On Wed, May 05, 2021 at 07:44:55PM +0200, Christian Borntraeger wrote:
>
>
> On 05.05.21 19:28, Tony Krowiak wrote:
> > The mdev remove callback for the vfio_ap device driver bails out with
> > -EBUSY if the mdev is in use by a KVM guest. The intended purpose was
> > to prevent the mdev from being removed while in use; however, returning a
> > non-zero rc does not prevent removal. This could result in a memory leak
> > of the resources allocated when the mdev was created. In addition, the
> > KVM guest will still have access to the AP devices assigned to the mdev
> > even though the mdev no longer exists.
> >
> > To prevent this scenario, cleanup will be done - including unplugging the
> > AP adapters, domains and control domains - regardless of whether the mdev
> > is in use by a KVM guest or not.
> [...]
> > static int vfio_ap_mdev_create(struct mdev_device *mdev)
> > {
> > struct ap_matrix_mdev *matrix_mdev;
> > @@ -366,16 +392,9 @@ static int vfio_ap_mdev_remove(struct mdev_device *mdev)
> > struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
> > mutex_lock(&matrix_dev->lock);
> > -
> > - /*
> > - * If the KVM pointer is in flux or the guest is running, disallow
> > - * un-assignment of control domain.
> > - */
> > - if (matrix_mdev->kvm_busy || matrix_mdev->kvm) {
> > - mutex_unlock(&matrix_dev->lock);
> > - return -EBUSY;
> > - }
> > -
> > + WARN(vfio_ap_mdev_has_crycb(matrix_mdev),
> > + "Removing mdev leaves KVM guest without any crypto devices");
> > + vfio_ap_mdev_clear_apcb(matrix_mdev);
>
> Triggering a kernel warning due to an administrative task is not good.
> Can't you simply clear the crycb? Maybe do a printk, but not a WARN.
+1
Jason
