| Message ID | 20220415201542.1496582-5-oupton@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: Clean up debugfs+stats init/destroy | expand |
On Fri, Apr 15, 2022, Oliver Upton wrote: > @@ -1049,7 +1050,7 @@ int __weak kvm_arch_create_vm_debugfs(struct kvm *kvm) > return 0; > } > > -static struct kvm *kvm_create_vm(unsigned long type) > +static struct kvm *kvm_create_vm(unsigned long type, int fd) I don't love passing in @fd, because actually doing anything but printing the @fd in a string is doomed to fail. Rather than pass the raw fd, what about passing in just its name? --- virt/kvm/kvm_main.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index d94c1d9ecaa9..ac76fc7f2e4d 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -964,7 +964,7 @@ static void kvm_destroy_vm_debugfs(struct kvm *kvm) } } -static int kvm_create_vm_debugfs(struct kvm *kvm, int fd) +static int kvm_create_vm_debugfs(struct kvm *kvm, const char *fdname) { static DEFINE_MUTEX(kvm_debugfs_lock); struct dentry *dent; @@ -987,7 +987,7 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd) if (!debugfs_initialized()) return 0; - snprintf(dir_name, sizeof(dir_name), "%d-%d", task_pid_nr(current), fd); + snprintf(dir_name, sizeof(dir_name), "%d-%s", task_pid_nr(current), fdname); mutex_lock(&kvm_debugfs_lock); dent = debugfs_lookup(dir_name, kvm_debugfs_dir); if (dent) { @@ -1076,7 +1076,7 @@ int __weak kvm_arch_create_vm_debugfs(struct kvm *kvm) return 0; } -static struct kvm *kvm_create_vm(unsigned long type, int fd) +static struct kvm *kvm_create_vm(unsigned long type, const char * fdname) { struct kvm *kvm = kvm_arch_alloc_vm(); struct kvm_memslots *slots; @@ -1174,7 +1174,7 @@ static struct kvm *kvm_create_vm(unsigned long type, int fd) goto out_err_mmu_notifier; } - r = kvm_create_vm_debugfs(kvm, fd); + r = kvm_create_vm_debugfs(kvm, fdname); if (r) goto out_err; @@ -4781,6 +4781,7 @@ EXPORT_SYMBOL_GPL(file_is_kvm); static int kvm_dev_ioctl_create_vm(unsigned long type) { + char fdname[ITOA_MAX_LEN + 1]; int r, fd; struct kvm *kvm; struct file *file; @@ -4789,7 +4790,9 @@ static int kvm_dev_ioctl_create_vm(unsigned long type) if (fd < 0) return fd; - kvm = kvm_create_vm(type, fd); + snprintf(fdname, sizeof(fdname), "%d", fd); + + kvm = kvm_create_vm(type, fdname); if (IS_ERR(kvm)) { r = PTR_ERR(kvm); goto put_fd; base-commit: 3d7c3ff77a78f103c2cf1104157a4132f56fd6d1 --
On Mon, May 16, 2022 at 3:19 PM Sean Christopherson <seanjc@google.com> wrote: > > On Fri, Apr 15, 2022, Oliver Upton wrote: > > @@ -1049,7 +1050,7 @@ int __weak kvm_arch_create_vm_debugfs(struct kvm *kvm) > > return 0; > > } > > > > -static struct kvm *kvm_create_vm(unsigned long type) > > +static struct kvm *kvm_create_vm(unsigned long type, int fd) > > I don't love passing in @fd, because actually doing anything but printing the > @fd in a string is doomed to fail. > > Rather than pass the raw fd, what about passing in just its name? Urgh. Yeah, that's fine by me. I'll squash this and resend. -- Thanks, Oliver
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1abbc6b07c19..54793de42d14 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -951,7 +951,7 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd) char dir_name[ITOA_MAX_LEN * 2]; struct kvm_stat_data *stat_data; const struct _kvm_stats_desc *pdesc; - int i, ret; + int i, ret = -ENOMEM; int kvm_debugfs_num_entries = kvm_vm_stats_header.num_desc + kvm_vcpu_stats_header.num_desc; @@ -980,13 +980,13 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd) sizeof(*kvm->debugfs_stat_data), GFP_KERNEL_ACCOUNT); if (!kvm->debugfs_stat_data) - return -ENOMEM; + goto out_err; for (i = 0; i < kvm_vm_stats_header.num_desc; ++i) { pdesc = &kvm_vm_stats_desc[i]; stat_data = kzalloc(sizeof(*stat_data), GFP_KERNEL_ACCOUNT); if (!stat_data) - return -ENOMEM; + goto out_err; stat_data->kvm = kvm; stat_data->desc = pdesc; @@ -1001,7 +1001,7 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd) pdesc = &kvm_vcpu_stats_desc[i]; stat_data = kzalloc(sizeof(*stat_data), GFP_KERNEL_ACCOUNT); if (!stat_data) - return -ENOMEM; + goto out_err; stat_data->kvm = kvm; stat_data->desc = pdesc; @@ -1013,12 +1013,13 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd) } ret = kvm_arch_create_vm_debugfs(kvm); - if (ret) { - kvm_destroy_vm_debugfs(kvm); - return i; - } + if (ret) + goto out_err; return 0; +out_err: + kvm_destroy_vm_debugfs(kvm); + return ret; } /* @@ -1049,7 +1050,7 @@ int __weak kvm_arch_create_vm_debugfs(struct kvm *kvm) return 0; } -static struct kvm *kvm_create_vm(unsigned long type) +static struct kvm *kvm_create_vm(unsigned long type, int fd) { struct kvm *kvm = kvm_arch_alloc_vm(); struct kvm_memslots *slots; @@ -1134,7 +1135,7 @@ static struct kvm *kvm_create_vm(unsigned long type) r = kvm_arch_post_init_vm(kvm); if (r) - goto out_err; + goto out_err_mmu_notifier; mutex_lock(&kvm_lock); list_add(&kvm->vm_list, &vm_list); @@ -1150,12 +1151,18 @@ static struct kvm *kvm_create_vm(unsigned long type) */ if (!try_module_get(kvm_chardev_ops.owner)) { r = -ENODEV; - goto out_err; + goto out_err_mmu_notifier; } + r = kvm_create_vm_debugfs(kvm, fd); + if (r) + goto out_err; + return kvm; out_err: + module_put(kvm_chardev_ops.owner); +out_err_mmu_notifier: #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER) if (kvm->mmu_notifier.ops) mmu_notifier_unregister(&kvm->mmu_notifier, current->mm); @@ -4760,7 +4767,7 @@ static int kvm_dev_ioctl_create_vm(unsigned long type) if (fd < 0) return fd; - kvm = kvm_create_vm(type); + kvm = kvm_create_vm(type, fd); if (IS_ERR(kvm)) { r = PTR_ERR(kvm); goto put_fd; @@ -4777,17 +4784,6 @@ static int kvm_dev_ioctl_create_vm(unsigned long type) goto put_kvm; } - /* - * Don't call kvm_put_kvm anymore at this point; file->f_op is - * already set, with ->release() being kvm_vm_release(). In error - * cases it will be called by the final fput(file) and will take - * care of doing kvm_put_kvm(kvm). - */ - if (kvm_create_vm_debugfs(kvm, r) < 0) { - fput(file); - r = -ENOMEM; - goto put_fd; - } kvm_uevent_notify_change(KVM_EVENT_CREATE_VM, kvm); fd_install(fd, file);
Doing debugfs creation after vm creation leaves things in a quasi-initialized state for a while. This is further complicated by the fact that we tear down debugfs from kvm_destroy_vm(). Align debugfs and stats init/destroy with the vm init/destroy pattern to avoid any headaches. Note the fix for a benign mistake in error handling for calls to kvm_arch_create_vm_debugfs() rolled in. Since all implementations of the function return 0 unconditionally it isn't actually a bug at the moment. Lastly, tear down debugfs/stats data in the kvm_create_vm_debugfs() error path. Previously it was safe to assume that kvm_destroy_vm() would take out the garbage, that is no longer the case. Signed-off-by: Oliver Upton <oupton@google.com> --- virt/kvm/kvm_main.c | 42 +++++++++++++++++++----------------------- 1 file changed, 19 insertions(+), 23 deletions(-)