On Tue, 22 Dec 2020 20:15:58 -0500
Tony Krowiak <akrow...@linux.ibm.com> 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 <akrow...@linux.ibm.com>
> Reviewed-by: Halil Pasic <pa...@linux.ibm.com>
> ---
>  drivers/s390/crypto/vfio_ap_ops.c     | 15 +++++++++++++++
>  drivers/s390/crypto/vfio_ap_private.h |  2 ++
>  2 files changed, 17 insertions(+)
> 
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c 
> b/drivers/s390/crypto/vfio_ap_ops.c
> index 2d58b39977be..44b3a81cadfb 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -293,6 +293,20 @@ 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)
> +{
> +     if (vfio_ap_mdev_has_crycb(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;
> @@ -308,6 +322,7 @@ 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;
> diff --git a/drivers/s390/crypto/vfio_ap_private.h 
> b/drivers/s390/crypto/vfio_ap_private.h
> index 4e5cc72fc0db..d2d26ba18602 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;

What happened to the following hunk from v12?

@@ -1218,13 +1233,9 @@ 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)
-               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;
 }

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