Re: [Xen-devel] [PATCH v3 3/3] tools: introduce parameter max_wp_ram_ranges.

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Fri, Feb 5, 2016 at 3:13 PM, Zhiyuan Lv <zhiyuan.lv@xxxxxxxxx> wrote:
>> My question is, suppose a single GTT / gpu thread / tree has 9000
>> ranges.  It would be trivial for an attacker to break into the
>> operating system and *construct* such a tree, but it's entirely
>> possible that due to a combination of memory fragmentation and very
>> large usage, the normal driver might accidentally create such a GTT.
>> In that case, the device model will not be able to write-protect all
>> the pages in the single GTT, and thus will not be able to correctly
>> track changes to the currently-active GTT.  What does your device
>> model do in that case?
>
> We can live with the partially write protected tree. That is because
> GPU's workload execution is controlled by the device model. We still
> have chance to update the shadow page table before we submit workload
> to GPU. The impact is performance not correctness. Thanks!

Right -- so it's actually never a hard limit.  That's good to know.

 -George

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