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Fri, 28 Aug 2026 11:54:40 +0000 (GMT) Received: from p-imbrenda.ehn-de.ibm.com (unknown [9.224.75.30]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 28 Aug 2026 11:54:40 +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 v3 8/8] KVM: s390: Fix race in _destroy_pages_crste() Date: Fri, 28 Aug 2026 13:54:39 +0200 Message-ID: <20260828115439.145885-9-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260828115439.145885-1-imbrenda@linux.ibm.com> References: <20260828115439.145885-1-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: 1LwTlKzOYUsZDSBUZ-eYbqdLSiewIe-u X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODI4MDA5OSBTYWx0ZWRfX/kH8CVAeW+Gr DmuOME8M05Js3nsDq4Ke59h1bk63h3oUDujecTsBBRMB9NEx4cV3ovT/8EDgjiuzGomT62VUHbZ /P+LJaIZhJISNGafooBOVNIW1FvwNrnaXp3aDAclOq9glMUhIfKn87r1LDzH12bImOZzog5oPSx z+JSIQvfb6buWRMhNbL3kBbC17NlLQvAWBCDc8VePuEorob6ru5XXiHS7/YAUePNqG9AWHaea1v xO1M7JCpBBPzzAFASvX6hYhg9JnUaCU38q2rIezpQ1KtW67+0aBNGJNHmDHxxn9J/+pm0wpucGg sRU/FPINcw9PID9Num1TiTDGBfcuPbcxPuFn5lS6YJhKC41b+JfuBNd+PQwYBdPHw9Zvxr1Pi7N hKuQ9OOfI6kUDY/8M22PWtayPwCBcl1ysmYfgJTQfTe9tOtNryhrxEWCB9xufpEsAxfp31SkTc2 i68zBrE7rPBF3FQDmMw== X-Authority-Analysis: v=2.4 cv=Y/nIdBeN c=1 sm=1 tr=0 ts=6a917708 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=N6WJw_kgbt6RfBQfb4YA:9 X-Proofpoint-Spam-Info: AW1haW4tMjYwODI4MDA5OSBTYWx0ZWRfX9o6gHJF/YqrK Gd4Psj5GJTLnpAA78067VNr0mDgN2bXmBy/Mrw6M4nHimO6QbEtfzd62vCe1QWhLdt6S6Uz9Lu0 U5GYMophmphcuHKfUmirWENVIDaVVds= X-Proofpoint-ORIG-GUID: 1LwTlKzOYUsZDSBUZ-eYbqdLSiewIe-u 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=2026-08-28_03,2026-08-27_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 impostorscore=0 priorityscore=1501 adultscore=0 bulkscore=0 suspectscore=0 malwarescore=0 clxscore=1015 lowpriorityscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608280099 Use READ_ONCE() in _destroy_pages_crste() to read the crste, avoid dereferencing the pointer multiple times. Fixes: a2c17f9270cc ("KVM: s390: New gmap code") Signed-off-by: Claudio Imbrenda --- arch/s390/kvm/gmap/gmap.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/s390/kvm/gmap/gmap.c b/arch/s390/kvm/gmap/gmap.c index 4968330e9553..3f3fa864cc36 100644 --- a/arch/s390/kvm/gmap/gmap.c +++ b/arch/s390/kvm/gmap/gmap.c @@ -994,11 +994,13 @@ static long _destroy_pages_pte(union pte *ptep, gfn_t gfn, gfn_t next, struct da static long _destroy_pages_crste(union crste *crstep, gfn_t gfn, gfn_t next, struct dat_walk *walk) { phys_addr_t origin, cur, end; + union crste crste; - if (!crstep->h.fc || !crstep->s.fc1.pr) + crste = READ_ONCE(*crstep); + if (!crste.h.fc || !crste.s.fc1.pr) return 0; - origin = crste_origin_large(*crstep); + origin = crste_origin_large(crste); cur = ((max(gfn, walk->start) - gfn) << PAGE_SHIFT) + origin; end = ((min(next, walk->end) - gfn) << PAGE_SHIFT) + origin; for ( ; cur < end; cur += PAGE_SIZE) -- 2.55.0