Re: [PATCH v9 09/22] s390: vfio-ap: register matrix device with VFIO mdev framework

Tony Krowiak
2018-09-10T13:38:32Z

On 09/06/2018 04:49 AM, Pierre Morel wrote:
> On 13/08/2018 23:48, Tony Krowiak wrote:
>> From: Tony Krowiak <akrowiak@linux.ibm.com>
>>
>> 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]
>>
>> A symbolic link to the mediated device will also be created
>> in the vfio_ap matrix's directory:
>>
>> /sys/devices/vfio_ap/matrix/[$uuid]
>>
>> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
>> Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
>> Tested-by: Michael Mueller <mimu@linux.ibm.com>
>> Tested-by: Farhan Ali <alifm@linux.ibm.com>
>> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
>> ---
>> MAINTAINERS | 1 +
>> drivers/s390/crypto/Makefile | 2 +-
>> drivers/s390/crypto/vfio_ap_drv.c | 23 ++++++
>> drivers/s390/crypto/vfio_ap_ops.c | 124
>> +++++++++++++++++++++++++++++++++
>> drivers/s390/crypto/vfio_ap_private.h | 45 ++++++++++++
>> include/uapi/linux/vfio.h | 1 +
>> 6 files changed, 195 insertions(+), 1 deletions(-)
>> create mode 100644 drivers/s390/crypto/vfio_ap_ops.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index e84c559..f60dd56 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -12427,6 +12427,7 @@ W:
>> http://www.ibm.com/developerworks/linux/linux390/
>> S: Supported
>> F: drivers/s390/crypto/vfio_ap_drv.c
>> F: drivers/s390/crypto/vfio_ap_private.h
>> +F: drivers/s390/crypto/vfio_ap_ops.c
>>
>> S390 ZFCP DRIVER
>> M: Steffen Maier <maier@linux.ibm.com>
>> diff --git a/drivers/s390/crypto/Makefile b/drivers/s390/crypto/Makefile
>> index 48e466e..8d36b05 100644
>> --- a/drivers/s390/crypto/Makefile
>> +++ b/drivers/s390/crypto/Makefile
>> @@ -17,5 +17,5 @@ pkey-objs := pkey_api.o
>> obj-$(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 5069580..fa04c5a 100644
>> --- a/drivers/s390/crypto/vfio_ap_drv.c
>> +++ b/drivers/s390/crypto/vfio_ap_drv.c
>> @@ -11,6 +11,7 @@
>> #include <linux/mod_devicetable.h>
>> #include <linux/slab.h>
>> #include <linux/string.h>
>> +#include <asm/zcrypt.h>
>> #include "vfio_ap_private.h"
>>
>> #define VFIO_AP_ROOT_NAME "vfio_ap"
>> @@ -65,6 +66,19 @@ static int vfio_ap_matrix_dev_init(void)
>> return ret;
>> }
>>
>> + mutex_init(&matrix_dev.lock);
>> + INIT_LIST_HEAD(&matrix_dev.mdev_list);
>> +
>> + /* Test if PQAP(QCI) instruction is available */
>> + if (test_facility(12)) {
>> + ret = ap_qci(&matrix_dev.info);
>> + if (ret) {
>> + root_device_unregister(root_device);
>> + return ret;
>> + }
>> + }
>> +
>> + atomic_set(&matrix_dev.available_instances, MAX_ZDEV_ENTRIES_EXT);
>> matrix_dev.device.type = &vfio_ap_dev_type;
>> dev_set_name(&matrix_dev.device, "%s", VFIO_AP_DEV_NAME);
>> matrix_dev.device.type = &vfio_ap_dev_type;
>> @@ -105,11 +119,20 @@ int __init vfio_ap_init(void)
>> return ret;
>> }
>>
>> + ret = vfio_ap_mdev_register();
>> + if (ret) {
>> + ap_driver_unregister(&vfio_ap_drv);
>> + vfio_ap_matrix_dev_destroy();
>> +
>> + return ret;
>> + }
>> +
>> return 0;
>> }
>>
>> void __exit vfio_ap_exit(void)
>> {
>> + vfio_ap_mdev_unregister();
>> ap_driver_unregister(&vfio_ap_drv);
>> vfio_ap_matrix_dev_destroy();
>> }
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c
>> b/drivers/s390/crypto/vfio_ap_ops.c
>> new file mode 100644
>> index 0000000..8018c2d
>> --- /dev/null
>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>> @@ -0,0 +1,124 @@
>> +// 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>
>> + * Halil Pasic <pasic@linux.ibm.com>
>> + * Pierre Morel <pmorel@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 VFIO_AP_MDEV_TYPE_HWVIRT "passthrough"
>> +#define VFIO_AP_MDEV_NAME_HWVIRT "VFIO AP Passthrough Device"
>> +
>> +static void vfio_ap_matrix_init(struct ap_config_info *info,
>> + struct ap_matrix *matrix)
>> +{
>> + matrix->apm_max = info->apxa ? info->Na : 63;
>> + matrix->aqm_max = info->apxa ? info->Nd : 15;
>> + matrix->adm_max = info->apxa ? info->Nd : 15;
>> +}
>> +
>> +static int vfio_ap_mdev_create(struct kobject *kobj, struct
>> mdev_device *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));
>> + vfio_ap_matrix_init(&matrix_dev.info, &matrix_mdev->matrix);
>> + mdev_set_drvdata(mdev, matrix_mdev);
>> +
>> + if (atomic_dec_if_positive(&matrix_dev.available_instances) < 0) {
>> + kfree(matrix_mdev);
>> + return -EPERM;
>> + }
>> +
>> + mutex_lock(&matrix_dev.lock);
>> + list_add(&matrix_mdev->list, &matrix_dev.mdev_list);
>> + mutex_unlock(&matrix_dev.lock);
>> +
> Hi Tony,
>
> You need to initialize the matrix_mdev->list before
> using it.

Why? Initialization only sets its prev and next pointers to point to
itself. The
list_add immediately sets those pointers to insert it into the
matrix_dev.mdev_list,
so what would be the purose?

>
>
> Regards,
> Pierre
>
>