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    SubjectRe: [PATCH v5 05/13] s390: vfio-ap: register matrix device with VFIO mdev framework
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    On 05/16/2018 06:42 AM, Cornelia Huck wrote:
    > On Mon, 7 May 2018 11:11:44 -0400
    > Tony Krowiak <akrowiak@linux.vnet.ibm.com> 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.vnet.ibm.com>
    >> ---
    >> 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.)
    >
    >> + * Author(s): Tony Krowiak <akrowiak@linux.vnet.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"
    >> +
    >> +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?

    Disregard my last response to this, I'm an idiot; it is the return of a
    negative number from this function that causes the create to fail.

    >
    >> +
    >> + 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?

    Okay, will do.

    >
    >> +
    >> + 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?

    'One mediated matrix device for every guest using AP devices' is most
    accurate. I'll make the change.

    >
    >> + * 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_ */


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