Re: [Qemu-devel] [PATCH 0/2] vfio: type1 iommu hugepage support

[Konrad Rzeszutek Wilk]

On Fri, May 24, 2013 at 11:24:26AM -0600, Alex Williamson wrote:
> This series let's the vfio type1 iommu backend take advantage of iommu
> large page support.  See patch 2/2 for the details.  This has been
> tested on both amd_iommu and intel_iommu, but only my AMD system has
> large page support.  I'd appreciate any testing and feedback on other
> systems, particularly vt-d systems supporting large pages.  Mapping
> efficiency should be improved a bit without iommu hugepages, but I
> hope that it's much more noticeable with huge pages, especially for
> very large QEMU guests.

I took a very very quick look - and I am wondering if there should also
be a flag to turn it on/off in ther kernel in such case? Especially in the 
field if a user finds out that their particular IOMMU chipset might
be doing something funky with large-pages ?

> 
> This change includes a clarification to the mapping expectations for
> users of the type1 iommu, but is compatible with known users and works
> with existing QEMU userspace supporting vfio.  Thanks,
> 
> Alex
> 
> ---
> 
> Alex Williamson (2):
>       vfio: Convert type1 iommu to use rbtree
>       vfio: hugepage support for vfio_iommu_type1
> 
> 
>  drivers/vfio/vfio_iommu_type1.c |  607 
> ++++++++++++++++++++++++---------------
>  include/uapi/linux/vfio.h       |    8 -
>  2 files changed, 387 insertions(+), 228 deletions(-)
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