From: Christoph Hellwig <hch@lst.de>
To: Stefano Stabellini <sstabellini@kernel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
gross@suse.com, boris.ostrovsky@oracle.com
Cc: xen-devel@lists.xenproject.org, iommu@lists.linux-foundation.org,
x86@kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH 09/13] swiotlb-xen: use the same foreign page check everywhere
Date: Mon, 2 Sep 2019 15:03:35 +0200 [thread overview]
Message-ID: <20190902130339.23163-10-hch@lst.de> (raw)
In-Reply-To: <20190902130339.23163-1-hch@lst.de>
xen_dma_map_page uses a different and more complicated check for foreign
pages than the other three cache maintainance helpers. Switch it to the
simpler pfn_valid method a well, and document the scheme with a single
improved comment in xen_dma_map_page.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
---
include/xen/arm/page-coherent.h | 31 +++++++++----------------------
1 file changed, 9 insertions(+), 22 deletions(-)
diff --git a/include/xen/arm/page-coherent.h b/include/xen/arm/page-coherent.h
index 0e244f4fec1a..07c104dbc21f 100644
--- a/include/xen/arm/page-coherent.h
+++ b/include/xen/arm/page-coherent.h
@@ -41,23 +41,17 @@ static inline void xen_dma_map_page(struct device *hwdev, struct page *page,
dma_addr_t dev_addr, unsigned long offset, size_t size,
enum dma_data_direction dir, unsigned long attrs)
{
- unsigned long page_pfn = page_to_xen_pfn(page);
- unsigned long dev_pfn = XEN_PFN_DOWN(dev_addr);
- unsigned long compound_pages =
- (1<<compound_order(page)) * XEN_PFN_PER_PAGE;
- bool local = (page_pfn <= dev_pfn) &&
- (dev_pfn - page_pfn < compound_pages);
+ unsigned long pfn = PFN_DOWN(dev_addr);
/*
- * Dom0 is mapped 1:1, while the Linux page can span across
- * multiple Xen pages, it's not possible for it to contain a
- * mix of local and foreign Xen pages. So if the first xen_pfn
- * == mfn the page is local otherwise it's a foreign page
- * grant-mapped in dom0. If the page is local we can safely
- * call the native dma_ops function, otherwise we call the xen
- * specific function.
+ * Dom0 is mapped 1:1, and while the Linux page can span across multiple
+ * Xen pages, it is not possible for it to contain a mix of local and
+ * foreign Xen pages. Calling pfn_valid on a foreign mfn will always
+ * return false, so if pfn_valid returns true the pages is local and we
+ * can use the native dma-direct functions, otherwise we call the Xen
+ * specific version.
*/
- if (local)
+ if (pfn_valid(pfn))
dma_direct_map_page(hwdev, page, offset, size, dir, attrs);
else
__xen_dma_map_page(hwdev, page, dev_addr, offset, size, dir, attrs);
@@ -67,14 +61,7 @@ static inline void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
size_t size, enum dma_data_direction dir, unsigned long attrs)
{
unsigned long pfn = PFN_DOWN(handle);
- /*
- * Dom0 is mapped 1:1, while the Linux page can be spanned accross
- * multiple Xen page, it's not possible to have a mix of local and
- * foreign Xen page. Dom0 is mapped 1:1, so calling pfn_valid on a
- * foreign mfn will always return false. If the page is local we can
- * safely call the native dma_ops function, otherwise we call the xen
- * specific function.
- */
+
if (pfn_valid(pfn))
dma_direct_unmap_page(hwdev, handle, size, dir, attrs);
else
--
2.20.1
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next prev parent reply other threads:[~2019-09-02 13:06 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-02 13:03 swiotlb-xen cleanups v3 Christoph Hellwig
2019-09-02 13:03 ` [PATCH 01/13] xen/arm: use dma-noncoherent.h calls for xen-swiotlb cache maintainance Christoph Hellwig
2019-09-02 13:03 ` [PATCH 02/13] xen/arm: consolidate page-coherent.h Christoph Hellwig
2019-09-02 13:03 ` [PATCH 03/13] xen/arm: use dev_is_dma_coherent Christoph Hellwig
2019-09-02 13:03 ` [PATCH 04/13] xen/arm: simplify dma_cache_maint Christoph Hellwig
2019-09-02 13:03 ` [PATCH 05/13] xen/arm: remove xen_dma_ops Christoph Hellwig
2019-09-02 13:03 ` [PATCH 06/13] xen: remove the exports for xen_{create, destroy}_contiguous_region Christoph Hellwig
2019-09-02 13:03 ` [PATCH 07/13] swiotlb-xen: remove xen_swiotlb_dma_mmap and -xen_swiotlb_dma_get_sgtable Christoph Hellwig
2019-09-02 13:03 ` [PATCH 08/13] swiotlb-xen: always use dma-direct helpers to alloc coherent pages Christoph Hellwig
2019-09-03 22:15 ` Boris Ostrovsky
2019-09-03 22:25 ` Boris Ostrovsky
2019-09-04 7:00 ` Christoph Hellwig
2019-09-02 13:03 ` Christoph Hellwig [this message]
2019-09-02 13:03 ` [PATCH 10/13] swiotlb-xen: simplify cache maintainance Christoph Hellwig
2019-09-02 13:03 ` [PATCH 11/13] swiotlb-xen: remove page-coherent.h Christoph Hellwig
2019-09-02 13:03 ` [PATCH 12/13] swiotlb-xen: merge xen_unmap_single into xen_swiotlb_unmap_page Christoph Hellwig
2019-09-02 13:03 ` [PATCH 13/13] arm64: use asm-generic/dma-mapping.h Christoph Hellwig
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