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 56EE33CF02D; Mon, 6 Jul 2026 08:53:10 +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=1783327995; cv=none; b=GLcUm8ckT/xKbmh+yFIfCKgSqmgMdR00FFld7jB4+n//cyIGDHCmVoaFa3HYxWozTn7nLus585JIlbHyBztPdjebGGodMn+o+W5ieYfZiq0i3uw0NmpvFZwFb1nMVedpLEQqVW0Z/a4ANMGruNO51m5F4HJQ3ih3/K6areE+6Vs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783327995; c=relaxed/simple; bh=llvN3IZFcUshVTAczuCJUjfOKA8YD9Z811nBogXAWp0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=M0p/Cu0T/GsxBX0aMKTkUsOx5Bf32kSj7I0gZ2L/J9dAPqRyM2lQiXelej9Ji9Uar2WrdlgO5fiNuUrIe989T+EyO08zUEL6M9ykQT60cJN9e3vrja0kBkMhcFrI4Ne3xkMvwUpcNoIKVGkd790GN66AAfQTt0KlNB+krr24iFk= 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=rcF93HKP; 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="rcF93HKP" 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 665MJ01l2305858; Mon, 6 Jul 2026 08:52:39 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=gmIW2Lo8Ag1p9dPld 1JaBPWJ+Hy0kuL3TR8h9zOY+PI=; b=rcF93HKP2CIoa5yt6qTSAURM91wjHB9Ow KdwxNj0wu0jnPCWT8jmH1+OFF2719Aw98WXyYl0EEDU+2UUnHtCyZGgGqd9LZZl8 dFyzuqJ7/ZedM4EZqeP7NAtS6R7fy5IOQrgrxYlPb59990IMpggSTxBFIw7Ms/pw 9AGY9DfskHYt2FnASUTmxB5DoRFalcVqhJ8kAbsblJn/FzopfR+cHSO3adBQV/5T nTNgDBwDhctp3kLIEjAnth43HFRC8rAzgDlVdURcjRZUagdcSPJk5v108VqqP4Me l86+L9fo7YfTLs6yR37tKoF47+sOvXaLLri/+8UrdbdQ1xD/+YSWg== Received: from ppma21.wdc07v.mail.ibm.com (5b.69.3da9.ip4.static.sl-reverse.com [169.61.105.91]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4f6sp3gk7b-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 06 Jul 2026 08:52:38 +0000 (GMT) Received: from pps.filterd (ppma21.wdc07v.mail.ibm.com [127.0.0.1]) by ppma21.wdc07v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 6668nfcd013189; Mon, 6 Jul 2026 08:52:37 GMT Received: from smtprelay03.fra02v.mail.ibm.com ([9.218.2.224]) by ppma21.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4f7dgjvtw3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 06 Jul 2026 08:52:37 +0000 (GMT) Received: from smtpav05.fra02v.mail.ibm.com (smtpav05.fra02v.mail.ibm.com [10.20.54.104]) by smtprelay03.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 6668qUhu51315136 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 6 Jul 2026 08:52:30 GMT Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 52AF020043; Mon, 6 Jul 2026 08:52:30 +0000 (GMT) Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E077F2004D; Mon, 6 Jul 2026 08:52:29 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 6 Jul 2026 08:52:29 +0000 (GMT) From: Steffen Eiden To: kvm@vger.kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Cc: Alexander Gordeev , Andreas Grapentin , Arnd Bergmann , Catalin Marinas , Christian Borntraeger , Claudio Imbrenda , David Hildenbrand , Friedrich Welter , Gautam Gala , Hariharan Mari , Heiko Carstens , Hendrik Brueckner , Ilya Leoshkevich , Janosch Frank , Joey Gouly , Marc Zyngier , Nico Boehr , Nina Schoetterl-Glausch , Oliver Upton , Paolo Bonzini , Suzuki K Poulose , Sven Schnelle , Ulrich Weigand , Vasily Gorbik , Will Deacon , Zenghui Yu Subject: [PATCH v4 01/27] VFIO: take reference to the KVM module Date: Mon, 6 Jul 2026 10:52:01 +0200 Message-ID: <20260706085229.979525-2-seiden@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260706085229.979525-1-seiden@linux.ibm.com> References: <20260706085229.979525-1-seiden@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-Authority-Analysis: v=2.4 cv=KsJ9H2WN c=1 sm=1 tr=0 ts=6a4b6cd6 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=20KFwNOVAAAA:8 a=VnNF1IyMAAAA:8 a=r1p2_3pzAAAA:8 a=d-V1UPfWWZlnQKifVG0A:9 a=r_pkcD-q9-ctt7trBg_g:22 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzA2MDA4OCBTYWx0ZWRfX9b+V/vQxM3ug yZq/dYqEcW54DFpO9LkAyQOjqHr9C5fPPLgpQsU8KgZ1tJNe4RN6kko310Iwn5Dk0NibMrfckZq +s96xpGeUM8zOvko4OGvThXozGsGJxM= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzA2MDA4OCBTYWx0ZWRfXxDxYJSNBcaMT H3AcgJisD7N2ZV1ETChlmZ5hRva8e7oViLYuTEZVKs5Ym5FX7DJucP3aM1nOFS7y4Rl6J3uRoCF vg91b73CcOpP1OHKppBsnOUXdh3plkQ6JbGebUskgnPVf1uSVCGKo6/z39ANNz+DIW/jmJFd/8N s191Xoda0ijk73e4AoyclR3aqRmSXW00PKbGSQnyLzsvA8J/tzDiMlDWoq8fSZCy2X4KSYLIkKc rMjbJp4QIBYwC7kmWgYcgN3ZXdBh+9JNNs3gQRIrQHNB7BIWMuCDxYDp8qgsKD/jc6zrz6aZmrf yotojyc+wG+NGmJRQbfjEATVAi3f9JxCkrtVChQoL4wTHHA0THrUXCy14E/iArO3ygb5Q242wyS wjsGBiW4F2y5sCUyXHk7+jlI4IEjiDlYC9F8lvqL4kEku3mXIhero2tMeLHSGgu70MRBwKIEbPQ JgV6RUtgBbr25j1Ouxw== X-Proofpoint-ORIG-GUID: GKcqpM7IKKFfKLjVx_hpnSB4EZgBbzJa X-Proofpoint-GUID: GKcqpM7IKKFfKLjVx_hpnSB4EZgBbzJa 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=2026-07-05_02,2026-07-03_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 malwarescore=0 spamscore=0 adultscore=0 clxscore=1015 suspectscore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607060088 From: Paolo Bonzini VFIO is implicitly taking a reference to the KVM module between vfio_device_get_kvm_safe and vfio_device_put_kvm, thanks to symbol_get and symbol_put. In preparation for removing symbol_get and symbol_put themselves from VFIO, actually store a pointer to the KVM module and use module_get()/module_put() to keep KVM alive. Signed-off-by: Paolo Bonzini Reviewed-by: Steffen Eiden Acked-by: Alex Williamson --- drivers/vfio/device_cdev.c | 2 +- drivers/vfio/group.c | 5 +++-- drivers/vfio/vfio.h | 15 ++++++++++----- drivers/vfio/vfio_main.c | 38 ++++++++++++++++++++++++-------------- include/linux/vfio.h | 3 ++- virt/kvm/vfio.c | 4 ++-- 6 files changed, 42 insertions(+), 25 deletions(-) diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c index 54abf312cf04..a729be99d06c 100644 --- a/drivers/vfio/device_cdev.c +++ b/drivers/vfio/device_cdev.c @@ -56,7 +56,7 @@ int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep) static void vfio_df_get_kvm_safe(struct vfio_device_file *df) { spin_lock(&df->kvm_ref_lock); - vfio_device_get_kvm_safe(df->device, df->kvm); + vfio_device_get_kvm_safe(df->device, df->kvm, df->kvm_module); spin_unlock(&df->kvm_ref_lock); } diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c index b2299e5bc6df..fc24c0b2cc6f 100644 --- a/drivers/vfio/group.c +++ b/drivers/vfio/group.c @@ -163,7 +163,7 @@ static int vfio_group_ioctl_set_container(struct vfio_group *group, static void vfio_device_group_get_kvm_safe(struct vfio_device *device) { spin_lock(&device->group->kvm_ref_lock); - vfio_device_get_kvm_safe(device, device->group->kvm); + vfio_device_get_kvm_safe(device, device->group->kvm, device->group->kvm_module); spin_unlock(&device->group->kvm_ref_lock); } @@ -860,10 +860,11 @@ bool vfio_group_enforced_coherent(struct vfio_group *group) return ret; } -void vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm) +void vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm, struct module *kvm_module) { spin_lock(&group->kvm_ref_lock); group->kvm = kvm; + group->kvm_module = kvm_module; spin_unlock(&group->kvm_ref_lock); } diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h index e4b72e79b7e3..8209da17246c 100644 --- a/drivers/vfio/vfio.h +++ b/drivers/vfio/vfio.h @@ -22,8 +22,9 @@ struct vfio_device_file { u8 access_granted; u32 devid; /* only valid when iommufd is valid */ - spinlock_t kvm_ref_lock; /* protect kvm field */ + spinlock_t kvm_ref_lock; /* protect kvm and kvm_module fields */ struct kvm *kvm; + struct module *kvm_module; struct iommufd_ctx *iommufd; /* protected by struct vfio_device_set::lock */ }; @@ -89,6 +90,7 @@ struct vfio_group { enum vfio_group_type type; struct mutex group_lock; struct kvm *kvm; + struct module *kvm_module; struct file *opened_file; struct iommufd_ctx *iommufd; spinlock_t kvm_ref_lock; @@ -107,7 +109,7 @@ void vfio_device_group_unuse_iommu(struct vfio_device *device); void vfio_df_group_close(struct vfio_device_file *df); struct vfio_group *vfio_group_from_file(struct file *file); bool vfio_group_enforced_coherent(struct vfio_group *group); -void vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm); +void vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm, struct module *kvm_module); bool vfio_device_has_container(struct vfio_device *device); int __init vfio_group_init(void); void vfio_group_cleanup(void); @@ -170,7 +172,8 @@ static inline bool vfio_group_enforced_coherent(struct vfio_group *group) return true; } -static inline void vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm) +static inline void vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm, + struct module *kvm_module) { } @@ -434,11 +437,13 @@ static inline void vfio_virqfd_exit(void) #endif #if IS_ENABLED(CONFIG_KVM) -void vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm); +void vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm, + struct module *kvm_module); void vfio_device_put_kvm(struct vfio_device *device); #else static inline void vfio_device_get_kvm_safe(struct vfio_device *device, - struct kvm *kvm) + struct kvm *kvm, + struct module *kvm_module) { } diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c index ed538aebb0b8..8289aca97b6b 100644 --- a/drivers/vfio/vfio_main.c +++ b/drivers/vfio/vfio_main.c @@ -448,7 +448,8 @@ void vfio_unregister_group_dev(struct vfio_device *device) EXPORT_SYMBOL_GPL(vfio_unregister_group_dev); #if IS_ENABLED(CONFIG_KVM) -void vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm) +void vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm, + struct module *kvm_module) { void (*pfn)(struct kvm *kvm); bool (*fn)(struct kvm *kvm); @@ -459,25 +460,31 @@ void vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm) if (!kvm) return; + if (!try_module_get(kvm_module)) + return; + pfn = symbol_get(kvm_put_kvm); if (WARN_ON(!pfn)) - return; + goto out_put_mod; fn = symbol_get(kvm_get_kvm_safe); - if (WARN_ON(!fn)) { - symbol_put(kvm_put_kvm); - return; - } + if (WARN_ON(!fn)) + goto out_put_sym; ret = fn(kvm); symbol_put(kvm_get_kvm_safe); - if (!ret) { - symbol_put(kvm_put_kvm); - return; - } + if (!ret) + goto out_put_sym; device->put_kvm = pfn; device->kvm = kvm; + device->kvm_module = kvm_module; + return; + +out_put_sym: + symbol_put(kvm_put_kvm); +out_put_mod: + module_put(kvm_module); } void vfio_device_put_kvm(struct vfio_device *device) @@ -496,6 +503,8 @@ void vfio_device_put_kvm(struct vfio_device *device) clear: device->kvm = NULL; + module_put(device->kvm_module); + device->kvm_module = NULL; } #endif @@ -1520,7 +1529,7 @@ bool vfio_file_enforced_coherent(struct file *file) } EXPORT_SYMBOL_GPL(vfio_file_enforced_coherent); -static void vfio_device_file_set_kvm(struct file *file, struct kvm *kvm) +static void vfio_device_file_set_kvm(struct file *file, struct kvm *kvm, struct module *kvm_module) { struct vfio_device_file *df = file->private_data; @@ -1531,6 +1540,7 @@ static void vfio_device_file_set_kvm(struct file *file, struct kvm *kvm) */ spin_lock(&df->kvm_ref_lock); df->kvm = kvm; + df->kvm_module = kvm_module; spin_unlock(&df->kvm_ref_lock); } @@ -1542,16 +1552,16 @@ static void vfio_device_file_set_kvm(struct file *file, struct kvm *kvm) * When a VFIO device is first opened the KVM will be available in * device->kvm if one was associated with the file. */ -void vfio_file_set_kvm(struct file *file, struct kvm *kvm) +void vfio_file_set_kvm(struct file *file, struct kvm *kvm, struct module *kvm_module) { struct vfio_group *group; group = vfio_group_from_file(file); if (group) - vfio_group_set_kvm(group, kvm); + vfio_group_set_kvm(group, kvm, kvm_module); if (vfio_device_from_file(file)) - vfio_device_file_set_kvm(file, kvm); + vfio_device_file_set_kvm(file, kvm, kvm_module); } EXPORT_SYMBOL_GPL(vfio_file_set_kvm); diff --git a/include/linux/vfio.h b/include/linux/vfio.h index 31b826efba00..5bfec0339804 100644 --- a/include/linux/vfio.h +++ b/include/linux/vfio.h @@ -55,6 +55,7 @@ struct vfio_device { unsigned int migration_flags; u8 precopy_info_v2; struct kvm *kvm; + struct module *kvm_module; /* Members below here are private, not for driver use */ unsigned int index; @@ -377,7 +378,7 @@ static inline bool vfio_file_has_dev(struct file *file, struct vfio_device *devi #endif bool vfio_file_is_valid(struct file *file); bool vfio_file_enforced_coherent(struct file *file); -void vfio_file_set_kvm(struct file *file, struct kvm *kvm); +void vfio_file_set_kvm(struct file *file, struct kvm *kvm, struct module *kvm_module); #define VFIO_PIN_PAGES_MAX_ENTRIES (PAGE_SIZE/sizeof(unsigned long)) diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c index 6cdc4e9a333a..c593f31136f9 100644 --- a/virt/kvm/vfio.c +++ b/virt/kvm/vfio.c @@ -37,13 +37,13 @@ struct kvm_vfio { static void kvm_vfio_file_set_kvm(struct file *file, struct kvm *kvm) { - void (*fn)(struct file *file, struct kvm *kvm); + void (*fn)(struct file *file, struct kvm *kvm, struct module *kvm_module); fn = symbol_get(vfio_file_set_kvm); if (!fn) return; - fn(file, kvm); + fn(file, kvm, kvm ? THIS_MODULE : NULL); symbol_put(vfio_file_set_kvm); } -- 2.53.0