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Tue, 28 Apr 2026 16:05:28 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 28 Apr 2026 16:05:28 +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: [RFC PATCH v2 03/28] KVM, vfio: remove symbol_get(kvm_put_kvm) from vfio Date: Tue, 28 Apr 2026 18:05:00 +0200 Message-ID: <20260428160527.1378085-4-seiden@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260428160527.1378085-1-seiden@linux.ibm.com> References: <20260428160527.1378085-1-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-Proofpoint-ORIG-GUID: -QXboBkip70_d1llBqYzXAJDdwZ7VnxT X-Authority-Analysis: v=2.4 cv=Ft81OWrq c=1 sm=1 tr=0 ts=69f0dacd cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=20KFwNOVAAAA:8 a=VnNF1IyMAAAA:8 a=r1p2_3pzAAAA:8 a=Iid1VeoRPhL8jyw1u-UA:9 a=r_pkcD-q9-ctt7trBg_g:22 X-Proofpoint-GUID: -QXboBkip70_d1llBqYzXAJDdwZ7VnxT X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDI4MDE1MSBTYWx0ZWRfX8eJFi2zG4Lzr 8hQiN2chErpEopbvQg2Y0QxgwakR5C/bj+gWmIsQ1XE+grlni9Uph/rX4hMEOn3pGE9hXnWrIgw ViJ13qtFaUyOO9UB8GU3BjdIPJYACp5HRipJ+6i0bzB1UhDvcJsZbXA1BOqyB5+d9FmmHAWTTb2 fDsY+dPUHTUxeIrnhSmZNbuosrzcbJjCYpClmdH6um6DBfU/p97nYSmB9UduuLX7skDeuGiHtO/ Hy1EL+XlBo4wYGhdBiEwmZVfziL2alX3Q3deXFck2MLku+SfMDw8PMx5b7Fv9Y1vRIeHLVbWqgb xxaMEFSFU2fE9SfcbgAV0zumj9WG3Z9RBgOGX9UoYQB/zVKsp9ssKcfnnknOpZdOB10z/lWvb+A Qq53NmTPiU7ZgcWGnS4AVN/MuqnDrCH61yE4i9MP5TlXTTjF2czZ/XL0lVFEHz+GywQAmGD5UCV 29SybtU0AhBsntIFJag== 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=2026-04-28_05,2026-04-28_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 lowpriorityscore=0 bulkscore=0 spamscore=0 impostorscore=0 clxscore=1015 malwarescore=0 phishscore=0 suspectscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2604280151 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 either the arm64 or the s390 implementation of kvm_destroy_vm. Signed-off-by: Paolo Bonzini Reviewed-by: Steffen Eiden Acked-by: Alex Williamson --- drivers/vfio/vfio_main.c | 24 +++--------------------- include/linux/kvm_host.h | 1 - include/linux/kvm_types.h | 8 ++++++++ include/linux/vfio.h | 1 - virt/kvm/kvm_main.c | 9 ++------- 5 files changed, 13 insertions(+), 30 deletions(-) diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c index cb6eaabd64ce..f27a1d00c21e 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 @@ -435,9 +435,6 @@ 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, struct module *kvm_module) { - void (*pfn)(struct kvm *kvm); - bool ret; - lockdep_assert_held(&device->dev_set->lock); if (!kvm) @@ -446,21 +443,13 @@ void vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm, struc if (!try_module_get(kvm_module)) return; - pfn = symbol_get(kvm_put_kvm); - if (WARN_ON(!pfn)) + if (!kvm_get_kvm_safe(kvm)) goto out_put_mod; - ret = kvm_get_kvm_safe(kvm); - 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); } @@ -472,14 +461,7 @@ 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: + kvm_put_kvm(device->kvm); device->kvm = NULL; module_put(device->kvm_module); device->kvm_module = NULL; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 5163b541c82d..ca06f9bda028 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1064,7 +1064,6 @@ 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 4cb68c71a13c..8a9be07cb8dd 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) @@ -162,6 +163,13 @@ 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 6e3796814da7..27a718a0bc01 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 @@ -1155,6 +1156,7 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname) BUILD_BUG_ON(offsetof(struct kvm, rc) != 0); 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++) { @@ -1317,13 +1319,6 @@ 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