 
        return dma_addr;
+}
+
+struct phys_addr dma_addr_to_phys_addr(char *dma_addr)
+{
+       int index = (dma_addr - iotlb_virt_start) >> IO_TLB_SHIFT;
+       struct phys_addr buffer = io_tlb_orig_addr[index];
+       buffer.offset += (long)dma_addr & ((1 << IO_TLB_SHIFT) - 1);
+       buffer.page += buffer.offset >> PAGE_SHIFT;
+       buffer.offset &= PAGE_SIZE - 1;
+       return buffer;
 }
 
 /*
@@ -400,7 +408,7 @@ unmap_single(struct device *hwdev, char 
        unsigned long flags;
        int i, count, nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
        int index = (dma_addr - iotlb_virt_start) >> IO_TLB_SHIFT;
-       struct phys_addr buffer = io_tlb_orig_addr[index];
+       struct phys_addr buffer = dma_addr_to_phys_addr(dma_addr);
 
        /*
         * First, sync the memory before unmapping the entry
@@ -440,8 +448,7 @@ static void
 static void
 sync_single(struct device *hwdev, char *dma_addr, size_t size, int dir)
 {
-       int index = (dma_addr - iotlb_virt_start) >> IO_TLB_SHIFT;
-       struct phys_addr buffer = io_tlb_orig_addr[index];
+       struct phys_addr buffer = dma_addr_to_phys_addr(dma_addr);
        BUG_ON((dir != DMA_FROM_DEVICE) && (dir != DMA_TO_DEVICE));
        __sync_single(buffer, dma_addr, size, dir);
 }

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