Re: [PATCH 2/5] vfio: introduce the VFIO_DMA_MAP_FLAG_NOEXEC flag

[Andy Lutomirski]

On Mon, Oct 13, 2014 at 6:09 AM, Antonios Motakis
<a.motakis@xxxxxxxxxxxxxxxxxxxxxx> wrote:
> We introduce the VFIO_DMA_MAP_FLAG_NOEXEC flag to the VFIO dma map call,
> and expose its availability via the capability VFIO_DMA_NOEXEC_IOMMU.
> This way the user can control whether the XN flag will be set on the
> requested mappings. The IOMMU_NOEXEC flag needs to be available for all
> the IOMMUs of the container used.

Since you sent this to the linux-api list, I'll bite: what's the XN
flag?  I know what PROT_EXEC does when you mmap something, and I
presume that vfio is mmappable, but I don't actually have any clue
what this patch does.

I assume that this does not have anything to do with a non-CPU DMA
master executing code in main memory, because that makes rather little
sense.  (Or maybe it really does, in which case: weird.)

--Andy
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