Merge tag 'vfio-v7.1-rc1-pt2' of https://github.com/awilliam/linux-vfio

Pull more VFIO updates from Alex Williamson:

 - Fix ordering of dma-buf cleanup versus device disabling in vfio-pci
   (Matt Evans)

 - Resolve an inconsistent and incorrect use of spinlock-irq in the
   virtio vfio-pci variant by conversion to mutex and proceed to
   modernize and simplify driver with use of guards (Alex Williamson)

 - Resurrect the removal of the remaining class_create() call in vfio,
   replacing with const struct class and class_register() (Jori
   Koolstra, Alex Williamson)

 - Fix NULL pointer dereference, properly serialize interrupt setup, and
   cleanup interrupt state tracking in the cdx vfio bus driver (Prasanna
   Kumar T S M, Alex Williamson)

* tag 'vfio-v7.1-rc1-pt2' of https://github.com/awilliam/linux-vfio:
  vfio/cdx: Consolidate MSI configured state onto cdx_irqs
  vfio/cdx: Serialize VFIO_DEVICE_SET_IRQS with a per-device mutex
  vfio/cdx: Fix NULL pointer dereference in interrupt trigger path
  vfio: replace vfio->device_class with a const struct class
  vfio/virtio: Use guard() for bar_mutex in legacy I/O
  vfio/virtio: Use guard() for migf->lock where applicable
  vfio/virtio: Use guard() for list_lock where applicable
  vfio/virtio: Convert list_lock from spinlock to mutex
  vfio/pci: Clean up DMABUFs before disabling function

10 files changed, 107 insertions, 106 deletions

diff --git a/drivers/vfio/cdx/intr.c b/drivers/vfio/cdx/intr.c
index 8f4402cec9c5..4439481fe633 100644
--- a/drivers/vfio/cdx/intr.c
+++ b/drivers/vfio/cdx/intr.c
@@ -32,26 +32,27 @@ static int vfio_cdx_msi_enable(struct vfio_cdx_device *vdev, int nvec)
 		return -ENOMEM;
 
 	ret = cdx_enable_msi(cdx_dev);
-	if (ret) {
-		kfree(vdev->cdx_irqs);
-		return ret;
-	}
+	if (ret)
+		goto err_free;
 
 	/* Allocate cdx MSIs */
 	ret = msi_domain_alloc_irqs(dev, MSI_DEFAULT_DOMAIN, nvec);
-	if (ret) {
-		cdx_disable_msi(cdx_dev);
-		kfree(vdev->cdx_irqs);
-		return ret;
-	}
+	if (ret)
+		goto err_disable;
 
 	for (msi_idx = 0; msi_idx < nvec; msi_idx++)
 		vdev->cdx_irqs[msi_idx].irq_no = msi_get_virq(dev, msi_idx);
 
 	vdev->msi_count = nvec;
-	vdev->config_msi = 1;
 
 	return 0;
+
+err_disable:
+	cdx_disable_msi(cdx_dev);
+err_free:
+	kfree(vdev->cdx_irqs);
+	vdev->cdx_irqs = NULL;
+	return ret;
 }
 
 static int vfio_cdx_msi_set_vector_signal(struct vfio_cdx_device *vdev,
@@ -129,7 +130,7 @@ static void vfio_cdx_msi_disable(struct vfio_cdx_device *vdev)
 
 	vfio_cdx_msi_set_block(vdev, 0, vdev->msi_count, NULL);
 
-	if (!vdev->config_msi)
+	if (!vdev->cdx_irqs)
 		return;
 
 	msi_domain_free_irqs_all(dev, MSI_DEFAULT_DOMAIN);
@@ -138,7 +139,6 @@ static void vfio_cdx_msi_disable(struct vfio_cdx_device *vdev)
 
 	vdev->cdx_irqs = NULL;
 	vdev->msi_count = 0;
-	vdev->config_msi = 0;
 }
 
 static int vfio_cdx_set_msi_trigger(struct vfio_cdx_device *vdev,
@@ -152,6 +152,8 @@ static int vfio_cdx_set_msi_trigger(struct vfio_cdx_device *vdev,
 	if (start + count > cdx_dev->num_msi)
 		return -EINVAL;
 
+	guard(mutex)(&vdev->cdx_irqs_lock);
+
 	if (!count && (flags & VFIO_IRQ_SET_DATA_NONE)) {
 		vfio_cdx_msi_disable(vdev);
 		return 0;
@@ -161,7 +163,7 @@ static int vfio_cdx_set_msi_trigger(struct vfio_cdx_device *vdev,
 		s32 *fds = data;
 		int ret;
 
-		if (vdev->config_msi)
+		if (vdev->cdx_irqs)
 			return vfio_cdx_msi_set_block(vdev, start, count,
 						  fds);
 		ret = vfio_cdx_msi_enable(vdev, cdx_dev->num_msi);
@@ -175,6 +177,9 @@ static int vfio_cdx_set_msi_trigger(struct vfio_cdx_device *vdev,
 		return ret;
 	}
 
+	if (!vdev->cdx_irqs)
+		return -EINVAL;
+
 	for (i = start; i < start + count; i++) {
 		if (!vdev->cdx_irqs[i].trigger)
 			continue;
@@ -206,12 +211,5 @@ int vfio_cdx_set_irqs_ioctl(struct vfio_cdx_device *vdev,
 /* Free All IRQs for the given device */
 void vfio_cdx_irqs_cleanup(struct vfio_cdx_device *vdev)
 {
-	/*
-	 * Device does not support any interrupt or the interrupts
-	 * were not configured
-	 */
-	if (!vdev->cdx_irqs)
-		return;
-
 	vfio_cdx_set_msi_trigger(vdev, 0, 0, 0, VFIO_IRQ_SET_DATA_NONE, NULL);
 }
diff --git a/drivers/vfio/cdx/main.c b/drivers/vfio/cdx/main.c
index 8ab97405b2bd..b31ed4be7bdc 100644
--- a/drivers/vfio/cdx/main.c
+++ b/drivers/vfio/cdx/main.c
@@ -8,6 +8,23 @@
 
 #include "private.h"
 
+static int vfio_cdx_init_dev(struct vfio_device *core_vdev)
+{
+	struct vfio_cdx_device *vdev =
+		container_of(core_vdev, struct vfio_cdx_device, vdev);
+
+	mutex_init(&vdev->cdx_irqs_lock);
+	return 0;
+}
+
+static void vfio_cdx_release_dev(struct vfio_device *core_vdev)
+{
+	struct vfio_cdx_device *vdev =
+		container_of(core_vdev, struct vfio_cdx_device, vdev);
+
+	mutex_destroy(&vdev->cdx_irqs_lock);
+}
+
 static int vfio_cdx_open_device(struct vfio_device *core_vdev)
 {
 	struct vfio_cdx_device *vdev =
@@ -273,6 +290,8 @@ static int vfio_cdx_mmap(struct vfio_device *core_vdev,
 
 static const struct vfio_device_ops vfio_cdx_ops = {
 	.name		= "vfio-cdx",
+	.init		= vfio_cdx_init_dev,
+	.release	= vfio_cdx_release_dev,
 	.open_device	= vfio_cdx_open_device,
 	.close_device	= vfio_cdx_close_device,
 	.ioctl		= vfio_cdx_ioctl,
diff --git a/drivers/vfio/cdx/private.h b/drivers/vfio/cdx/private.h
index 172e48caa3a0..4c00bf633356 100644
--- a/drivers/vfio/cdx/private.h
+++ b/drivers/vfio/cdx/private.h
@@ -6,6 +6,8 @@
 #ifndef VFIO_CDX_PRIVATE_H
 #define VFIO_CDX_PRIVATE_H
 
+#include <linux/mutex.h>
+
 #define VFIO_CDX_OFFSET_SHIFT    40
 
 static inline u64 vfio_cdx_index_to_offset(u32 index)
@@ -31,11 +33,11 @@ struct vfio_cdx_region {
 struct vfio_cdx_device {
 	struct vfio_device	vdev;
 	struct vfio_cdx_region	*regions;
+	struct mutex		cdx_irqs_lock;
 	struct vfio_cdx_irq	*cdx_irqs;
 	u32			flags;
 #define BME_SUPPORT BIT(0)
 	u32			msi_count;
-	u8			config_msi;
 };
 
 #ifdef CONFIG_GENERIC_MSI_IRQ
diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
index 8ceca24ac136..54abf312cf04 100644
--- a/drivers/vfio/device_cdev.c
+++ b/drivers/vfio/device_cdev.c
@@ -293,14 +293,8 @@ int vfio_df_ioctl_detach_pt(struct vfio_device_file *df,
 	return 0;
 }
 
-static char *vfio_device_devnode(const struct device *dev, umode_t *mode)
+int vfio_cdev_init(void)
 {
-	return kasprintf(GFP_KERNEL, "vfio/devices/%s", dev_name(dev));
-}
-
-int vfio_cdev_init(struct class *device_class)
-{
-	device_class->devnode = vfio_device_devnode;
 	return alloc_chrdev_region(&device_devt, 0,
 				   MINORMASK + 1, "vfio-dev");
 }
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index ad52abc46c04..3f8d093aacf8 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -734,10 +734,10 @@ void vfio_pci_core_close_device(struct vfio_device *core_vdev)
 #if IS_ENABLED(CONFIG_EEH)
 	eeh_dev_release(vdev->pdev);
 #endif
-	vfio_pci_core_disable(vdev);
-
 	vfio_pci_dma_buf_cleanup(vdev);
 
+	vfio_pci_core_disable(vdev);
+
 	mutex_lock(&vdev->igate);
 	vfio_pci_eventfd_replace_locked(vdev, &vdev->err_trigger, NULL);
 	vfio_pci_eventfd_replace_locked(vdev, &vdev->req_trigger, NULL);
diff --git a/drivers/vfio/pci/virtio/common.h b/drivers/vfio/pci/virtio/common.h
index cb3d5e57d3a3..3ccbd49e6abe 100644
--- a/drivers/vfio/pci/virtio/common.h
+++ b/drivers/vfio/pci/virtio/common.h
@@ -68,7 +68,7 @@ struct virtiovf_migration_file {
 	enum virtiovf_migf_state state;
 	enum virtiovf_load_state load_state;
 	/* synchronize access to the lists */
-	spinlock_t list_lock;
+	struct mutex list_lock;
 	struct list_head buf_list;
 	struct list_head avail_list;
 	struct virtiovf_data_buffer *buf;
diff --git a/drivers/vfio/pci/virtio/legacy_io.c b/drivers/vfio/pci/virtio/legacy_io.c
index 1ed349a55629..f022301e60d6 100644
--- a/drivers/vfio/pci/virtio/legacy_io.c
+++ b/drivers/vfio/pci/virtio/legacy_io.c
@@ -34,7 +34,9 @@ virtiovf_issue_legacy_rw_cmd(struct virtiovf_pci_core_device *virtvdev,
 	common = pos < VIRTIO_PCI_CONFIG_OFF(msix_enabled);
 	/* offset within the relevant configuration area */
 	offset = common ? pos : pos - VIRTIO_PCI_CONFIG_OFF(msix_enabled);
-	mutex_lock(&virtvdev->bar_mutex);
+
+	guard(mutex)(&virtvdev->bar_mutex);
+
 	if (read) {
 		if (common)
 			ret = virtio_pci_admin_legacy_common_io_read(pdev, offset,
@@ -43,14 +45,12 @@ virtiovf_issue_legacy_rw_cmd(struct virtiovf_pci_core_device *virtvdev,
 			ret = virtio_pci_admin_legacy_device_io_read(pdev, offset,
 					count, bar0_buf + pos);
 		if (ret)
-			goto out;
+			return ret;
 		if (copy_to_user(buf, bar0_buf + pos, count))
-			ret = -EFAULT;
+			return -EFAULT;
 	} else {
-		if (copy_from_user(bar0_buf + pos, buf, count)) {
-			ret = -EFAULT;
-			goto out;
-		}
+		if (copy_from_user(bar0_buf + pos, buf, count))
+			return -EFAULT;
 
 		if (common)
 			ret = virtio_pci_admin_legacy_common_io_write(pdev, offset,
@@ -59,8 +59,7 @@ virtiovf_issue_legacy_rw_cmd(struct virtiovf_pci_core_device *virtvdev,
 			ret = virtio_pci_admin_legacy_device_io_write(pdev, offset,
 					count, bar0_buf + pos);
 	}
-out:
-	mutex_unlock(&virtvdev->bar_mutex);
+
 	return ret;
 }
 
diff --git a/drivers/vfio/pci/virtio/migrate.c b/drivers/vfio/pci/virtio/migrate.c
index 7e11834ad512..4b1e5502f0a7 100644
--- a/drivers/vfio/pci/virtio/migrate.c
+++ b/drivers/vfio/pci/virtio/migrate.c
@@ -142,9 +142,8 @@ end:
 
 static void virtiovf_put_data_buffer(struct virtiovf_data_buffer *buf)
 {
-	spin_lock_irq(&buf->migf->list_lock);
+	guard(mutex)(&buf->migf->list_lock);
 	list_add_tail(&buf->buf_elm, &buf->migf->avail_list);
-	spin_unlock_irq(&buf->migf->list_lock);
 }
 
 static int
@@ -170,21 +169,21 @@ virtiovf_get_data_buffer(struct virtiovf_migration_file *migf, size_t length)
 
 	INIT_LIST_HEAD(&free_list);
 
-	spin_lock_irq(&migf->list_lock);
+	mutex_lock(&migf->list_lock);
 	list_for_each_entry_safe(buf, temp_buf, &migf->avail_list, buf_elm) {
 		list_del_init(&buf->buf_elm);
 		if (buf->allocated_length >= length) {
-			spin_unlock_irq(&migf->list_lock);
+			mutex_unlock(&migf->list_lock);
 			goto found;
 		}
 		/*
 		 * Prevent holding redundant buffers. Put in a free
-		 * list and call at the end not under the spin lock
+		 * list and call at the end not under the mutex
 		 * (&migf->list_lock) to minimize its scope usage.
 		 */
 		list_add(&buf->buf_elm, &free_list);
 	}
-	spin_unlock_irq(&migf->list_lock);
+	mutex_unlock(&migf->list_lock);
 	buf = virtiovf_alloc_data_buffer(migf, length);
 
 found:
@@ -225,10 +224,9 @@ static void virtiovf_clean_migf_resources(struct virtiovf_migration_file *migf)
 
 static void virtiovf_disable_fd(struct virtiovf_migration_file *migf)
 {
-	mutex_lock(&migf->lock);
+	guard(mutex)(&migf->lock);
 	migf->state = VIRTIOVF_MIGF_STATE_ERROR;
 	migf->filp->f_pos = 0;
-	mutex_unlock(&migf->lock);
 }
 
 static void virtiovf_disable_fds(struct virtiovf_pci_core_device *virtvdev)
@@ -295,6 +293,7 @@ static int virtiovf_release_file(struct inode *inode, struct file *filp)
 	struct virtiovf_migration_file *migf = filp->private_data;
 
 	virtiovf_disable_fd(migf);
+	mutex_destroy(&migf->list_lock);
 	mutex_destroy(&migf->lock);
 	kfree(migf);
 	return 0;
@@ -305,32 +304,27 @@ virtiovf_get_data_buff_from_pos(struct virtiovf_migration_file *migf,
 				loff_t pos, bool *end_of_data)
 {
 	struct virtiovf_data_buffer *buf;
-	bool found = false;
 
 	*end_of_data = false;
-	spin_lock_irq(&migf->list_lock);
+	guard(mutex)(&migf->list_lock);
+
 	if (list_empty(&migf->buf_list)) {
 		*end_of_data = true;
-		goto end;
+		return NULL;
 	}
 
 	buf = list_first_entry(&migf->buf_list, struct virtiovf_data_buffer,
 			       buf_elm);
 	if (pos >= buf->start_pos &&
-	    pos < buf->start_pos + buf->length) {
-		found = true;
-		goto end;
-	}
+	    pos < buf->start_pos + buf->length)
+		return buf;
 
 	/*
 	 * As we use a stream based FD we may expect having the data always
 	 * on first chunk
 	 */
 	migf->state = VIRTIOVF_MIGF_STATE_ERROR;
-
-end:
-	spin_unlock_irq(&migf->list_lock);
-	return found ? buf : NULL;
+	return NULL;
 }
 
 static ssize_t virtiovf_buf_read(struct virtiovf_data_buffer *vhca_buf,
@@ -369,10 +363,9 @@ static ssize_t virtiovf_buf_read(struct virtiovf_data_buffer *vhca_buf,
 	}
 
 	if (*pos >= vhca_buf->start_pos + vhca_buf->length) {
-		spin_lock_irq(&vhca_buf->migf->list_lock);
+		guard(mutex)(&vhca_buf->migf->list_lock);
 		list_del_init(&vhca_buf->buf_elm);
 		list_add_tail(&vhca_buf->buf_elm, &vhca_buf->migf->avail_list);
-		spin_unlock_irq(&vhca_buf->migf->list_lock);
 	}
 
 	return done;
@@ -391,11 +384,10 @@ static ssize_t virtiovf_save_read(struct file *filp, char __user *buf, size_t le
 		return -ESPIPE;
 	pos = &filp->f_pos;
 
-	mutex_lock(&migf->lock);
-	if (migf->state == VIRTIOVF_MIGF_STATE_ERROR) {
-		done = -ENODEV;
-		goto out_unlock;
-	}
+	guard(mutex)(&migf->lock);
+
+	if (migf->state == VIRTIOVF_MIGF_STATE_ERROR)
+		return -ENODEV;
 
 	while (len) {
 		ssize_t count;
@@ -404,34 +396,24 @@ static ssize_t virtiovf_save_read(struct file *filp, char __user *buf, size_t le
 		if (first_loop_call) {
 			first_loop_call = false;
 			/* Temporary end of file as part of PRE_COPY */
-			if (end_of_data && migf->state == VIRTIOVF_MIGF_STATE_PRECOPY) {
-				done = -ENOMSG;
-				goto out_unlock;
-			}
-			if (end_of_data && migf->state != VIRTIOVF_MIGF_STATE_COMPLETE) {
-				done = -EINVAL;
-				goto out_unlock;
-			}
+			if (end_of_data && migf->state == VIRTIOVF_MIGF_STATE_PRECOPY)
+				return -ENOMSG;
+			if (end_of_data && migf->state != VIRTIOVF_MIGF_STATE_COMPLETE)
+				return -EINVAL;
 		}
 
 		if (end_of_data)
-			goto out_unlock;
+			return done;
 
-		if (!vhca_buf) {
-			done = -EINVAL;
-			goto out_unlock;
-		}
+		if (!vhca_buf)
+			return -EINVAL;
 
 		count = virtiovf_buf_read(vhca_buf, &buf, &len, pos);
-		if (count < 0) {
-			done = count;
-			goto out_unlock;
-		}
+		if (count < 0)
+			return count;
 		done += count;
 	}
 
-out_unlock:
-	mutex_unlock(&migf->lock);
 	return done;
 }
 
@@ -549,9 +531,10 @@ virtiovf_add_buf_header(struct virtiovf_data_buffer *header_buf,
 	header_buf->length = sizeof(header);
 	header_buf->start_pos = header_buf->migf->max_pos;
 	migf->max_pos += header_buf->length;
-	spin_lock_irq(&migf->list_lock);
-	list_add_tail(&header_buf->buf_elm, &migf->buf_list);
-	spin_unlock_irq(&migf->list_lock);
+
+	scoped_guard(mutex, &migf->list_lock)
+		list_add_tail(&header_buf->buf_elm, &migf->buf_list);
+
 	return 0;
 }
 
@@ -616,9 +599,10 @@ virtiovf_read_device_context_chunk(struct virtiovf_migration_file *migf,
 
 	buf->start_pos = buf->migf->max_pos;
 	migf->max_pos += buf->length;
-	spin_lock(&migf->list_lock);
-	list_add_tail(&buf->buf_elm, &migf->buf_list);
-	spin_unlock_irq(&migf->list_lock);
+
+	scoped_guard(mutex, &migf->list_lock)
+		list_add_tail(&buf->buf_elm, &migf->buf_list);
+
 	return 0;
 
 out_header:
@@ -687,7 +671,7 @@ virtiovf_pci_save_device_data(struct virtiovf_pci_core_device *virtvdev,
 	mutex_init(&migf->lock);
 	INIT_LIST_HEAD(&migf->buf_list);
 	INIT_LIST_HEAD(&migf->avail_list);
-	spin_lock_init(&migf->list_lock);
+	mutex_init(&migf->list_lock);
 	migf->virtvdev = virtvdev;
 
 	lockdep_assert_held(&virtvdev->state_mutex);
@@ -1077,7 +1061,7 @@ virtiovf_pci_resume_device_data(struct virtiovf_pci_core_device *virtvdev)
 	mutex_init(&migf->lock);
 	INIT_LIST_HEAD(&migf->buf_list);
 	INIT_LIST_HEAD(&migf->avail_list);
-	spin_lock_init(&migf->list_lock);
+	mutex_init(&migf->list_lock);
 
 	buf = virtiovf_alloc_data_buffer(migf, VIRTIOVF_TARGET_INITIAL_BUF_SIZE);
 	if (IS_ERR(buf)) {
diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index 0854f3fa1a22..e4b72e79b7e3 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -377,7 +377,7 @@ int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep);
 long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
 				struct vfio_device_bind_iommufd __user *arg);
 void vfio_df_unbind_iommufd(struct vfio_device_file *df);
-int vfio_cdev_init(struct class *device_class);
+int vfio_cdev_init(void);
 void vfio_cdev_cleanup(void);
 #else
 static inline void vfio_init_device_cdev(struct vfio_device *device)
@@ -410,7 +410,7 @@ static inline void vfio_df_unbind_iommufd(struct vfio_device_file *df)
 {
 }
 
-static inline int vfio_cdev_init(struct class *device_class)
+static inline int vfio_cdev_init(void)
 {
 	return 0;
 }
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 8666f35fb3f0..6222376ab6ab 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -49,7 +49,6 @@
 #define VFIO_MAGIC 0x5646494f /* "VFIO" */
 
 static struct vfio {
-	struct class			*device_class;
 	struct ida			device_ida;
 	struct vfsmount			*vfs_mount;
 	int				fs_count;
@@ -64,6 +63,16 @@ MODULE_PARM_DESC(enable_unsafe_noiommu_mode, "Enable UNSAFE, no-IOMMU mode.  Thi
 
 static DEFINE_XARRAY(vfio_device_set_xa);
 
+static char *vfio_device_devnode(const struct device *dev, umode_t *mode)
+{
+	return kasprintf(GFP_KERNEL, "vfio/devices/%s", dev_name(dev));
+}
+
+static const struct class vfio_device_class = {
+	.name		= "vfio-dev",
+	.devnode	= vfio_device_devnode
+};
+
 int vfio_assign_device_set(struct vfio_device *device, void *set_id)
 {
 	unsigned long idx = (unsigned long)set_id;
@@ -299,7 +308,7 @@ static int vfio_init_device(struct vfio_device *device, struct device *dev,
 
 	device_initialize(&device->device);
 	device->device.release = vfio_device_release;
-	device->device.class = vfio.device_class;
+	device->device.class = &vfio_device_class;
 	device->device.parent = device->dev;
 	return 0;
 
@@ -1804,13 +1813,11 @@ static int __init vfio_init(void)
 		goto err_virqfd;
 
 	/* /sys/class/vfio-dev/vfioX */
-	vfio.device_class = class_create("vfio-dev");
-	if (IS_ERR(vfio.device_class)) {
-		ret = PTR_ERR(vfio.device_class);
+	ret = class_register(&vfio_device_class);
+	if (ret)
 		goto err_dev_class;
-	}
 
-	ret = vfio_cdev_init(vfio.device_class);
+	ret = vfio_cdev_init();
 	if (ret)
 		goto err_alloc_dev_chrdev;
 
@@ -1819,8 +1826,7 @@ static int __init vfio_init(void)
 	return 0;
 
 err_alloc_dev_chrdev:
-	class_destroy(vfio.device_class);
-	vfio.device_class = NULL;
+	class_unregister(&vfio_device_class);
 err_dev_class:
 	vfio_virqfd_exit();
 err_virqfd:
@@ -1833,8 +1839,7 @@ static void __exit vfio_cleanup(void)
 	vfio_debugfs_remove_root();
 	ida_destroy(&vfio.device_ida);
 	vfio_cdev_cleanup();
-	class_destroy(vfio.device_class);
-	vfio.device_class = NULL;
+	class_unregister(&vfio_device_class);
 	vfio_virqfd_exit();
 	vfio_group_cleanup();
 	xa_destroy(&vfio_device_set_xa);