Re: [RFC 5/9] VFIO: Extend external user API

Eric Auger
2014-08-27T15:21:24Z

On 08/26/2014 09:02 PM, Alex Williamson wrote:
> On Mon, 2014-08-25 at 15:27 +0200, Eric Auger wrote:
>> New functions are added to be called from ARM KVM-VFIO device.
>>
>> - vfio_device_get_external_user enables to get a vfio device from
>> its fd
>> - vfio_device_put_external_user puts the vfio device
>> - vfio_external_get_type enables to retrieve the type of the device
>> (PCI or platform)
>> - vfio_external_get_base_device enables to get the
>> struct device*, useful to access the platform_device
>>
>> Signed-off-by: Eric Auger <eric.auger@linaro.org>
>> ---
>> drivers/vfio/vfio.c | 35 +++++++++++++++++++++++++++++++++++
>> include/linux/vfio.h | 4 ++++
>> 2 files changed, 39 insertions(+)
>>
>> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
>> index 8e84471..c93b9e4 100644
>> --- a/drivers/vfio/vfio.c
>> +++ b/drivers/vfio/vfio.c
>> @@ -1401,6 +1401,41 @@ void vfio_group_put_external_user(struct vfio_group *group)
>> }
>> EXPORT_SYMBOL_GPL(vfio_group_put_external_user);
>>
>> +struct vfio_device *vfio_device_get_external_user(struct file *filep)
>> +{
>> + struct vfio_device *vdev = filep->private_data;
>> +
>> + if (filep->f_op != &vfio_device_fops)
>> + return ERR_PTR(-EINVAL);
>> +
>> + vfio_device_get(vdev);
>> + return vdev;
>> +}
>> +EXPORT_SYMBOL_GPL(vfio_device_get_external_user);
>> +
>> +void vfio_device_put_external_user(struct vfio_device *vdev)
>> +{
>> + vfio_device_put(vdev);
>> +}
>> +EXPORT_SYMBOL_GPL(vfio_device_put_external_user);
>> +
>> +int vfio_external_get_type(struct vfio_device *vdev)
>> +{
>> + if (!strcmp(vdev->ops->name, "vfio-platform"))
>> + return VFIO_DEVICE_FLAGS_PLATFORM;
>> + else if (!strcmp(vdev->ops->name, "vfio-pci"))
>> + return VFIO_DEVICE_FLAGS_PCI;
>> + else
>> + return -EINVAL;
>> +}
>> +EXPORT_SYMBOL_GPL(vfio_external_get_type);
>
> Returning the bit of the flag we use in get_device_info looks rather
> sloppy here. Should we define a new enum for use with this? Actually,
> is this interface even necessary? If we can get the struct device then
> we can get the bus_type and keep vfio out of this.

thanks for the nit. I will try to get rid of it using it.
>
> For both of these last two, I like to use the convention that where
> there is a "get" there is a matching "put". These aren't reference
> counting anything, so let's not use get in the name.

I will rename.

Thanks

Eric
>
>> +
>> +struct device *vfio_external_get_base_device(struct vfio_device *vdev)
>> +{
>> + return vdev->dev;
>> +}
>> +EXPORT_SYMBOL_GPL(vfio_external_get_base_device);
>> +
>
> Looks almost too simple, but reviewing the object lifecycles, this all
> looks safe. Thanks,
>
> Alex
>
>> int vfio_external_user_iommu_id(struct vfio_group *group)
>> {
>> return iommu_group_id(group->iommu_group);
>> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
>> index ffe04ed..19e98eb 100644
>> --- a/include/linux/vfio.h
>> +++ b/include/linux/vfio.h
>> @@ -99,6 +99,10 @@ extern void vfio_group_put_external_user(struct vfio_group *group);
>> extern int vfio_external_user_iommu_id(struct vfio_group *group);
>> extern long vfio_external_check_extension(struct vfio_group *group,
>> unsigned long arg);
>> +extern struct vfio_device *vfio_device_get_external_user(struct file *filep);
>> +extern void vfio_device_put_external_user(struct vfio_device *vdev);
>> +extern int vfio_external_get_type(struct vfio_device *vdev);
>> +extern struct device *vfio_external_get_base_device(struct vfio_device *vdev);
>>
>> struct pci_dev;
>> #ifdef CONFIG_EEH
>
>
>