Re: [PATCH v13 07/15] s390/vfio-ap: introduce shadow APCB

Halil Pasic
2021-01-12T00:55:29Z

On Tue, 22 Dec 2020 20:15:58 -0500
Tony Krowiak <akrowiak@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 <akrowiak@linux.ibm.com>
> Reviewed-by: Halil Pasic <pasic@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;
}