From 571ee1b6859869a09ed718d390aac2b9414646a2 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Thu, 9 Oct 2014 18:30:08 +0800 Subject: [PATCH] kvm: vfio: fix unregister kvm_device_ops of vfio After commit 80ce163 (KVM: VFIO: register kvm_device_ops dynamically), kvm_device_ops of vfio can be registered dynamically. Commit 3c3c29fd (kvm-vfio: do not use module_init) move the dynamic register invoked by kvm_init in order to fix broke unloading of the kvm module. However, kvm_device_ops of vfio is unregistered after rmmod kvm-intel module which lead to device type collision detection warning after kvm-intel module reinsmod. WARNING: CPU: 1 PID: 10358 at /root/cathy/kvm/arch/x86/kvm/../../../virt/kvm/kvm_main.c:3289 kvm_init+0x234/0x282 [kvm]() Modules linked in: kvm_intel(O+) kvm(O) nfsv3 nfs_acl auth_rpcgss oid_registry nfsv4 dns_resolver nfs fscache lockd sunrpc pci_stub bridge stp llc autofs4 8021q cpufreq_ondemand ipv6 joydev microcode pcspkr igb i2c_algo_bit ehci_pci ehci_hcd e1000e i2c_i801 ixgbe ptp pps_core hwmon mdio tpm_tis tpm ipmi_si ipmi_msghandler acpi_cpufreq isci libsas scsi_transport_sas button dm_mirror dm_region_hash dm_log dm_mod [last unloaded: kvm_intel] CPU: 1 PID: 10358 Comm: insmod Tainted: G W O 3.17.0-rc1 #2 Hardware name: Intel Corporation S2600CP/S2600CP, BIOS RMLSDP.86I.00.29.D696.1311111329 11/11/2013 0000000000000cd9 ffff880ff08cfd18 ffffffff814a61d9 0000000000000cd9 0000000000000000 ffff880ff08cfd58 ffffffff810417b7 ffff880ff08cfd48 ffffffffa045bcac ffffffffa049c420 0000000000000040 00000000000000ff Call Trace: [] dump_stack+0x49/0x60 [] warn_slowpath_common+0x7c/0x96 [] ? kvm_init+0x234/0x282 [kvm] [] warn_slowpath_null+0x15/0x17 [] kvm_init+0x234/0x282 [kvm] [] vmx_init+0x1bf/0x42a [kvm_intel] [] ? vmx_check_processor_compat+0x64/0x64 [kvm_intel] [] do_one_initcall+0xe3/0x170 [] ? __vunmap+0xad/0xb8 [] do_init_module+0x2b/0x174 [] load_module+0x43e/0x569 [] ? do_init_module+0x174/0x174 [] ? copy_module_from_user+0x39/0x82 [] ? module_sect_show+0x20/0x20 [] SyS_init_module+0x54/0x81 [] system_call_fastpath+0x16/0x1b ---[ end trace 0626f4a3ddea56f3 ]--- The bug can be reproduced by: rmmod kvm_intel.ko insmod kvm_intel.ko without rmmod/insmod kvm.ko This patch fixes the bug by unregistering kvm_device_ops of vfio when the kvm-intel module is removed. Reported-by: Liu Rongrong Fixes: 3c3c29fd0d7cddc32862c350d0700ce69953e3bd Signed-off-by: Wanpeng Li Signed-off-by: Paolo Bonzini --- include/linux/kvm_host.h | 1 + virt/kvm/kvm_main.c | 7 +++++++ virt/kvm/vfio.c | 5 +++++ virt/kvm/vfio.h | 4 ++++ 4 files changed, 17 insertions(+) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 28be31f49250..ea53b04993f2 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1080,6 +1080,7 @@ void kvm_device_get(struct kvm_device *dev); void kvm_device_put(struct kvm_device *dev); struct kvm_device *kvm_device_from_filp(struct file *filp); int kvm_register_device_ops(struct kvm_device_ops *ops, u32 type); +void kvm_unregister_device_ops(u32 type); extern struct kvm_device_ops kvm_mpic_ops; extern struct kvm_device_ops kvm_xics_ops; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 384eaa7b02fa..25ffac9e947d 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2354,6 +2354,12 @@ int kvm_register_device_ops(struct kvm_device_ops *ops, u32 type) return 0; } +void kvm_unregister_device_ops(u32 type) +{ + if (kvm_device_ops_table[type] != NULL) + kvm_device_ops_table[type] = NULL; +} + static int kvm_ioctl_create_device(struct kvm *kvm, struct kvm_create_device *cd) { @@ -3328,5 +3334,6 @@ void kvm_exit(void) kvm_arch_exit(); kvm_irqfd_exit(); free_cpumask_var(cpus_hardware_enabled); + kvm_vfio_ops_exit(); } EXPORT_SYMBOL_GPL(kvm_exit); diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c index 281e7cf2b8e5..620e37f741b8 100644 --- a/virt/kvm/vfio.c +++ b/virt/kvm/vfio.c @@ -283,3 +283,8 @@ int kvm_vfio_ops_init(void) { return kvm_register_device_ops(&kvm_vfio_ops, KVM_DEV_TYPE_VFIO); } + +void kvm_vfio_ops_exit(void) +{ + kvm_unregister_device_ops(KVM_DEV_TYPE_VFIO); +} diff --git a/virt/kvm/vfio.h b/virt/kvm/vfio.h index 92eac75d6b62..ab88c7dc0514 100644 --- a/virt/kvm/vfio.h +++ b/virt/kvm/vfio.h @@ -3,11 +3,15 @@ #ifdef CONFIG_KVM_VFIO int kvm_vfio_ops_init(void); +void kvm_vfio_ops_exit(void); #else static inline int kvm_vfio_ops_init(void) { return 0; } +static inline void kvm_vfio_ops_exit(void) +{ +} #endif #endif