On Tue, May 02, 2023 at 03:28:40PM +0200, David Hildenbrand wrote: > On 02.05.23 15:10, Jason Gunthorpe wrote: > > On Tue, May 02, 2023 at 03:04:27PM +0200, Christian Borntraeger wrote: > > \> > We can reintroduce a flag to permit exceptions if this is really broken, are you > > > > able to test? I don't have an s390 sat around :) > > > > > > Matt (Rosato on cc) probably can. In the end, it would mean having > > > <memoryBacking> > > > <source type="file"/> > > > </memoryBacking> > > > > This s390 code is the least of the problems, after this series VFIO > > won't startup at all with this configuration. > > Good question if the domain would fail to start. I recall that IOMMUs for > zPCI are special on s390x. [1] Not upstream they aren't. > Well, zPCI is special. I cannot immediately tell when we would trigger > long-term pinning. zPCI uses the standard IOMMU stuff, so it uses a normal VFIO container and the normal pin_user_pages() path. > [1] https://www.mail-archive.com/qemu-devel@xxxxxxxxxx/msg875728.html AFIACT this is talking about the nested IOMMU translation stuff. RPCIT is the hypercall to invalidate the nested IOMMU table. I expect s390 is going to have another go at implementing this using iommufd. The stuff in that series like KVM_S390_ZPCIOP_REG_IOAT didn't make it upstream. Jason
