Re: [v6 1/3] vfio: vfio_register_notifier: classify iommu notifier

[Jike Song <jike.song@intel.com>]

On 11/19/2016 01:55 AM, Alex Williamson wrote:
> On Fri, 18 Nov 2016 19:01:47 +0800
> Jike Song <jike.song@intel.com> wrote:
> 
>> Currently vfio_register_notifier assumes that there is only one
>> notifier chain, which is in vfio_iommu. However, the user might
>> also be interested in events other than vfio_iommu, for example,
>> vfio_group. Refactor vfio_{un}register_notifier implementation
>> to make it feasible.
>>
>> Cc: Alex Williamson <alex.williamson@redhat.com>
>> Cc: Kirti Wankhede <kwankhede@nvidia.com>
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com>
>> Signed-off-by: Jike Song <jike.song@intel.com>
>> ---
>>  drivers/vfio/vfio.c  | 87 +++++++++++++++++++++++++++++++++++++++-------------
>>  include/linux/vfio.h | 16 ++++++++--
>>  2 files changed, 78 insertions(+), 25 deletions(-)
>>
>> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
>> index c815067..ec62bec 100644
>> --- a/drivers/vfio/vfio.c
>> +++ b/drivers/vfio/vfio.c
>> @@ -2007,23 +2007,24 @@ int vfio_unpin_pages(struct device *dev, unsigned long *user_pfn, int npage)
>>  }
>>  EXPORT_SYMBOL(vfio_unpin_pages);
>>  
>> -int vfio_register_notifier(struct device *dev, struct notifier_block *nb)
>> +static int vfio_register_iommu_notifier(struct vfio_group *group,
>> +					unsigned long *events,
>> +					struct notifier_block *nb)
>>  {
>>  	struct vfio_container *container;
>> -	struct vfio_group *group;
>>  	struct vfio_iommu_driver *driver;
>>  	int ret;
>>  
>> -	if (!dev || !nb)
>> -		return -EINVAL;
>> +	/* clear known events */
>> +	*events &= ~VFIO_IOMMU_NOTIFY_DMA_UNMAP;
>>  
>> -	group = vfio_group_get_from_dev(dev);
>> -	if (IS_ERR(group))
>> -		return PTR_ERR(group);
>> +	/* refuse to register if still events remaining */
>> +	if (*events)
>> +		return -EINVAL;
>>  
>>  	ret = vfio_group_add_container_user(group);
>>  	if (ret)
>> -		goto err_register_nb;
>> +		return -EINVAL;
>>  
>>  	container = group->container;
>>  	down_read(&container->group_lock);
>> @@ -2037,29 +2038,19 @@ int vfio_register_notifier(struct device *dev, struct notifier_block *nb)
>>  	up_read(&container->group_lock);
>>  	vfio_group_try_dissolve_container(group);
>>  
>> -err_register_nb:
>> -	vfio_group_put(group);
>>  	return ret;
>>  }
>> -EXPORT_SYMBOL(vfio_register_notifier);
>>  
>> -int vfio_unregister_notifier(struct device *dev, struct notifier_block *nb)
>> +static int vfio_unregister_iommu_notifier(struct vfio_group *group,
>> +					  struct notifier_block *nb)
>>  {
>>  	struct vfio_container *container;
>> -	struct vfio_group *group;
>>  	struct vfio_iommu_driver *driver;
>>  	int ret;
>>  
>> -	if (!dev || !nb)
>> -		return -EINVAL;
>> -
>> -	group = vfio_group_get_from_dev(dev);
>> -	if (IS_ERR(group))
>> -		return PTR_ERR(group);
>> -
>>  	ret = vfio_group_add_container_user(group);
>>  	if (ret)
>> -		goto err_unregister_nb;
>> +		return -EINVAL;
>>  
>>  	container = group->container;
>>  	down_read(&container->group_lock);
>> @@ -2074,7 +2065,59 @@ int vfio_unregister_notifier(struct device *dev, struct notifier_block *nb)
>>  	up_read(&container->group_lock);
>>  	vfio_group_try_dissolve_container(group);
>>  
>> -err_unregister_nb:
>> +	return ret;
>> +}
>> +
>> +int vfio_register_notifier(struct device *dev, vfio_notify_type_t type,
>> +			   unsigned long *events,
>> +			   struct notifier_block *nb)
>> +{
>> +	struct vfio_group *group;
>> +	int ret;
>> +
>> +	if (!dev || !nb)
>> +		return -EINVAL;
>> +	if (!events || *events == 0)
>> +		return -EINVAL;
> 
> nit, we could test all these within a single if()
> 

Will do that in next version.

>> +
>> +	group = vfio_group_get_from_dev(dev);
>> +	if (IS_ERR(group))
>> +		return PTR_ERR(group);
>> +
>> +	switch (type) {
>> +	case VFIO_IOMMU_NOTIFY:
>> +		ret = vfio_register_iommu_notifier(group, events, nb);
>> +		break;
>> +	default:
>> +		ret = EINVAL;
> 
> -EINVAL
> ^
> 

Ough, sorry .. will fix it in next version.

--
Thanks,
Jike
>> +	}
>> +
>> +	vfio_group_put(group);
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL(vfio_register_notifier);
>> +
>> +int vfio_unregister_notifier(struct device *dev, vfio_notify_type_t type,
>> +			     struct notifier_block *nb)
>> +{
>> +	struct vfio_group *group;
>> +	int ret;
>> +
>> +	if (!dev || !nb)
>> +		return -EINVAL;
>> +
>> +	group = vfio_group_get_from_dev(dev);
>> +	if (IS_ERR(group))
>> +		return PTR_ERR(group);
>> +
>> +	switch (type) {
>> +	case VFIO_IOMMU_NOTIFY:
>> +		ret = vfio_unregister_iommu_notifier(group, nb);
>> +		break;
>> +	default:
>> +		ret = -EINVAL;
>> +	}
>> +
>>  	vfio_group_put(group);
>>  	return ret;
>>  }
>> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
>> index 15ff042..6f3ff31 100644
>> --- a/include/linux/vfio.h
>> +++ b/include/linux/vfio.h
>> @@ -107,14 +107,24 @@ extern int vfio_pin_pages(struct device *dev, unsigned long *user_pfn,
>>  extern int vfio_unpin_pages(struct device *dev, unsigned long *user_pfn,
>>  			    int npage);
>>  
>> -#define VFIO_IOMMU_NOTIFY_DMA_UNMAP	(1)
>> -
>> +typedef unsigned short vfio_notify_type_t;
>>  extern int vfio_register_notifier(struct device *dev,
>> +				  vfio_notify_type_t type,
>> +				  unsigned long *required_events,
>>  				  struct notifier_block *nb);
>> -
>>  extern int vfio_unregister_notifier(struct device *dev,
>> +				    vfio_notify_type_t type,
>>  				    struct notifier_block *nb);
>>  
>> +/* each type has independent events */
>> +enum vfio_notify_type {
>> +	VFIO_IOMMU_NOTIFY = (__force vfio_notify_type_t)0,
>> +};
>> +
>> +/* events for VFIO_IOMMU_NOTIFY */
>> +#define VFIO_IOMMU_NOTIFY_DMA_UNMAP	BIT(0)
>> +
>> +
>>  /*
>>   * Sub-module helpers
>>   */
>