On Mon, 19 Aug 2019 11:51:17 +1000 Alexey Kardashevskiy <a...@ozlabs.ru> wrote:
> The @tcegrp variable is used in 1) a loop over attached groups > 2) it stores a pointer to a newly allocated tce_iommu_group if 1) found > nothing. However the error handler does not distinguish how we got there > and incorrectly releases memory for a found+incompatible group. > > This fixes it by adding another error handling case. > > Fixes: 0bd971676e68 ("powerpc/powernv/npu: Add compound IOMMU groups") > Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru> > --- Applied to vfio next branch with Paul's R-b. Thanks, Alex > > The bug is there since 2157e7b82f3b but it would not appear in practice > before 0bd971676e68, hence that "Fixes". Or it still should be > 157e7b82f3b ("vfio: powerpc/spapr: Register memory and define IOMMU v2") > ? > > Found it when tried adding a "compound PE" (GPU + NPUs) to a container > with a passed through xHCI host. The compatibility test (->create_table > should be equal) treats them as incompatible which might a bug (or > we are just suboptimal here) on its own. > > --- > drivers/vfio/vfio_iommu_spapr_tce.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c > b/drivers/vfio/vfio_iommu_spapr_tce.c > index 8ce9ad21129f..babef8b00daf 100644 > --- a/drivers/vfio/vfio_iommu_spapr_tce.c > +++ b/drivers/vfio/vfio_iommu_spapr_tce.c > @@ -1234,7 +1234,7 @@ static long tce_iommu_take_ownership_ddw(struct > tce_container *container, > static int tce_iommu_attach_group(void *iommu_data, > struct iommu_group *iommu_group) > { > - int ret; > + int ret = 0; > struct tce_container *container = iommu_data; > struct iommu_table_group *table_group; > struct tce_iommu_group *tcegrp = NULL; > @@ -1287,13 +1287,13 @@ static int tce_iommu_attach_group(void *iommu_data, > !table_group->ops->release_ownership) { > if (container->v2) { > ret = -EPERM; > - goto unlock_exit; > + goto free_exit; > } > ret = tce_iommu_take_ownership(container, table_group); > } else { > if (!container->v2) { > ret = -EPERM; > - goto unlock_exit; > + goto free_exit; > } > ret = tce_iommu_take_ownership_ddw(container, table_group); > if (!tce_groups_attached(container) && !container->tables[0]) > @@ -1305,10 +1305,11 @@ static int tce_iommu_attach_group(void *iommu_data, > list_add(&tcegrp->next, &container->group_list); > } > > -unlock_exit: > +free_exit: > if (ret && tcegrp) > kfree(tcegrp); > > +unlock_exit: > mutex_unlock(&container->lock); > > return ret;