Re: [PATCH v5 05/13] s390: vfio-ap: register matrix device with VFIO mdev framework
From: Tony Krowiak
Date: Wed May 16 2018 - 08:18:03 EST
On 05/16/2018 06:42 AM, Cornelia Huck wrote:
On Mon, 7 May 2018 11:11:44 -0400
Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx> wrote:
Registers the matrix device created by the VFIO AP device
driver with the VFIO mediated device framework.
Registering the matrix device will create the sysfs
structures needed to create mediated matrix devices
each of which will be used to configure the AP matrix
for a guest and connect it to the VFIO AP device driver.
Registering the matrix device with the VFIO mediated device
framework will create the following sysfs structures:
/sys/devices/vfio_ap
... [matrix]
...... [mdev_supported_types]
......... [vfio_ap-passthrough]
............ create
To create a mediated device for the AP matrix device, write a UUID
to the create file:
uuidgen > create
A symbolic link to the mediated device's directory will be created in the
devices subdirectory named after the generated $uuid:
/sys/devices/vfio_ap
... [matrix]
...... [mdev_supported_types]
......... [vfio_ap-passthrough]
............ [devices]
............... [$uuid]
Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx>
---
MAINTAINERS | 1 +
drivers/s390/crypto/Makefile | 2 +-
drivers/s390/crypto/vfio_ap_drv.c | 9 +++
drivers/s390/crypto/vfio_ap_ops.c | 106 +++++++++++++++++++++++++++++++++
drivers/s390/crypto/vfio_ap_private.h | 17 +++++
5 files changed, 134 insertions(+), 1 deletions(-)
create mode 100644 drivers/s390/crypto/vfio_ap_ops.c
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
new file mode 100644
index 0000000..d7d36fb
--- /dev/null
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Adjunct processor matrix VFIO device driver callbacks.
+ *
+ * Copyright IBM Corp. 2017
Should be '2018' (also in some other files in this series; please
double check.)
Gee, I thought I got all of these fixed. I must have a gremlin in my
laptop.
+ * Author(s): Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx>
+ *
+ */
+#include <linux/string.h>
+#include <linux/vfio.h>
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/ctype.h>
+
+#include "vfio_ap_private.h"
+
+#define VFOP_AP_MDEV_TYPE_HWVIRT "passthrough"
+#define VFIO_AP_MDEV_NAME_HWVIRT "VFIO AP Passthrough Device"
+
+static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
+{
+ struct ap_matrix *ap_matrix = to_ap_matrix(mdev_parent_dev(mdev));
+
+ ap_matrix->available_instances--;
Shouldn't the code check whether available_instances is actually > 0?
It is my understanding that once the available_instances hits zero, the
mdev
framework will not allow any more mediated devices to be created, so the
value should always be greater than zero when this function is invoked.
I did an experiment to verify my understanding. I initialized the
available_instances
to 1. I was able to create 2 mediated devices. It seems that the
framework refuses to
create a mediated device only after the available_instances sysfs
attribute is a negative
number, so I have two choices: Initialize available_instances to one
less than desires;
add the check you suggested. I think I'll go with the latter.
+
+ return 0;
+}
+
+static int vfio_ap_mdev_remove(struct mdev_device *mdev)
+{
+ struct ap_matrix *ap_matrix = to_ap_matrix(mdev_parent_dev(mdev));
+
+ ap_matrix->available_instances++;
+
+ return 0;
+}
+
+static ssize_t name_show(struct kobject *kobj, struct device *dev, char *buf)
+{
+ return sprintf(buf, "%s\n", VFIO_AP_MDEV_NAME_HWVIRT);
+}
+
+MDEV_TYPE_ATTR_RO(name);
+
+static ssize_t available_instances_show(struct kobject *kobj,
+ struct device *dev, char *buf)
+{
+ struct ap_matrix *ap_matrix;
+
+ ap_matrix = to_ap_matrix(dev);
Move this with the declaration?
+
+ return sprintf(buf, "%d\n", ap_matrix->available_instances);
+}
+
+MDEV_TYPE_ATTR_RO(available_instances);
+
+static ssize_t device_api_show(struct kobject *kobj, struct device *dev,
+ char *buf)
+{
+ return sprintf(buf, "%s\n", VFIO_DEVICE_API_AP_STRING);
+}
+
+MDEV_TYPE_ATTR_RO(device_api);
+
+static struct attribute *vfio_ap_mdev_type_attrs[] = {
+ &mdev_type_attr_name.attr,
+ &mdev_type_attr_device_api.attr,
+ &mdev_type_attr_available_instances.attr,
+ NULL,
+};
+
+static struct attribute_group vfio_ap_mdev_hwvirt_type_group = {
+ .name = VFOP_AP_MDEV_TYPE_HWVIRT,
+ .attrs = vfio_ap_mdev_type_attrs,
+};
+
+static struct attribute_group *vfio_ap_mdev_type_groups[] = {
+ &vfio_ap_mdev_hwvirt_type_group,
+ NULL,
+};
+
+static const struct mdev_parent_ops vfio_ap_matrix_ops = {
+ .owner = THIS_MODULE,
+ .supported_type_groups = vfio_ap_mdev_type_groups,
+ .create = vfio_ap_mdev_create,
+ .remove = vfio_ap_mdev_remove,
+};
+
+int vfio_ap_mdev_register(struct ap_matrix *ap_matrix)
+{
+ int ret;
+
+ ret = mdev_register_device(&ap_matrix->device, &vfio_ap_matrix_ops);
+ if (ret)
+ return ret;
+
+ ap_matrix->available_instances = AP_MATRIX_MAX_AVAILABLE_INSTANCES;
+
+ return 0;
+}
+
+void vfio_ap_mdev_unregister(struct ap_matrix *ap_matrix)
+{
+ ap_matrix->available_instances--;
+ mdev_unregister_device(&ap_matrix->device);
+}
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index cf23675..afd8dbc 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -10,14 +10,31 @@
#define _VFIO_AP_PRIVATE_H_
#include <linux/types.h>
+#include <linux/device.h>
+#include <linux/mdev.h>
#include "ap_bus.h"
#define VFIO_AP_MODULE_NAME "vfio_ap"
#define VFIO_AP_DRV_NAME "vfio_ap"
+/**
+ * There must be one mediated matrix device per guest. If every APQN is assigned
One, or at most one? Or one for every guest using ap devices?
+ * to a guest, then the maximum number of guests with a unique APQN assigned
+ * would be 255 adapters x 255 domains = 72351 guests.
+ */
+#define AP_MATRIX_MAX_AVAILABLE_INSTANCES 72351
struct ap_matrix {
struct device device;
+ int available_instances;
};
+static inline struct ap_matrix *to_ap_matrix(struct device *dev)
+{
+ return container_of(dev, struct ap_matrix, device);
+}
+
+extern int vfio_ap_mdev_register(struct ap_matrix *ap_matrix);
+extern void vfio_ap_mdev_unregister(struct ap_matrix *ap_matrix);
+
#endif /* _VFIO_AP_PRIVATE_H_ */