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Re: [Xen-devel] [RFC] xen/arm: Handling cache maintenance instructions by set/way

Hi Konrad,

On 12/06/2017 03:10 PM, Konrad Rzeszutek Wilk wrote:
The suggested policy is based on the KVM one:
        - If we trap a S/W instructions, we enable VM trapping (e.g 
detect cache being turned on/off, and do a full clean.
        - We flush the caches on both caches being turned on and off.
        - Once the caches are enabled, we stop trapping VM instructions.

Doing a full clean will require to go through the P2M and flush the entries
one by one. At the moment, all the memory is mapped. As you can imagine
flushing guest with hundreds of MB will take a very long time (Linux timeout
during CPU bring).

Yikes. Since you mention 'based on the KVM one' - did they solve this particular
problem or do they also have the same issue?

KVM is using populate on demand by default.


Julien Grall

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