Re: [PATCH v2 2/7] s390: vfio-ap: maintain a shadow of the guest's CRYCB

[Pierre Morel]

On 06/05/2019 21:53, Tony Krowiak wrote:
> On 5/6/19 2:49 AM, Pierre Morel wrote:
> > On 03/05/2019 23:14, Tony Krowiak wrote:
> > > This patch introduces a shadow of the CRYCB being used by a guest. This
> > > will enable to more effectively manage dynamic changes to the AP
> > > resources installed on the host that may be assigned to an mdev device
> > > and being used by a guest. For example:
> > >
> > > * AP adapter cards can be dynamically added to and removed from the AP
> > > ÂÂ configuration via the SE or an SCLP command.
> > >
> > > * AP resources that disappear and reappear due to hardware malfunctions.
> > >
> > > * AP queues bound to and unbound from the vfio_ap device driver by a
> > > ÂÂ root user.
> > >
> > > Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
> > > ---
> > > Â drivers/s390/crypto/vfio_ap_ops.cÂÂÂÂ | 91 
> > > ++++++++++++++++++++++++++++++++---
> > > Â drivers/s390/crypto/vfio_ap_private.h |Â 2 +
> > > Â 2 files changed, 87 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/drivers/s390/crypto/vfio_ap_ops.c 
> > > b/drivers/s390/crypto/vfio_ap_ops.c
> > > index b88a2a2ba075..44a04b4aa9ae 100644
> > > --- a/drivers/s390/crypto/vfio_ap_ops.c
> > > +++ b/drivers/s390/crypto/vfio_ap_ops.c
> > > @@ -297,6 +297,45 @@ static void 
> > > vfio_ap_mdev_wait_for_qempty(unsigned long apid, unsigned long apqi)
> > > ÂÂÂÂÂ } while (--retry);
> > > Â }
> > > +/*
> > > + * vfio_ap_mdev_update_crycb
> > > + *
> > > + * @matrix_mdev: the mediated matrix device
> > > + *
> > > + * Updates the AP matrix in the guest's CRYCB from it's shadow masks.
> > > + *
> > > + * Returns zero if the guest's CRYCB is successfully updated; 
> > > otherwise,
> > > + * returns -ENODEV if a guest is not running or does not have a CRYCB.
> > > + */
> > > +static int vfio_ap_mdev_update_crycb(struct ap_matrix_mdev 
> > > *matrix_mdev)
> > > +{
> > > +ÂÂÂ if (!matrix_mdev->kvm || !matrix_mdev->kvm->arch.crypto.crycbd)
> > > +ÂÂÂÂÂÂÂ return -ENODEV;
> > > +
> > > +ÂÂÂ kvm_arch_crypto_set_masks(matrix_mdev->kvm,
> > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ matrix_mdev->shadow_crycb->apm,
> > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ matrix_mdev->shadow_crycb->aqm,
> > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ matrix_mdev->shadow_crycb->adm);
> > > +
> > > +ÂÂÂ return 0;
> > > +}
> > > +
> > > +static int match_apqn(struct device *dev, void *data)
> > > +{
> > > +ÂÂÂ struct ap_queue *apq = to_ap_queue(dev);
> > > +
> > > +ÂÂÂ return (apq->qid == *(unsigned long *)(data)) ? 1 : 0;
> > > +}
> > > +
> > > +static struct device *vfio_ap_get_queue_dev(unsigned long apid,
> > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ unsigned long apqi)
> > > +{
> > > +ÂÂÂ unsigned long apqn = AP_MKQID(apid, apqi);
> > > +
> > > +ÂÂÂ return driver_find_device(&matrix_dev->vfio_ap_drv->driver, NULL,
> > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ &apqn, match_apqn);
> > > +}
> > > +
> > > Â /**
> > > ÂÂ * assign_adapter_store
> > > ÂÂ *
> > > @@ -805,14 +844,9 @@ static int vfio_ap_mdev_group_notifier(struct 
> > > notifier_block *nb,
> > > ÂÂÂÂÂ if (ret)
> > > ÂÂÂÂÂÂÂÂÂ return NOTIFY_DONE;
> > > -ÂÂÂ /* If there is no CRYCB pointer, then we can't copy the masks */
> > > -ÂÂÂ if (!matrix_mdev->kvm->arch.crypto.crycbd)
> > > +ÂÂÂ if (vfio_ap_mdev_update_crycb(matrix_mdev))
> > > ÂÂÂÂÂÂÂÂÂ return NOTIFY_DONE;
> > > -ÂÂÂ kvm_arch_crypto_set_masks(matrix_mdev->kvm, 
> > > matrix_mdev->matrix.apm,
> > > -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ matrix_mdev->matrix.aqm,
> > > -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ matrix_mdev->matrix.adm);
> > > -
> > > ÂÂÂÂÂ return NOTIFY_OK;
> > > Â }
> > > @@ -867,12 +901,55 @@ static int vfio_ap_mdev_reset_queues(struct 
> > > mdev_device *mdev)
> > > ÂÂÂÂÂ return rc;
> > > Â }
> > > +static int vfio_ap_mdev_create_shadow_crycb(struct ap_matrix_mdev 
> > > *matrix_mdev)
> > > +{
> > > +ÂÂÂ unsigned long apid, apqi, domid;
> > > +ÂÂÂ struct device *dev;
> > > +
> > > +ÂÂÂ matrix_mdev->shadow_crycb = 
> > > kzalloc(sizeof(*matrix_mdev->shadow_crycb),
> > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ GFP_KERNEL);
> > > +ÂÂÂ if (!matrix_mdev->shadow_crycb)
> > > +ÂÂÂÂÂÂÂ return -ENOMEM;
> > > +
> > > +ÂÂÂ vfio_ap_matrix_init(&matrix_dev->info, matrix_mdev->shadow_crycb);
> > > +
> > > +ÂÂÂ /*
> > > +ÂÂÂÂ * Examine each APQN assigned to the mdev device. Set the APID 
> > > and APQI
> > > +ÂÂÂÂ * in the shadow CRYCB if and only if the queue device 
> > > identified by
> > > +ÂÂÂÂ * the APQN is in the configuration.
> > > +ÂÂÂÂ */
> > > +ÂÂÂ for_each_set_bit_inv(apid, matrix_mdev->matrix.apm,
> > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ matrix_mdev->matrix.apm_max + 1) {
> > > +ÂÂÂÂÂÂÂ for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm,
> > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ matrix_mdev->matrix.aqm_max + 1) {
> > > +ÂÂÂÂÂÂÂÂÂÂÂ dev = vfio_ap_get_queue_dev(apid, apqi);
> > > +ÂÂÂÂÂÂÂÂÂÂÂ if (dev) {
> > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ set_bit_inv(apid,
> > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ matrix_mdev->shadow_crycb->apm);
> > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ set_bit_inv(apqi,
> > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ matrix_mdev->shadow_crycb->aqm);
> > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ put_device(dev);
> > > +ÂÂÂÂÂÂÂÂÂÂÂ }
> >
> > I think that if we do not find a device here we have a problem.
> > Don't we?
>
> Other than the fact that the guest will not have any AP devices,
> what would be the problem? What would you suggest?

Suppose we have in matrix_mdev->matrix:
1-2
1-3
2-2
2-3

We set the shadow_crycb with:
we find 1-2 we set 1 2
we find 1-3 we se 1 3
we find 2-2 we set 2 2
we do not find 2-3

we have set apm(1,2) aqm(2,3)
the guest can access 2-3 but we do not have the device.

Pierre

--
Pierre Morel
Linux/KVM/QEMU in BÃblingen - Germany