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=unavailable 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 38A45C43219 for ; Thu, 2 May 2019 07:57:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0D2822085A for ; Thu, 2 May 2019 07:57:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726321AbfEBH5x (ORCPT ); Thu, 2 May 2019 03:57:53 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:33644 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725905AbfEBH5w (ORCPT ); Thu, 2 May 2019 03:57:52 -0400 Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x427vlJl117593 for ; Thu, 2 May 2019 03:57:51 -0400 Received: from e06smtp01.uk.ibm.com (e06smtp01.uk.ibm.com [195.75.94.97]) by mx0a-001b2d01.pphosted.com with ESMTP id 2s7uh2jpsq-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 02 May 2019 03:57:50 -0400 Received: from localhost by e06smtp01.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 2 May 2019 08:57:33 +0100 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x427vW5a52428928 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 2 May 2019 07:57:32 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id F0574A4040; Thu, 2 May 2019 07:57:31 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 56C2FA4051; Thu, 2 May 2019 07:57:31 +0000 (GMT) Received: from [9.145.190.191] (unknown [9.145.190.191]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 2 May 2019 07:57:31 +0000 (GMT) Reply-To: pmorel@linux.ibm.com Subject: Re: [PATCH v7 3/4] s390: ap: implement PAPQ AQIC interception in kernel From: Pierre Morel 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> <622a9ab0-579d-17f4-6fa1-74d73da13b19@linux.ibm.com> Date: Thu, 2 May 2019 09:57:31 +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: <622a9ab0-579d-17f4-6fa1-74d73da13b19@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: 19050207-4275-0000-0000-0000033087E4 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19050207-4276-0000-0000-0000383FE5F4 Message-Id: <42185132-dfc4-c997-3d69-31e43d25e525@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-05-02_03:,, 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=658 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905020061 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 30/04/2019 16:09, Pierre Morel wrote: > 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. My answer is not clear: ap_aqic() is used only once, during the bus probe, in the all code to enable interrupt and is never used to disable interrupt. Interrupt disabling is only done by using ap_zapq() or ap_rapq() which can not be intercepted. > > 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