Re: [Qemu-devel] [PATCH RFC v4 15/20] intel_iommu: provide its own replay() callback

[Alex Williamson <alex.williamson@redhat.com>]

On Sun, 22 Jan 2017 16:51:18 +0800
Peter Xu <peterx@redhat.com> wrote:

> On Sun, Jan 22, 2017 at 03:56:10PM +0800, Jason Wang wrote:
> >   
> > >+            trace_vtd_page_walk_one(level, entry.iova, entry.translated_addr,
> > >+                                    entry.addr_mask, entry.perm);
> > >+            if (hook_fn) {
> > >+                ret = hook_fn(&entry, private);  
> > 
> > For better performance, we could try to merge adjacent mappings here. I
> > think both vfio and vhost support this and it can save a lot of ioctls.  
> 
> Looks so, and this is in my todo list.
> 
> Do you mind I do it later after this series merged? I would really
> appreciate if we can have this codes settled down first (considering
> that this series has been dangling for half a year, or more, startint
> from Aviv's series), and I am just afraid this will led to
> unconvergence of this series (and I believe there are other places
> that can be enhanced in the future as well).

NAK, we can't merge mappings per my comment on 18/20.  You're looking
at an entirely new or at best revised version of the vfio IOMMU
interface to do so.  vfio does not support invalidations at a smaller
granularity than the original mapping.  Thanks,

Alex