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Subject: Re: [PATCH v9 09/22] s390: vfio-ap: register matrix device with VFIO
 mdev framework
To:     pmorel@linux.ibm.com, Tony Krowiak <akrowiak@linux.vnet.ibm.com>,
        linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
Cc:     freude@de.ibm.com, schwidefsky@de.ibm.com,
        heiko.carstens@de.ibm.com, borntraeger@de.ibm.com,
        cohuck@redhat.com, kwankhede@nvidia.com,
        bjsdjshi@linux.vnet.ibm.com, pbonzini@redhat.com,
        alex.williamson@redhat.com, pmorel@linux.vnet.ibm.com,
        alifm@linux.vnet.ibm.com, mjrosato@linux.vnet.ibm.com,
        jjherne@linux.vnet.ibm.com, thuth@redhat.com,
        pasic@linux.vnet.ibm.com, berrange@redhat.com,
        fiuczy@linux.vnet.ibm.com, buendgen@de.ibm.com,
        frankja@linux.ibm.com
References: <1534196899-16987-1-git-send-email-akrowiak@linux.vnet.ibm.com>
 <1534196899-16987-10-git-send-email-akrowiak@linux.vnet.ibm.com>
 <af1cd7a8-446c-ddf6-cf17-886dd259da3d@linux.ibm.com>
From:   Tony Krowiak <akrowiak@linux.ibm.com>
Date:   Mon, 10 Sep 2018 09:38:32 -0400
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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
>
>