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Mon, 3 Aug 2026 16:09:27 +0000 (GMT) From: Claudio Imbrenda To: pbonzini@redhat.com Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, frankja@linux.ibm.com, borntraeger@de.ibm.com Subject: [GIT PULL v1 22/23] KVM: s390: Fix ordering when adding to SCA Date: Mon, 3 Aug 2026 18:09:23 +0200 Message-ID: <20260803160924.236807-23-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260803160924.236807-1-imbrenda@linux.ibm.com> References: <20260803160924.236807-1-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-GUID: CbLGreLhmnohvOSUdu4p6CoTGXQyxgdA X-Proofpoint-ORIG-GUID: CbLGreLhmnohvOSUdu4p6CoTGXQyxgdA X-Proofpoint-Spam-Info: AW1haW4tMjYwODAzMDE0MSBTYWx0ZWRfXxt8Op/KpwwLo YaA28KF75CigUUMnReJHGJ+/bU0rr5FoU9tA5rbGKv4NgyxfltEZPb+KWhuXopLBknR5RAltCmn jCC4t5kTtRsfJaIY1tdq/+7+CZ6wx5U= X-Authority-Analysis: v=2.4 cv=K8cS2SWI c=1 sm=1 tr=0 ts=6a70bd3e cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=Mk4uVEwlW67fdkdk104A:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODAzMDE0MSBTYWx0ZWRfX00BPcaITr0WH mkfZp4Vlj5/IV7Pj4rzndvztNTxSBM97UOZuk6J05HarH/HgNiSO4TqFScOhZHg8k98rP4OjyuP NSEX1xmsVMskoT01su6bAACs7wUc3X1oKNXMjIFVEVqEKklJIRtqbfXmGxDnZJSDlbIyjDDKvPi s9qSrjGltD+uWa4LPYEGKM5KzUWc5TsHfd3G/+meQwN71ohkD9kumjuQ8z5YssNPt1ob2/NIni5 FR2I0S2Bf9+vHhkFBO0m/PIJIHLZAX5WOZ71tjZ9UT+weYuybViW4bpb29WIk88A27buBrTNkSx ypvMLBV5rYFuj1YxD6UcNV6SkKuPPTAXxVJmfaqxl8onCduzocA753FjLLdFe1HUOgi+4HbRj1z 7AsAhd1Ho/CzJ336OfRl/zKqGtT3aaoyQnXrUbjQP4sh2CbfVcyLSAObwC8l06WIWqvZFbS3Zkj IHLK8XMBq0VMmed3VEA== 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_03,2026-08-03_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 spamscore=0 impostorscore=0 bulkscore=0 priorityscore=1501 lowpriorityscore=0 malwarescore=0 phishscore=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-2608030141 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") Reviewed-by: Steffen Eiden Reviewed-by: Janosch Frank Signed-off-by: Claudio Imbrenda Message-ID: <20260803124040.126471-13-imbrenda@linux.ibm.com> --- 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