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Subject[PATCH v6 14/21] s390: vfio-ap: implement mediated device open callback
Date
Implements the open callback on the mediated matrix device.
The function registers a group notifier to receive notification
of the VFIO_GROUP_NOTIFY_SET_KVM event. When notified,
the vfio_ap device driver will get access to the guest's
kvm structure. The open callback must ensure that only one
mediated device shall be opened per guest.

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
---
drivers/s390/crypto/vfio_ap_ops.c | 128 +++++++++++++++++++++++++++++++++
drivers/s390/crypto/vfio_ap_private.h | 2 +
2 files changed, 130 insertions(+), 0 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index bc7398d..58be495 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -11,6 +11,10 @@
#include <linux/device.h>
#include <linux/list.h>
#include <linux/ctype.h>
+#include <linux/bitops.h>
+#include <linux/kvm_host.h>
+#include <linux/module.h>
+#include <asm/kvm.h>

#include "vfio_ap_private.h"

@@ -748,12 +752,136 @@ static ssize_t matrix_show(struct device *dev, struct device_attribute *attr,
NULL
};

+/**
+ * Verify that the AP instructions are available on the guest and are to be
+ * interpreted by the firmware. The former is indicated via the
+ * KVM_S390_VM_CPU_FEAT_AP CPU model feature and the latter by apie crypto
+ * flag.
+ */
+static int kvm_ap_validate_crypto_setup(struct kvm *kvm)
+{
+ if (test_bit_inv(KVM_S390_VM_CPU_FEAT_AP, kvm->arch.cpu_feat) &&
+ kvm->arch.crypto.apie)
+ return 0;
+
+ pr_err("%s: interpretation of AP instructions not available",
+ VFIO_AP_MODULE_NAME);
+
+ return -EOPNOTSUPP;
+}
+
+static int vfio_ap_mdev_group_notifier(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct ap_matrix_mdev *matrix_mdev;
+
+ if (action == VFIO_GROUP_NOTIFY_SET_KVM) {
+ matrix_mdev = container_of(nb, struct ap_matrix_mdev,
+ group_notifier);
+ matrix_mdev->kvm = data;
+ }
+
+ return NOTIFY_OK;
+}
+
+/**
+ * vfio_ap_mdev_open_once
+ *
+ * @matrix_mdev: a mediated matrix device
+ *
+ * Return 0 if no other mediated matrix device has been opened for the
+ * KVM guest assigned to @matrix_mdev; otherwise, returns an error.
+ */
+static int vfio_ap_mdev_open_once(struct ap_matrix_mdev *matrix_mdev)
+{
+ int ret = 0;
+ struct ap_matrix_mdev *lstdev;
+
+ spin_lock_bh(&mdev_list_lock);
+
+ list_for_each_entry(lstdev, &mdev_list, list) {
+ if ((lstdev->kvm == matrix_mdev->kvm) &&
+ (lstdev != matrix_mdev)) {
+ ret = -EPERM;
+ break;
+ }
+ }
+
+ if (ret) {
+ pr_err("%s: mdev %s open failed for guest %s",
+ VFIO_AP_MODULE_NAME, matrix_mdev->name,
+ matrix_mdev->kvm->arch.dbf->name);
+ pr_err("%s: mdev %s already opened for guest %s",
+ VFIO_AP_MODULE_NAME, lstdev->name,
+ lstdev->kvm->arch.dbf->name);
+ }
+
+ spin_unlock_bh(&mdev_list_lock);
+ return ret;
+}
+
+static int vfio_ap_mdev_open(struct mdev_device *mdev)
+{
+ struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
+ struct ap_matrix_dev *matrix_dev =
+ to_ap_matrix_dev(mdev_parent_dev(mdev));
+ unsigned long events;
+ int ret;
+
+ if (!try_module_get(THIS_MODULE))
+ return -ENODEV;
+
+ ret = vfio_ap_verify_queues_reserved(matrix_dev, matrix_mdev->name,
+ &matrix_mdev->matrix);
+ if (ret)
+ goto out_err;
+
+ matrix_mdev->group_notifier.notifier_call = vfio_ap_mdev_group_notifier;
+ events = VFIO_GROUP_NOTIFY_SET_KVM;
+
+ ret = vfio_register_notifier(mdev_dev(mdev), VFIO_GROUP_NOTIFY,
+ &events, &matrix_mdev->group_notifier);
+ if (ret)
+ goto out_err;
+
+ ret = kvm_ap_validate_crypto_setup(matrix_mdev->kvm);
+ if (ret)
+ goto out_kvm_err;
+
+ ret = vfio_ap_mdev_open_once(matrix_mdev);
+ if (ret)
+ goto out_kvm_err;
+
+ return 0;
+
+out_kvm_err:
+ vfio_unregister_notifier(mdev_dev(mdev), VFIO_GROUP_NOTIFY,
+ &matrix_mdev->group_notifier);
+ matrix_mdev->kvm = NULL;
+out_err:
+ module_put(THIS_MODULE);
+
+ return ret;
+}
+
+static void vfio_ap_mdev_release(struct mdev_device *mdev)
+{
+ struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
+
+ vfio_unregister_notifier(mdev_dev(mdev), VFIO_GROUP_NOTIFY,
+ &matrix_mdev->group_notifier);
+ matrix_mdev->kvm = NULL;
+ module_put(THIS_MODULE);
+}
+
static const struct mdev_parent_ops vfio_ap_matrix_ops = {
.owner = THIS_MODULE,
.supported_type_groups = vfio_ap_mdev_type_groups,
.mdev_attr_groups = vfio_ap_mdev_attr_groups,
.create = vfio_ap_mdev_create,
.remove = vfio_ap_mdev_remove,
+ .open = vfio_ap_mdev_open,
+ .release = vfio_ap_mdev_release,
};

int vfio_ap_mdev_register(struct ap_matrix_dev *matrix_dev)
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index ae771f5..7792b45 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -56,6 +56,8 @@ struct ap_matrix_mdev {
const char *name;
struct list_head list;
struct ap_matrix matrix;
+ struct notifier_block group_notifier;
+ struct kvm *kvm;
};

static struct ap_matrix_dev *to_ap_matrix_dev(struct device *dev)
--
1.7.1
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