On 2021/1/28 7:46, Alex Williamson wrote:
> On Fri, 22 Jan 2021 17:26:35 +0800
> Keqian Zhu <zhukeqi...@huawei.com> 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 <zhukeqi...@huawei.com>
>> ---
>> 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,
Right. Devices of a specific group must be closed before detach this group.
Detach the last group have checked this, so vfio_iommu_type1_release doesn't
need to do this check again.
Could you please queue this patch and delete this check btw? Thanks. ;-)
Keqian.
>
> Alex
>
>> +
>> if (iommu->external_domain) {
>> vfio_release_domain(iommu->external_domain, true);
>> - vfio_sanity_check_pfn_list(iommu);
>> kfree(iommu->external_domain);
>> }
>>
>
> .
>
