On Fri, 22 Jan 2021 17:26:35 +0800
Keqian Zhu <zhukeqian1@xxxxxxxxxx> wrote:
> vfio_sanity_check_pfn_list() is used to check whether pfn_list and
> notifier are empty when remove the external domain, so it makes a
> wrong assumption that only external domain will use the pinning
> interface.
>
> Now we apply the pfn_list check when a vfio_dma is removed and apply
> the notifier check when all domains are removed.
>
> Fixes: a54eb55045ae ("vfio iommu type1: Add support for mediated devices")
> Signed-off-by: Keqian Zhu <zhukeqian1@xxxxxxxxxx>
> ---
> drivers/vfio/vfio_iommu_type1.c | 33 ++++++++++-----------------------
> 1 file changed, 10 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 161725395f2f..d8c10f508321 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -957,6 +957,7 @@ static long vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma,
>
> static void vfio_remove_dma(struct vfio_iommu *iommu, struct vfio_dma *dma)
> {
> + WARN_ON(!RB_EMPTY_ROOT(&dma->pfn_list));
> vfio_unmap_unpin(iommu, dma, true);
> vfio_unlink_dma(iommu, dma);
> put_task_struct(dma->task);
> @@ -2250,23 +2251,6 @@ static void vfio_iommu_unmap_unpin_reaccount(struct vfio_iommu *iommu)
> }
> }
>
> -static void vfio_sanity_check_pfn_list(struct vfio_iommu *iommu)
> -{
> - struct rb_node *n;
> -
> - n = rb_first(&iommu->dma_list);
> - for (; n; n = rb_next(n)) {
> - struct vfio_dma *dma;
> -
> - dma = rb_entry(n, struct vfio_dma, node);
> -
> - if (WARN_ON(!RB_EMPTY_ROOT(&dma->pfn_list)))
> - break;
> - }
> - /* mdev vendor driver must unregister notifier */
> - WARN_ON(iommu->notifier.head);
> -}
> -
> /*
> * Called when a domain is removed in detach. It is possible that
> * the removed domain decided the iova aperture window. Modify the
> @@ -2366,10 +2350,10 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
> kfree(group);
>
> if (list_empty(&iommu->external_domain->group_list)) {
> - vfio_sanity_check_pfn_list(iommu);
> -
> - if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu))
> + if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)) {
> + WARN_ON(iommu->notifier.head);
> vfio_iommu_unmap_unpin_all(iommu);
> + }
>
> kfree(iommu->external_domain);
> iommu->external_domain = NULL;
> @@ -2403,10 +2387,12 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
> */
> if (list_empty(&domain->group_list)) {
> if (list_is_singular(&iommu->domain_list)) {
> - if (!iommu->external_domain)
> + if (!iommu->external_domain) {
> + WARN_ON(iommu->notifier.head);
> vfio_iommu_unmap_unpin_all(iommu);
> - else
> + } else {
> vfio_iommu_unmap_unpin_reaccount(iommu);
> + }
> }
> iommu_domain_free(domain->domain);
> list_del(&domain->next);
> @@ -2488,9 +2474,10 @@ static void vfio_iommu_type1_release(void *iommu_data)
> struct vfio_iommu *iommu = iommu_data;
> struct vfio_domain *domain, *domain_tmp;
>
> + WARN_ON(iommu->notifier.head);
I don't see that this does any harm, but isn't it actually redundant?
It seems vfio-core only calls the iommu backend release function after
removing all the groups, so the tests in _detach_group should catch all
cases. We're expecting the vfio bus/mdev driver to remove the notifier
when a device is closed, which necessarily occurs before detaching the
group. Thanks,
Alex
> +
> if (iommu->external_domain) {
> vfio_release_domain(iommu->external_domain, true);
> - vfio_sanity_check_pfn_list(iommu);
> kfree(iommu->external_domain);
> }
>
