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Mon, 27 Apr 2020 21:49:00 +0000 Received: from b01ledav002.gho.pok.ibm.com (b01ledav002.gho.pok.ibm.com [9.57.199.107]) by b01cxnp22036.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 03RLmxRE14942958 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 27 Apr 2020 21:48:59 GMT Received: from b01ledav002.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1C549124054; Mon, 27 Apr 2020 21:48:59 +0000 (GMT) Received: from b01ledav002.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 95A15124052; Mon, 27 Apr 2020 21:48:58 +0000 (GMT) Received: from cpe-172-100-175-116.stny.res.rr.com (unknown [9.85.200.21]) by b01ledav002.gho.pok.ibm.com (Postfix) with ESMTP; Mon, 27 Apr 2020 21:48:58 +0000 (GMT) Subject: Re: [PATCH v7 01/15] s390/vfio-ap: store queue struct in hash table for quick access To: Halil Pasic , Harald Freudenberger Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, borntraeger@de.ibm.com, cohuck@redhat.com, mjrosato@linux.ibm.com, pmorel@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> <20200407192015.19887-2-akrowiak@linux.ibm.com> <20200424055732.7663896d.pasic@linux.ibm.com> <20200427171739.76291a74.pasic@linux.ibm.com> From: Tony Krowiak Message-ID: <6ea12752-d23f-abe4-8d5f-3e7738984576@linux.ibm.com> Date: Mon, 27 Apr 2020 17:48:58 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200427171739.76291a74.pasic@linux.ibm.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=2020-04-27_16:2020-04-27,2020-04-27 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 adultscore=0 lowpriorityscore=0 priorityscore=1501 malwarescore=0 mlxlogscore=999 suspectscore=3 impostorscore=0 bulkscore=0 spamscore=0 mlxscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004270172 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/27/20 11:17 AM, Halil Pasic wrote: > On Mon, 27 Apr 2020 15:05:23 +0200 > Harald Freudenberger wrote: > >> On 24.04.20 05:57, Halil Pasic wrote: >>> On Tue, 7 Apr 2020 15:20:01 -0400 >>> Tony Krowiak wrote: >>> >>>> Rather than looping over potentially 65535 objects, let's store the >>>> structures for caching information about queue devices bound to the >>>> vfio_ap device driver in a hash table keyed by APQN. >>> @Harald: >>> Would it make sense to make the efficient lookup of an apqueue base >>> on its APQN core AP functionality instead of each driver figuring it out >>> on it's own? >>> >>> If I'm not wrong the zcrypt device/driver(s) must the problem of >>> looking up a queue based on its APQN as well. >>> >>> For instance struct ep11_cprb has a target_id filed >>> (arch/s390/include/uapi/asm/zcrypt.h). >>> >>> Regards, >>> Halil >> Hi Halil >> >> no, the zcrypt drivers don't have this problem. They build up their own device object which >> includes a pointer to the base ap device. > I'm a bit confused. Doesn't your code loop first trough the ap_card > objects to find the APID portion of the APQN, and then loop the queue > list of the matching card to find the right ap_queue object? Or did I > miss something? Isn't that what _zcrypt_send_ep11_cprb() does? Can you > point me to the code that avoids the lookup (by apqn) for zcrypt? The code you reference, _zcrypt_send_ep11_cprb(), does loop through each queue associated with each card, but it doesn't appear to be looking for a queue with a particular APQN. It appears to be looking for a queue meeting a specific set of conditions. At least that's my take after taking a very brief look at the code, so I'm not sure that applies here. > > > If you look at the new function of vfio_ap_get_queue(unsigned long apqn) > it basically about finding the queue based on the apqn, with the > difference that it is vfio specific. > > Regards, > Halil > >> However, this is not a big issue, as the ap_bus holds a list of ap_card objects and within each >> ap_card object there exists a list of ap_queues. > > >