Re: [PATCH 00/23] Add KVM support for PPC64 (970) hosts

[Avi Kivity <avi@redhat.com>]

On 07/08/2009 09:22 AM, Benjamin Herrenschmidt wrote:
> On Tue, 2009-07-07 at 19:08 +0300, Avi Kivity wrote:
>    
>>> Or is using mmu_notifiers mandatory? :-).
>>>        
>> It's highly recommended.
>>      
>
> Considering how "differnent" the ppc MMU is, I'm not sure mmu notifiers
> is necessarily the right approach but we definitely should have a close
> look.
>    

I don't see how the mmu structure matters.  All mmu notifiers does is 
tell you when Linux wants to drop a pte, it's completely up to you how 
to use this information.

There are three ways of dealing with the problem:

- ignore it (ia64, ppc)

Easy to implement, but you can't swap or do any fancy stuff like page 
migration.  If you have a large tlb/shadow, you pin a lot of pages.

- use mmu notifiers (x86)

Need reverse mapping to convert guest physical addresses to shadow/tlb 
addresses.  Not difficult to implement but requires careful locking.

- s390 (s390)

You can s390 your problems away if you have s390 hardware.

Can you explain your concerns?

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