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Fri, 31 Jul 2026 13:01:50 +0000 (GMT) Received: from p-imbrenda.ibmuc.com (unknown [9.111.4.62]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 31 Jul 2026 13:01:50 +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 v7 12/14] KVM: s390: Fix ordering when adding to SCA Date: Fri, 31 Jul 2026 15:01:36 +0200 Message-ID: <20260731130138.173983-13-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260731130138.173983-1-imbrenda@linux.ibm.com> References: <20260731130138.173983-1-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: AW1haW4tMjYwNzMxMDA5NiBTYWx0ZWRfX3CyY+nnpGGNu Yg65Zy5O3buNR0ni2lET5YdheD96XiNk8PgkhMqyOzeCs/ilIPROYX1Uv3HWiefLkTp6Dy69DRR TNT2Zbcc+K1xpgx0VufC0hdhfpusKFI= X-Proofpoint-GUID: Xh89OLpgrZIBOYtzOz5gJ8DkgEibMMox X-Proofpoint-ORIG-GUID: Xh89OLpgrZIBOYtzOz5gJ8DkgEibMMox X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzMxMDA5NiBTYWx0ZWRfX2xiGA8EyeXz9 L+eixoMWOYbxVzk2F8fEV5TydjtQ/q6GOTyDCik/uhYujjabPuQipB+f0pE5M4kFBkeg9he5Zet rEfMTMFkpUS6Huy1Xw7OIbDY0I4EZu3Ay855yjexuhCQeWLXS+Ww3pikAwadCu3j5tIFZX0Fb1O adv28okDhZewvj+5BWlPB4hNH+uWh8RP34GFgxbQPTU2F3D90qn1GoITBnALMyNEJ+kBeZlpPKZ XWnp5Th9Zvs92jh1YYJoS17LhwgV09AMFPCG6KNcKUr//uGf87dnOvHYKwfJJ6pmRiwle3Zc0Q4 N9I6LPp/ykNiNWZNCaFMP8xwLyILfZhViQxGO5AA33bL8+jPxiqJmhjjl853pe10/bx8ncF75Gf 2qYibDFmoP9r1eI6v4Dm0BnLyr19NoPMJWMOzp1xb2dYuauBegr5X8wfXpU3QnIsj24CzuGuGqn Di736QksryFEh6Z0Adg== X-Authority-Analysis: v=2.4 cv=X5Vi7mTe c=1 sm=1 tr=0 ts=6a6c9cc7 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==: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=2026-07-31_04,2026-07-30_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-2607310096 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