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

From: Paul Mackerras <[email-masked]>
Date: Wed, 18 Jul 2018 16:28:31 +1000

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.