Re: [Qemu-devel] [RFC PATCH v2 00/12] iommu: add MemTxAttrs argument to IOMMU translate function

[Peter Maydell]

On 17 May 2018 at 13:46, Paolo Bonzini <address@hidden> wrote:
> Yes, this also sounds good.  It does have the same issue for VFIO that
> get_num_indexes() would be called too late to fail (and again, in a
> place where it's hard to fail).
>
> Maybe the index count and the index-from/to-attrs translation should be
> static (index-to-attrs could use the same pair of MemTxAttrs for "which
> bits matter" and "what value should they have"), so that VFIO can
> inspect it and decide if it's okay to proceed with e.g. the first iommu_idx?

Well, they need to be static in the sense that the IOMMU can't
change its opinion later about what it has. So as long as you
have a pointer to the IOMMU you can ask it how many indexes it has.

thanks
-- PMM