On 13/02/2019 07:52, Alex Williamson wrote: > 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, Fair comment, sorry for the salad. How about this? === VFIO TCE IOMMU v2 owns IOMMU tables. When we detach an IOMMU group from a container, we need to unset these tables from the group which we do by calling unset_window(). We also unset tables when removing a DMA window via the VFIO_IOMMU_SPAPR_TCE_REMOVE ioctl. === > > 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); >> } > -- Alexey
