Re: [patch 1/5] KVM: add basic paravirt support (v2)

[Avi Kivity <avi@qumranet.com>]

Marcelo Tosatti wrote:
> Add basic KVM paravirt support. Avoid vm-exits on IO delays.
>
> Add KVM_GET_PARA_FEATURES ioctl so paravirt features can be reported in a
> single bitmask. This allows the host to disable features on runtime if 
> appropriate, which would require one ioctl per feature otherwise.
>
> The limit of 32 features can be extended to 64 if needed, beyond that a new 
> MSR is required.
>
> v1->v2:
> - replace KVM_CAP_CLOCKSOURCE with KVM_CAP_PARA_FEATURES
> - cover FEATURE_CLOCKSOURCE
>
>
>   

I don't understand the motivation for this.  A handful of ioctl()s at 
init time are hardly time consuming.

There is the advantage that paravirt kernel advances are reflected 
automatically without changes in userspace, but sometimes this is a 
disadvantage (it means there is no way to disable it, for instance).


-- 
error compiling committee.c: too many arguments to function


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