Re: [PATCH 5/6] kvm, x86: use ro page and don't copy shared page

Gleb Natapov
2010-07-18T15:23:28Z

On Sun, Jul 18, 2010 at 06:14:11PM +0300, Avi Kivity wrote:
> On 07/17/2010 07:31 AM, Gleb Natapov wrote:
> >>>
> >>>Currently pages allocated for guest memory are required to be RW, so after your series
> >>>behaviour will remain exactly the same as before.
> >>Except KSM pages.
> >>
> >KSM page will be COWed by __get_user_pages_fast(addr, 1, 1, page) in
> >get_user_page_and_protection() just like it COWed now, no?
>
> Well, we don't want to COW it on write faults.
>
> The optimal behaviour is:
>
> - write faults: COW and instantiate a writeable spte
So do we or don't we want to COW on write faults?

--
Gleb.