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Thu, 09 Apr 2020 14:18:44 +0000 Received: from b03ledav001.gho.boulder.ibm.com (b03ledav001.gho.boulder.ibm.com [9.17.130.232]) by b03cxnp08027.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 039EIeC34784668 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 9 Apr 2020 14:18:40 GMT Received: from b03ledav001.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BD9DC6E05D; Thu, 9 Apr 2020 14:18:40 +0000 (GMT) Received: from b03ledav001.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8CBF06E054; Thu, 9 Apr 2020 14:18:39 +0000 (GMT) Received: from cpe-172-100-173-215.stny.res.rr.com (unknown [9.85.171.227]) by b03ledav001.gho.boulder.ibm.com (Postfix) with ESMTP; Thu, 9 Apr 2020 14:18:39 +0000 (GMT) Subject: Re: [PATCH v7 06/15] s390/vfio-ap: sysfs attribute to display the guest CRYCB To: Cornelia Huck Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, freude@linux.ibm.com, borntraeger@de.ibm.com, mjrosato@linux.ibm.com, pmorel@linux.ibm.com, pasic@linux.ibm.com, alex.williamson@redhat.com, kwankhede@nvidia.com, jjherne@linux.ibm.com, fiuczy@linux.ibm.com References: <20200407192015.19887-1-akrowiak@linux.ibm.com> <20200407192015.19887-7-akrowiak@linux.ibm.com> <20200408123344.1a9032e1.cohuck@redhat.com> <60c6bfb6-dd0a-75dc-1043-8dffe983220a@linux.ibm.com> <20200408184606.309d9cd9.cohuck@redhat.com> From: Tony Krowiak Message-ID: Date: Thu, 9 Apr 2020 10:18:38 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <20200408184606.309d9cd9.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.676 definitions=2020-04-09_04:2020-04-07,2020-04-09 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 adultscore=0 impostorscore=0 spamscore=0 priorityscore=1501 bulkscore=0 malwarescore=0 lowpriorityscore=0 mlxlogscore=999 mlxscore=0 clxscore=1015 suspectscore=3 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004090105 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/8/20 12:46 PM, Cornelia Huck wrote: > On Wed, 8 Apr 2020 12:38:49 -0400 > Tony Krowiak wrote: > >> On 4/8/20 6:33 AM, Cornelia Huck wrote: >>> On Tue, 7 Apr 2020 15:20:06 -0400 >>> Tony Krowiak 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 >>>> --- >>>> 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? > I was thinking of using e.g. 400 instead of 444 for the permissions. > > I'm not sure if the info about what subset of the queues the guest > actually uses is all that interesting (except for managing guests); but > if I see guest information being exposed, I get a little wary, so I > just stumbled over this. > > Maybe I'll come back to that once I have looked at the series in more > detail, but this might not be a problem at all. I created this patch primarily because I found it very helpful when testing. It saved me from logging on to the guest and executing lszcrypt to verify the AP configuration for the guest. I thought this might also add value for a system administrator responsible for KVM guests. It would not be a problem to remove this patch or change the permissions for the attribute. Let me know when you complete the series review. Thanks. > >>> >>>> + >>>> 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, >>>> }; >>>>