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Mon, 3 Aug 2026 12:40:46 +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 v8 12/13] KVM: s390: Fix ordering when adding to SCA Date: Mon, 3 Aug 2026 14:40:39 +0200 Message-ID: <20260803124040.126471-13-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260803124040.126471-1-imbrenda@linux.ibm.com> References: <20260803124040.126471-1-imbrenda@linux.ibm.com> Precedence: bulk X-Mailing-List: kvm@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: AW1haW4tMjYwODAzMDExMCBTYWx0ZWRfXxHzVOFYr1kzz Hov6aWiR1YAS0vXp+JXMtVVQU36X1IlYI9vD6XraCim1SLQd/5K+t8xqNn3ANzyI50NSaCumhU8 t9VLF27p1k90jBQiWngQMcAcNZpzWXw= X-Authority-Analysis: v=2.4 cv=I7VVgtgg c=1 sm=1 tr=0 ts=6a708c56 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VnNF1IyMAAAA:8 a=DpaZzcUc-R7GdRs0254A:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODAzMDExMCBTYWx0ZWRfX2rbK8XZ+AOgs w1hTcNlJAaCWO1vl9fSv2D+kGupHaUZ2xECa4ogbcyswEWcmn9X2+3dDKee76FR64p3qiXlIf0z 9OVE/noc62JPjw9ifPZ+vcP7rBBBjEG7GSV9c5EMxpSeb3YZByJgv5DnUr96jsphkkRFayG6ZxC qy+SdMEA9Gr+8EC/CwOVgy2vnl57CuWvGEsZ1hZ2//ufsUokH7E5MrhuvGvwQk3wBY7UwxrS8w8 CxTr9rervC2/fXsYCmM5GPN3c1Yzk/Boetzrjh5raUsFQ3abPztXRbOOEI/WSdw/7MF+wKnzHVd 3EWiuYUU1bHyW2SrJNgk3YuRBr876TOmlF3chmIlfR7+ZCEx3sluSIqNH+w7jjtNZFywcX2eEBK fNiZxaeEi4Wx7cshP92oS391I7RVQG25bVMhUj3tsrXV1b/I2zW/epWP94EESSJxAY+J9hEZGnM a2ze8yigQ0Y7H1Mr/3A== X-Proofpoint-ORIG-GUID: 7rLfAkHWlYQUo97yIxm2-XveVALHTIsW X-Proofpoint-GUID: 7rLfAkHWlYQUo97yIxm2-XveVALHTIsW X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-03_03,2026-07-30_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 impostorscore=0 clxscore=1015 priorityscore=1501 suspectscore=0 malwarescore=0 adultscore=0 lowpriorityscore=0 phishscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608030110 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 9b8a35e7dc82..518a69c55e85 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -3485,8 +3485,8 @@ 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