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

[Tony Krowiak]

On 10/28/20 4:11 AM, Halil Pasic wrote:

On Thu, 22 Oct 2020 13:12:01 -0400
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>
---
  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 <pa...@linux.ibm.com>

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;