Re: [PATCH v11 06/14] s390/vfio-ap: introduce shadow APCB

[Tony Krowiak <akrowiak@xxxxxxxxxxxxx>]

On 10/28/20 4:11 AM, Halil Pasic wrote:
> On Thu, 22 Oct 2020 13:12:01 -0400
> Tony Krowiak <akrowiak@xxxxxxxxxxxxx> wrote:
>
> > The APCB is a field within the CRYCB that provides the AP configuration
> > to a KVM guest. Let's introduce a shadow copy of the KVM guest's APCB and
> > maintain it for the lifespan of the guest.
> >
> > Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
> > ---
> >   drivers/s390/crypto/vfio_ap_ops.c     | 24 +++++++++++++++++++-----
> >   drivers/s390/crypto/vfio_ap_private.h |  2 ++
> >   2 files changed, 21 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> > index 9e9fad560859..9791761aa7fd 100644
> > --- a/drivers/s390/crypto/vfio_ap_ops.c
> > +++ b/drivers/s390/crypto/vfio_ap_ops.c
> > @@ -320,6 +320,19 @@ static void vfio_ap_matrix_init(struct ap_config_info *info,
> >   	matrix->adm_max = info->apxa ? info->Nd : 15;
> >   }
> >   
> > +static bool vfio_ap_mdev_has_crycb(struct ap_matrix_mdev *matrix_mdev)
> > +{
> > +	return (matrix_mdev->kvm && matrix_mdev->kvm->arch.crypto.crycbd);
> > +}
> > +
> > +static void vfio_ap_mdev_commit_shadow_apcb(struct ap_matrix_mdev *matrix_mdev)
> > +{
> > +	kvm_arch_crypto_set_masks(matrix_mdev->kvm,
> > +				  matrix_mdev->shadow_apcb.apm,
> > +				  matrix_mdev->shadow_apcb.aqm,
> > +				  matrix_mdev->shadow_apcb.adm);
> > +}
> > +
> >   static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
> >   {
> >   	struct ap_matrix_mdev *matrix_mdev;
> > @@ -335,6 +348,7 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
> >   
> >   	matrix_mdev->mdev = mdev;
> >   	vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->matrix);
> > +	vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->shadow_apcb);
> >   	hash_init(matrix_mdev->qtable);
> >   	mdev_set_drvdata(mdev, matrix_mdev);
> >   	matrix_mdev->pqap_hook.hook = handle_pqap;
> > @@ -1213,13 +1227,12 @@ static int vfio_ap_mdev_group_notifier(struct notifier_block *nb,
> >   	if (ret)
> >   		return NOTIFY_DONE;
> >   
> > -	/* If there is no CRYCB pointer, then we can't copy the masks */
> > -	if (!matrix_mdev->kvm->arch.crypto.crycbd)
> > +	if (!vfio_ap_mdev_has_crycb(matrix_mdev))
> >   		return NOTIFY_DONE;
> >   
> > -	kvm_arch_crypto_set_masks(matrix_mdev->kvm, matrix_mdev->matrix.apm,
> > -				  matrix_mdev->matrix.aqm,
> > -				  matrix_mdev->matrix.adm);
> > +	memcpy(&matrix_mdev->shadow_apcb, &matrix_mdev->matrix,
> > +	       sizeof(matrix_mdev->shadow_apcb));
> > +	vfio_ap_mdev_commit_shadow_apcb(matrix_mdev);
> >   
> >   	return NOTIFY_OK;
> >   }
> > @@ -1329,6 +1342,7 @@ static void vfio_ap_mdev_release(struct mdev_device *mdev)
> >   		kvm_put_kvm(matrix_mdev->kvm);
> >   		matrix_mdev->kvm = NULL;
> >   	}
> > +
> Unrelated change.
>
> Otherwise patch looks OK.
>
> Reviewed-by: Halil Pasic <pasic@xxxxxxxxxxxxx>

I'll fix it. Thanks for your review.

> >   	mutex_unlock(&matrix_dev->lock);
> >   
> >   	vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
> > diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
> > index c1d8b5507610..fc8634cee485 100644
> > --- a/drivers/s390/crypto/vfio_ap_private.h
> > +++ b/drivers/s390/crypto/vfio_ap_private.h
> > @@ -75,6 +75,7 @@ struct ap_matrix {
> >    * @list:	allows the ap_matrix_mdev struct to be added to a list
> >    * @matrix:	the adapters, usage domains and control domains assigned to the
> >    *		mediated matrix device.
> > + * @shadow_apcb:    the shadow copy of the APCB field of the KVM guest's CRYCB
> >    * @group_notifier: notifier block used for specifying callback function for
> >    *		    handling the VFIO_GROUP_NOTIFY_SET_KVM event
> >    * @kvm:	the struct holding guest's state
> > @@ -82,6 +83,7 @@ struct ap_matrix {
> >   struct ap_matrix_mdev {
> >   	struct list_head node;
> >   	struct ap_matrix matrix;
> > +	struct ap_matrix shadow_apcb;
> >   	struct notifier_block group_notifier;
> >   	struct notifier_block iommu_notifier;
> >   	struct kvm *kvm;