linux-kernel - Re: [PATCH v9 6/6] KVM: arm64: Expose new KVM cap for cacheable PFNMAP

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Date: Fri, 4 Jul 2025 16:20:07 +0000
From: Ankit Agrawal <ankita@...dia.com>
To: Jason Gunthorpe <jgg@...dia.com>, David Hildenbrand <david@...hat.com>
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Subject: Re: [PATCH v9 6/6] KVM: arm64: Expose new KVM cap for cacheable
 PFNMAP

Thanks Jason and David for reviewing the patch!

>> >
>> > I don't know if any VMM will ever use this, but it looks OK
>>
>> So, should we defer it to the point where we actually have a use case?
>>
>> I mean, patch #4 could be simplified by modifying arm64 code in patch #5
>> only. No need for a common kvm_arch function etc.
>
> IDK, I think Marc and Oliver are right it makes sense to have it, I
> just don't really see how a VMM would make use of it..
>
> Jason

Right, it was also pointed out that the VMM could make use of it
for early termination during VM migration between incompatible 
systems (i.e. across systems with and without FWB and CACHE DIC).