From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 78ABD1CAB8; Wed, 20 Dec 2023 07:34:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="FiCRL98J" Received: from pps.filterd (m0353722.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 3BK6DlFT014863; Wed, 20 Dec 2023 07:34:07 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding; s=pp1; bh=RAyJIrFEdM1E1zR7KhwABJaajTgwiicXjDICi085Y84=; b=FiCRL98JoC7a2OZ0bAdtI+GD/wlvTKj9ODhuMTw9Yqch2qplfCMkv3TumdJZOkUIrAgC 8ilM6ZdM6/5ZSbvFZlAKUYk6mHEWUaHxfL0ojO/w0CwB5ufr/01bxgOUl7wSl99IR+u1 Y21QKtLvjLSHR1z4mBFz/aVmT6ny8OaYMrQT9xrI3x1iMUyXSPw/izRLuF2Q9vLR122q pL1o1PXp5k6igzvykiN6KfsH3rmvul0eCRhy5mY9t/VzB9kTGH4/JEDRwtuqyMxbh8Ix 1yjMhvlvrUutOOICeAHxMfYhfN0qxt5JAqpqjqzSTPrj0eTlthXWKhBVkQ42v8hzbcuo nQ== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3v3ttd9nme-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 20 Dec 2023 07:34:06 +0000 Received: from m0353722.ppops.net (m0353722.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 3BK7Rw1x010535; Wed, 20 Dec 2023 07:34:06 GMT Received: from ppma22.wdc07v.mail.ibm.com (5c.69.3da9.ip4.static.sl-reverse.com [169.61.105.92]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3v3ttd9nku-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 20 Dec 2023 07:34:06 +0000 Received: from pps.filterd (ppma22.wdc07v.mail.ibm.com [127.0.0.1]) by ppma22.wdc07v.mail.ibm.com (8.17.1.19/8.17.1.19) with ESMTP id 3BK7FKEP004792; Wed, 20 Dec 2023 07:34:05 GMT Received: from smtprelay04.fra02v.mail.ibm.com ([9.218.2.228]) by ppma22.wdc07v.mail.ibm.com (PPS) with ESMTPS id 3v1pkyw6rc-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 20 Dec 2023 07:34:05 +0000 Received: from smtpav05.fra02v.mail.ibm.com (smtpav05.fra02v.mail.ibm.com [10.20.54.104]) by smtprelay04.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 3BK7Y0I841353710 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 20 Dec 2023 07:34:02 GMT Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D4DB020043; Wed, 20 Dec 2023 07:34:00 +0000 (GMT) Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C2F1120040; Wed, 20 Dec 2023 07:34:00 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.152.85.9]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTPS; Wed, 20 Dec 2023 07:34:00 +0000 (GMT) Received: by tuxmaker.boeblingen.de.ibm.com (Postfix, from userid 25651) id 86F2BE03E5; Wed, 20 Dec 2023 08:34:00 +0100 (CET) From: Christian Borntraeger To: KVM Cc: Christian Borntraeger , Janosch Frank , David Hildenbrand , linux-s390 , Thomas Huth , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Alexander Gordeev Subject: [PATCH] KVM: s390: vsie: fix race during shadow creation Date: Wed, 20 Dec 2023 08:34:00 +0100 Message-ID: <20231220073400.257813-1-borntraeger@linux.ibm.com> X-Mailer: git-send-email 2.41.0 Precedence: bulk X-Mailing-List: linux-s390@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: gkYja45xLKjYBKrSzgtB9y3puMeIS2gf X-Proofpoint-ORIG-GUID: OIoBNjeb5EMuqXDxGrTY2Udan2_R4W0B X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.997,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-12-20_02,2023-12-14_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=868 phishscore=0 lowpriorityscore=0 impostorscore=0 adultscore=0 bulkscore=0 malwarescore=0 suspectscore=0 mlxscore=0 priorityscore=1501 clxscore=1011 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2312200050 Right now it is possible to see gmap->private being zero in kvm_s390_vsie_gmap_notifier resulting in a crash. This is due to the fact that we add gmap->private == kvm after creation: static int acquire_gmap_shadow(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page) { [...] gmap = gmap_shadow(vcpu->arch.gmap, asce, edat); if (IS_ERR(gmap)) return PTR_ERR(gmap); gmap->private = vcpu->kvm; Instead of tracking kvm in the shadow gmap, simply use the parent one. Cc: David Hildenbrand Signed-off-by: Christian Borntraeger --- arch/s390/kvm/vsie.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c index 8207a892bbe2..6b06d8ec41b5 100644 --- a/arch/s390/kvm/vsie.c +++ b/arch/s390/kvm/vsie.c @@ -579,14 +579,17 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page) void kvm_s390_vsie_gmap_notifier(struct gmap *gmap, unsigned long start, unsigned long end) { - struct kvm *kvm = gmap->private; struct vsie_page *cur; unsigned long prefix; struct page *page; + struct kvm *kvm; int i; if (!gmap_is_shadow(gmap)) return; + + kvm = gmap->parent->private; + /* * Only new shadow blocks are added to the list during runtime, * therefore we can safely reference them all the time. @@ -1220,7 +1223,6 @@ static int acquire_gmap_shadow(struct kvm_vcpu *vcpu, gmap = gmap_shadow(vcpu->arch.gmap, asce, edat); if (IS_ERR(gmap)) return PTR_ERR(gmap); - gmap->private = vcpu->kvm; vcpu->kvm->stat.gmap_shadow_create++; WRITE_ONCE(vsie_page->gmap, gmap); return 0; -- 2.41.0