On Tue, 21 Oct 2014 10:11:43 +0200 Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > > > On 10/21/2014 08:11 AM, Martin Schwidefsky wrote: > >> I agree with Dave (I thought I disagreed, but I changed my mind while > >> writing down my thoughts). Just define mm_forbids_zeropage in > >> arch/s390/include/asm, and make it return mm->context.use_skey---with a > >> comment explaining how this is only for processes that use KVM, and then > >> only for guests that use storage keys. > > > > The mm_forbids_zeropage() sure will work for now, but I think a vma flag > > is the better solution. This is analog to VM_MERGEABLE or VM_NOHUGEPAGE, > > the best solution would be to only mark those vmas that are mapped to > > the guest. That we have not found a way to do that yet in a sensible way > > does not change the fact that "no-zero-page" is a per-vma property, no? > > I agree it should be per-VMA. However, right now the code is > complicated unnecessarily by making it a per-VMA flag. Also, setting > the flag per VMA should probably be done in > kvm_arch_prepare_memory_region together with some kind of storage key > notifier. This is not very much like Dominik's patch. All in all, > mm_forbids_zeropage() provides a non-intrusive and non-controversial way > to fix the bug. Later on, switching to vma_forbids_zeropage() will be > trivial as far as mm/ code is concerned. > Thank you for all the feedback, will cook up a new version. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
