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Thu, 28 May 2026 11:47:29 +0000 (GMT) Received: from p-imbrenda.aag-de.ibm.com (unknown [9.52.223.175]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 28 May 2026 11:47:29 +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 Subject: [PATCH v1 7/7] KVM: s390: Prevent memslots outside the ASCE range Date: Thu, 28 May 2026 13:47:27 +0200 Message-ID: <20260528114727.142178-8-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260528114727.142178-1-imbrenda@linux.ibm.com> References: <20260528114727.142178-1-imbrenda@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=QLJYgALL c=1 sm=1 tr=0 ts=6a182b58 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=luRVYIaq7LDw4LXNCHgA:9 X-Proofpoint-GUID: q3_HyjhyF85ocYk2gIX7fwULMAmJERZR X-Proofpoint-ORIG-GUID: q3_HyjhyF85ocYk2gIX7fwULMAmJERZR X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTI4MDExNyBTYWx0ZWRfXynznqF7zW8m5 PHCiX1QU2GYHhEvuFR6eR5gJYym9l696ZZIjiBf3p4lyAXBIbMwK3jFLRKtBLHHa+VYHTgsD222 QkO8y6P96qMXtkxq137fU756TaWtIv2suEw7vag31F5Y16KrhgXsNshDuSHfrVlZjQswIs7LR7h 2Zkhy+BU3NIXIclELpIhCoeaHH6p14hP1uG5/xBII8WanU3pPalbQEUpUQVv1hKYzqoQXogGZ3y NhUwksJCl0xtDtwuq8WVhvQ+S0YRQhk1NLn0dYzGZa0vu56JXjxRlMEFU7/jz+6skR074QyUzPx gWFBtP/mcbkae1tejy5dp8iIyDyyfMaUFSzTMWxGDVO7PLRURa6+nGJE7whGJWDYdyXa9d1Qb4V rTunCLW+nd1mHHJL3cv/QvFNG3lbW5pwCOZyWYxroBMK/GQEj+ZpQ8BzhTFXbNxNMW9xXhDmOvd 6jyOce4FhizCyfxZzPQ== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-05-28_03,2026-05-28_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 impostorscore=0 malwarescore=0 adultscore=0 lowpriorityscore=0 phishscore=0 clxscore=1015 priorityscore=1501 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605210000 definitions=main-2605280117 With KVM_S390_VM_MEM_LIMIT_SIZE, userspace can set the highest address allowed for the VM. Creating a memslot that lies over the maximum address does not make sense and is only a potential source of bugs. Prevent creation of memslots over the maximum address, and prevent the maximum address from being reduced below the end of existing memslots. Signed-off-by: Claudio Imbrenda --- arch/s390/kvm/kvm-s390.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index e09960c2e6ed..875f6e2a4a52 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -1015,8 +1015,26 @@ static int kvm_s390_set_mem_control(struct kvm *kvm, struct kvm_device_attr *att return -EINVAL; ret = -EBUSY; - if (!kvm->created_vcpus) - ret = gmap_set_limit(kvm->arch.gmap, gpa_to_gfn(new_limit)); + if (!kvm->created_vcpus) { + struct kvm_memslots *slots; + struct kvm_memory_slot *ms; + int bkt; + + ret = 0; + mutex_lock(&kvm->slots_arch_lock); + slots = kvm_memslots(kvm); + if (slots && !kvm_memslots_empty(slots)) { + kvm_for_each_memslot(ms, bkt, slots) { + if (gpa_to_gfn(new_limit) < ms->base_gfn + ms->npages) { + ret = -EBUSY; + break; + } + } + } + if (!ret) + ret = gmap_set_limit(kvm->arch.gmap, gpa_to_gfn(new_limit)); + mutex_unlock(&kvm->slots_arch_lock); + } VM_EVENT(kvm, 3, "SET: max guest address: %lu", new_limit); VM_EVENT(kvm, 3, "New guest asce: 0x%p", (void *)kvm->arch.gmap->asce.val); @@ -5672,6 +5690,8 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, return -EINVAL; if ((new->base_gfn + new->npages) * PAGE_SIZE > kvm->arch.mem_limit) return -EINVAL; + if (!asce_contains_gfn(kvm->arch.gmap->asce, new->base_gfn + new->npages - 1)) + return -EINVAL; } if (!kvm->arch.migration_mode) -- 2.54.0