linux-kernel - Re: [PATCH v6 13/21] s390: vfio-ap: sysfs interface to view matrix mdev matrix

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Message-Id: <2ebe297c-79e7-1cfd-05a9-1ab8943a0203@linux.ibm.com>
Date:   Fri, 13 Jul 2018 14:24:47 +0200
From:   Tony Krowiak <akrowiak@...ux.ibm.com>
To:     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
Subject: Re: [PATCH v6 13/21] s390: vfio-ap: sysfs interface to view matrix
 mdev matrix

On 07/09/2018 04:38 PM, Pierre Morel wrote:
> On 09/07/2018 14:20, Pierre Morel wrote:
>> On 29/06/2018 23:11, Tony Krowiak wrote:
>>> Provides a sysfs interface to view the AP matrix configured for the
>>> mediated matrix device.
>>>
>>> The relevant sysfs structures are:
>>>
>>> /sys/devices/vfio_ap
>>> ... [matrix]
>>> ...... [mdev_supported_types]
>>> ......... [vfio_ap-passthrough]
>>> ............ [devices]
>>> ...............[$uuid]
>>> .................. matrix
>>>
>>> To view the matrix configured for the mediated matrix device,
>>> print the matrix file:
>>>
>>>     cat matrix
>>>
>>> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
>>> ---
>>>   drivers/s390/crypto/vfio_ap_ops.c |   31 
>>> +++++++++++++++++++++++++++++++
>>>   1 files changed, 31 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c 
>>> b/drivers/s390/crypto/vfio_ap_ops.c
>>> index c8f31f3..bc7398d 100644
>>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>>> @@ -697,6 +697,36 @@ static ssize_t control_domains_show(struct 
>>> device *dev,
>>>   }
>>>   DEVICE_ATTR_RO(control_domains);
>>>
>>> +static ssize_t matrix_show(struct device *dev, struct 
>>> device_attribute *attr,
>>> +               char *buf)
>>> +{
>>> +    struct mdev_device *mdev = mdev_from_dev(dev);
>>> +    struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
>>> +    char *bufpos = buf;
>>> +    unsigned long apid;
>>> +    unsigned long apqi;
>>> +    unsigned long napm = matrix_mdev->matrix.apm_max + 1;
>>> +    unsigned long naqm = matrix_mdev->matrix.aqm_max + 1;
>>> +    int nchars = 0;
>>> +    int n;
>>> +
>>> +    for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, napm) {
>>> +        n = sprintf(bufpos, "%02lx\n", apid);
>>> +        bufpos += n;
>>> +        nchars += n;
>>> +
>>> +        for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, naqm) {
>>> +            n = sprintf(bufpos, "%02lx.%04lx\n", apid, apqi);
>>> +            bufpos += n;
>>> +            nchars += n;
>>> +        }
>>> +    }
>>> +
>>> +    return nchars;
>>> +}
>>> +DEVICE_ATTR_RO(matrix);
>>> +
>>> +
>>>   static struct attribute *vfio_ap_mdev_attrs[] = {
>>>       &dev_attr_assign_adapter.attr,
>>>       &dev_attr_unassign_adapter.attr,
>>> @@ -705,6 +735,7 @@ static ssize_t control_domains_show(struct 
>>> device *dev,
>>>       &dev_attr_assign_control_domain.attr,
>>>       &dev_attr_unassign_control_domain.attr,
>>>       &dev_attr_control_domains.attr,
>>> +    &dev_attr_matrix.attr,
>>>       NULL,
>>>   };
>>>
>>
>> I have still the same remark: what you show here is not what is 
>> currently
>> used by the SIE.
>> It is not irrelevant but what the guest really use may be more 
>> interesting
>> for the admin.
>>
>>
> OK, you implement the right view it in patch 16/21.
>
> Still, what is the purpose of showing this view?

I find it to have great value when configuring the mdev. It provides a 
view of
what has been configured thus far.

>
>
>