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Subject[PATCH v8 15/22] s390: vfio-ap: implement mediated device open callback
Date
From: Tony Krowiak <akrowiak@linux.ibm.com>

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>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
Tested-by: Michael Mueller <mimu@linux.ibm.com>
Tested-by: Farhan Ali <alifm@linux.ibm.com>
Tested-by: Pierre Morel <pmorel@linux.ibm.com>
Acked-by: Pierre Morel <pmorel@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
drivers/s390/crypto/vfio_ap_ops.c | 175 ++++++++++++++++++++++++++++++++-
drivers/s390/crypto/vfio_ap_private.h | 2 +
2 files changed, 176 insertions(+), 1 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 61a25d4..ea96b95 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -13,6 +13,10 @@
#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"

@@ -55,6 +59,9 @@ static int vfio_ap_mdev_remove(struct mdev_device *mdev)
{
struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);

+ if (matrix_mdev->kvm)
+ return -EBUSY;
+
mutex_lock(&matrix_dev.lock);
list_del(&matrix_mdev->list);
mutex_unlock(&matrix_dev.lock);
@@ -291,6 +298,10 @@ static ssize_t assign_adapter_store(struct device *dev,
struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
unsigned long max_apid = matrix_mdev->matrix.apm_max;

+ /* If the guest is running, disallow assignment of adapter */
+ if (matrix_mdev->kvm)
+ return -EBUSY;
+
ret = kstrtoul(buf, 0, &apid);
if (ret)
return ret;
@@ -348,6 +359,10 @@ static ssize_t unassign_adapter_store(struct device *dev,
struct mdev_device *mdev = mdev_from_dev(dev);
struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);

+ /* If the guest is running, disallow un-assignment of adapter */
+ if (matrix_mdev->kvm)
+ return -EBUSY;
+
ret = kstrtoul(buf, 0, &apid);
if (ret)
return ret;
@@ -393,6 +408,10 @@ static ssize_t assign_domain_store(struct device *dev,
struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
unsigned long max_apqi = matrix_mdev->matrix.aqm_max;

+ /* If the guest is running, disallow assignment of domain */
+ if (matrix_mdev->kvm)
+ return -EBUSY;
+
ret = kstrtoul(buf, 0, &apqi);
if (ret)
return ret;
@@ -432,6 +451,10 @@ static ssize_t unassign_domain_store(struct device *dev,
struct mdev_device *mdev = mdev_from_dev(dev);
struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);

+ /* If the guest is running, disallow un-assignment of domain */
+ if (matrix_mdev->kvm)
+ return -EBUSY;
+
ret = kstrtoul(buf, 0, &apqi);
if (ret)
return ret;
@@ -470,6 +493,10 @@ static ssize_t assign_control_domain_store(struct device *dev,
struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
unsigned long maxid = matrix_mdev->matrix.adm_max;

+ /* If the guest is running, disallow assignment of control domain */
+ if (matrix_mdev->kvm)
+ return -EBUSY;
+
ret = kstrtoul(buf, 0, &id);
if (ret)
return ret;
@@ -514,6 +541,10 @@ static ssize_t unassign_control_domain_store(struct device *dev,
struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
unsigned long max_domid = matrix_mdev->matrix.adm_max;

+ /* If the guest is running, disallow un-assignment of control domain */
+ if (matrix_mdev->kvm)
+ return -EBUSY;
+
ret = kstrtoul(buf, 0, &domid);
if (ret)
return ret;
@@ -602,7 +633,6 @@ static ssize_t matrix_show(struct device *dev, struct device_attribute *attr,
}
DEVICE_ATTR_RO(matrix);

-
static struct attribute *vfio_ap_mdev_attrs[] = {
&dev_attr_assign_adapter.attr,
&dev_attr_unassign_adapter.attr,
@@ -624,12 +654,155 @@ 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;
+
+ return -EOPNOTSUPP;
+}
+
+static void kvm_ap_merge_bitmasks(unsigned long *dst, unsigned long *mask1,
+ unsigned long *mask2, unsigned long nbits)
+{
+ int i;
+
+ for (i = 0; i < BITS_TO_LONGS(nbits); i++)
+ dst[i] = mask1[i] | mask2[i];
+}
+
+static void vfio_ap_mdev_copy_masks(struct ap_matrix_mdev *matrix_mdev)
+{
+ int nbytes;
+ unsigned long *apm, *aqm, *adm;
+ struct kvm_s390_crypto_cb *crycb = matrix_mdev->kvm->arch.crypto.crycb;
+
+ switch (matrix_mdev->kvm->arch.crypto.crycbd & CRYCB_FORMAT_MASK) {
+ case CRYCB_FORMAT2:
+ apm = (unsigned long *)crycb->apcb1.apm;
+ aqm = (unsigned long *)crycb->apcb1.aqm;
+ adm = (unsigned long *)crycb->apcb1.adm;
+ break;
+ case CRYCB_FORMAT1:
+ case CRYCB_FORMAT0:
+ default:
+ apm = (unsigned long *)crycb->apcb0.apm;
+ aqm = (unsigned long *)crycb->apcb0.aqm;
+ adm = (unsigned long *)crycb->apcb0.adm;
+ break;
+ }
+
+ nbytes = DIV_ROUND_UP(matrix_mdev->matrix.apm_max + 1, BITS_PER_BYTE);
+ memcpy(apm, matrix_mdev->matrix.apm, nbytes);
+ nbytes = DIV_ROUND_UP(matrix_mdev->matrix.aqm_max + 1, BITS_PER_BYTE);
+ memcpy(aqm, matrix_mdev->matrix.aqm, nbytes);
+ kvm_ap_merge_bitmasks(adm, aqm, adm, matrix_mdev->matrix.adm_max + 1);
+}
+
+/**
+ * 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,
+ struct kvm *kvm)
+{
+ struct ap_matrix_mdev *m;
+
+ mutex_lock(&matrix_dev.lock);
+
+ list_for_each_entry(m, &matrix_dev.mdev_list, list) {
+ if ((m != matrix_mdev) && (m->kvm == matrix_mdev->kvm)) {
+ mutex_unlock(&matrix_dev.lock);
+ return -EPERM;
+ }
+ }
+
+ mutex_unlock(&matrix_dev.lock);
+
+ return 0;
+}
+
+static int vfio_ap_mdev_group_notifier(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ int ret;
+ struct ap_matrix_mdev *matrix_mdev;
+
+ if (action != VFIO_GROUP_NOTIFY_SET_KVM)
+ return NOTIFY_OK;
+
+ matrix_mdev = container_of(nb, struct ap_matrix_mdev, group_notifier);
+
+ matrix_mdev->kvm = data;
+ if (data == NULL)
+ return NOTIFY_OK;
+
+ ret = vfio_ap_mdev_open_once(matrix_mdev, data);
+ if (ret)
+ return ret;
+
+ ret = kvm_ap_validate_crypto_setup(matrix_mdev->kvm);
+ if (ret)
+ return ret;
+
+ vfio_ap_mdev_copy_masks(matrix_mdev);
+
+ return NOTIFY_OK;
+}
+
+static int vfio_ap_mdev_open(struct mdev_device *mdev)
+{
+ struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
+ unsigned long events;
+ int ret;
+
+
+ if (!try_module_get(THIS_MODULE))
+ return -ENODEV;
+
+ 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) {
+ module_put(THIS_MODULE);
+ return ret;
+ }
+
+ return 0;
+}
+
+static void vfio_ap_mdev_release(struct mdev_device *mdev)
+{
+ struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
+
+ kvm_arch_crypto_clear_masks(matrix_mdev->kvm);
+ 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(void)
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index 1724258..6fa77cf 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -66,6 +66,8 @@ struct ap_matrix_mdev {
const char *name;
struct list_head list;
struct ap_matrix matrix;
+ struct notifier_block group_notifier;
+ struct kvm *kvm;
};

static inline struct device *to_device(struct ap_matrix_dev *matrix_dev)
--
1.7.1
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