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Thu, 30 Jul 2026 16:27:16 +0000 (GMT) Received: from p-imbrenda.ehn-de.ibm.com (unknown [9.224.75.30]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 30 Jul 2026 16:27:16 +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 v6 11/14] KVM: s390: Fix ordering when adding to SCA Date: Thu, 30 Jul 2026 18:27:11 +0200 Message-ID: <20260730162714.133327-12-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730162714.133327-1-imbrenda@linux.ibm.com> References: <20260730162714.133327-1-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-ORIG-GUID: r5aI1u3D3BQX-OIsPhSB2lJzYrAAxFUo X-Proofpoint-Spam-Info: AW1haW4tMjYwNzMwMDEyMyBTYWx0ZWRfX8DMPFp144Gfg GBAkxyWNGIEbh42S/3FrsZR4+lMF3ikh6aM2oVhi/H9c1Gj8qVFeBen53NMTTVnLg4iUdX+Bg0g rQVzdX44P5oWpzw8X0pd+WDHWLEsmqw= X-Authority-Analysis: v=2.4 cv=E/z9Y6dl c=1 sm=1 tr=0 ts=6a6b7b6b cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=DpaZzcUc-R7GdRs0254A:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzMwMDEyMyBTYWx0ZWRfX2JnSSCo8ftvc qEGZCv+5PgR8VgqUuB/XJYViqsIqtBff0tFRIQkWefw62goF4D/xCM14ETqD0fCcir/bwOlaG15 9P+khmGhB4Q6eo7809MmrKxbLepiiTUlDGPIUuaxBQ4kqz1BBGxAejpiX8SHHSE/vJVaevsBVYW gGS+HxBc076I+XKZNEvYk1HlNjb0X/nBca13yPPKxDRCSK4tLf31+HpH6Xde0jfXV4dKqSAdybf Ce+xrq+1dUoEiz67e69DEYPngOtASh42jJJpAECyYyIPfuDmpFovVmPLoVBZC6hUU2GFJULDsSk axhspQpdQ6nqKcmFWhXhLQ8AyUm1MI1kE+306Gu2TwLs1uvEOOKQGr067OPd+lH3U6PBjE5V3/Z FCfLH9XCvBrVjTeJEHodD65MpEP2wiHeeP6Y2/dPT3MHXnPUfSOjzNPaK1cMR02LQqOzDRVDxXz z2MdRp8kAxsG0EIym1Q== X-Proofpoint-GUID: r5aI1u3D3BQX-OIsPhSB2lJzYrAAxFUo 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=2026-07-30_04,2026-07-30_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 priorityscore=1501 spamscore=0 clxscore=1015 phishscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 impostorscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607300123 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 7395d7863670..ba600c948887 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -3484,8 +3484,8 @@ 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