On 15/11/16 11:59, Peter Xu wrote:
> When one IOMMU memory region is splitted into multiple memory sections,
Out of curiosity - when does this happen?
> vfio will register multiple same notifiers to a vIOMMU for the same
> region. That's not sensible. What we need is to register one IOMMU
> notifier for each IOMMU region, not per section.
>
> Solution is simple - we traverse the container->giommu_list, and skip
> the registration if memory region is already registered.
>
> To make vfio's region_add() short, vfio_listener_region_add_iommu() is
> introduced.
>
> Signed-off-by: Peter Xu <pet...@redhat.com>
> ---
> hw/vfio/common.c | 56
> +++++++++++++++++++++++++++++++++++---------------------
> 1 file changed, 35 insertions(+), 21 deletions(-)
>
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 801578b..5279fd1 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -360,6 +360,40 @@ out:
> rcu_read_unlock();
> }
>
> +static void vfio_listener_region_add_iommu(VFIOContainer *container,
> + MemoryRegionSection *section,
> + hwaddr iova,
> + hwaddr end)
> +{
> + VFIOGuestIOMMU *giommu;
> +
> + QLIST_FOREACH(giommu, &container->giommu_list, giommu_next) {
> + if (giommu->iommu == section->mr) {
> + /* We have already registered with this MR, skip */
> + return;
> + }
> + }
> +
> + trace_vfio_listener_region_add_iommu(iova, end);
> +
> + /*
> + * FIXME: For VFIO iommu types which have KVM acceleration to
> + * avoid bouncing all map/unmaps through qemu this way, this
> + * would be the right place to wire that up (tell the KVM
> + * device emulation the VFIO iommu handles to use).
> + */
> + giommu = g_malloc0(sizeof(*giommu));
> + giommu->iommu = section->mr;
> + giommu->iommu_offset = section->offset_within_address_space -
> + section->offset_within_region;
> + giommu->container = container;
> + giommu->n.notify = vfio_iommu_map_notify;
> + giommu->n.notifier_flags = IOMMU_NOTIFIER_ALL;
> + QLIST_INSERT_HEAD(&container->giommu_list, giommu, giommu_next);
> + memory_region_register_iommu_notifier(giommu->iommu, &giommu->n);
> + memory_region_iommu_replay(giommu->iommu, &giommu->n, false);
> +}
> +
> static void vfio_listener_region_add(MemoryListener *listener,
> MemoryRegionSection *section)
> {
> @@ -439,27 +473,7 @@ static void vfio_listener_region_add(MemoryListener
> *listener,
> memory_region_ref(section->mr);
>
> if (memory_region_is_iommu(section->mr)) {
> - VFIOGuestIOMMU *giommu;
> -
> - trace_vfio_listener_region_add_iommu(iova, end);
> - /*
> - * FIXME: For VFIO iommu types which have KVM acceleration to
> - * avoid bouncing all map/unmaps through qemu this way, this
> - * would be the right place to wire that up (tell the KVM
> - * device emulation the VFIO iommu handles to use).
> - */
> - giommu = g_malloc0(sizeof(*giommu));
> - giommu->iommu = section->mr;
> - giommu->iommu_offset = section->offset_within_address_space -
> - section->offset_within_region;
> - giommu->container = container;
> - giommu->n.notify = vfio_iommu_map_notify;
> - giommu->n.notifier_flags = IOMMU_NOTIFIER_ALL;
> - QLIST_INSERT_HEAD(&container->giommu_list, giommu, giommu_next);
> -
> - memory_region_register_iommu_notifier(giommu->iommu, &giommu->n);
> - memory_region_iommu_replay(giommu->iommu, &giommu->n, false);
> -
> + vfio_listener_region_add_iommu(container, section, iova, end);
> return;
> }
>
>
--
Alexey
