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

[Tony Krowiak]

On 12/22/20 2:43 PM, Halil Pasic wrote:
> On Tue, 22 Dec 2020 16:57:06 +0100
> Cornelia Huck <cohuck@xxxxxxxxxx> wrote:
>
> > On Tue, 22 Dec 2020 10:37:01 -0500
> > Tony Krowiak <akrowiak@xxxxxxxxxxxxx> wrote:
> >
> > > On 12/21/20 11:05 PM, Halil Pasic wrote:
> > > > On Mon, 21 Dec 2020 13:56:25 -0500
> > > > Tony Krowiak <akrowiak@xxxxxxxxxxxxx> 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