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 C929E38B133; Thu, 30 Jul 2026 16:27:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.158.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785428847; cv=none; b=D1ysM5Vsp2dNkE9qliEydHGwHtvT3+TL2DBwNxdDokgBDft15WES3IYHvKzPFifYjxAP//SXCus9SdS0BixCOcJ4xZWU5mvetIbAvLZ/1YQl3B0G58tvuNvPcGeIIvX0/zKqaKULUg2yKvOJBDj1HAW1VMuTsNsqaYc1nRZCqT4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785428847; c=relaxed/simple; bh=UX0J+8NWNoUeQjimlvrotXYZvH60p5wmUlP6qznpzy0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=shwCogwqWyCvH6wO5CDU2WwKgNOHl27AVqKdDCj4IwltgCAP2CjABYUpyH3XL0afZsKnq3BUN/OHbVGV0NzWMUxTYjpDQqMKkTJw/H38Q9pHVUgH9EEUhR6ygyedkMcYrz6aIBm5ZdiLvNs4kQrxq5NaupqF4iPK2TLtgn3pX3E= 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=tkvjYXJv; arc=none smtp.client-ip=148.163.158.5 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="tkvjYXJv" Received: from pps.filterd (m0356516.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 66UFm2gT3354184; Thu, 30 Jul 2026 16:27:23 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=SOL2ihsdwgztw7W/L NtakmRxjzYVmF7eWgw9blb865w=; b=tkvjYXJvL79/pytLeBUvWmgHfRTf/As1D /JKAuTWRIoyRvuoqAl9ySOW6e9imqzkv33c0gFn62fOkoO5XrMh+ZuelJHR2Y7a9 RxO/mWuSHFraBwQrdHMs8MK50YKH5Zf8Ee+MXfBd5qqJpw0316B5aXi1ju4I/SZn sftMdoj9qU1zIDtDhvsLmIFTaHgfYSME0AoLuqxplpbYllm3ZfwUwRuMX0HUE+ND bazGHIe1rnGQQB8zBykOT8/7bg95vllh1aoyn5/4s4EEDtL0A9C+gCNtnnVfz90a ueTSUjvrRufsRKlQegQRLF+NpPb95xf9lBxM56rOdhL6mDITGh5xw== Received: from ppma23.wdc07v.mail.ibm.com (5d.69.3da9.ip4.static.sl-reverse.com [169.61.105.93]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4fmuyjfvks-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 30 Jul 2026 16:27:22 +0000 (GMT) Received: from pps.filterd (ppma23.wdc07v.mail.ibm.com [127.0.0.1]) by ppma23.wdc07v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 66UGQJFU010787; Thu, 30 Jul 2026 16:27:22 GMT Received: from smtprelay04.fra02v.mail.ibm.com ([9.218.2.228]) by ppma23.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4fn8yhm1vk-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 30 Jul 2026 16:27:22 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (smtpav02.fra02v.mail.ibm.com [10.20.54.101]) by smtprelay04.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 66UGRGEJ20120272 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 30 Jul 2026 16:27:16 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id EEEDB2004B; Thu, 30 Jul 2026 16:27:15 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CAAFB20043; Thu, 30 Jul 2026 16:27:15 +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 16:27:15 +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 06/14] KVM: s390: Fix race in __do_essa() Date: Thu, 30 Jul 2026 18:27:06 +0200 Message-ID: <20260730162714.133327-7-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-Spam-Info: AW1haW4tMjYwNzMwMDEyMyBTYWx0ZWRfX9MGShhIdsCEn yXST98qnLaonpyYMiGK/W+MpdVE/SDkLLpP4hArOQR5XktjxrRkCwTAPaEDf/nVUZJKBy9WJXzA 3ZE7NNLixGG5TK8r9lZwRJ8gwh5BvlA= X-Proofpoint-GUID: 9hiolngRPalOXRT7bhYVKcFvuhG1dXts X-Proofpoint-ORIG-GUID: 9hiolngRPalOXRT7bhYVKcFvuhG1dXts X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzMwMDEyMyBTYWx0ZWRfX8a929fkyspFC OBQkqF7CXxtB29JE33bNazQLLUUqacVwMeRWjvO1AETS91KqlxO85V0c6QU4pDr9ooNhFgZMKjt 3sgrDPRnb/OYGzxuNljHrZ7dHV9ug27qKP5TYGbzuxEyJ+obxXDFTr428RonubTKBomTuK/QEb5 hj1dj2/U1w4cmCHTepiyGpPC+Sc3FpP0lLJnGm7rK0Z8lP+5M2m6y0Pgs1T2DDgqD0/E6vxo3Os QEXaOYBiGHzXeDF0B6qDIw/pHNLXgFjHcfY0h50jJuTkGGoETEBq9FUsDckLuG5/bwzpq0IKbgi EqA9+bLsb9yI1MXdjzLw7zb4wQylRqGhGCrN4Div5AXKrDxsSoI4SN1POCPKNB/4K4mVKv0w0db IFd3HHsoSxNZG4LlasDyH/PZwYwSJQ8Bve7B1OCwie/rQPPOeerrbEUIZsEwA2tlXdECS2gDOSk 5+/9yps9FJpxQmGfNBg== X-Authority-Analysis: v=2.4 cv=X5Vi7mTe c=1 sm=1 tr=0 ts=6a6b7b6a cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VnNF1IyMAAAA:8 a=vVGDtJNaOgRaVfleRDgA:9 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 clxscore=1015 impostorscore=0 lowpriorityscore=0 phishscore=0 priorityscore=1501 malwarescore=0 spamscore=0 suspectscore=0 bulkscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607300123 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_arch_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 | 20 ++++++++++---------- arch/s390/kvm/priv.c | 5 +++-- 2 files changed, 13 insertions(+), 12 deletions(-) diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index de3cb6111bd4..24c3bfcd5db2 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -1219,8 +1219,8 @@ static void kvm_s390_sync_request_broadcast(struct kvm *kvm, int req) /* * Must be called with kvm->srcu held to avoid races on memslots, and with - * kvm->slots_lock to avoid races with ourselves, kvm_s390_vm_stop_migration(), - * and kvm_s390_get_cmma_bits(). + * kvm->slots_arch_lock to avoid races with ourselves, + * kvm_s390_vm_stop_migration(), and kvm_s390_get_cmma_bits(). */ static int kvm_s390_vm_start_migration(struct kvm *kvm) { @@ -1265,7 +1265,7 @@ static int kvm_s390_vm_start_migration(struct kvm *kvm) } /* - * Must be called with kvm->slots_lock to avoid races with ourselves, + * Must be called with kvm->slots_arch_lock to avoid races with ourselves, * kvm_s390_vm_start_migration() and kvm_s390_get_cmma_bits(). */ static int kvm_s390_vm_stop_migration(struct kvm *kvm) @@ -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; } @@ -3001,9 +3002,8 @@ 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) @@ -3017,9 +3017,9 @@ 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