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Wed, 29 Jul 2026 15:29:40 +0000 (GMT) Received: from p-imbrenda.ehn-de.ibm.com (unknown [9.224.75.30]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 29 Jul 2026 15:29:40 +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 v5 11/13] KVM: s390: Fix ordering when adding to SCA Date: Wed, 29 Jul 2026 17:29:36 +0200 Message-ID: <20260729152938.782383-12-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260729152938.782383-1-imbrenda@linux.ibm.com> References: <20260729152938.782383-1-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-Spam-Info: AW1haW4tMjYwNzI5MDEyMyBTYWx0ZWRfX5C+jk7dyaCdm 2n+Lqe6sYsPmRpWoyh5d6V/aswFImhbRQb0MFvLEHi4Oethrdgz5k1oLTuieOv6pFVTGKW0iuX3 KegTU3w93x951PsrZpWNe5YWrF8FpPk= X-Proofpoint-GUID: iExcwQuTp6AgBSgCMjX7nRveE_s1iQoQ X-Proofpoint-ORIG-GUID: iExcwQuTp6AgBSgCMjX7nRveE_s1iQoQ X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzI5MDEyMyBTYWx0ZWRfXxuNDO0a9nEpR bv9cGz7BeCXrEsGtoezPbaogprSeLY8nuMjUkQlRBdl1plSeSONWZZlCoIFcUR/DoAhQiPYDFR8 KDUtyBgm3zod6ja4XN0KMzF1fmlNrPk4s4jrBPi0/liNydkdLCmO69irHE/sEnn+JFiO1UCXK1g DVGzbshs9Lgtn2lz+zW+flZn+RSa2YlGT+zsjavCPe6hfFtQhkNhJmwXEDA2RxUzuUX7OzbG51g Uc5WpRLkQPJ2Yo07hRlC5akJGNA0g6oJwV0Xt+eJgpnSnvhMe3VfQ3lG7xLJKr+fOR39AMuVvk3 JbdGv2AkGknfjJa+KP9+d+ciEQONbvVNcxpfcqE+yvJTKOiXoeKSkV0GHa5cWyldzJYxEExB0uL s5SbML66op129AYY2MA81tbThkjQs2Jwh6m/80OdHQmHUsNqbGc0iWKNtXxtUsOWfj2OIi1pBOH eobAc7Uh+EuVrDXvXyg== X-Authority-Analysis: v=2.4 cv=X5Vi7mTe c=1 sm=1 tr=0 ts=6a6a1c6b cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VnNF1IyMAAAA:8 a=DpaZzcUc-R7GdRs0254A:9 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=2026-07-29_06,2026-07-29_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 phishscore=0 priorityscore=1501 malwarescore=0 spamscore=0 suspectscore=0 bulkscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607290123 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 Reviewed-by: Steffen Eiden Reviewed-by: Janosch Frank --- 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 fbe9abf365df..cdda7a00a0ff 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