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Message-ID: <4c9350cd-c2ce-dc84-9a29-210907d2a2a2@redhat.com>
Date: Thu, 8 Sep 2022 11:39:07 +0200
From: Eric Auger <eric.auger@...hat.com>
To: Yi Liu <yi.l.liu@...el.com>, Kevin Tian <kevin.tian@...el.com>,
Zhenyu Wang <zhenyuw@...ux.intel.com>,
Zhi Wang <zhi.a.wang@...el.com>,
Jani Nikula <jani.nikula@...ux.intel.com>,
Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
Rodrigo Vivi <rodrigo.vivi@...el.com>,
Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
David Airlie <airlied@...ux.ie>,
Daniel Vetter <daniel@...ll.ch>,
Eric Farman <farman@...ux.ibm.com>,
Matthew Rosato <mjrosato@...ux.ibm.com>,
Halil Pasic <pasic@...ux.ibm.com>,
Vineeth Vijayan <vneethv@...ux.ibm.com>,
Peter Oberparleiter <oberpar@...ux.ibm.com>,
Heiko Carstens <hca@...ux.ibm.com>,
Vasily Gorbik <gor@...ux.ibm.com>,
Alexander Gordeev <agordeev@...ux.ibm.com>,
Christian Borntraeger <borntraeger@...ux.ibm.com>,
Sven Schnelle <svens@...ux.ibm.com>,
Tony Krowiak <akrowiak@...ux.ibm.com>,
Jason Herne <jjherne@...ux.ibm.com>,
Harald Freudenberger <freude@...ux.ibm.com>,
Diana Craciun <diana.craciun@....nxp.com>,
Alex Williamson <alex.williamson@...hat.com>,
Cornelia Huck <cohuck@...hat.com>,
Longfang Liu <liulongfang@...wei.com>,
Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>,
Jason Gunthorpe <jgg@...pe.ca>,
Yishai Hadas <yishaih@...dia.com>,
Kirti Wankhede <kwankhede@...dia.com>,
Leon Romanovsky <leon@...nel.org>,
Abhishek Sahu <abhsahu@...dia.com>,
intel-gvt-dev@...ts.freedesktop.org,
intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
kvm@...r.kernel.org
Subject: Re: [PATCH v2 15/15] vfio: Add struct device to vfio_device
On 9/8/22 11:17, Yi Liu wrote:
> On 2022/9/8 17:06, Eric Auger wrote:
>> Hi Kevin,
>>
>> On 9/1/22 16:37, Kevin Tian wrote:
>>> From: Yi Liu <yi.l.liu@...el.com>
>>>
>>> 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.
>>>
>>> Add Documentation/ABI/testing/sysfs-devices-vfio-dev.
>>>
>>> Also take this chance to rename chardev 'vfio' to 'vfio-group' in
>>> /proc/devices.
>>>
>>> Suggested-by: Jason Gunthorpe <jgg@...dia.com>
>>> Signed-off-by: Yi Liu <yi.l.liu@...el.com>
>>> Signed-off-by: Kevin Tian <kevin.tian@...el.com>
>>> Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
>>> ---
>>> .../ABI/testing/sysfs-devices-vfio-dev | 8 +++
>>> drivers/vfio/vfio_main.c | 67
>>> +++++++++++++++----
>>> include/linux/vfio.h | 6 +-
>>> 3 files changed, 66 insertions(+), 15 deletions(-)
>>> create mode 100644 Documentation/ABI/testing/sysfs-devices-vfio-dev
>>>
>>> diff --git a/Documentation/ABI/testing/sysfs-devices-vfio-dev
>>> b/Documentation/ABI/testing/sysfs-devices-vfio-dev
>>> new file mode 100644
>>> index 000000000000..e21424fd9666
>>> --- /dev/null
>>> +++ b/Documentation/ABI/testing/sysfs-devices-vfio-dev
>>> @@ -0,0 +1,8 @@
>>> +What: /sys/.../<device>/vfio-dev/vfioX/
>>> +Date: September 2022
>>> +Contact: Yi Liu <yi.l.liu@...el.com>
>>> +Description:
>>> + This directory is created when the device is bound to a
>>> + vfio driver. The layout under this directory matches what
>>> + exists for a standard 'struct device'. 'X' is a unique
>>> + index marking this device in vfio.
>>> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
>>> index bfa675d314ab..141f55c3faf5 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 {
>>> @@ -483,12 +485,13 @@ static struct vfio_device
>>> *vfio_group_get_device(struct vfio_group *group,
>>> * VFIO driver API
>>> */
>>> /* 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
>>> @@ -498,7 +501,6 @@ void vfio_device_release(struct kref *kref)
>>> */
>>> device->ops->release(device);
>>> }
>>> -EXPORT_SYMBOL_GPL(vfio_device_release);
>>> /*
>>> * Alloc and initialize vfio_device so it can be registered to vfio
>>> @@ -546,6 +548,13 @@ int vfio_init_device(struct vfio_device
>>> *device, struct device *dev,
>>> {
>>> 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;
>>> @@ -556,11 +565,15 @@ int vfio_init_device(struct vfio_device
>>> *device, struct device *dev,
>>> goto out_uninit;
>>> }
>>> - 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_uninit:
>>> vfio_release_device_set(device);
>>> + ida_free(&vfio.device_ida, device->index);
>>> return ret;
>>> }
>>> EXPORT_SYMBOL_GPL(vfio_init_device);
>>> @@ -657,6 +670,7 @@ 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);
>>> @@ -673,16 +687,21 @@ 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);
>>> @@ -692,6 +711,12 @@ 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)
>>> @@ -779,6 +804,9 @@ 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);
>>> @@ -2145,6 +2173,7 @@ 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);
>>> @@ -2160,12 +2189,20 @@ 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;
>>> - ret = alloc_chrdev_region(&vfio.group_devt, 0, MINORMASK + 1,
>>> "vfio");
>>> + /* /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-group");
>>> if (ret)
>>> goto err_alloc_chrdev;
>>> @@ -2181,9 +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;
>>> }
>>> @@ -2195,8 +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 f03447c8774d..5c13f74da1bb 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;
>> I am not totally clear about remaining 'struct device *dev;' in
>> vfio_device struct. I see it used in some places. Is it supposed to
>> disappear at some point?
>
> no, Eric. *dev will not disappear, it stores the dev pointet passed in by
> caller of vfio_init_device().
yeah I see but you have device->device.parent = device->dev;
Eric
>
>>> @@ -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);
>>
>> Thanks
>>
>> Eric
>>
>
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