[Xen-devel] [PATCH] swiotlb-xen: update dev_addr after swapping pages

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

In xen_swiotlb_map_page and xen_swiotlb_map_sg_attrs, if the original
page is not suitable, we swap it for another page from the swiotlb 
pool.

In these cases, we don't update the previously calculated dma address
for the page before calling xen_dma_map_page. Thus, we end up calling
xen_dma_map_page passing the wrong dev_addr, resulting in
xen_dma_map_page mistakenly assuming that the page is foreign when it is
local.

Fix the bug by updating dev_addr appropriately.

This change has no effect on x86, because xen_dma_map_page is a stub
there.

Signed-off-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Signed-off-by: Pooya Keshavarzi <Pooya.Keshavarzi@xxxxxxxxxxxx>
Tested-by: Pooya Keshavarzi <Pooya.Keshavarzi@xxxxxxxxxxxx>

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index f905d6e..f8afc6d 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -414,9 +414,9 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct 
page *page,
        if (map == SWIOTLB_MAP_ERROR)
                return DMA_ERROR_CODE;
 
+       dev_addr = xen_phys_to_bus(map);
        xen_dma_map_page(dev, pfn_to_page(map >> PAGE_SHIFT),
                                        dev_addr, map & ~PAGE_MASK, size, dir, 
attrs);
-       dev_addr = xen_phys_to_bus(map);
 
        /*
         * Ensure that the address returned is DMA'ble
@@ -575,13 +575,14 @@ void xen_swiotlb_unmap_page(struct device *hwdev, 
dma_addr_t dev_addr,
                                sg_dma_len(sgl) = 0;
                                return 0;
                        }
+                       dev_addr = xen_phys_to_bus(map);
                        xen_dma_map_page(hwdev, pfn_to_page(map >> PAGE_SHIFT),
                                                dev_addr,
                                                map & ~PAGE_MASK,
                                                sg->length,
                                                dir,
                                                attrs);
-                       sg->dma_address = xen_phys_to_bus(map);
+                       sg->dma_address = dev_addr;
                } else {
                        /* we are not interested in the dma_addr returned by
                         * xen_dma_map_page, only in the potential cache 
flushes executed

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel