| Message ID | 20190826121944.515-8-hch@lst.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [01/11] xen/arm: use dma-noncoherent.h calls for xen-swiotlb cache maintainance | expand |
On Mon, 26 Aug 2019, Christoph Hellwig wrote: > 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 >
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
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> --- include/xen/arm/page-coherent.h | 31 +++++++++---------------------- 1 file changed, 9 insertions(+), 22 deletions(-)