Re: [PATCH v7 06/15] s390/vfio-ap: sysfs attribute to display the guest CRYCB

Tony Krowiak
2020-04-08T16:38:58Z

On 4/8/20 6:33 AM, Cornelia Huck wrote:
> On Tue, 7 Apr 2020 15:20:06 -0400
> Tony Krowiak <akrowiak@linux.ibm.com> wrote:
>
>> The matrix of adapters and domains configured in a guest's CRYCB may
>> differ from the matrix of adapters and domains assigned to the matrix mdev,
>> so this patch introduces a sysfs attribute to display the CRYCB of a guest
>> using the matrix mdev. For a matrix mdev denoted by $uuid, the crycb for a
>> guest using the matrix mdev can be displayed as follows:
>>
>> cat /sys/devices/vfio_ap/matrix/$uuid/guest_matrix
>>
>> If a guest is not using the matrix mdev at the time the crycb is displayed,
>> an error (ENODEV) will be returned.
>>
>> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
>> ---
>> drivers/s390/crypto/vfio_ap_ops.c | 58 +++++++++++++++++++++++++++++++
>> 1 file changed, 58 insertions(+)
>> +static DEVICE_ATTR_RO(guest_matrix);
> Hm... should information like the guest configuration be readable by
> everyone? Or should it be restricted a bit more?

Why? The matrix attribute already displays the APQNs of the queues
assigned to the matrix mdev. The guest_matrix attribute merely displays
a subset of the matrix (i.e., the APQNs assigned to the mdev that reference
queue devices bound to the vfio_ap device driver).

How can this be restricted?

>
>> +
>> static struct attribute *vfio_ap_mdev_attrs[] = {
>> &dev_attr_assign_adapter.attr,
>> &dev_attr_unassign_adapter.attr,
>> @@ -1050,6 +1107,7 @@ static struct attribute *vfio_ap_mdev_attrs[] = {
>> &dev_attr_unassign_control_domain.attr,
>> &dev_attr_control_domains.attr,
>> &dev_attr_matrix.attr,
>> + &dev_attr_guest_matrix.attr,
>> NULL,
>> };
>>