Re: [PATCH v2 2/3] memory: Allow a MemoryRegion to be marked no_vhost

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

* Michael S. Tsirkin (mst@redhat.com) wrote:
> On Mon, Jan 13, 2020 at 05:36:46PM +0000, Dr. David Alan Gilbert (git) wrote:
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > 
> > Allow a memory region to be marked as 'no_vhost' and
> > exclude that region from vhost's list build.
> > 
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> 
> I thought we agreed vfio needs this as well?
> I'd rather this had some meaning not just "no vhost" ...
> no_dma?

VFIO tends to be unplugged on migration anyway (at the moment);
but I'm happy to change the name if everyone is happy with the rest of
the series and we can agree on the new name,

Dave

> > ---
> >  hw/virtio/vhost.c     |  3 ++-
> >  include/exec/memory.h | 21 +++++++++++++++++++++
> >  memory.c              | 15 +++++++++++++++
> >  3 files changed, 38 insertions(+), 1 deletion(-)
> > 
> > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> > index 774d87d98e..462498bfe6 100644
> > --- a/hw/virtio/vhost.c
> > +++ b/hw/virtio/vhost.c
> > @@ -402,7 +402,8 @@ static bool vhost_section(struct vhost_dev *dev, MemoryRegionSection *section)
> >      bool log_dirty = memory_region_get_dirty_log_mask(section->mr) &
> >                       ~(1 << DIRTY_MEMORY_MIGRATION);
> >      result = memory_region_is_ram(section->mr) &&
> > -        !memory_region_is_rom(section->mr);
> > +             !memory_region_is_rom(section->mr) &&
> > +             !memory_region_get_no_vhost(section->mr);
> >  
> >      /* Vhost doesn't handle any block which is doing dirty-tracking other
> >       * than migration; this typically fires on VGA areas.
> > diff --git a/include/exec/memory.h b/include/exec/memory.h
> > index aef8123d48..f475c06d63 100644
> > --- a/include/exec/memory.h
> > +++ b/include/exec/memory.h
> > @@ -394,6 +394,7 @@ struct MemoryRegion {
> >      bool ram_device;
> >      bool enabled;
> >      bool warning_printed; /* For reservations */
> > +    bool no_vhost;
> >      uint8_t vga_logging_count;
> >      MemoryRegion *alias;
> >      hwaddr alias_offset;
> > @@ -1625,6 +1626,26 @@ void memory_region_set_readonly(MemoryRegion *mr, bool readonly);
> >   */
> >  void memory_region_set_nonvolatile(MemoryRegion *mr, bool nonvolatile);
> >  
> > +/**
> > + * memory_region_set_no_vhost: Make vhost ignore a memory region
> > + *
> > + * Makes vhost ignore a memory region, useful if it isn't real
> > + * DMAble memory and is at inconvenient addresses
> > + *
> > + * @mr: the region being updated.
> > + * @no_vhost: true to ignore
> > + */
> > +void memory_region_set_no_vhost(MemoryRegion *mr, bool no_vhost);
> > +
> > +/**
> > + * memory_region_set_no_vhost: Test if memory region is marked no vhost
> > + *
> > + * Test if the no_vhost flag is set on the memory region
> > + *
> > + * @mr: the region being tested.
> > + */
> > +bool memory_region_get_no_vhost(const MemoryRegion *mr);
> > +
> >  /**
> >   * memory_region_rom_device_set_romd: enable/disable ROMD mode
> >   *
> > diff --git a/memory.c b/memory.c
> > index d7b9bb6951..9371998e30 100644
> > --- a/memory.c
> > +++ b/memory.c
> > @@ -2136,6 +2136,21 @@ void memory_region_set_nonvolatile(MemoryRegion *mr, bool nonvolatile)
> >      }
> >  }
> >  
> > +void memory_region_set_no_vhost(MemoryRegion *mr, bool no_vhost)
> > +{
> > +    if (mr->no_vhost != no_vhost) {
> > +        memory_region_transaction_begin();
> > +        mr->no_vhost = no_vhost;
> > +        memory_region_update_pending |= mr->enabled;
> > +        memory_region_transaction_commit();
> > +    }
> > +}
> > +
> > +bool memory_region_get_no_vhost(const MemoryRegion *mr)
> > +{
> > +    return mr->no_vhost;
> > +}
> > +
> >  void memory_region_rom_device_set_romd(MemoryRegion *mr, bool romd_mode)
> >  {
> >      if (mr->romd_mode != romd_mode) {
> > -- 
> > 2.24.1
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK