Re: [Xen-devel] [PATCH v8 0/8] xen/arm: introduce GNTTABOP_cache_flush

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 20.10.14 at 11:47, <stefano.stabellini@xxxxxxxxxxxxx> wrote:
> Hi all,
> this patch series introduces a new hypercall to perform cache
> maintenance operations on behalf of the guest. It is useful for dom0 to
> be able to cache flush pages involved in a dma operation with
> non-coherent devices.
> 
> It also removes XENFEAT_grant_map_identity as the feature is no longer
> necessary: it was used to achieve the same goal but the guest can now
> use the hypercall instead. Keeping the flag would also have a
> significant performance impact as a new p2m mapping gets created and
> then destroyed for every grant that is mapped and unmapped in dom0.
> 
> 
> Changes in v8:
> - remove unused #include;
> - set max_nr_grant_frames as __initdata;
> - set max_grant_frames and max_maptrack_frames as __read_mostly;
> - respent coding style for comments;
> - remove MAX_MAPTRACK_TO_GRANTS_RATIO;
> - avoid security issues, use two separate opaque variables to store the
> input argument and the output argument;

Security issues?

Jan


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