On Tue, 28 Sep 2021 13:06:26 +0200 Christian Borntraeger <borntraeger@xxxxxxxxxx> wrote: > Am 28.09.21 um 12:59 schrieb Heiko Carstens: > > On Thu, Sep 09, 2021 at 06:22:39PM +0200, David Hildenbrand wrote: > >> Resend because I missed ccing people on the actual patches ... > >> > >> RFC because the patches are essentially untested and I did not actually > >> try to trigger any of the things these patches are supposed to fix. It > >> merely matches my current understanding (and what other code does :) ). I > >> did compile-test as far as possible. > >> > >> After learning more about the wonderful world of page tables and their > >> interaction with the mmap_sem and VMAs, I spotted some issues in our > >> page table walkers that allow user space to trigger nasty behavior when > >> playing dirty tricks with munmap() or mmap() of hugetlb. While some issues > >> should be hard to trigger, others are fairly easy because we provide > >> conventient interfaces (e.g., KVM_S390_GET_SKEYS and KVM_S390_SET_SKEYS). > >> > >> Future work: > >> - Don't use get_locked_pte() when it's not required to actually allocate > >> page tables -- similar to how storage keys are now handled. Examples are > >> get_pgste() and __gmap_zap. > >> - Don't use get_locked_pte() and instead let page fault logic allocate page > >> tables when we actually do need page tables -- also, similar to how > >> storage keys are now handled. Examples are set_pgste_bits() and > >> pgste_perform_essa(). > >> - Maybe switch to mm/pagewalk.c to avoid custom page table walkers. For > >> __gmap_zap() that's very easy. > >> > >> Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx> > >> Cc: Janosch Frank <frankja@xxxxxxxxxxxxx> > >> Cc: Cornelia Huck <cohuck@xxxxxxxxxx> > >> Cc: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx> > >> Cc: Heiko Carstens <hca@xxxxxxxxxxxxx> > >> Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx> > >> Cc: Niklas Schnelle <schnelle@xxxxxxxxxxxxx> > >> Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx> > >> Cc: Ulrich Weigand <Ulrich.Weigand@xxxxxxxxxx> > > > > For the whole series: > > Acked-by: Heiko Carstens <hca@xxxxxxxxxxxxx> > > > > Christian, given that this is mostly about KVM I'd assume this should > > go via the KVM tree. Patch 6 (pci_mmio) is already upstream. > > Right, I think I will queue this even without testing for now. > Claudio, is patch 7 ok for you with the explanation from David? yes
