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Mon, 27 Jul 2026 15:03:04 +0000 (GMT) Received: from p-imbrenda.ibmuc.com (unknown [9.111.1.146]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 27 Jul 2026 15:03:04 +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 v3 09/10] KVM: s390: Fix ordering when adding to SCA Date: Mon, 27 Jul 2026 17:02:53 +0200 Message-ID: <20260727150254.236021-10-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260727150254.236021-1-imbrenda@linux.ibm.com> References: <20260727150254.236021-1-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-GUID: tpzrEJBn7uZqdGAPFvDi0NVGbcg0_iQY X-Proofpoint-ORIG-GUID: tpzrEJBn7uZqdGAPFvDi0NVGbcg0_iQY X-Proofpoint-Spam-Info: AW1haW4tMjYwNzI3MDE0MCBTYWx0ZWRfX6tRGQynodyzD 8Gtd5I5ffxXG61JFSqlf/qVN8litZmSsfs3YplTKvQ1Nnkm+kkjxWWdSft4DCQ7A4tn9DqtfK22 JKTaQdUKAFu4NtwgQ+SVlzrxSDqDBbs= X-Authority-Analysis: v=2.4 cv=dYuwG3Xe c=1 sm=1 tr=0 ts=6a677330 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=ENZFvArl5UWzb2BATEMA:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzI3MDE0MCBTYWx0ZWRfX3UGZx7Z4AtRQ QKI75cr5V/ogg917vIU0Zg+fyFLvH4wn2Osq1LYLNpZtR6MiyRV23fIGlWnXYzvt0IRUB+c4dME VnEDrXxLO73K6Z4ZePHDWmGkR36h4QIy6WRI37VYcnmEAhfoQGHRET6JArtctAMyEuX0SyzcRus 9yooksAuPeC/D3VPDmXxQkU4KQxu2lMTcehCBjowMrmRNRh7eyfkDZaQaNqQnzxIKfUFdFe0TX3 VYExENVnzy9/4P8QrA70UZT3eCtqRMgU7cmicqRmcJohTFFbczeBVlAp1f2BTx3TiapJAH6ni1q aQbzVzEmjKwWOEV+mEPOXxw9DYMzb7TyPtl7ejNmHjF+6/i/lPQievMvDV5ns/rmkmc2WnYFiPA 9aSWQyZl7/tz55FaFMk6FKbxVbJ/cLnZhbtLx9t4IGBzmh0YkKIzMV+pmugQ7hu6WTJj6ZaGi+A 4Bh92HduLikZVOoh6Fw== 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=2026-07-27_04,2026-07-24_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 impostorscore=0 clxscore=1015 phishscore=0 malwarescore=0 spamscore=0 lowpriorityscore=0 bulkscore=0 suspectscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607270140 When adding a new vCPU to the SCA area, the validity bit in the MCN was set before the pointer to the state description, potentially allowing for a race. Fix by setting the pointer before setting the bit. Fixes: 14542a0a54c5 ("KVM: S390: Remove sca_lock") Signed-off-by: Claudio Imbrenda --- arch/s390/kvm/kvm-s390.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 8afb88a2b73d..85dcd40b2fa1 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -3481,8 +3481,8 @@ static void sca_add_vcpu(struct kvm_vcpu *vcpu) if (!kvm_s390_use_sca_entries()) return; + WRITE_ONCE(sca->cpu[vcpu->vcpu_id].sda, virt_to_phys(vcpu->arch.sie_block)); set_bit_inv(vcpu->vcpu_id, (unsigned long *)sca->mcn); - sca->cpu[vcpu->vcpu_id].sda = virt_to_phys(vcpu->arch.sie_block); } static int sca_can_add_vcpu(struct kvm *kvm, unsigned int id) -- 2.55.0