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Tue, 28 Jun 2022 08:59:04 +0000 (GMT) Received: from [9.171.42.158] (unknown [9.171.42.158]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 28 Jun 2022 08:59:03 +0000 (GMT) Message-ID: <207a01aa-d92c-4a17-7b2f-aed59da4ce09@linux.ibm.com> Date: Tue, 28 Jun 2022 10:59:03 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Subject: Re: [PATCH v10 2/3] KVM: s390: guest support for topology function Content-Language: en-US To: Pierre Morel , kvm@vger.kernel.org Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, cohuck@redhat.com, david@redhat.com, thuth@redhat.com, imbrenda@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, wintera@linux.ibm.com, seiden@linux.ibm.com, nrb@linux.ibm.com References: <20220620125437.37122-1-pmorel@linux.ibm.com> <20220620125437.37122-3-pmorel@linux.ibm.com> From: Janis Schoetterl-Glausch In-Reply-To: <20220620125437.37122-3-pmorel@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 860zfobV2qBY6qSuhgetDywiU7s0RGhA X-Proofpoint-ORIG-GUID: Zm5aoLnQUkF1x_3ZV6vOGLl-qLAwG7PX X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.883,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-06-27_09,2022-06-24_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 clxscore=1015 priorityscore=1501 phishscore=0 lowpriorityscore=0 impostorscore=0 mlxlogscore=999 malwarescore=0 adultscore=0 mlxscore=0 spamscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2204290000 definitions=main-2206280035 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 6/20/22 14:54, Pierre Morel wrote: > We report a topology change to the guest for any CPU hotplug. > > The reporting to the guest is done using the Multiprocessor > Topology-Change-Report (MTCR) bit of the utility entry in the guest's > SCA which will be cleared during the interpretation of PTF. > > On every vCPU creation we set the MCTR bit to let the guest know the > next time he uses the PTF with command 2 instruction that the > topology changed and that he should use the STSI(15.1.x) instruction > to get the topology details. > > STSI(15.1.x) gives information on the CPU configuration topology. > Let's accept the interception of STSI with the function code 15 and > let the userland part of the hypervisor handle it when userland > support the CPU Topology facility. > > Signed-off-by: Pierre Morel > --- > arch/s390/include/asm/kvm_host.h | 11 ++++++++--- > arch/s390/kvm/kvm-s390.c | 27 ++++++++++++++++++++++++++- > arch/s390/kvm/priv.c | 15 +++++++++++---- > arch/s390/kvm/vsie.c | 3 +++ > 4 files changed, 48 insertions(+), 8 deletions(-) > [...] > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index 8fcb56141689..95b96019ca8e 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -1691,6 +1691,25 @@ static int kvm_s390_get_cpu_model(struct kvm *kvm, struct kvm_device_attr *attr) > return ret; > } > > +/** > + * kvm_s390_sca_set_mtcr I wonder if there is a better name, kvm_s390_report_topology_change maybe? > + * @kvm: guest KVM description > + * > + * Is only relevant if the topology facility is present, > + * the caller should check KVM facility 11 > + * > + * Updates the Multiprocessor Topology-Change-Report to signal > + * the guest with a topology change. > + */ > +static void kvm_s390_sca_set_mtcr(struct kvm *kvm) > +{ Do we need a sca_lock read_section here? If we don't why not? Did not see one up the stack, but I might have overlooked something. > + struct bsca_block *sca = kvm->arch.sca; /* SCA version doesn't matter */ > + > + ipte_lock(kvm); > + sca->utility |= SCA_UTILITY_MTCR; > + ipte_unlock(kvm); > +} > + [...]