From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12F62C43219 for ; Tue, 30 Apr 2019 14:10:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DF46020652 for ; Tue, 30 Apr 2019 14:10:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726819AbfD3OKI (ORCPT ); Tue, 30 Apr 2019 10:10:08 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:33354 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726758AbfD3OKI (ORCPT ); Tue, 30 Apr 2019 10:10:08 -0400 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x3UE3qWZ076192 for ; Tue, 30 Apr 2019 10:10:07 -0400 Received: from e06smtp01.uk.ibm.com (e06smtp01.uk.ibm.com [195.75.94.97]) by mx0a-001b2d01.pphosted.com with ESMTP id 2s6q3ctt1j-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 30 Apr 2019 10:10:06 -0400 Received: from localhost by e06smtp01.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 30 Apr 2019 15:10:04 +0100 Received: from b06cxnps4076.portsmouth.uk.ibm.com (9.149.109.198) by e06smtp01.uk.ibm.com (192.168.101.131) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 30 Apr 2019 15:10:01 +0100 Received: from b06wcsmtp001.portsmouth.uk.ibm.com (b06wcsmtp001.portsmouth.uk.ibm.com [9.149.105.160]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x3UE9xmd39780582 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 30 Apr 2019 14:09:59 GMT Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BEE96A405C; Tue, 30 Apr 2019 14:09:59 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 12383A4054; Tue, 30 Apr 2019 14:09:59 +0000 (GMT) Received: from [9.145.13.117] (unknown [9.145.13.117]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 30 Apr 2019 14:09:59 +0000 (GMT) Reply-To: pmorel@linux.ibm.com Subject: Re: [PATCH v7 3/4] s390: ap: implement PAPQ AQIC interception in kernel To: Halil Pasic Cc: borntraeger@de.ibm.com, alex.williamson@redhat.com, cohuck@redhat.com, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, frankja@linux.ibm.com, akrowiak@linux.ibm.com, david@redhat.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, freude@linux.ibm.com, mimu@linux.ibm.com References: <1556283688-556-1-git-send-email-pmorel@linux.ibm.com> <1556283688-556-4-git-send-email-pmorel@linux.ibm.com> <20190430152605.3bb21f31.pasic@linux.ibm.com> From: Pierre Morel Date: Tue, 30 Apr 2019 16:09:58 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190430152605.3bb21f31.pasic@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19043014-4275-0000-0000-0000032FF55F X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19043014-4276-0000-0000-0000383F4E5C Message-Id: <622a9ab0-579d-17f4-6fa1-74d73da13b19@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-04-30_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=863 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904300089 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 30/04/2019 15:26, Halil Pasic wrote: > On Fri, 26 Apr 2019 15:01:27 +0200 > Pierre Morel wrote: > >> +/** >> + * vfio_ap_clrirq: Disable Interruption for a APQN >> + * >> + * @dev: the device associated with the ap_queue >> + * @q: the vfio_ap_queue holding AQIC parameters >> + * >> + * Issue the host side PQAP/AQIC >> + * On success: unpin the NIB saved in *q and unregister from GIB >> + * interface >> + * >> + * Return the ap_queue_status returned by the ap_aqic() >> + */ >> +static struct ap_queue_status vfio_ap_clrirq(struct vfio_ap_queue *q) >> +{ >> + struct ap_qirq_ctrl aqic_gisa = {}; >> + struct ap_queue_status status; >> + int checks = 10; >> + >> + status = ap_aqic(q->apqn, aqic_gisa, NULL); >> + if (!status.response_code) { >> + while (status.irq_enabled && checks--) { >> + msleep(20); > > Hm, that seems like a lot of time to me. And I suppose we are holding the > kvm lock: e.g. no other instruction can be interpreted by kvm in the > meantime. > >> + status = ap_tapq(q->apqn, NULL); >> + } >> + if (checks >= 0) >> + vfio_ap_free_irq_data(q); > > Actually we don't have to wait for the async part to do it's magic > (indicated by the status.irq_enabled --> !status.irq_enabled transition) > in the instruction handler. We have to wait so we can unpin the NIB but > that could be done async (e.g. workqueue). > > BTW do you have any measurements here? How many msleep(20) do we > experience for one clear on average? No idea but it is probably linked to the queue state and usage history. I can use a lower sleep time and increment the retry count. > > If linux is not using clear (you told so offline, and I also remember > something similar), we can probably get away with something like this, > and do it properly (from performance standpoint) later. In the Linux AP code it is only used once, in the explicit ap_queue_enable_interruption() function. Yes, thanks, I will keep it as is, may be just play with msleep()time and retry count. Regards, Pierre > > Regards, > Halil > >> + else >> + WARN_ONCE("%s: failed disabling IRQ", __func__); >> + } >> + >> + return status; >> +} > -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany