Re: [PATCH v6 08/21] s390: vfio-ap: register matrix device with VFIO mdev framework

Pierre Morel
2018-07-09T14:17:34Z

On 29/06/2018 23:11, Tony Krowiak 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@linux.ibm.com>
> ---
> MAINTAINERS | 1 +
> drivers/s390/crypto/Makefile | 2 +-
> drivers/s390/crypto/vfio_ap_drv.c | 9 ++
> drivers/s390/crypto/vfio_ap_ops.c | 131 +++++++++++++++++++++++++++++++++
> drivers/s390/crypto/vfio_ap_private.h | 22 +++++-
> 5 files changed, 161 insertions(+), 4 deletions(-)
> create mode 100644 drivers/s390/crypto/vfio_ap_ops.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 0515dae..3217803 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -12410,6 +12410,7 @@ W: http://www.ibm.com/developerworks/linux/linux390/
> S: Supported
> F: drivers/s390/crypto/vfio_ap_drv.c
> F: drivers/s390/crypto/vfio_ap_private.h
> +F: drivers/s390/crypto/vfio_ap_ops.c
>
> S390 ZFCP DRIVER
> M: Steffen Maier <maier@linux.ibm.com>
> diff --git a/drivers/s390/crypto/Makefile b/drivers/s390/crypto/Makefile
> index 48e466e..8d36b05 100644
> --- a/drivers/s390/crypto/Makefile
> +++ b/drivers/s390/crypto/Makefile
> @@ -17,5 +17,5 @@ pkey-objs := pkey_api.o
> obj-$(CONFIG_PKEY) += pkey.o
>
> # adjunct processor matrix
> -vfio_ap-objs := vfio_ap_drv.o
> +vfio_ap-objs := vfio_ap_drv.o vfio_ap_ops.o
> obj-$(CONFIG_VFIO_AP) += vfio_ap.o
> diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
> index 93db312..b6ff7a4 100644
> --- a/drivers/s390/crypto/vfio_ap_drv.c
> +++ b/drivers/s390/crypto/vfio_ap_drv.c
> @@ -127,11 +127,20 @@ int __init vfio_ap_init(void)
> return ret;
> }
>
> + ret = vfio_ap_mdev_register(matrix_dev);
> + if (ret) {
> + ap_driver_unregister(&vfio_ap_drv);
> + vfio_ap_matrix_dev_destroy(matrix_dev);
> +
> + return ret;
> + }
> +
> return 0;
> }
>
> void __exit vfio_ap_exit(void)
> {
> + vfio_ap_mdev_unregister(matrix_dev);
> ap_driver_unregister(&vfio_ap_drv);
> vfio_ap_matrix_dev_destroy(matrix_dev);
> }
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> new file mode 100644
> index 0000000..4e61e33
> --- /dev/null
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -0,0 +1,131 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Adjunct processor matrix VFIO device driver callbacks.
> + *
> + * Copyright IBM Corp. 2018
> + * Author(s): Tony Krowiak <akrowiak@linux.ibm.com>
> + *
> + */
> +#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"
> +
> +DEFINE_SPINLOCK(mdev_list_lock);
> +LIST_HEAD(mdev_list);
> +
> +static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
> +{
> + struct ap_matrix_dev *matrix_dev =
> + to_ap_matrix_dev(mdev_parent_dev(mdev));
> + struct ap_matrix_mdev *matrix_mdev;
> +
> + matrix_mdev = kzalloc(sizeof(*matrix_mdev), GFP_KERNEL);
> + if (!matrix_mdev)
> + return -ENOMEM;
> +
> + matrix_mdev->name = dev_name(mdev_dev(mdev));
> + mdev_set_drvdata(mdev, matrix_mdev);
> +
> + if (atomic_dec_if_positive(&matrix_dev->available_instances) < 0) {
> + kfree(matrix_mdev);
> + return -EPERM;
> + }
> +
> + spin_lock_bh(&mdev_list_lock);
> + list_add(&matrix_mdev->list, &mdev_list);
> + spin_unlock_bh(&mdev_list_lock);
> +
> + return 0;
> +}
> +
> +static int vfio_ap_mdev_remove(struct mdev_device *mdev)
> +{
> + struct ap_matrix_dev *matrix_dev =
> + to_ap_matrix_dev(mdev_parent_dev(mdev));
> + struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
> +
> + spin_lock_bh(&mdev_list_lock);
> + list_del(&matrix_mdev->list);
> + spin_unlock_bh(&mdev_list_lock);
> + kfree(matrix_mdev);
> + mdev_set_drvdata(mdev, NULL);
> + atomic_inc(&matrix_dev->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_dev *matrix_dev = to_ap_matrix_dev(dev);
> +
> + return sprintf(buf, "%d\n",
> + atomic_read(&matrix_dev->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_dev *matrix_dev)
> +{
> + int ret;
> +
> + ret = mdev_register_device(&matrix_dev->device, &vfio_ap_matrix_ops);
> + if (ret)
> + return ret;
> +
> + atomic_set(&matrix_dev->available_instances,
> + AP_MATRIX_MAX_AVAILABLE_INSTANCES);
> +
> + return 0;
> +}
> +
> +void vfio_ap_mdev_unregister(struct ap_matrix_dev *matrix_dev)
> +{
> + mdev_unregister_device(&matrix_dev->device);
> +}
> diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
> index 19c0b60..3de1275 100644
> --- a/drivers/s390/crypto/vfio_ap_private.h
> +++ b/drivers/s390/crypto/vfio_ap_private.h
> @@ -10,20 +10,36 @@
> #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 for every guest using AP devices.
> + * If every APQN is assigned 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

Why isn't it 256 x 256 ?

>
> struct ap_matrix_dev {
> struct device device;
> + atomic_t available_instances;
> +};
> +
> +struct ap_matrix_mdev {
> + const char *name;
> + struct list_head list;
> };
>
> -static inline struct ap_matrix_dev
> -*to_ap_matrix_parent_dev(struct device *dev)
> +static struct ap_matrix_dev *to_ap_matrix_dev(struct device *dev)
> {
> - return container_of(dev, struct ap_matrix_dev, device.parent);
> + return container_of(dev, struct ap_matrix_dev, device);
> }
>
> +extern int vfio_ap_mdev_register(struct ap_matrix_dev *matrix_dev);
> +extern void vfio_ap_mdev_unregister(struct ap_matrix_dev *matrix_dev);
> +
> #endif /* _VFIO_AP_PRIVATE_H_ */

--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany