xen/arm/arm64: introduce xen_arch_need_swiotlb

Introduce an arch specific function to find out whether a particular dma
mapping operation needs to bounce on the swiotlb buffer.

On ARM and ARM64, if the page involved is a foreign page and the device
is not coherent, we need to bounce because at unmap time we cannot
execute any required cache maintenance operations (we don't know how to
find the pfn from the mfn).

No change of behaviour for x86.

Signed-off-by: Stefano Stabellini <[email protected]>
Reviewed-by: David Vrabel <[email protected]>
Reviewed-by: Catalin Marinas <[email protected]>
Acked-by: Ian Campbell <[email protected]>
Acked-by: Konrad Rzeszutek Wilk <[email protected]>
This commit is contained in:
Stefano Stabellini 2014-11-21 11:07:39 +00:00 • committed by David Vrabel
commit a4dba13089
4 changed files with 22 additions and 1 deletions

View file

@ -399,7 +399,9 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
* buffering it.
*/
if (dma_capable(dev, dev_addr, size) &&
!range_straddles_page_boundary(phys, size) && !swiotlb_force) {
!range_straddles_page_boundary(phys, size) &&
!xen_arch_need_swiotlb(dev, PFN_DOWN(phys), PFN_DOWN(dev_addr)) &&
!swiotlb_force) {
/* we are not interested in the dma_addr returned by
* xen_dma_map_page, only in the potential cache flushes executed
* by the function. */
@ -557,6 +559,7 @@ xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
dma_addr_t dev_addr = xen_phys_to_bus(paddr);
if (swiotlb_force ||
xen_arch_need_swiotlb(hwdev, PFN_DOWN(paddr), PFN_DOWN(dev_addr)) ||
!dma_capable(hwdev, dev_addr, sg->length) ||
range_straddles_page_boundary(paddr, sg->length)) {
phys_addr_t map = swiotlb_tbl_map_single(hwdev,