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 02239C43381 for ; Thu, 28 Feb 2019 13:16:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BCF162084D for ; Thu, 28 Feb 2019 13:16:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732156AbfB1NQU (ORCPT ); Thu, 28 Feb 2019 08:16:20 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:50946 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726271AbfB1NQT (ORCPT ); Thu, 28 Feb 2019 08:16:19 -0500 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 x1SD1S3X127013 for ; Thu, 28 Feb 2019 08:16:18 -0500 Received: from e06smtp03.uk.ibm.com (e06smtp03.uk.ibm.com [195.75.94.99]) by mx0a-001b2d01.pphosted.com with ESMTP id 2qxfhktnmc-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 28 Feb 2019 08:16:18 -0500 Received: from localhost by e06smtp03.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, 28 Feb 2019 13:16:12 -0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x1SDGAFW49676492 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 28 Feb 2019 13:16:10 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CB43BA405B; Thu, 28 Feb 2019 13:16:10 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id F3009A4057; Thu, 28 Feb 2019 13:16:09 +0000 (GMT) Received: from [9.152.224.140] (unknown [9.152.224.140]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 28 Feb 2019 13:16:09 +0000 (GMT) Reply-To: pmorel@linux.ibm.com Subject: Re: [PATCH v4 1/7] s390: ap: kvm: add PQAP interception for AQIC To: Cornelia Huck , Christian Borntraeger Cc: Tony Krowiak , alex.williamson@redhat.com, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, frankja@linux.ibm.com, pasic@linux.ibm.com, david@redhat.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, freude@linux.ibm.com, mimu@linux.ibm.com References: <1550849400-27152-1-git-send-email-pmorel@linux.ibm.com> <1550849400-27152-2-git-send-email-pmorel@linux.ibm.com> <9f1d9241-39b9-adbc-d0e9-cb702e609cbc@linux.ibm.com> <4dc59125-7f96-cba8-651b-382ed8f8bff8@linux.ibm.com> <8526f468-9a4d-68d2-3868-0dad5ce16f46@linux.ibm.com> <6058a017-6404-af3c-62ef-2452214ac97c@de.ibm.com> <2391adc2-6611-034c-61c5-feb46e2a751b@de.ibm.com> <20190228122251.75b31f62.cohuck@redhat.com> From: Pierre Morel Date: Thu, 28 Feb 2019 14:16:09 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190228122251.75b31f62.cohuck@redhat.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: 19022813-0012-0000-0000-000002FB4CE5 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19022813-0013-0000-0000-00002132F914 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-02-28_06:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1902280091 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 28/02/2019 12:22, Cornelia Huck wrote: > On Thu, 28 Feb 2019 12:03:38 +0100 > Christian Borntraeger wrote: > >> On 28.02.2019 10:42, Christian Borntraeger wrote: >> [...] >>>> Okay, let's go back to the genesis of this discussion; namely, my >>>> suggestion about moving the fc == 0x03 check into the hook code. If >>>> the vfio_ap module is not loaded, there will be no hook code. In that >>>> case, the check for the hook will fail and ultimately response code >>>> 0x01 will be set in the status word (which may not be the right thing >>>> to do?). You have not stated a single good reason for keeping this >>>> check, but I'm done with this silly argument. It certainly doesn't >>>> hurt anything. >>> >>> The instruction handler must handle the basic checks for the >>> instruction itself as outlined above. >>> >>> Do we want to allow QEMU to fully emulate everything (the ECA_APIE case being off)? >>> The we should pass along everything to QEMU, but this is already done with the >>> ECA_APIE check, correct? >>> >>> Do we agree that when we are beyond the ECA_APIE check, that we do not emulate >>> in QEMU and we have enabled the AP instructions interpretion? >>> If yes then this has some implication: >>> >>> 1. ECA is on and we should only get PQAP interception for specific FC (namely 3). >>> 2. What we certainly should check is the facility bit of the guest (65) and reject fc==3 >>> right away with a specification exception. I do not want the hook to mess with >>> the kvm cpu model. @Pierre would be good to actually check test_kvm_facility(vcpu->kvm, 65)) >>> 3. What shall we do when fc == 0x3? We can certainly do the check here OR in the >>> hook. As long as we have only fc==3 this does not matter. >>> >>> Correct? >> >> Thinking more about that, I think we should inject a specification exception for all >> unknown FCc != 0x3. That would also qualify for keeping it in the instruction handler. >> > > So, to summarize, the function should do: > - Is userspace supposed to emulate everything (!ECA_APIE)? Return > -EOPNOTSUPP to hand control to it. > - We are now interpreting the instruction in KVM. Do common checks > (PSTATE etc.) and inject exceptions, if needed. > - Now look at the fc; if there's a handler for it, call that; if not > (case does not attempt to call a specific handler, or no handler > registered), inject a specification exception. (Do we want pre-checks > like for facility 65 here, or in the handler?) > > That response code 0x01 thingy probably needs to go into the specific > handler function, if anywhere (don't know the semantics, sorry). What do you mean with specific handler function? If you mean a switch around the FC with static function's call, I agree, if you mean a jump into a hook I do not agree. > > Question: Will the handlers for the individual fcs need to generate > different exceptions on their own? I.e., do they need to do injections > themselves, or should the calling function possibly inject an exception > on error? There are some specificities. > > (Are there more possible fcs than 0x3 and whatever the other > subfunction was?) > Yes, at least 5 different FC are implemented in the Linux kernel today AFAIK. Regards, Pierre -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany