On Tue, May 21, 2024 at 12:49:39PM -0300, Jason Gunthorpe wrote: > On Mon, May 20, 2024 at 07:07:10AM -0700, Christoph Hellwig wrote: > > On Tue, May 07, 2024 at 02:20:44PM +0800, Yan Zhao wrote: > > > Introduce and export interface arch_clean_nonsnoop_dma() to flush CPU > > > caches for memory involved in non-coherent DMAs (DMAs that lack CPU cache > > > snooping). > > > > Err, no. There should really be no exported cache manipulation macros, > > as drivers are almost guaranteed to get this wrong. I've added > > Russell to the Cc list who has been extremtly vocal about this at least > > for arm. > > We could possibly move this under some IOMMU core API (ie flush and > map, unmap and flush), the iommu APIs are non-modular so this could > avoid the exported symbol. Though this would be pretty difficult for unmap as we don't have the pfns in the core code to flush. I don't think we have alot of good options but to make iommufd & VFIO handle this directly as they have the list of pages to flush on the unmap side. Use a namespace? Jason
