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Thu, 30 Jul 2026 16:27:15 +0000 (GMT) Received: from p-imbrenda.ehn-de.ibm.com (unknown [9.224.75.30]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 30 Jul 2026 16:27:15 +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 v6 04/14] KVM: s390: ucontrol: Fix sca_clear_ext_call() Date: Thu, 30 Jul 2026 18:27:04 +0200 Message-ID: <20260730162714.133327-5-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730162714.133327-1-imbrenda@linux.ibm.com> References: <20260730162714.133327-1-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-ORIG-GUID: bVpXfntj3CJFsOY4VkNMIFDHRvN1_ooD X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzMwMDEyMyBTYWx0ZWRfX/IDrZ2IaUerp naNiiog3cxNX04MeLJxfLDxiqzJK/Id8BbFGxB+ziydlmICpgq0BnYfja0c8zDc27WMAtb5xl/s Cweq48W3/3mmhCTTtSMaganyZ0XRUQLhof5BC88gujwPOdsS23TPgDCGo/s1akqcSySeT6DaMtY XG2zCYsZsrB1rJU20WemkX7qXzxHDCsd/Rf/BCYuJ4ywUj6YFox220f/Nn3/mYQyu8J5dkGWO19 ovXBEr1PGZTFIZ+7+AbYK4ngQp66O2MJE+roCft6HjbXZKxGqvayKvlvDwMqaeKgPFSP/UnZehD 79dlrU7aKKmurjPolQ4zibeMBRdVCm69pOLzoOgI45hARX84ssA5ApTsGNbilPpAgrKYuqPMAJQ yB8L4H4msX+QKekpozg7Bu/qmdBzvdF/X+0QdSSh3V3OY7ObmCi90UbOk3Eo58Kgtn5z5yLPRfM Suqrm5fe6vgzt3ZPzYw== X-Proofpoint-Spam-Info: AW1haW4tMjYwNzMwMDEyMyBTYWx0ZWRfXwmK6cKrroqn3 JowMYCtiCD2eGqNBKjwfQnYs7JpbymceXmFPWbiHfJ8Ogf4XWD/aH2O6nN2N8DKX/69Cm0RQ+bV nrHC0l6emG3ewg1b5JCX2Ty34kDP/8M= X-Authority-Analysis: v=2.4 cv=AZeB2XXG c=1 sm=1 tr=0 ts=6a6b7b6f cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=EUfh2IAhO5dQcouLE0wA:9 X-Proofpoint-GUID: bVpXfntj3CJFsOY4VkNMIFDHRvN1_ooD X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-30_04,2026-07-30_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 priorityscore=1501 phishscore=0 adultscore=0 impostorscore=0 clxscore=1015 malwarescore=0 suspectscore=0 lowpriorityscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607300123 When cleaning up a UCONTROL VM, sca_clear_ext_call() will touch memory outside of the allocated ESCA block, and UCONTROL VMs don't even use ESCA. Fix by not touching ESCA for UCONTROL VMs, and fence the KVM_S390_INTERRUPT ioctl altogether. Opportunistically add checks in sca_ext_call_pending() and sca_inject_ext_call() to make sure UCONTROL VMs won't call those functions ever. Signed-off-by: Claudio Imbrenda Fixes: 7d43bafcff17 ("KVM: s390: Make provisions for ESCA utilization") --- arch/s390/kvm/interrupt.c | 19 ++++++++++++++----- arch/s390/kvm/kvm-s390.c | 3 +++ 2 files changed, 17 insertions(+), 5 deletions(-) diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index 2acdff130fa6..6013f28e3461 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -45,13 +45,16 @@ static struct kvm_s390_gib *gib; static int sca_ext_call_pending(struct kvm_vcpu *vcpu, int *src_id) { struct esca_block *sca = vcpu->kvm->arch.sca; - union esca_sigp_ctrl sigp_ctrl = sca->cpu[vcpu->vcpu_id].sigp_ctrl; + union esca_sigp_ctrl sigp_ctrl; if (!kvm_s390_test_cpuflags(vcpu, CPUSTAT_ECALL_PEND)) return 0; + if (KVM_BUG_ON(kvm_is_ucontrol(vcpu->kvm), vcpu->kvm)) + return -EINVAL; BUG_ON(!kvm_s390_use_sca_entries()); + sigp_ctrl = sca->cpu[vcpu->vcpu_id].sigp_ctrl; if (src_id) *src_id = sigp_ctrl.scn; @@ -60,13 +63,16 @@ static int sca_ext_call_pending(struct kvm_vcpu *vcpu, int *src_id) static int sca_inject_ext_call(struct kvm_vcpu *vcpu, int src_id) { - struct esca_block *sca = vcpu->kvm->arch.sca; - union esca_sigp_ctrl *sigp_ctrl = &sca->cpu[vcpu->vcpu_id].sigp_ctrl; union esca_sigp_ctrl old_val, new_val = {.scn = src_id, .c = 1}; + struct esca_block *sca = vcpu->kvm->arch.sca; + union esca_sigp_ctrl *sigp_ctrl; int expect, rc; BUG_ON(!kvm_s390_use_sca_entries()); + if (KVM_BUG_ON(kvm_is_ucontrol(vcpu->kvm), vcpu->kvm)) + return -EINVAL; + sigp_ctrl = &sca->cpu[vcpu->vcpu_id].sigp_ctrl; old_val = READ_ONCE(*sigp_ctrl); old_val.c = 0; @@ -84,10 +90,13 @@ static int sca_inject_ext_call(struct kvm_vcpu *vcpu, int src_id) static void sca_clear_ext_call(struct kvm_vcpu *vcpu) { struct esca_block *sca = vcpu->kvm->arch.sca; - union esca_sigp_ctrl *sigp_ctrl = &sca->cpu[vcpu->vcpu_id].sigp_ctrl; + union esca_sigp_ctrl *sigp_ctrl; - if (!kvm_s390_use_sca_entries() || !vcpu->arch.initialized) + if (!kvm_s390_use_sca_entries() || !vcpu->arch.initialized || kvm_is_ucontrol(vcpu->kvm)) return; + + /* Initialize after the above check, to prevent going out of bounds */ + sigp_ctrl = &sca->cpu[vcpu->vcpu_id].sigp_ctrl; kvm_s390_clear_cpuflags(vcpu, CPUSTAT_ECALL_PEND); WRITE_ONCE(sigp_ctrl->value, 0); diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 58cec3703c2d..19ce7ebb83c5 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -2934,6 +2934,9 @@ int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) case KVM_S390_INTERRUPT: { struct kvm_s390_interrupt s390int; + r = -EINVAL; + if (kvm_is_ucontrol(kvm)) + break; r = -EFAULT; if (copy_from_user(&s390int, argp, sizeof(s390int))) break; -- 2.55.0