Re: [PATCH 3/4] KVM: MMU: track dirty page in speculative path properly

[Marcelo Tosatti <mtosatti@redhat.com>]

On Wed, Jul 14, 2010 at 09:24:22AM +0800, Xiao Guangrong wrote:
> 
> 
> Marcelo Tosatti wrote:
> > On Tue, Jul 13, 2010 at 05:45:27PM +0800, Xiao Guangrong wrote:
> >> In speculative path, the page is not real write-access, no need mark it
> >> dirty, so clear dirty bit in this path and later examine this bit when
> >> we release the page
> >>
> >> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
> >> ---
> >>  arch/x86/kvm/mmu.c |   24 +++++++++++-------------
> >>  1 files changed, 11 insertions(+), 13 deletions(-)
> > 
> > Unfortunately all pages that kvm creates translations for are marked
> > dirty due to get_user_pages(w=1), except KSM which makes them read-only
> > later.
> 
> Marcelo, i have looked into get_user_pages() function, but not catch where
> to make page dirty, could you point it out for me? :-)

See set_page_dirty call in mm/memory.c::follow_page.