swiotlb-xen: remove BUG_ON in xen_bus_to_phys

On x86 truncation cannot occur because config XEN depends on X86_64 ||
(X86_32 && X86_PAE).

On ARM truncation can occur without CONFIG_ARM_LPAE, when the dma
operation involves foreign grants. However in that case the physical
address returned by xen_bus_to_phys is actually invalid (there is no mfn
to pfn tracking for foreign grants on ARM) and it is not used.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: stable@vger.kernel.org

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 498b6544fd6264856fc8e47d66cb43d410b61fa8..153cf14821257310ad5d54a5b829bf195ace434a 100644 (file)
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -96,8 +96,6 @@ static inline phys_addr_t xen_bus_to_phys(dma_addr_t baddr)
        dma_addr_t dma = (dma_addr_t)pfn << PAGE_SHIFT;
        phys_addr_t paddr = dma;
 
-       BUG_ON(paddr != dma); /* truncation has occurred, should never happen */
-
        paddr |= baddr & ~PAGE_MASK;
 
        return paddr;