From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Date: Fri, 21 Nov 2014 11:10:39 +0000 (+0000)
Subject: swiotlb-xen: remove BUG_ON in xen_bus_to_phys
X-Git-Tag: v3.16.35~3287
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=de705e65b8e65fce1151597df50efadf3e0e150a;p=thirdparty%2Fkernel%2Fstable.git

swiotlb-xen: remove BUG_ON in xen_bus_to_phys

commit c884227eaae9936f8ecbde6e1387bccdab5f4e90 upstream.

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>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index bc6fb0d24ad53..f21282da98768 100644
--- 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;