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Message-Id: <8f40992c-5dbe-92a2-2b9d-d29bd3647567@linux.ibm.com>
Date: Mon, 10 Sep 2018 23:58:29 +0200
From: Halil Pasic <pasic@...ux.ibm.com>
To: Tony Krowiak <akrowiak@...ux.ibm.com>, pmorel@...ux.ibm.com,
Tony Krowiak <akrowiak@...ux.vnet.ibm.com>,
linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org
Cc: freude@...ibm.com, schwidefsky@...ibm.com,
heiko.carstens@...ibm.com, borntraeger@...ibm.com,
cohuck@...hat.com, kwankhede@...dia.com,
bjsdjshi@...ux.vnet.ibm.com, pbonzini@...hat.com,
alex.williamson@...hat.com, pmorel@...ux.vnet.ibm.com,
alifm@...ux.vnet.ibm.com, mjrosato@...ux.vnet.ibm.com,
jjherne@...ux.vnet.ibm.com, thuth@...hat.com,
pasic@...ux.vnet.ibm.com, berrange@...hat.com,
fiuczy@...ux.vnet.ibm.com, buendgen@...ibm.com,
frankja@...ux.ibm.com
Subject: Re: [PATCH v9 09/22] s390: vfio-ap: register matrix device with VFIO
mdev framework
On 09/10/2018 03:38 PM, Tony Krowiak wrote:
> On 09/06/2018 04:49 AM, Pierre Morel wrote:
>> On 13/08/2018 23:48, Tony Krowiak wrote:
>>> From: Tony Krowiak <akrowiak@...ux.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/[$uuid]
>>>
>>> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
>>> Reviewed-by: Halil Pasic <pasic@...ux.ibm.com>
>>> Tested-by: Michael Mueller <mimu@...ux.ibm.com>
>>> Tested-by: Farhan Ali <alifm@...ux.ibm.com>
>>> Signed-off-by: Christian Borntraeger <borntraeger@...ibm.com>
>>> ---
>>> MAINTAINERS | 1 +
>>> drivers/s390/crypto/Makefile | 2 +-
>>> drivers/s390/crypto/vfio_ap_drv.c | 23 ++++++
>>> drivers/s390/crypto/vfio_ap_ops.c | 124 +++++++++++++++++++++++++++++++++
>>> drivers/s390/crypto/vfio_ap_private.h | 45 ++++++++++++
>>> include/uapi/linux/vfio.h | 1 +
>>> 6 files changed, 195 insertions(+), 1 deletions(-)
>>> create mode 100644 drivers/s390/crypto/vfio_ap_ops.c
>>>
>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>> index e84c559..f60dd56 100644
>>> --- a/MAINTAINERS
>>> +++ b/MAINTAINERS
>>> @@ -12427,6 +12427,7 @@ W: http://www.ibm.com/developerworks/linux/linux390/
>>> S: Supported
>>> F: drivers/s390/crypto/vfio_ap_drv.c
>>> F: drivers/s390/crypto/vfio_ap_private.h
>>> +F: drivers/s390/crypto/vfio_ap_ops.c
>>>
>>> S390 ZFCP DRIVER
>>> M: Steffen Maier <maier@...ux.ibm.com>
>>> diff --git a/drivers/s390/crypto/Makefile b/drivers/s390/crypto/Makefile
>>> index 48e466e..8d36b05 100644
>>> --- a/drivers/s390/crypto/Makefile
>>> +++ b/drivers/s390/crypto/Makefile
>>> @@ -17,5 +17,5 @@ pkey-objs := pkey_api.o
>>> obj-$(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@...ux.ibm.com>
>>> + * Halil Pasic <pasic@...ux.ibm.com>
>>> + * Pierre Morel <pmorel@...ux.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?
>
I think the source of the confusion is that matrix_mdev->list a new element to be
added to the matrix_dev.mdev_list and not a sentinel node of some list (which in
a sense stands for the list as a whole).
Regards,
Halil
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