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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 12 Feb 2020 12:44:55 -0000 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 01CCisdb58654900 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 12 Feb 2020 12:44:54 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2EDF24C04A; Wed, 12 Feb 2020 12:44:54 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C57364C044; Wed, 12 Feb 2020 12:44:53 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.152.224.71]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 12 Feb 2020 12:44:53 +0000 (GMT) Subject: Re: [PATCH v2 RFC] KVM: s390/interrupt: do not pin adapter interrupt pages To: Cornelia Huck Cc: david@redhat.com, Ulrich.Weigand@de.ibm.com, aarcange@redhat.com, akpm@linux-foundation.org, frankja@linux.vnet.ibm.com, gor@linux.ibm.com, imbrenda@linux.ibm.com, kvm@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, mimu@linux.ibm.com, thuth@redhat.com References: <567B980B-BDA5-4EF3-A96E-1542D11F2BD4@redhat.com> <20200211092341.3965-1-borntraeger@de.ibm.com> <20200212133908.6c6c9072.cohuck@redhat.com> From: Christian Borntraeger Autocrypt: addr=borntraeger@de.ibm.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <20200212133908.6c6c9072.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 20021212-0016-0000-0000-000002E6223A X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 20021212-0017-0000-0000-000033491D81 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.572 definitions=2020-02-12_07:2020-02-11,2020-02-12 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 clxscore=1015 mlxscore=0 impostorscore=0 bulkscore=0 suspectscore=0 malwarescore=0 mlxlogscore=869 priorityscore=1501 phishscore=0 adultscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002120101 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 12.02.20 13:39, Cornelia Huck wrote: [...] >> + */ >> + return 0; > > Given that this function now always returns 0, we basically get a > completely useless roundtrip into the kernel when userspace is trying > to setup the mappings. > > Can we define a new IO_ADAPTER_MAPPING_NOT_NEEDED or so capability that > userspace can check? Nack. This is one system call per initial indicator ccw. This is so seldom and cheap that I do not see a point in optimizing this. > This change in behaviour probably wants a change in the documentation > as well. Yep. [...] >> @@ -2951,12 +2900,15 @@ int kvm_set_routing_entry(struct kvm *kvm, >> const struct kvm_irq_routing_entry *ue) >> { >> int ret; >> + u64 uaddr; >> >> switch (ue->type) { >> case KVM_IRQ_ROUTING_S390_ADAPTER: >> e->set = set_adapter_int; >> - e->adapter.summary_addr = ue->u.adapter.summary_addr; >> - e->adapter.ind_addr = ue->u.adapter.ind_addr; >> + uaddr = gmap_translate(kvm->arch.gmap, ue->u.adapter.summary_addr); > > Can gmap_translate() return -EFAULT here? The code above only seems to > check for 0... do we want to return an error here? Yes. > >> + e->adapter.summary_addr = uaddr; >> + uaddr = gmap_translate(kvm->arch.gmap, ue->u.adapter.ind_addr); >> + e->adapter.ind_addr = uaddr; >> e->adapter.summary_offset = ue->u.adapter.summary_offset; >> e->adapter.ind_offset = ue->u.adapter.ind_offset; >> e->adapter.adapter_id = ue->u.adapter.adapter_id; >