On Mon, 11 Feb 2019 18:49:17 +1100 Alexey Kardashevskiy <aik@xxxxxxxxx> wrote: > VFIO TCE IOMMU v2 owns IOMMU tables so when detach a IOMMU group from > a container, we need to unset those from a group so we call unset_window() > so do we unconditionally. We also unset tables when removing a DMA window Patch looks ok, but this first sentence trails off into a bit of a word salad. Care to refine a bit? Thanks, Alex > via the VFIO_IOMMU_SPAPR_TCE_REMOVE ioctl. > > The window removal checks if the table actually exists (hidden inside > tce_iommu_find_table()) but the group detaching does not so the user > may see duplicating messages: > pci 0009:03 : [PE# fd] Removing DMA window #0 > pci 0009:03 : [PE# fd] Removing DMA window #1 > pci 0009:03 : [PE# fd] Removing DMA window #0 > pci 0009:03 : [PE# fd] Removing DMA window #1 > > At the moment this is not a problem as the second invocation > of unset_window() writes zeroes to the HW registers again and exits early > as there is no table. > > Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx> > --- > > When doing VFIO PCI hot unplug, first we remove the DMA window and > set container->tables[num] - this is a first couple of messages. > Then we detach the group and then we see another couple of the same > messages which confused myself. > --- > drivers/vfio/vfio_iommu_spapr_tce.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c > index c424913..8dbb270 100644 > --- a/drivers/vfio/vfio_iommu_spapr_tce.c > +++ b/drivers/vfio/vfio_iommu_spapr_tce.c > @@ -1235,7 +1235,8 @@ static void tce_iommu_release_ownership_ddw(struct tce_container *container, > } > > for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) > - table_group->ops->unset_window(table_group, i); > + if (container->tables[i]) > + table_group->ops->unset_window(table_group, i); > > table_group->ops->release_ownership(table_group); > }
