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

Tony Krowiak
2021-01-14T21:36:08Z

On 1/11/21 5:50 PM, Halil Pasic wrote:
> 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?

That's a very good question, I'll reinstate it.

>
> @@ -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;
> }