linux-kernel - [PATCH v16 05/14] s390/vfio-ap: introduce shadow APCB

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Date:   Mon, 10 May 2021 12:44:14 -0400
From:   Tony Krowiak <akrowiak@...ux.ibm.com>
To:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     jjherne@...ux.ibm.com, freude@...ux.ibm.com,
        borntraeger@...ibm.com, cohuck@...hat.com, mjrosato@...ux.ibm.com,
        pasic@...ux.ibm.com, alex.williamson@...hat.com,
        kwankhede@...dia.com, fiuczy@...ux.ibm.com,
        Tony Krowiak <akrowiak@...ux.ibm.com>
Subject: [PATCH v16 05/14] s390/vfio-ap: introduce shadow APCB

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@...ux.ibm.com>
Reviewed-by: Halil Pasic <pasic@...ux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_ops.c     | 10 ++++++----
 drivers/s390/crypto/vfio_ap_private.h |  2 ++
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index e391b9cfe32b..8f705b0e12e4 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -353,6 +353,7 @@ static int vfio_ap_mdev_create(struct mdev_device *mdev)
 	matrix_mdev->mdev = mdev;
 	vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->matrix);
 	init_waitqueue_head(&matrix_mdev->wait_for_kvm);
+	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;
@@ -1222,12 +1223,13 @@ static int vfio_ap_mdev_set_kvm(struct ap_matrix_mdev *matrix_mdev,
 		}
 
 		kvm_get_kvm(kvm);
+		memcpy(&matrix_mdev->shadow_apcb, &matrix_mdev->matrix,
+		       sizeof(struct ap_matrix));
 		matrix_mdev->kvm_busy = true;
 		mutex_unlock(&matrix_dev->lock);
-		kvm_arch_crypto_set_masks(kvm,
-					  matrix_mdev->matrix.apm,
-					  matrix_mdev->matrix.aqm,
-					  matrix_mdev->matrix.adm);
+		kvm_arch_crypto_set_masks(kvm, matrix_mdev->shadow_apcb.apm,
+					  matrix_mdev->shadow_apcb.aqm,
+					  matrix_mdev->shadow_apcb.adm);
 		mutex_lock(&matrix_dev->lock);
 		kvm->arch.crypto.pqap_hook = &matrix_mdev->pqap_hook;
 		matrix_mdev->kvm = kvm;
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index af3f53a3ea4c..6f4f1f5bd611 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;
 	bool kvm_busy;
-- 
2.30.2