Messages in this thread | | | Subject | Re: Writable module parameters in KVM | From | Paolo Bonzini <> | Date | Wed, 26 May 2021 18:30:02 +0200 |
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On 26/05/21 17:44, Sean Christopherson wrote: >> Sure, making them writable is okay. > > making a param writable (new or existing) must come with strong > justification for taking on the extra complexity.
I agree. It's the same for every change, and it's the reason why most parameters are read-only: no justification for the extra complexity. But if somebody has a usecase, it can be considered.
> Making 'npt' writable is probably feasible ('ept' would be beyond messy), but I > strongly prefer to keep it read-only. The direct impacts on the MMU and SVM > aren't too bad, but NPT is required for SEV and VLS, affects kvm_cpu_caps, etc... > And, no offense to win98, there's isn't a strong use case because outside of > personal usage, the host admin/VMM doesn't know that the guest will be running a > broken kernel.
Making 'npt' writable would be beyond messy too; allowing select VMs to disable EPT/NPT might be simpler, but not that much. I can't say offhand if the code would be ugly or not.
Paolo
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