[Xen-devel] [PATCH V2] xen-swiotlb: use actually allocated size on check physical continuous

[Joe Jin <joe.jin@xxxxxxxxxx>]

xen_swiotlb_{alloc,free}_coherent() allocate/free memory by order,
but passed required size to range_straddles_page_boundary(),
when first pages are physical continuous,
range_straddles_page_boundary() returned true, then did not
exchanged memory with Xen, later on free memory, it tried to
exchanged non-contiguous memory with Xen, then kernel panic.

Signed-off-by: Joe Jin <joe.jin@xxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: Christoph Helwig <hch@xxxxxx>
Cc: Dongli Zhang <dongli.zhang@xxxxxxxxxx>
Cc: John Sobecki <john.sobecki@xxxxxxxxxx>

---
 drivers/xen/swiotlb-xen.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index a6f9ba85dc4b..aa081f806728 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -303,6 +303,9 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t 
size,
        */
        flags &= ~(__GFP_DMA | __GFP_HIGHMEM);
 
+       /* Convert the size to actually allocated. */
+       size = 1UL << (order + XEN_PAGE_SHIFT);
+
        /* On ARM this function returns an ioremap'ped virtual address for
         * which virt_to_phys doesn't return the corresponding physical
         * address. In fact on ARM virt_to_phys only works for kernel direct
@@ -351,6 +354,9 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t 
size, void *vaddr,
         * physical address */
        phys = xen_bus_to_phys(dev_addr);
 
+       /* Convert the size to actually allocated. */
+       size = 1UL << (order + XEN_PAGE_SHIFT);
+
        if (((dev_addr + size - 1 <= dma_mask)) ||
            range_straddles_page_boundary(phys, size))
                xen_destroy_contiguous_region(phys, order);
-- 
2.15.2 (Apple Git-101.1)



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