Re: [Xen-devel] [PATCH 09/10] log-dirty: Refine common code to support PML

[Kai Huang <kai.huang@xxxxxxxxxxxxxxx>]

On 04/10/2015 05:31 PM, Tim Deegan wrote:
> At 15:38 +0800 on 10 Apr (1428680289), Kai Huang wrote:
> > On 04/09/2015 08:27 PM, Tim Deegan wrote:
> > > At 10:35 +0800 on 27 Mar (1427452553), Kai Huang wrote:
> > > > --- a/xen/arch/x86/mm/paging.c
> > > > +++ b/xen/arch/x86/mm/paging.c
> > > > @@ -411,7 +411,18 @@ static int paging_log_dirty_op(struct domain *d,
> > > >        int i4, i3, i2;
> > > >    
> > > >        if ( !resuming )
> > > > +    {
> > > >            domain_pause(d);
> > > > +
> > > > +        /*
> > > > +         * Only need to flush when not resuming, as domain was paused in
> > > > +         * resuming case therefore it's not possible to have any new dirty
> > > > +         * page.
> > > > +         */
> > > > +        if ( d->arch.paging.log_dirty.flush_cached_dirty )
> > > > +            d->arch.paging.log_dirty.flush_cached_dirty(d);
> > > I think there are too many layers of indirection here. :)  How about:
> > >    - don't add a flush_cached_dirty() function to the log_dirty ops.
> > >    - just call p2m_flush_hardware_cached_dirty(d) here.
> > >
> > > Would that work OK?
> > Thanks for pointing out.
> >
> > Is it nature to call p2m layer functions in paging.c? If there's no
> > restriction on it, calling p2m_flush_hardware_cached_dirty is more
> > clear, and it should work.
> Yes, calling public p2m functions directly is OK -- it's the internal
> function pointers like ->get_entry() that aren't supposed to be called
> from outside p2m code.  I guess that's not terribly clear - maybe it
> needs some better comments.
Pretty clear to me now. Thanks. Will do.:)

Thanks,
-Kai
> Tim.

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