On Tue, 11 Jul 2023 17:24:40 +0200 Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx> wrote: > On Tue, 11 Jul 2023 13:36:27 +0100 > Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > > > On Tue, Jul 11, 2023 at 11:07:06AM +0200, Christian Borntraeger wrote: > > > Am 10.07.23 um 22:43 schrieb Matthew Wilcox (Oracle): > > > > This patchset changes the API used by the MM to set up page table entries. > > > > The four APIs are: > > > > set_ptes(mm, addr, ptep, pte, nr) > > > > update_mmu_cache_range(vma, addr, ptep, nr) > > > > flush_dcache_folio(folio) > > > > flush_icache_pages(vma, page, nr) > > > > > > > > flush_dcache_folio() isn't technically new, but no architecture > > > > implemented it, so I've done that for them. The old APIs remain around > > > > but are mostly implemented by calling the new interfaces. > > > > > > > > The new APIs are based around setting up N page table entries at once. > > > > The N entries belong to the same PMD, the same folio and the same VMA, > > > > so ptep++ is a legitimate operation, and locking is taken care of for > > > > you. Some architectures can do a better job of it than just a loop, > > > > but I have hesitated to make too deep a change to architectures I don't > > > > understand well. > > > > > > > > One thing I have changed in every architecture is that PG_arch_1 is now a > > > > per-folio bit instead of a per-page bit. This was something that would > > > > have to happen eventually, and it makes sense to do it now rather than > > > > iterate over every page involved in a cache flush and figure out if it > > > > needs to happen. > > > > > > I think we do use PG_arch_1 on s390 for our secure page handling and > > > making this perf folio instead of physical page really seems wrong > > > and it probably breaks this code. > > > > Per-page flags are going away in the next few years, so you're going to > > For each 4k physical page frame, we need to keep track whether it is > secure or not. > > A bit in struct page seems the most logical choice. If that's not > possible anymore, how would you propose we should do? > > > need a new design. s390 seems to do a lot of unusual things. I wish > > s390 is an unusual architecture. we are working on un-weirding our > code, but it takes time > This issue sounds fatal for this version of this patchset?
