Re: [Qemu-devel] [PATCH v2] vhost: Allow adjoining regions

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Alex Williamson (alex.williamson@redhat.com) wrote:
> On Fri, 23 Mar 2018 15:39:39 +0000
> "Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:
> 
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > 
> > My rework of section adding combines overlapping or adjoining regions,
> > but checks they're actually the same underlying RAM block.
> > Fix the case where two blocks adjoin but don't overlap; that new region
> > should get added (but not combined), but my previous patch was disallowing it.
> > 
> > Fixes: c1ece84e7c9
> > 
> > Reported-by: Alex Williamson <alex.williamson@redhat.com>
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > ---
> 
> 
> Ping?  This error report is a regression and should be considered for
> 2.12.
> 
> Tested-by: Alex Williamson <alex.williamson@redhat.com>

It's a change in vhost - so mst is taking it ?

Dave

> 
> >  hw/virtio/vhost.c | 13 +++++++++----
> >  1 file changed, 9 insertions(+), 4 deletions(-)
> > 
> > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> > index 250f886acb..2a720cca3d 100644
> > --- a/hw/virtio/vhost.c
> > +++ b/hw/virtio/vhost.c
> > @@ -595,10 +595,15 @@ static void vhost_region_add_section(struct vhost_dev *dev,
> >                                          prev_sec->offset_within_address_space,
> >                                          prev_sec->offset_within_region);
> >              } else {
> > -                error_report("%s: Overlapping but not coherent sections "
> > -                             "at %"PRIx64,
> > -                             __func__, mrs_gpa);
> > -                return;
> > +                /* adjoining regions are fine, but overlapping ones with
> > +                 * different blocks/offsets shouldn't happen
> > +                 */
> > +                if (mrs_gpa != prev_gpa_end + 1) {
> > +                    error_report("%s: Overlapping but not coherent sections "
> > +                                 "at %"PRIx64,
> > +                                 __func__, mrs_gpa);
> > +                    return;
> > +                }
> >              }
> >          }
> >      }
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK