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Thu, 2 Apr 2026 04:21:26 +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: Andreas Grapentin , Arnd Bergmann , Catalin Marinas , Christian Borntraeger , Claudio Imbrenda , David Hildenbrand , Gautam Gala , Hendrik Brueckner , Janosch Frank , Joey Gouly , Marc Zyngier , Nina Schoetterl-Glausch , Oliver Upton , Paolo Bonzini , Suzuki K Poulose , Ulrich Weigand , Will Deacon , Zenghui Yu Subject: [PATCH v1 03/27] KVM, vfio: remove symbol_get(kvm_put_kvm) from vfio Date: Thu, 2 Apr 2026 06:20:59 +0200 Message-ID: <20260402042125.3948963-4-seiden@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260402042125.3948963-1-seiden@linux.ibm.com> References: <20260402042125.3948963-1-seiden@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: hQBMhy9HLCCQzxvZtKP_zmRNQVxIyBUJ X-Authority-Analysis: v=2.4 cv=KslAGGWN c=1 sm=1 tr=0 ts=69cdeecb cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=20KFwNOVAAAA:8 a=VnNF1IyMAAAA:8 a=Iid1VeoRPhL8jyw1u-UA:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDAyMDAzNCBTYWx0ZWRfXxRFLOg61Tfgd r3j6Kfo7hL2jY55oEhYtWiMqNkPghLtwGjOQ2OH54mLzLprTA8BxCqXBVd5GDI2GNVn/GBKFaWo 72btgVmGMYyyqqwQRNirCd1pBFPvN9XdNPZGrhn26A7PCarfSdi81e3QIfDOyPD7JnVC2u8Ohi2 8qRrsqyaTIJmPm1RXzWXLn0E8P0xhGL7hFtYrrYzE6K7pVDTcUV90pzAEAp9vhuhhvgCZmY73vs 3bCBrMoyRE/LcDuADMPrQ4oWhCKPcP5kk+N1pA0hLxoQxl45GoJER2N1B+cmG2RwDxVlVYhgFAe 7mDAapmOtic4S1x01/Ymn74AMROIuThySzGlUYKKKor/p6vVveDS8x4P6f/g1dUbh/7xxXxWv/E jF+900F6Gm+DTecd67/iImwQZMV/qKy355cwJ942/ndxeP9gaq9Pt2gKVzMLYL1EV0bL79aGEer O7qnA68CJ3mFVzX8o5A== X-Proofpoint-ORIG-GUID: hQBMhy9HLCCQzxvZtKP_zmRNQVxIyBUJ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-02_01,2026-04-01_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 lowpriorityscore=0 priorityscore=1501 suspectscore=0 phishscore=0 adultscore=0 bulkscore=0 impostorscore=0 clxscore=1011 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2603050001 definitions=main-2604020034 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260401_212143_994027_414337DB X-CRM114-Status: GOOD ( 20.81 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Paolo Bonzini Right now, KVM and VFIO are using symbol_get to access each other's symbols because of a circular reference between the modules, as well as to avoid loading them unnecessarily. The remaining use in VFIO is for kvm_put_kvm, which is not inline because it needs to call kvm_destroy_vm. However, storing the address of kvm_destroy_vm in the "struct kvm" is enough to remove the dependency from VFIO. This also makes it possible to direct kvm_put_kvm to different implementations of kvm_destroy_vm. Signed-off-by: Paolo Bonzini Signed-off-by: Steffen Eiden --- drivers/vfio/vfio_main.c | 29 +++++------------------------ include/linux/kvm_host.h | 1 - include/linux/kvm_types.h | 9 +++++++++ include/linux/vfio.h | 1 - virt/kvm/kvm_main.c | 9 ++------- 5 files changed, 16 insertions(+), 33 deletions(-) diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c index 42f515519d87..e9c6353c74d8 100644 --- a/drivers/vfio/vfio_main.c +++ b/drivers/vfio/vfio_main.c @@ -17,7 +17,7 @@ #include #include #if IS_ENABLED(CONFIG_KVM) -#include +#include #endif #include #include @@ -436,9 +436,6 @@ EXPORT_SYMBOL_GPL(vfio_unregister_group_dev); void vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm, struct module *kvm_module) { - void (*pfn)(struct kvm *kvm); - bool ret; - lockdep_assert_held(&device->dev_set->lock); if (!kvm) @@ -447,19 +444,10 @@ void vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm, if (!try_module_get(kvm_module)) return; - pfn = symbol_get(kvm_put_kvm); - if (WARN_ON(!pfn)) - return; - - ret = kvm_get_kvm_safe(kvm); - if (!ret) { - symbol_put(kvm_put_kvm); - return; + if (kvm_get_kvm_safe(kvm)) { + device->kvm = kvm; + device->kvm_module = kvm_module; } - - device->put_kvm = pfn; - device->kvm = kvm; - device->kvm_module = kvm_module; } void vfio_device_put_kvm(struct vfio_device *device) @@ -469,15 +457,8 @@ void vfio_device_put_kvm(struct vfio_device *device) if (!device->kvm) return; - if (WARN_ON(!device->put_kvm)) - goto clear; - - device->put_kvm(device->kvm); - device->put_kvm = NULL; - symbol_put(kvm_put_kvm); - -clear: module_put(device->kvm_module); + kvm_put_kvm(device->kvm); device->kvm_module = NULL; device->kvm = NULL; } diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index dc18ee99bba4..13f903993ed0 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1065,7 +1065,6 @@ static inline void kvm_irqfd_exit(void) int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module); void kvm_exit(void); -void kvm_put_kvm(struct kvm *kvm); bool file_is_kvm(struct file *file); void kvm_put_kvm_no_destroy(struct kvm *kvm); diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h index add7cc2016e8..aadee536771a 100644 --- a/include/linux/kvm_types.h +++ b/include/linux/kvm_types.h @@ -144,6 +144,7 @@ struct kvm_vcpu_stat_generic { struct kvm_refcount { refcount_t users_count; + void (*destroy)(struct kvm *kvm); }; static inline void kvm_get_kvm(struct kvm *kvm) @@ -164,6 +165,14 @@ static inline bool kvm_get_kvm_safe(struct kvm *kvm) return refcount_inc_not_zero(&rc->users_count); } +static inline void kvm_put_kvm(struct kvm *kvm) +{ + struct kvm_refcount *rc = (struct kvm_refcount *)kvm; + + if (refcount_dec_and_test(&rc->users_count)) + rc->destroy(kvm); +} + #endif /* !__ASSEMBLER__ */ #endif /* __KVM_TYPES_H__ */ diff --git a/include/linux/vfio.h b/include/linux/vfio.h index 69a8d527b0e8..5c69532d6127 100644 --- a/include/linux/vfio.h +++ b/include/linux/vfio.h @@ -65,7 +65,6 @@ struct vfio_device { unsigned int open_count; struct completion comp; struct iommufd_access *iommufd_access; - void (*put_kvm)(struct kvm *kvm); struct inode *inode; #if IS_ENABLED(CONFIG_IOMMUFD) struct iommufd_device *iommufd_device; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index cb5e01f92503..642f9e9638cc 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -120,6 +120,7 @@ static struct dentry *kvm_debugfs_dir; static const struct file_operations stat_fops_per_vm; +static void kvm_destroy_vm(struct kvm *kvm); static long kvm_vcpu_ioctl(struct file *file, unsigned int ioctl, unsigned long arg); #ifdef CONFIG_KVM_COMPAT @@ -1154,6 +1155,7 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname) goto out_err_no_irq_routing; refcount_set(&kvm->rc.users_count, 1); + kvm->rc.destroy = kvm_destroy_vm; for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) { for (j = 0; j < 2; j++) { @@ -1316,13 +1318,6 @@ static void kvm_destroy_vm(struct kvm *kvm) mmdrop(mm); } -void kvm_put_kvm(struct kvm *kvm) -{ - if (refcount_dec_and_test(&kvm->rc.users_count)) - kvm_destroy_vm(kvm); -} -EXPORT_SYMBOL_GPL(kvm_put_kvm); - /* * Used to put a reference that was taken on behalf of an object associated * with a user-visible file descriptor, e.g. a vcpu or device, if installation -- 2.51.0