[PATCH 15/15] vfio: Add struct device to vfio_device

From: Kevin Tian
Date: Sat Aug 27 2022 - 05:53:14 EST

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From: Yi Liu <yi.l.liu@xxxxxxxxx>

and replace kref. With it a 'vfio-dev/vfioX' node is created under the
sysfs path of the parent, indicating the device is bound to a vfio
driver, e.g.:

/sys/devices/pci0000\:6f/0000\:6f\:01.0/vfio-dev/vfio0

It is also a preparatory step toward adding cdev for supporting future
device-oriented uAPI.

Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
Signed-off-by: Kevin Tian <kevin.tian@xxxxxxxxx>
---
drivers/vfio/vfio_main.c | 70 +++++++++++++++++++++++++++++++++-------
include/linux/vfio.h | 6 ++--
2 files changed, 61 insertions(+), 15 deletions(-)

diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 0c5d120aeced..9ad0cbb83f1c 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -46,6 +46,8 @@ static struct vfio {
struct mutex group_lock; /* locks group_list */
struct ida group_ida;
dev_t group_devt;
+ struct class *device_class;
+ struct ida device_ida;
} vfio;

struct vfio_iommu_driver {
@@ -524,11 +526,19 @@ EXPORT_SYMBOL_GPL(_vfio_alloc_device);
*
* Only vfio-ccw driver should call this interface.
*/
+static void vfio_device_release(struct device *dev);
int vfio_init_device(struct vfio_device *device, struct device *dev,
const struct vfio_device_ops *ops)
{
int ret;

+ ret = ida_alloc_max(&vfio.device_ida, MINORMASK, GFP_KERNEL);
+ if (ret < 0) {
+ dev_dbg(dev, "Error to alloc index\n");
+ return ret;
+ }
+
+ device->index = ret;
init_completion(&device->comp);
device->dev = dev;
device->ops = ops;
@@ -536,11 +546,18 @@ int vfio_init_device(struct vfio_device *device, struct device *dev,
if (ops->init) {
ret = ops->init(device);
if (ret)
- return ret;
+ goto out_ida;
}

- kref_init(&device->kref);
+ device_initialize(&device->device);
+ device->device.release = vfio_device_release;
+ device->device.class = vfio.device_class;
+ device->device.parent = device->dev;
return 0;
+
+out_ida:
+ ida_free(&vfio.device_ida, device->index);
+ return ret;
}
EXPORT_SYMBOL_GPL(vfio_init_device);

@@ -556,12 +573,13 @@ void vfio_free_device(struct vfio_device *device)
EXPORT_SYMBOL_GPL(vfio_free_device);

/* Release helper called by vfio_put_device() */
-void vfio_device_release(struct kref *kref)
+static void vfio_device_release(struct device *dev)
{
struct vfio_device *device =
- container_of(kref, struct vfio_device, kref);
+ container_of(dev, struct vfio_device, device);

vfio_release_device_set(device);
+ ida_free(&vfio.device_ida, device->index);

/*
* kvfree() cannot be done here due to a life cycle mess in
@@ -571,7 +589,6 @@ void vfio_device_release(struct kref *kref)
*/
device->ops->release(device);
}
-EXPORT_SYMBOL_GPL(vfio_device_release);

static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev,
enum vfio_group_type type)
@@ -654,6 +671,7 @@ static int __vfio_register_dev(struct vfio_device *device,
struct vfio_group *group)
{
struct vfio_device *existing_device;
+ int ret;

if (IS_ERR(group))
return PTR_ERR(group);
@@ -670,16 +688,21 @@ static int __vfio_register_dev(struct vfio_device *device,
dev_WARN(device->dev, "Device already exists on group %d\n",
iommu_group_id(group->iommu_group));
vfio_device_put_registration(existing_device);
- if (group->type == VFIO_NO_IOMMU ||
- group->type == VFIO_EMULATED_IOMMU)
- iommu_group_remove_device(device->dev);
- vfio_group_put(group);
- return -EBUSY;
+ ret = -EBUSY;
+ goto err_out;
}

/* Our reference on group is moved to the device */
device->group = group;

+ ret = dev_set_name(&device->device, "vfio%d", device->index);
+ if (ret)
+ goto err_out;
+
+ ret = device_add(&device->device);
+ if (ret)
+ goto err_out;
+
/* Refcounting can't start until the driver calls register */
refcount_set(&device->refcount, 1);

@@ -689,6 +712,12 @@ static int __vfio_register_dev(struct vfio_device *device,
mutex_unlock(&group->device_lock);

return 0;
+err_out:
+ if (group->type == VFIO_NO_IOMMU ||
+ group->type == VFIO_EMULATED_IOMMU)
+ iommu_group_remove_device(device->dev);
+ vfio_group_put(group);
+ return ret;
}

int vfio_register_group_dev(struct vfio_device *device)
@@ -776,6 +805,9 @@ void vfio_unregister_group_dev(struct vfio_device *device)
group->dev_counter--;
mutex_unlock(&group->device_lock);

+ /* Balances device_add in register path */
+ device_del(&device->device);
+
if (group->type == VFIO_NO_IOMMU || group->type == VFIO_EMULATED_IOMMU)
iommu_group_remove_device(device->dev);

@@ -2142,6 +2174,7 @@ static int __init vfio_init(void)
int ret;

ida_init(&vfio.group_ida);
+ ida_init(&vfio.device_ida);
mutex_init(&vfio.group_lock);
mutex_init(&vfio.iommu_drivers_lock);
INIT_LIST_HEAD(&vfio.group_list);
@@ -2157,11 +2190,18 @@ static int __init vfio_init(void)
vfio.class = class_create(THIS_MODULE, "vfio");
if (IS_ERR(vfio.class)) {
ret = PTR_ERR(vfio.class);
- goto err_class;
+ goto err_group_class;
}

vfio.class->devnode = vfio_devnode;

+ /* /sys/class/vfio-dev/vfioX */
+ vfio.device_class = class_create(THIS_MODULE, "vfio-dev");
+ if (IS_ERR(vfio.device_class)) {
+ ret = PTR_ERR(vfio.device_class);
+ goto err_dev_class;
+ }
+
ret = alloc_chrdev_region(&vfio.group_devt, 0, MINORMASK + 1, "vfio");
if (ret)
goto err_alloc_chrdev;
@@ -2178,9 +2218,12 @@ static int __init vfio_init(void)
err_driver_register:
unregister_chrdev_region(vfio.group_devt, MINORMASK + 1);
err_alloc_chrdev:
+ class_destroy(vfio.device_class);
+ vfio.device_class = NULL;
+err_dev_class:
class_destroy(vfio.class);
vfio.class = NULL;
-err_class:
+err_group_class:
misc_deregister(&vfio_dev);
return ret;
}
@@ -2192,8 +2235,11 @@ static void __exit vfio_cleanup(void)
#ifdef CONFIG_VFIO_NOIOMMU
vfio_unregister_iommu_driver(&vfio_noiommu_ops);
#endif
+ ida_destroy(&vfio.device_ida);
ida_destroy(&vfio.group_ida);
unregister_chrdev_region(vfio.group_devt, MINORMASK + 1);
+ class_destroy(vfio.device_class);
+ vfio.device_class = NULL;
class_destroy(vfio.class);
vfio.class = NULL;
misc_deregister(&vfio_dev);
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index a36a65b966b5..ae398c2f18eb 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -45,7 +45,8 @@ struct vfio_device {
struct kvm *kvm;

/* Members below here are private, not for driver use */
- struct kref kref; /* object life cycle */
+ unsigned int index;
+ struct device device; /* device.kref covers object life circle */
refcount_t refcount; /* user count on registered device*/
unsigned int open_count;
struct completion comp;
@@ -154,10 +155,9 @@ struct vfio_device *_vfio_alloc_device(size_t size, struct device *dev,
int vfio_init_device(struct vfio_device *device, struct device *dev,
const struct vfio_device_ops *ops);
void vfio_free_device(struct vfio_device *device);
-void vfio_device_release(struct kref *kref);
static inline void vfio_put_device(struct vfio_device *device)
{
- kref_put(&device->kref, vfio_device_release);
+ put_device(&device->device);
}

int vfio_register_group_dev(struct vfio_device *device);
--
2.21.3

Next message: Yu Kuai: "[PATCH v2 0/3] blk-throttle cleanups"
Previous message: Kevin Tian: "[PATCH 14/15] vfio: Rename vfio_device_put() and vfio_device_try_get()"
In reply to: Kevin Tian: "[PATCH 14/15] vfio: Rename vfio_device_put() and vfio_device_try_get()"
Next in thread: Alex Williamson: "Re: [PATCH 15/15] vfio: Add struct device to vfio_device"
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