Re: [Qemu-devel] [PATCH v5 4/7] vhost: Merge sections added to temporary list

[Michael S. Tsirkin]

On Mon, Jan 08, 2018 at 06:07:30PM +0000, Dr. David Alan Gilbert wrote:
> * Igor Mammedov (address@hidden) wrote:
> > On Mon, 18 Dec 2017 20:13:37 +0000
> > "Dr. David Alan Gilbert (git)" <address@hidden> wrote:
> > 
> > > From: "Dr. David Alan Gilbert" <address@hidden>
> > > 
> > > As sections are reported by the listener to the _nop and _add
> > > methods, add them to the temporary section list but now merge them
> > > with the previous section if the new one abuts and the backend allows.
> > > 
> > > Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> > beside small nit patch looks good to me, so with it fixed
> > 
> > Reviewed-by: Igor Mammedov <address@hidden>
> > 
> > > ---
> > >  hw/virtio/trace-events |  2 ++
> > >  hw/virtio/vhost.c      | 70 
> > > +++++++++++++++++++++++++++++++++++++++++++-------
> > >  2 files changed, 63 insertions(+), 9 deletions(-)
> > > 
> > > diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
> > > index 4a493bcd46..0e63c8739d 100644
> > > --- a/hw/virtio/trace-events
> > > +++ b/hw/virtio/trace-events
> > > @@ -1,6 +1,8 @@
> > >  # See docs/devel/tracing.txt for syntax documentation.
> > >  
> > >  # hw/virtio/vhost.c
> > > +vhost_region_add_section(const char *name, uint64_t gpa, uint64_t size, 
> > > uint64_t host) "%s: 0x%"PRIx64"+0x%"PRIx64" @ 0x%"PRIx64
> > > +vhost_region_add_section_abut(const char *name, uint64_t new_size) "%s: 
> > > 0x%"PRIx64
> > >  vhost_section(const char *name, int r) "%s:%d"
> > >  
> > >  # hw/virtio/virtio.c
> > > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> > > index 18611f0d40..57d15acd2b 100644
> > > --- a/hw/virtio/vhost.c
> > > +++ b/hw/virtio/vhost.c
> > > @@ -709,14 +709,65 @@ out:
> > >      return;
> > >  }
> > >  
> > > -static void vhost_add_section(struct vhost_dev *dev,
> > > -                              MemoryRegionSection *section)
> > > +/* Adds the section data to the tmp_section structure.
> > > + * It relies on the listener calling us in memory address order
> > > + * and for each region (via the _add and _nop methods) to
> > > + * join neighbours.
> > > + */
> > > +static void vhost_region_add_section(struct vhost_dev *dev,
> > > +                                 MemoryRegionSection *section)
> > wrong alignment, should be on '('
> 
> Fixed, thanks.
> 
> Dave

This is too big by now. I'm applying as is and you can fix with
a patch on top.

> > >  {
> > > -    ++dev->n_tmp_sections;
> > > -    dev->tmp_sections = g_renew(MemoryRegionSection, dev->tmp_sections,
> > > -                                dev->n_tmp_sections);
> > > -    dev->tmp_sections[dev->n_tmp_sections - 1] = *section;
> > > -    memory_region_ref(section->mr);
> > > +    bool need_add = true;
> > > +    uint64_t mrs_size = int128_get64(section->size);
> > > +    uint64_t mrs_gpa = section->offset_within_address_space;
> > > +    uintptr_t mrs_host = 
> > > (uintptr_t)memory_region_get_ram_ptr(section->mr) +
> > > +                         section->offset_within_region;
> > > +
> > > +    trace_vhost_region_add_section(section->mr->name, mrs_gpa, mrs_size,
> > > +                                   mrs_host);
> > > +
> > > +    if (dev->n_tmp_sections) {
> > > +        /* Since we already have at least one section, lets see if
> > > +         * this extends it; since we're scanning in order, we only
> > > +         * have to look at the last one, and the FlatView that calls
> > > +         * us shouldn't have overlaps.
> > > +         */
> > > +        MemoryRegionSection *prev_sec = dev->tmp_sections +
> > > +                                               (dev->n_tmp_sections - 1);
> > > +        uint64_t prev_gpa_start = prev_sec->offset_within_address_space;
> > > +        uint64_t prev_size = int128_get64(prev_sec->size);
> > > +        uint64_t prev_gpa_end   = range_get_last(prev_gpa_start, 
> > > prev_size);
> > > +        uint64_t prev_host_start =
> > > +                        
> > > (uintptr_t)memory_region_get_ram_ptr(prev_sec->mr) +
> > > +                        prev_sec->offset_within_region;
> > > +        uint64_t prev_host_end   = range_get_last(prev_host_start, 
> > > prev_size);
> > > +
> > > +        if (prev_gpa_end + 1 == mrs_gpa &&
> > > +            prev_host_end + 1 == mrs_host &&
> > > +            section->mr == prev_sec->mr &&
> > > +            (!dev->vhost_ops->vhost_backend_can_merge ||
> > > +                dev->vhost_ops->vhost_backend_can_merge(dev,
> > > +                    mrs_host, mrs_size,
> > > +                    prev_host_start, prev_size))) {
> > > +            /* The two sections abut */
> > > +            need_add = false;
> > > +            prev_sec->size = int128_add(prev_sec->size, section->size);
> > > +            trace_vhost_region_add_section_abut(section->mr->name,
> > > +                                                mrs_size + prev_size);
> > > +        }
> > > +    }
> > > +
> > > +    if (need_add) {
> > > +        ++dev->n_tmp_sections;
> > > +        dev->tmp_sections = g_renew(MemoryRegionSection, 
> > > dev->tmp_sections,
> > > +                                    dev->n_tmp_sections);
> > > +        dev->tmp_sections[dev->n_tmp_sections - 1] = *section;
> > > +        /* The flatview isn't stable and we don't use it, making it NULL
> > > +         * means we can memcmp the list.
> > > +         */
> > > +        dev->tmp_sections[dev->n_tmp_sections - 1].fv = NULL;
> > > +        memory_region_ref(section->mr);
> > > +    }
> > >  }
> > >  
> > >  static void vhost_region_add(MemoryListener *listener,
> > > @@ -728,11 +779,12 @@ static void vhost_region_add(MemoryListener 
> > > *listener,
> > >      if (!vhost_section(section)) {
> > >          return;
> > >      }
> > > +    vhost_region_add_section(dev, section);
> > >  
> > > -    vhost_add_section(dev, section);
> > >      vhost_set_memory(listener, section, true);
> > >  }
> > >  
> > > +/* Called on regions that have not changed */
> > >  static void vhost_region_nop(MemoryListener *listener,
> > >                               MemoryRegionSection *section)
> > >  {
> > > @@ -743,7 +795,7 @@ static void vhost_region_nop(MemoryListener *listener,
> > >          return;
> > >      }
> > >  
> > > -    vhost_add_section(dev, section);
> > > +    vhost_region_add_section(dev, section);
> > >  }
> > >  
> > >  static void vhost_region_del(MemoryListener *listener,
> > 
> --
> Dr. David Alan Gilbert / address@hidden / Manchester, UK