On Tue, Mar 28, 2017 at 11:48:36AM -0600, Alex Williamson wrote: > On Tue, 28 Mar 2017 20:05:29 +1100 > Alexey Kardashevskiy <a...@ozlabs.ru> wrote: > > > At the moment VFIO PCI device initialization works as follows: > > vfio_realize > > vfio_get_group > > vfio_connect_container > > register memory listeners (1) > > update QEMU groups lists > > vfio_kvm_device_add_group > > > > Then (example for pseries) the machine reset hook triggers region_add() > > for all regions where listeners from (1) are listening: > > > > ppc_spapr_reset > > spapr_phb_reset > > spapr_tce_table_enable > > memory_region_add_subregion > > vfio_listener_region_add > > vfio_spapr_create_window > > > > This scheme works fine until we need to handle VFIO PCI device hotplug > > _and_ we want to enable in-kernel acceleration on, i.e. after PCI hotplug > > we need a place to call > > ioctl(vfio_kvm_device_fd, KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE). > > Since the ioctl needs a LIOBN fd (from sPAPRTCETable) and a IOMMU group fd > > (from VFIOGroup), vfio_listener_region_add() seems to be the only place > > for this ioctl(). > > > > However this only works during boot time because the machine reset > > happens strictly after all devices are finalized. When hotplug happens, > > vfio_listener_region_add() is called when a memory listener is registered > > but when this happens: > > 1. new group is not added to the container->group_list yet; > > 2. VFIO KVM device is unaware of the new IOMMU group. > > > > This moves bits around to have all necessary VFIO infrastructure > > in place for both initial startup and hotplug cases. > > > > Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru> > > --- > > hw/vfio/common.c | 21 +++++++++++---------- > > 1 file changed, 11 insertions(+), 10 deletions(-) > > > > diff --git a/hw/vfio/common.c b/hw/vfio/common.c > > index f3ba9b9007..c75c7594d5 100644 > > --- a/hw/vfio/common.c > > +++ b/hw/vfio/common.c > > @@ -1086,6 +1086,16 @@ static int vfio_connect_container(VFIOGroup *group, > > AddressSpace *as, > > goto free_container_exit; > > } > > > > + container->initialized = true; > > This ignores the purpose of this variable, which is to make runtime > mapping faults fatal, but device realize time faults simply cause the > device to be rejected. This cannot be moved above > memory_listener_register().
Apart from that, the rest of the code motion looks ok, though. Even
if it weren't for the hotplug case, have the container/group
more-or-less initialized before registering the listener makes more
logical sense to me.
>
> > +
> > + vfio_kvm_device_add_group(group);
> > +
> > + QLIST_INIT(&container->group_list);
> > + QLIST_INSERT_HEAD(&space->containers, container, next);
> > +
> > + group->container = container;
> > + QLIST_INSERT_HEAD(&container->group_list, group, container_next);
> > +
> > container->listener = vfio_memory_listener;
> >
> > memory_listener_register(&container->listener, container->space->as);
> > @@ -1097,16 +1107,9 @@ static int vfio_connect_container(VFIOGroup *group,
> > AddressSpace *as,
> > goto listener_release_exit;
> > }
> >
> > - container->initialized = true;
> > -
> > - QLIST_INIT(&container->group_list);
> > - QLIST_INSERT_HEAD(&space->containers, container, next);
> > -
> > - group->container = container;
> > - QLIST_INSERT_HEAD(&container->group_list, group, container_next);
> > -
> > return 0;
> > listener_release_exit:
> > + vfio_kvm_device_del_group(group);
>
>
> Where's the QLIST cleanup?
Moving it does introduce more intermediate cleanup cases which need to
be handled, though..
>
>
> > vfio_listener_release(container);
> >
> > free_container_exit:
> > @@ -1210,8 +1213,6 @@ VFIOGroup *vfio_get_group(int groupid, AddressSpace
> > *as, Error **errp)
> >
> > QLIST_INSERT_HEAD(&vfio_group_list, group, next);
> >
> > - vfio_kvm_device_add_group(group);
> > -
> > return group;
> >
> > close_fd_exit:
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
signature.asc
Description: PGP signature
