From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (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 1188E39CD1E; Tue, 28 Jul 2026 17:07:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.156.1 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785258443; cv=none; b=ePN3x//GoWYHSpgOZ/nNK7jkLbKih/CKIJwgtCkDKdKmk2R+0N2FwuL9hrAEPIRW7Vradz1BgBIEcbtF0av+mbzuY6iQSgIvHGNZJAihZEQcVXKjrBF20IOWRK1drsutDAOEBjkqOPjgb2Rd6EigNTMXYxyU6jg3nxMqw4CcFA8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785258443; c=relaxed/simple; bh=hIvI11nOSu7atb9Lqq+9FR261JXTxF9nepvusj6EJbs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hoiyROhFdIi48upaph0jVAfGI2aJf+66kZBTZDOSH26DlHQPQdhG0LdlmSTClNBdarN9i7tx7NckKfJkl44DHUT+ZA8Piv44WEn4xQwHcjdj1WsXEOtaHZ4g3dFck8OpMKqhU7zEyGubnlXF9tCdgXRzIBEYIxZ/ylDnZPGx9qs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=pMY3AQnp; arc=none smtp.client-ip=148.163.156.1 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="pMY3AQnp" Received: from pps.filterd (m0360083.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 66SElfJU1459264; Tue, 28 Jul 2026 17:07:19 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:date:from:in-reply-to:message-id :mime-version:references:subject:to; s=pp1; bh=8Zg8feFLdlKGUV3+6 KUEhfIs/ihaEDKP127pDSK810Q=; b=pMY3AQnpGUq6qvXBt7HBQq7jC1NubwvwV b+vxnIUhygpgh22zURX/xFUKWwBa84LjRRRlX2KH5PYUqZ88jdVoxhUdj7pEcstb dfHJbqRdxby2vwr4ni+IfwoUfaJvLcvOjhB4Pu575xAQ6UshGtsPaTQQGvEaWHsy UNVKQookXCRKcmNPbBQA8qx1UrnPwFSRuRl0TLYVQoz6S0Jgxc/OCgn8CSZPpPzA 57t7HgUGGaq46Kk9XXsh6/HjsqUbFy1ueyXokITBTFiyQi5y5tTYODqY4lBFW1lg IPguOk/9g/wwXCq6eZmbdzfvabX33IZWORrlikRzlIUhIqBiRl7TA== Received: from ppma12.dal12v.mail.ibm.com (dc.9e.1632.ip4.static.sl-reverse.com [50.22.158.220]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4fmuw7egxp-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 28 Jul 2026 17:07:18 +0000 (GMT) Received: from pps.filterd (ppma12.dal12v.mail.ibm.com [127.0.0.1]) by ppma12.dal12v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 66SGuHfY031377; Tue, 28 Jul 2026 17:07:18 GMT Received: from smtprelay05.fra02v.mail.ibm.com ([9.218.2.225]) by ppma12.dal12v.mail.ibm.com (PPS) with ESMTPS id 4fn7fqb4gj-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 28 Jul 2026 17:07:18 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (smtpav06.fra02v.mail.ibm.com [10.20.54.105]) by smtprelay05.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 66SH7CDp47645058 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 28 Jul 2026 17:07:12 GMT Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 313802004B; Tue, 28 Jul 2026 17:07:12 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5EB9720040; Tue, 28 Jul 2026 17:07:11 +0000 (GMT) Received: from p-imbrenda.ibmuc.com (unknown [9.111.73.241]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 28 Jul 2026 17:07:11 +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 v4 03/13] KVM: s390: Fix race in __do_essa() Date: Tue, 28 Jul 2026 19:06:58 +0200 Message-ID: <20260728170708.294400-4-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260728170708.294400-1-imbrenda@linux.ibm.com> References: <20260728170708.294400-1-imbrenda@linux.ibm.com> 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: END7G7NzEIk-tSGit0pN3edRIaz2T__2 X-Proofpoint-ORIG-GUID: END7G7NzEIk-tSGit0pN3edRIaz2T__2 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzI4MDE0OSBTYWx0ZWRfX0wjdv2jGeeW5 KNbXlHY59boJe2HpkM4/9i/UBKdLeZxAJNNtI1S1wkcE5B8bW55aLBZP95sA3p3hyHsLJ3i6QZm VqWDVAFgVbCVVgSrMd+oem0+btzItFIojN5T0kiN1jLkZKlYYmNF3NSfHeqGs22Z7wrdi1aBFn5 uXLyTq2u0atpRLu7k3SPiPhVBC35GQS8F0huV+pCduu8OG5qr4dx62c380NLQ1+GckGzF9ciOP0 l/xfYficLtMBmk0t94zIplt0ZlOQMYCkds7/z1LdEV3TtlsTlwD67kjX1ea9gH+OqDeWy+UdOBO BSohHliZJj+GoXdsD6DrwaHxd+vdKDW6TzFQFeXLI+CPV8g/CaT0m7n9zYKqRYSQSNgA2innZje 1F7pzcEiyWju7+vgoa0dH0Y+BYTZCE9cN+7MSEOW84Qi+YOHuGHuOqXQK5aw6K4TbvMGr6lOhTF cWAWPMkdL55rXfJLmEQ== X-Authority-Analysis: v=2.4 cv=SKFykuvH c=1 sm=1 tr=0 ts=6a68e1c7 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=Ucc7pKXXu02aIaGplMgA:9 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzI4MDE0OSBTYWx0ZWRfX65OY78UM/3i0 7j7jbsFGNmfg4MBN1up0SgjTAZNIZMgKRMneSQ+RjyHF5sXXQWMzfPE+wYgsIQsCRYD82S8aa0w SVNPy3IHQd6z7jM17RkP4wkej9lSy30= 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=2026-07-28_04,2026-07-28_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 clxscore=1015 adultscore=0 lowpriorityscore=0 bulkscore=0 impostorscore=0 phishscore=0 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607280149 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/kvm-s390.c | 14 +++++++------- arch/s390/kvm/priv.c | 5 +++-- 2 files changed, 10 insertions(+), 9 deletions(-) diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 7bc6426f5f4d..100911ee793a 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -1300,7 +1300,9 @@ static int kvm_s390_vm_set_migration(struct kvm *kvm, { int res = -ENXIO; - mutex_lock(&kvm->slots_lock); + guard(srcu)(&kvm->srcu); + guard(mutex)(&kvm->slots_arch_lock); + switch (attr->attr) { case KVM_S390_VM_MIGRATION_START: res = kvm_s390_vm_start_migration(kvm); @@ -1311,7 +1313,6 @@ static int kvm_s390_vm_set_migration(struct kvm *kvm, default: break; } - mutex_unlock(&kvm->slots_lock); return res; } @@ -2998,9 +2999,8 @@ int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) r = -EFAULT; if (copy_from_user(&args, argp, sizeof(args))) break; - mutex_lock(&kvm->slots_lock); - r = kvm_s390_get_cmma_bits(kvm, &args); - mutex_unlock(&kvm->slots_lock); + scoped_guard(mutex, &kvm->slots_arch_lock) + r = kvm_s390_get_cmma_bits(kvm, &args); if (!r) { r = copy_to_user(argp, &args, sizeof(args)); if (r) @@ -3014,9 +3014,9 @@ int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) r = -EFAULT; if (copy_from_user(&args, argp, sizeof(args))) break; - mutex_lock(&kvm->slots_lock); + mutex_lock(&kvm->slots_arch_lock); r = kvm_s390_set_cmma_bits(kvm, &args); - mutex_unlock(&kvm->slots_lock); + mutex_unlock(&kvm->slots_arch_lock); break; } case KVM_S390_PV_COMMAND: { diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c index ea5a99537346..b1ba24c346ef 100644 --- a/arch/s390/kvm/priv.c +++ b/arch/s390/kvm/priv.c @@ -1261,8 +1261,9 @@ 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_arch_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