Commit b74ed7a6 authored by Oliver Upton's avatar Oliver Upton Committed by Paolo Bonzini
Browse files

KVM: Actually create debugfs in kvm_create_vm() 



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: default avatarOliver Upton <oupton@google.com>
Message-Id: <20220720092259.3491733-6-oliver.upton@linux.dev>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 59f82aad

virt/kvm/kvm_main.c

+19 −17
Original line number Original line Diff line number Diff line
@@ -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);