Re: State of current pv_ops backend for KVM?

Anthony Liguori
2007-05-30T02:51:25Z

Rusty Russell wrote:
> On Mon, 2007-05-28 at 20:54 -0500, Anthony Liguori wrote:
>
>> Howdy,
>>
>> Does anyone know what the state of a pv_ops backend for KVM is? I know
>> Ingo has an implementation that implements CR3 caching but I don't see
>> any branches in Avi's git tree.
>>
>> Perhaps we should try for a simple pv_ops backend for 2.6.23 seeing as
>> how the host infrastructure is there? I'd be willing to do some leg
>> work here...
>>
>
> "Me too". It's at least worth toying with the mmu batching stuff to see
> if that can shave some cycles there: it seems that cr3 caching is the
> main win for context switch so batching there won't help.
>

I'm working on a simple patch that just adds the infrastructure.

> IIRC Ingo used a magic MSR to detect kvm, and there was a question mark
> over that.

I am not too worried about using an MSR. There's really no fool proof
method here. The only thing to do IMHO is move the kvm pv_ops backend
into a separate file and add appropriate Kconfig stuff.

> VMI uses a different technique, which is probably worth
> considering...
>

VMI can determine that it's under VMware since VMware has to publish an
option ROM. It's quite neat, but overkill for what we're doing (since
we're not going to be using a ROM anyway).

Regards,

Anthony Liguori

> Cheers,
> Rusty.