Re: [PATCH v10 10/16] s390/vfio-ap: allow configuration of matrix mdev in use by a KVM guest

[Tony Krowiak]

On 9/26/20 8:03 PM, Halil Pasic wrote:
> On Fri, 21 Aug 2020 15:56:10 -0400
> Tony Krowiak <akrowiak@xxxxxxxxxxxxx> wrote:
>
> > The current support for pass-through crypto adapters does not allow
> > configuration of a matrix mdev when it is in use by a KVM guest. Let's
> > allow AP resources - i.e., adapters, domains and control domains - to be
> > assigned to or unassigned from a matrix mdev while it is in use by a guest.
> > This is in preparation for the introduction of support for dynamic
> > configuration of the AP matrix for a running KVM guest.
> AFAIU this will let the user do the assign, which will however only take
> effect if the same mdev is re-used with a freshly constructed VM, or?
>
> This is however supposed to change real soon (in patch 11). From the
> perspective of bisectability we would end up with a single commit that
> acts funny.
>
> How about switching up patches 10 and 11. This way the changes you have
> in the current 11 would remain dormant until the changes in the current
> 10 enable the complete new feature (hotplug)?

I can do that, but maybe it makes more sense to squash patches 10
and 11 since they are completely dependent on each other. What say
you?

> > Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
> > ---
> >   drivers/s390/crypto/vfio_ap_ops.c | 24 ------------------------
> >   1 file changed, 24 deletions(-)
> >
> > diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> > index 24fd47e43b80..cf3321eb239b 100644
> > --- a/drivers/s390/crypto/vfio_ap_ops.c
> > +++ b/drivers/s390/crypto/vfio_ap_ops.c
> > @@ -773,10 +773,6 @@ static ssize_t assign_adapter_store(struct device *dev,
> >   	struct mdev_device *mdev = mdev_from_dev(dev);
> >   	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
> >   
> > -	/* If the guest is running, disallow assignment of adapter */
> > -	if (matrix_mdev->kvm)
> > -		return -EBUSY;
> > -
> >   	ret = kstrtoul(buf, 0, &apid);
> >   	if (ret)
> >   		return ret;
> > @@ -828,10 +824,6 @@ static ssize_t unassign_adapter_store(struct device *dev,
> >   	struct mdev_device *mdev = mdev_from_dev(dev);
> >   	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
> >   
> > -	/* If the guest is running, disallow un-assignment of adapter */
> > -	if (matrix_mdev->kvm)
> > -		return -EBUSY;
> > -
> >   	ret = kstrtoul(buf, 0, &apid);
> >   	if (ret)
> >   		return ret;
> > @@ -891,10 +883,6 @@ static ssize_t assign_domain_store(struct device *dev,
> >   	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
> >   	unsigned long max_apqi = matrix_mdev->matrix.aqm_max;
> >   
> > -	/* If the guest is running, disallow assignment of domain */
> > -	if (matrix_mdev->kvm)
> > -		return -EBUSY;
> > -
> >   	ret = kstrtoul(buf, 0, &apqi);
> >   	if (ret)
> >   		return ret;
> > @@ -946,10 +934,6 @@ static ssize_t unassign_domain_store(struct device *dev,
> >   	struct mdev_device *mdev = mdev_from_dev(dev);
> >   	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
> >   
> > -	/* If the guest is running, disallow un-assignment of domain */
> > -	if (matrix_mdev->kvm)
> > -		return -EBUSY;
> > -
> >   	ret = kstrtoul(buf, 0, &apqi);
> >   	if (ret)
> >   		return ret;
> > @@ -991,10 +975,6 @@ static ssize_t assign_control_domain_store(struct device *dev,
> >   	struct mdev_device *mdev = mdev_from_dev(dev);
> >   	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
> >   
> > -	/* If the guest is running, disallow assignment of control domain */
> > -	if (matrix_mdev->kvm)
> > -		return -EBUSY;
> > -
> >   	ret = kstrtoul(buf, 0, &id);
> >   	if (ret)
> >   		return ret;
> > @@ -1036,10 +1016,6 @@ static ssize_t unassign_control_domain_store(struct device *dev,
> >   	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
> >   	unsigned long max_domid =  matrix_mdev->matrix.adm_max;
> >   
> > -	/* If the guest is running, disallow un-assignment of control domain */
> > -	if (matrix_mdev->kvm)
> > -		return -EBUSY;
> > -
> >   	ret = kstrtoul(buf, 0, &domid);
> >   	if (ret)
> >   		return ret;