linux-kernel - [PATCH v8 13/13] swiotlb-xen: remove BUG_ON in xen_bus_to

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Date:	Mon, 10 Nov 2014 16:14:05 +0000
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	<xen-devel@...ts.xensource.com>
CC:	<konrad.wilk@...cle.com>, <Ian.Campbell@...rix.com>,
	<david.vrabel@...rix.com>, <linux-kernel@...r.kernel.org>,
	<Stefano.Stabellini@...citrix.com>,
	<linux-arm-kernel@...ts.infradead.org>, <catalin.marinas@....com>,
	Stefano Stabellini <stefano.stabellini@...citrix.com>
Subject: [PATCH v8 13/13] 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@...citrix.com>
---
 drivers/xen/swiotlb-xen.c |    2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 498b654..153cf14 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;
-- 
1.7.10.4

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