Re: [PATCH v4] s390/vfio-ap: clean up vfio_ap resources when KVM pointer invalidated

Tony Krowiak
2020-12-22T23:15:59Z

On 12/22/20 2:43 PM, Halil Pasic wrote:
> On Tue, 22 Dec 2020 16:57:06 +0100
> Cornelia Huck <cohuck@redhat.com> wrote:
>
>> On Tue, 22 Dec 2020 10:37:01 -0500
>> Tony Krowiak <akrowiak@linux.ibm.com> wrote:
>>
>>> On 12/21/20 11:05 PM, Halil Pasic wrote:
>>>> On Mon, 21 Dec 2020 13:56:25 -0500
>>>> Tony Krowiak <akrowiak@linux.ibm.com> wrote:
>>>>> static int vfio_ap_mdev_group_notifier(struct notifier_block *nb,
>>>>> unsigned long action, void *data)
>>>>> {
>>>>> - int ret;
>>>>> + int ret, notify_rc = NOTIFY_DONE;
>>>>> struct ap_matrix_mdev *matrix_mdev;
>>>>>
>>>>> if (action != VFIO_GROUP_NOTIFY_SET_KVM)
>>>>> return NOTIFY_OK;
>>>>>
>>>>> matrix_mdev = container_of(nb, struct ap_matrix_mdev, group_notifier);
>>>>> + mutex_lock(&matrix_dev->lock);
>>>>>
>>>>> if (!data) {
>>>>> - matrix_mdev->kvm = NULL;
>>>>> - return NOTIFY_OK;
>>>>> + if (matrix_mdev->kvm)
>>>>> + vfio_ap_mdev_unset_kvm(matrix_mdev);
>>>>> + notify_rc = NOTIFY_OK;
>>>>> + goto notify_done;
>>>>> }
>>>>>
>>>>> ret = vfio_ap_mdev_set_kvm(matrix_mdev, data);
>>>>> if (ret)
>>>>> - return NOTIFY_DONE;
>>>>> + goto notify_done;
>>>>>
>>>>> /* If there is no CRYCB pointer, then we can't copy the masks */
>>>>> if (!matrix_mdev->kvm->arch.crypto.crycbd)
>>>>> - return NOTIFY_DONE;
>>>>> + goto notify_done;
>>>>>
>>>>> kvm_arch_crypto_set_masks(matrix_mdev->kvm, matrix_mdev->matrix.apm,
>>>>> matrix_mdev->matrix.aqm,
>>>>> matrix_mdev->matrix.adm);
>>>>>
>>>>> - return NOTIFY_OK;
>>>> Shouldn't there be an
>>>> + notify_rc = NOTIFY_OK;
>>>> here? I mean you initialize notify_rc to NOTIFY_DONE, in the !data branch
>>>> on success you set notify_rc to NOTIFY_OK, but in the !!data branch it
>>>> just stays NOTIFY_DONE. Or am I missing something?
>>> I don't think it matters much since NOTIFY_OK and NOTIFY_DONE have
>>> no further effect on processing of the notification queue, but I believe
>>> you are correct, this is a change from what we originally had. I can
>>> restore the original return values if you'd prefer.
>> Even if they have the same semantics now, that might change in the
>> future; restoring the original behaviour looks like the right thing to
>> do.
> I agree. Especially since we do care to preserve the behavior in
> the !data branch. If there is no difference between the two, then it
> would probably make sense to clean that up globally.

Got it. I'm going to do a quick turnaround on the next version so we
can get this merged if need be. I will be taking off for Christmas vacation
and will be gone until sometime the first week in January.

>
> Regards,
> Halil