Re: [PATCH kernel v7 0/2] KVM: PPC: Check if IOMMU page is contained in the pinned physical page

On Tue, Jul 17, 2018 at 05:19:11PM +1000, Alexey Kardashevskiy wrote:

This is to improve page boundaries checking and should probably
be cc:stable. I came accross this while debugging nvlink2 passthrough
but the lack of checking might be exploited by the existing userspace.

The get_user_pages() comment says it should be "phased out" but the only
alternative seems to be get_user_pages_longterm(), should that be used
instead (this is longterm reference elevation, however it is not DAX,
whatever this implies)? get_user_pages_remote() seems unnecessarily
complicated because of @locked.


Changes:
v7:
* 2/2: do not fail if pte is not found, fall back to the default case instead

v6:
* 2/2: read pageshift from pte

v5:
* 2/2: changed compound pages handling

v4:
* 2/2: implemented less strict but still safe max pageshift as David suggested

v3:
* enforced huge pages not to cross preregistered chunk boundaries

v2:
* 2/2: explicitly check for compound pages before calling compound_order()


This is based on sha1
9d3cce1 Linus Torvalds "Linux 4.18-rc5".

Please comment. Thanks.



Alexey Kardashevskiy (2):
  vfio/spapr: Use IOMMU pageshift rather than pagesize
  KVM: PPC: Check if IOMMU page is contained in the pinned physical page

 arch/powerpc/include/asm/mmu_context.h |  4 ++--
 arch/powerpc/kvm/book3s_64_vio.c       |  2 +-
 arch/powerpc/kvm/book3s_64_vio_hv.c    |  6 ++++--
 arch/powerpc/mm/mmu_context_iommu.c    | 37 ++++++++++++++++++++++++++++++++--
 drivers/vfio/vfio_iommu_spapr_tce.c    | 10 ++++-----
 5 files changed, 47 insertions(+), 12 deletions(-)

Thanks, series applied to my kvm-ppc-next branch.

Paul.