[Xen-devel] [PATCH 8 of 9] swiotlb: cleanups to swiotlb_bounce()

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

Make swiotlb_bounce test each page for highness rather than relying on
CONFIG_HIGHMEM, and a couple of other cleanups.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
---
 lib/swiotlb.c |   61 +++++++++++++++++++++++++++++----------------------------
 1 file changed, 32 insertions(+), 29 deletions(-)

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -25,6 +25,7 @@
 #include <linux/swiotlb.h>
 #include <linux/string.h>
 #include <linux/swiotlb.h>
+#include <linux/pfn.h>
 #include <linux/types.h>
 #include <linux/ctype.h>
 #include <linux/highmem.h>
@@ -330,40 +331,42 @@
 /*
  * Bounce: copy the swiotlb buffer back to the original dma location
  */
-void swiotlb_bounce(phys_addr_t phys, char *dma_addr, size_t size,
-                 enum dma_data_direction dir)
+static void swiotlb_bounce(phys_addr_t phys, char *dma_addr, size_t size,
+                          enum dma_data_direction dir)
 {
-#ifdef CONFIG_HIGHMEM
-       /* The buffer may not have a mapping.  Map it in and copy */
-       unsigned int offset = ((unsigned long)phys &
-                              ((1 << PAGE_SHIFT) - 1));
-       char *buffer;
-       unsigned int sz = 0;
-       unsigned long flags;
+       unsigned long pfn = PFN_DOWN(phys);
 
-       while (size) {
-               sz = ((PAGE_SIZE - offset) > size) ? size :
-                       PAGE_SIZE - offset;
-               local_irq_save(flags);
-               buffer = kmap_atomic(pfn_to_page(phys >> PAGE_SHIFT),
-                                    KM_BOUNCE_READ);
+       if (PageHighMem(pfn_to_page(pfn))) {
+               /* The buffer does not have a mapping.  Map it in and copy */
+               unsigned int offset = phys & ~PAGE_MASK;
+               char *buffer;
+               unsigned int sz = 0;
+               unsigned long flags;
+
+               while (size) {
+                       sz = min(PAGE_SIZE - offset, size);
+
+                       local_irq_save(flags);
+                       buffer = kmap_atomic(pfn_to_page(pfn),
+                                            KM_BOUNCE_READ);
+                       if (dir == DMA_TO_DEVICE)
+                               memcpy(dma_addr, buffer + offset, sz);
+                       else
+                               memcpy(buffer + offset, dma_addr, sz);
+                       kunmap_atomic(buffer, KM_BOUNCE_READ);
+                       local_irq_restore(flags);
+
+                       size -= sz;
+                       pfn++;
+                       dma_addr += sz;
+                       offset = 0;
+               }
+       } else {
                if (dir == DMA_TO_DEVICE)
-                       memcpy(dma_addr, buffer + offset, sz);
+                       memcpy(dma_addr, phys_to_virt(phys), size);
                else
-                       memcpy(buffer + offset, dma_addr, sz);
-               kunmap_atomic(buffer, KM_BOUNCE_READ);
-               local_irq_restore(flags);
-               size -= sz;
-               phys += sz;
-               dma_addr += sz;
-               offset = 0;
+                       memcpy(phys_to_virt(phys), dma_addr, size);
        }
-#else
-       if (dir == DMA_TO_DEVICE)
-               memcpy(dma_addr, phys_to_virt(phys), size);
-       else
-               memcpy(phys_to_virt(phys), dma_addr, size);
-#endif
 }
 
 /*



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