Messages in this thread | | | Subject | Re: [PATCH resend RFC 0/9] s390: fixes, cleanups and optimizations for page table walkers | From | Christian Borntraeger <> | Date | Tue, 28 Sep 2021 13:06:26 +0200 |
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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@de.ibm.com> >> Cc: Janosch Frank <frankja@linux.ibm.com> >> Cc: Cornelia Huck <cohuck@redhat.com> >> Cc: Claudio Imbrenda <imbrenda@linux.ibm.com> >> Cc: Heiko Carstens <hca@linux.ibm.com> >> Cc: Vasily Gorbik <gor@linux.ibm.com> >> Cc: Niklas Schnelle <schnelle@linux.ibm.com> >> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> >> Cc: Ulrich Weigand <Ulrich.Weigand@de.ibm.com> > > For the whole series: > Acked-by: Heiko Carstens <hca@linux.ibm.com> > > 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?
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