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KVM: Actually create debugfs in kvm_create_vm()

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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>
Message-Id: <20220720092259.3491733-6-oliver.upton@linux.dev>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Oliver Upton 2022-07-20 09:22:51 +00:00 committed by Paolo Bonzini
parent 59f82aad59
commit b74ed7a68e
1 changed files with 19 additions and 17 deletions
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36
virt/kvm/kvm_main.c
View File

@ -1028,7 +1028,7 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, const char *fdname)
char dir_name[ITOA_MAX_LEN * 2]; char dir_name[ITOA_MAX_LEN * 2];
struct kvm_stat_data *stat_data; struct kvm_stat_data *stat_data;
const struct _kvm_stats_desc *pdesc; const struct _kvm_stats_desc *pdesc;
int i, ret; int i, ret = -ENOMEM;
int kvm_debugfs_num_entries = kvm_vm_stats_header.num_desc + int kvm_debugfs_num_entries = kvm_vm_stats_header.num_desc +
kvm_vcpu_stats_header.num_desc; kvm_vcpu_stats_header.num_desc;
@ -1054,13 +1054,13 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, const char *fdname)
sizeof(*kvm->debugfs_stat_data), sizeof(*kvm->debugfs_stat_data),
GFP_KERNEL_ACCOUNT); GFP_KERNEL_ACCOUNT);
if (!kvm->debugfs_stat_data) if (!kvm->debugfs_stat_data)
return -ENOMEM; goto out_err;
for (i = 0; i < kvm_vm_stats_header.num_desc; ++i) { for (i = 0; i < kvm_vm_stats_header.num_desc; ++i) {
pdesc = &kvm_vm_stats_desc[i]; pdesc = &kvm_vm_stats_desc[i];
stat_data = kzalloc(sizeof(*stat_data), GFP_KERNEL_ACCOUNT); stat_data = kzalloc(sizeof(*stat_data), GFP_KERNEL_ACCOUNT);
if (!stat_data) if (!stat_data)
return -ENOMEM; goto out_err;
stat_data->kvm = kvm; stat_data->kvm = kvm;
stat_data->desc = pdesc; stat_data->desc = pdesc;
@ -1075,7 +1075,7 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, const char *fdname)
pdesc = &kvm_vcpu_stats_desc[i]; pdesc = &kvm_vcpu_stats_desc[i];
stat_data = kzalloc(sizeof(*stat_data), GFP_KERNEL_ACCOUNT); stat_data = kzalloc(sizeof(*stat_data), GFP_KERNEL_ACCOUNT);
if (!stat_data) if (!stat_data)
return -ENOMEM; goto out_err;
stat_data->kvm = kvm; stat_data->kvm = kvm;
stat_data->desc = pdesc; stat_data->desc = pdesc;
@ -1087,12 +1087,13 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, const char *fdname)
} }
ret = kvm_arch_create_vm_debugfs(kvm); ret = kvm_arch_create_vm_debugfs(kvm);
if (ret) { if (ret)
kvm_destroy_vm_debugfs(kvm); goto out_err;
return i;
}
return 0; return 0;
out_err:
kvm_destroy_vm_debugfs(kvm);
return ret;
} }
/* /*
@ -1123,7 +1124,7 @@ int __weak kvm_arch_create_vm_debugfs(struct kvm *kvm)
return 0; return 0;
} }
static struct kvm *kvm_create_vm(unsigned long type) static struct kvm *kvm_create_vm(unsigned long type, const char *fdname)
{ {
struct kvm *kvm = kvm_arch_alloc_vm(); struct kvm *kvm = kvm_arch_alloc_vm();
struct kvm_memslots *slots; struct kvm_memslots *slots;
@ -1212,7 +1213,7 @@ static struct kvm *kvm_create_vm(unsigned long type)
r = kvm_arch_post_init_vm(kvm); r = kvm_arch_post_init_vm(kvm);
if (r) if (r)
goto out_err; goto out_err_mmu_notifier;
mutex_lock(&kvm_lock); mutex_lock(&kvm_lock);
list_add(&kvm->vm_list, &vm_list); list_add(&kvm->vm_list, &vm_list);
@ -1228,12 +1229,18 @@ static struct kvm *kvm_create_vm(unsigned long type)
*/ */
if (!try_module_get(kvm_chardev_ops.owner)) { if (!try_module_get(kvm_chardev_ops.owner)) {
r = -ENODEV; r = -ENODEV;
goto out_err; goto out_err_mmu_notifier;
} }
r = kvm_create_vm_debugfs(kvm, fdname);
if (r)
goto out_err;
return kvm; return kvm;
out_err: out_err:
module_put(kvm_chardev_ops.owner);
out_err_mmu_notifier:
#if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER) #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
if (kvm->mmu_notifier.ops) if (kvm->mmu_notifier.ops)
mmu_notifier_unregister(&kvm->mmu_notifier, current->mm); mmu_notifier_unregister(&kvm->mmu_notifier, current->mm);
@ -4900,7 +4907,7 @@ static int kvm_dev_ioctl_create_vm(unsigned long type)
snprintf(fdname, sizeof(fdname), "%d", fd); snprintf(fdname, sizeof(fdname), "%d", fd);
kvm = kvm_create_vm(type); kvm = kvm_create_vm(type, fdname);
if (IS_ERR(kvm)) { if (IS_ERR(kvm)) {
r = PTR_ERR(kvm); r = PTR_ERR(kvm);
goto put_fd; goto put_fd;
@ -4923,11 +4930,6 @@ static int kvm_dev_ioctl_create_vm(unsigned long type)
* cases it will be called by the final fput(file) and will take * cases it will be called by the final fput(file) and will take
* care of doing kvm_put_kvm(kvm). * care of doing kvm_put_kvm(kvm).
*/ */
if (kvm_create_vm_debugfs(kvm, fdname) < 0) {
fput(file);
r = -ENOMEM;
goto put_fd;
}
kvm_uevent_notify_change(KVM_EVENT_CREATE_VM, kvm); kvm_uevent_notify_change(KVM_EVENT_CREATE_VM, kvm);
fd_install(fd, file); fd_install(fd, file);