diff options
Diffstat (limited to 'virt/kvm/kvm_main.c')
| -rw-r--r-- | virt/kvm/kvm_main.c | 43 |
1 files changed, 35 insertions, 8 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 6c07dd423458..bcef324ccbf2 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1103,6 +1103,14 @@ void __weak kvm_arch_create_vm_debugfs(struct kvm *kvm) { } +/* Called only on cleanup and destruction paths when there are no users. */ +static inline struct kvm_io_bus *kvm_get_bus_for_destruction(struct kvm *kvm, + enum kvm_bus idx) +{ + return rcu_dereference_protected(kvm->buses[idx], + !refcount_read(&kvm->users_count)); +} + static struct kvm *kvm_create_vm(unsigned long type, const char *fdname) { struct kvm *kvm = kvm_arch_alloc_vm(); @@ -1228,7 +1236,7 @@ out_err_no_disable: out_err_no_arch_destroy_vm: WARN_ON_ONCE(!refcount_dec_and_test(&kvm->users_count)); for (i = 0; i < KVM_NR_BUSES; i++) - kfree(kvm_get_bus(kvm, i)); + kfree(kvm_get_bus_for_destruction(kvm, i)); kvm_free_irq_routing(kvm); out_err_no_irq_routing: cleanup_srcu_struct(&kvm->irq_srcu); @@ -1276,7 +1284,7 @@ static void kvm_destroy_vm(struct kvm *kvm) kvm_free_irq_routing(kvm); for (i = 0; i < KVM_NR_BUSES; i++) { - struct kvm_io_bus *bus = kvm_get_bus(kvm, i); + struct kvm_io_bus *bus = kvm_get_bus_for_destruction(kvm, i); if (bus) kvm_io_bus_destroy(bus); @@ -1312,6 +1320,7 @@ static void kvm_destroy_vm(struct kvm *kvm) kvm_free_memslots(kvm, &kvm->__memslots[i][1]); } cleanup_srcu_struct(&kvm->irq_srcu); + srcu_barrier(&kvm->srcu); cleanup_srcu_struct(&kvm->srcu); #ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES xa_destroy(&kvm->mem_attr_array); @@ -5843,6 +5852,18 @@ static int __kvm_io_bus_write(struct kvm_vcpu *vcpu, struct kvm_io_bus *bus, return -EOPNOTSUPP; } +static struct kvm_io_bus *kvm_get_bus_srcu(struct kvm *kvm, enum kvm_bus idx) +{ + /* + * Ensure that any updates to kvm_buses[] observed by the previous vCPU + * machine instruction are also visible to the vCPU machine instruction + * that triggered this call. + */ + smp_mb__after_srcu_read_lock(); + + return srcu_dereference(kvm->buses[idx], &kvm->srcu); +} + int kvm_io_bus_write(struct kvm_vcpu *vcpu, enum kvm_bus bus_idx, gpa_t addr, int len, const void *val) { @@ -5855,7 +5876,7 @@ int kvm_io_bus_write(struct kvm_vcpu *vcpu, enum kvm_bus bus_idx, gpa_t addr, .len = len, }; - bus = srcu_dereference(vcpu->kvm->buses[bus_idx], &vcpu->kvm->srcu); + bus = kvm_get_bus_srcu(vcpu->kvm, bus_idx); if (!bus) return -ENOMEM; r = __kvm_io_bus_write(vcpu, bus, &range, val); @@ -5874,7 +5895,7 @@ int kvm_io_bus_write_cookie(struct kvm_vcpu *vcpu, enum kvm_bus bus_idx, .len = len, }; - bus = srcu_dereference(vcpu->kvm->buses[bus_idx], &vcpu->kvm->srcu); + bus = kvm_get_bus_srcu(vcpu->kvm, bus_idx); if (!bus) return -ENOMEM; @@ -5924,7 +5945,7 @@ int kvm_io_bus_read(struct kvm_vcpu *vcpu, enum kvm_bus bus_idx, gpa_t addr, .len = len, }; - bus = srcu_dereference(vcpu->kvm->buses[bus_idx], &vcpu->kvm->srcu); + bus = kvm_get_bus_srcu(vcpu->kvm, bus_idx); if (!bus) return -ENOMEM; r = __kvm_io_bus_read(vcpu, bus, &range, val); @@ -5932,6 +5953,13 @@ int kvm_io_bus_read(struct kvm_vcpu *vcpu, enum kvm_bus bus_idx, gpa_t addr, } EXPORT_SYMBOL_GPL(kvm_io_bus_read); +static void __free_bus(struct rcu_head *rcu) +{ + struct kvm_io_bus *bus = container_of(rcu, struct kvm_io_bus, rcu); + + kfree(bus); +} + int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, int len, struct kvm_io_device *dev) { @@ -5970,8 +5998,7 @@ int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, memcpy(new_bus->range + i + 1, bus->range + i, (bus->dev_count - i) * sizeof(struct kvm_io_range)); rcu_assign_pointer(kvm->buses[bus_idx], new_bus); - synchronize_srcu_expedited(&kvm->srcu); - kfree(bus); + call_srcu(&kvm->srcu, &bus->rcu, __free_bus); return 0; } @@ -6033,7 +6060,7 @@ struct kvm_io_device *kvm_io_bus_get_dev(struct kvm *kvm, enum kvm_bus bus_idx, srcu_idx = srcu_read_lock(&kvm->srcu); - bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu); + bus = kvm_get_bus_srcu(kvm, bus_idx); if (!bus) goto out_unlock; |