Patch "swiotlb-xen: update dev_addr after swapping pages" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

swiotlb-xen: update dev_addr after swapping pages

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
swiotlb-xen-update-dev_addr-after-swapping-pages.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Stefano Stabellini <[email protected]>
Date: Thu, 19 Jan 2017 10:39:09 -0800
Subject: swiotlb-xen: update dev_addr after swapping pages

From: Stefano Stabellini <[email protected]>

[ Upstream commit f1225ee4c8fcf09afaa199b8b1f0450f38b8cd11 ]

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.

---
 drivers/xen/swiotlb-xen.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

@@ -409,9 +409,9 @@ dma_addr_t xen_swiotlb_map_page(struct d
 	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

@@ -567,13 +567,14 @@ xen_swiotlb_map_sg_attrs(struct device *
 				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

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/swiotlb-xen-update-dev_addr-after-swapping-pages.patch