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

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Konrad,

On 12/06/2017 03:10 PM, Konrad Rzeszutek Wilk wrote:
> .snip..
> > The suggested policy is based on the KVM one:
> >         - If we trap a S/W instructions, we enable VM trapping (e.g 
> > HCR_EL2.TVM) to
> > 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.

Cheers,

--
Julien Grall

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