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Re: [Xen-devel] [PATCH for-4.12] arm/p2m: do not invalidate p2m root if it is shared with IOMMU

On 29/01/2019 13:36, Andrii Anisov wrote:
Hello Julien,


On 28.01.19 18:54, Julien Grall wrote:
There should be no Set/Way in Linux 4.14. So I am a bit confused how can even reach this code.

Well, that is a proprietary kernel driver doing cache maintenance using Set/Way operations. And I'm not sure if we can avoid that :(

Which proprietary kernel driver? And in which context are Set/Way operations 

Using Set/Way is fundamentally broken partly because it does not deal with system caches. It also only applies to a given cache and the behavior will not be replicated to other CPUs. For more details, have a look at [1].

If you wonder, this worked by pure chance in older release. Running such software is a call for nasty behavior in your guest.


[1] https://www.youtube.com/watch?v=s07f82iiI-E

Julien Grall

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