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Wed, 20 May 2026 15:17:11 +0000 (GMT) Received: from p-imbrenda.aag-de.ibm.com (unknown [9.52.223.175]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 20 May 2026 15:17:11 +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 v1 1/4] KVM: s390: Implement KVM_PRE_FAULT_MEMORY Date: Wed, 20 May 2026 17:17:07 +0200 Message-ID: <20260520151710.231788-2-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260520151710.231788-1-imbrenda@linux.ibm.com> References: <20260520151710.231788-1-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: AW1haW4tMjYwNTIwMDE0NyBTYWx0ZWRfXxqw4N+BSWqdJ uxGpFdcDGYRKsQxOsdSYBbw/HKT3JZ8vkYR9EQU7LJoU2FS0UIkVyZxX9eGYyTQFlg721xeiLAN ftSduQxUo6dXkxHTLkTsGxR5xeFryyeNvJqXwJjGRAWO4boFiKQ8NckjPRoucZCCRO3jFLxJQPy F+aQvSIc7gGU40rwhShywY42LQgrnVQtnVlPkqfFUgmU0/F5QoCbxozUZU4C3oZo1KKGiwmHajz Io3Z/Bp27bhhgxOynyIZnN7XvUgGSdzO7kKtwqK/VXmOi2GWA+oRaxi7MYSgppzCAEMowkIYSKM 2UfpHU3G1912rQkIKvhCgRCrSXiYL3cvC4WKKceSmEjnDq1Npmvn2yAlIWhYWyLuO89kqm9AT4e VnpMJ9CG2iZlLo52BRYkNirBdS+ji2P9hXzxoWHwkRBGFtruGc/HhAMxLeKe6fX8gT2bOLStGZ+ 8Rl/8Vg5P9Nzknv8Q0g== X-Authority-Analysis: v=2.4 cv=Np/htcdJ c=1 sm=1 tr=0 ts=6a0dd07e cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==: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: oc7y2PLgWopLHQvrrJKdabQJLD7JIMsQ X-Proofpoint-GUID: AioF1MJ-EJ_BCgB7WqIPcKrdCWT6kYwG 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=2026-05-20_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=1011 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-2605200147 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 | 41 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 42 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..dd220f3d6e94 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 +5737,46 @@ 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 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 + * ends outside of a memslot, only the part inside the memslot is faulted in. + * 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 other errors happen while faulting-in the page (considered a + * bug, 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) +{ + unsigned long i; + int rc; + + if (kvm_is_ucontrol(vcpu->kvm)) + return -EINVAL; + + for (i = 0; i < range->size; i += PAGE_SIZE) { + rc = kvm_s390_faultin_gfn_simple(vcpu, NULL, gpa_to_gfn(range->gpa + i), false); + if (rc == PGM_ADDRESSING) + return i ? i : -ENOENT; + if (rc == -EINTR) + return i ? i : -EINTR; + if (rc) + return -EIO; + } + return i; +} + /** * kvm_test_age_gfn() - test young * @kvm: the kvm instance -- 2.54.0