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Thu, 21 May 2026 13:05:34 +0000 (GMT) Received: from p-imbrenda.aag-de.ibm.com (unknown [9.52.223.175]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 21 May 2026 13:05:34 +0000 (GMT) From: Claudio Imbrenda To: linux-kernel@vger.kernel.org Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, david@kernel.org, seiden@linux.ibm.com, nrb@linux.ibm.com, schlameuss@linux.ibm.com, gra@linux.ibm.com, pbonzini@redhat.com, seanjc@google.com, yan.y.zhao@intel.com, isaku.yamahata@intel.com Subject: [PATCH v2 2/5] KVM: s390: Implement KVM_PRE_FAULT_MEMORY Date: Thu, 21 May 2026 15:05:30 +0200 Message-ID: <20260521130533.156491-3-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260521130533.156491-1-imbrenda@linux.ibm.com> References: <20260521130533.156491-1-imbrenda@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIxMDEyNiBTYWx0ZWRfX8xplmGRRirD1 AzWnbZM6My3fIy2rAASivu8TaU2QLIWJInezz3IggwrhvdbOab1XjXjHX7pkGpTyxqLnuKIZLLH Dy+vZmg2DuIKo49PSq5KQVkVDT7TwGT+TpG/k3nMlY0wvcuURhtwtcdJMF/XnW8Bt8bU9ku4SRq DlpHt+kmdYRbBfse9SYlV8lfsfFK8oGGSXQtoBWcew2n8uAHfpkrwkAt0Cg+GsMpSM6pjGjq6YM JTqT3oEqDcrUz5tQMKWH9roF4wZcp6MuGHhK4voPdSuT14WTk2/K9324aulYxsAlLP7nwJ2Iy12 BQ3CBNuhXrxFNrLG0fBDyHL419lg9oPBUxtIy9W1RpA450ZiCFijA78A8Kd89Eh+UFi6myscg9R vWHwdUmxBnOFkp4kFcBeVy3PKHNI8/P7FK266vK7q/IyjZnNuQQeuiMSzZ0Ykhx6kcIe94RuUbY 4Hz65l4WalULufdt6vA== X-Authority-Analysis: v=2.4 cv=Np/htcdJ c=1 sm=1 tr=0 ts=6a0f0325 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=xyOPYXbJwbhnVPa3_EUA:9 X-Proofpoint-ORIG-GUID: oEqrLTKZM9VhQfsEs8maf72ksjhW1V9U X-Proofpoint-GUID: N-1SR1pmaxgXzbxWIlUE-DBHyHjPDDEK X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-21_02,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 spamscore=0 clxscore=1015 priorityscore=1501 impostorscore=0 lowpriorityscore=0 suspectscore=0 adultscore=0 phishscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605210126 Implement and enable the KVM_PRE_FAULT_MEMORY ioctl for s390. Faulted-in pages will be marked as accessed, unlike x86, otherwise they will trigger a minor fault when accessed. Avoiding such faults is one of the points of KVM_PRE_FAULT_MEMORY. Signed-off-by: Claudio Imbrenda --- arch/s390/kvm/Kconfig | 1 + arch/s390/kvm/kvm-s390.c | 45 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 46 insertions(+) diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig index 5b835bc6a194..8d3ee17a1bcb 100644 --- a/arch/s390/kvm/Kconfig +++ b/arch/s390/kvm/Kconfig @@ -30,6 +30,7 @@ config KVM select KVM_VFIO select VIRT_XFER_TO_GUEST_WORK select KVM_MMU_LOCKLESS_AGING + select KVM_GENERIC_PRE_FAULT_MEMORY help Support hosting paravirtualized guest machines using the SIE virtualization capability on the mainframe. This should work diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index e09960c2e6ed..f6521f16532a 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -630,6 +630,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_S390_USER_OPEREXEC: case KVM_CAP_S390_KEYOP: case KVM_CAP_S390_VSIE_ESAMODE: + case KVM_CAP_PRE_FAULT_MEMORY: r = 1; break; case KVM_CAP_SET_GUEST_DEBUG2: @@ -5736,6 +5737,50 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, return; } +/** + * kvm_arch_vcpu_pre_fault_memory() -- pre-fault and link gmap dat tables + * @vcpu: the vcpu that shall appear to have generated the fault-in. + * @range: the range that needs to be faulted in. + * + * The first page of the given range is faulted in and the corresponding gmap + * page tables are created, as if the given vCPU had performed a read + * operation. + * If the range starts outside any memslots, an error is returned. An error is + * also returned for UCONTROL VMs, which should instead use the + * KVM_S390_VCPU_FAULT ioctl. + * + * Return: + * * %-ENOENT if the range lies outside of a memslot. + * * %-EINVAL in case of invalid state (for example if the VM is UCONTROL). + * * %-EIO if errors happen while faulting-in the page (will trigger a warning + * in the caller). + * * other error codes < 0 in case of other errors. + * * otherwise a number > 0 of bytes that have been faulted in successfully. + */ +long kvm_arch_vcpu_pre_fault_memory(struct kvm_vcpu *vcpu, struct kvm_pre_fault_memory *range) +{ + struct guest_fault f = { .gfn = gpa_to_gfn(range->gpa), }; + gpa_t end; + int rc; + + if (kvm_is_ucontrol(vcpu->kvm)) + return -EINVAL; + + rc = kvm_s390_faultin_gfn(vcpu, NULL, &f); + if (rc == PGM_ADDRESSING) + return -ENOENT; + if (rc > 0) + return -EIO; + if (rc < 0) + return rc; + + if (f.ptep) + return PAGE_SIZE; + + end = ALIGN(range->gpa + PAGE_SIZE, f.crste_region3 ? _REGION3_SIZE : HPAGE_SIZE); + return min(range->size, end - range->gpa); +} + /** * kvm_test_age_gfn() - test young * @kvm: the kvm instance -- 2.54.0