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Thu, 2 Jul 2026 15:24:12 +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 v1 5/8] KVM: s390: Fix race in __do_essa() Date: Thu, 2 Jul 2026 17:24:03 +0200 Message-ID: <20260702152406.204782-6-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260702152406.204782-1-imbrenda@linux.ibm.com> References: <20260702152406.204782-1-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-Details-Enc: AW1haW4tMjYwNzAyMDE2MCBTYWx0ZWRfX5uPS6l/8somG wO/qkx4pFjgeislYq7+GoF3yuq367laATHoHUyTVkjYZbmVpIeiZ95bg04OGX83fie6mlz27BrG CJW02FeH+5Jxg/AH/U5mMbBpKyfYyYDsN6VgdflW4tGcOb3kIpYFh40/66Heo9Z3mMMpcWAiiyZ LtnXvS4e98Rhv5m3I0PrF5SiyCO3TQ6/NduPlLxmK7wZx3gYV1G5RT+BhLHcsaFIXQdh3Leu8TO 9ogYAHvnfKeAbjstor9qYS9pNR1FicPNSGFi+gRIGsRXSW9s1JpFSd/BWhbrT/Vb3xaqx2A6xmb 0fhd6NEoUOKOpJ+4Qw+hqJB7hKqfU8HoZ9qWnwmnN3D0D2n+HE4gUPu7nar5ZlgGWZ26T/x+2b1 BzfGM3wMQGD7UmgAVIQvC6uLdx1VIiMxyMLO2ABIZDLbTcLt6pb/eOhU1K/WxMSvCSsVG2086LV ljee2uSEYbgyL/0RrQA== X-Proofpoint-Spam-Info: AW1haW4tMjYwNzAyMDE2MCBTYWx0ZWRfX/pMc4WjH4vZI 8aFN8NL9Fa8LiryVBbkxXQAkI9CO4cPzj6Ecw8WuReKbg5nZqnIrMZq5RFVziDao3hngEjREEqe H7a6KZske29ZY+hsEi0FVa7kngJzMoU= X-Proofpoint-GUID: of2fOAy8MyWEmUlLKZcuXIPudkMQa1H8 X-Proofpoint-ORIG-GUID: of2fOAy8MyWEmUlLKZcuXIPudkMQa1H8 X-Authority-Analysis: v=2.4 cv=WZ88rUhX c=1 sm=1 tr=0 ts=6a4682a4 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=SEIsQiIyKFAhYTenhQEA:9 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-07-02_02,2026-06-26_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 adultscore=0 phishscore=0 clxscore=1015 bulkscore=0 impostorscore=0 priorityscore=1501 lowpriorityscore=0 suspectscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607020160 An unlikely race between __do_essa() and kvm_s390_vm_start_migration(), kvm_s390_vm_stop_migration(), or dat_get_cmma() was possible. Fix by locking kvm->slots_lock. Since this is not a hot path, the overhead of an additional mutex is negligible. Fixes: e38c884df921 ("KVM: s390: Switch to new gmap") Signed-off-by: Claudio Imbrenda --- arch/s390/kvm/priv.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c index ad0ddc433a73..b0f3a47b1829 100644 --- a/arch/s390/kvm/priv.c +++ b/arch/s390/kvm/priv.c @@ -1260,8 +1260,9 @@ static int handle_essa(struct kvm_vcpu *vcpu) /* Retry the ESSA instruction */ kvm_s390_retry_instr(vcpu); } else { - scoped_guard(read_lock, &vcpu->kvm->mmu_lock) - i = __do_essa(vcpu, orc); + scoped_guard(mutex, &vcpu->kvm->slots_lock) + scoped_guard(read_lock, &vcpu->kvm->mmu_lock) + i = __do_essa(vcpu, orc); if (i < 0) return i; /* Account for the possible extra cbrl entry */ -- 2.55.0