Re: [v8 1/3] vfio: vfio_register_notifier: classify iommu notifier

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

On 12/02/2016 01:45 AM, Alex Williamson wrote:
> On Thu, 1 Dec 2016 09:22:33 -0700
> Alex Williamson <alex.williamson@redhat.com> wrote:
> 
>> On Thu, 1 Dec 2016 09:21:22 -0700
>> Alex Williamson <alex.williamson@redhat.com> wrote:
>>
>>> On Thu,  1 Dec 2016 13:20:05 +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: Paolo Bonzini <pbonzini@redhat.com>
>>>> Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com>
>>>> Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>
>>>> Signed-off-by: Jike Song <jike.song@intel.com>
>>>> ---
>>>>  drivers/vfio/vfio.c             | 85 +++++++++++++++++++++++++++++------------
>>>>  drivers/vfio/vfio_iommu_type1.c |  8 ++++
>>>>  include/linux/vfio.h            | 17 +++++++--
>>>>  3 files changed, 82 insertions(+), 28 deletions(-)    
>>>
>>> I'm making the following fixup to merge this with Christophe's patch
>>> found here  https://lkml.org/lkml/2016/11/30/57  
>>
>> Whoops, somehow that got sent before I added the changes:
> 
> checkpatch.pl also complains about adding new typedefs, so perhaps
> vfio_notify_type_t is not way to go.  This is the patch as I have it
> now, I've also updated 2/3 to remove the typedef there.  If there are
> no objections, this is what I'll go with.  Thanks,

Thanks for the fixup! I actually saw the checkpatch.pl warning about
new typedef but scrupled to remove it :-)

--
Thanks,
Jike

> 
> commit 22195cbd3451a75abaf30651a61cf85c89061327
> Author: Jike Song <jike.song@intel.com>
> Date:   Thu Dec 1 13:20:05 2016 +0800
> 
>     vfio: vfio_register_notifier: classify iommu notifier
>     
>     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: Paolo Bonzini <pbonzini@redhat.com>
>     Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com>
>     Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>
>     Signed-off-by: Jike Song <jike.song@intel.com>
>     [aw: merge with commit 816ca69ea9c7 ("vfio: Fix handling of error returned by 'vfio_group_get_from_dev()'"), remove typedef]
>     Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> 
> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index 7b39313..6cc2a9f 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -2008,59 +2008,44 @@ 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;
> -
> -	group = vfio_group_get_from_dev(dev);
> -	if (!group)
> -		return -ENODEV;
> -
>  	ret = vfio_group_add_container_user(group);
>  	if (ret)
> -		goto err_register_nb;
> +		return -EINVAL;
>  
>  	container = group->container;
>  	down_read(&container->group_lock);
>  
>  	driver = container->iommu_driver;
>  	if (likely(driver && driver->ops->register_notifier))
> -		ret = driver->ops->register_notifier(container->iommu_data, nb);
> +		ret = driver->ops->register_notifier(container->iommu_data,
> +						     events, nb);
>  	else
>  		ret = -ENOTTY;
>  
>  	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 (!group)
> -		return -ENODEV;
> -
>  	ret = vfio_group_add_container_user(group);
>  	if (ret)
> -		goto err_unregister_nb;
> +		return -EINVAL;
>  
>  	container = group->container;
>  	down_read(&container->group_lock);
> @@ -2075,7 +2060,56 @@ 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, enum vfio_notify_type type,
> +			   unsigned long *events, struct notifier_block *nb)
> +{
> +	struct vfio_group *group;
> +	int ret;
> +
> +	if (!dev || !nb || !events || (*events == 0))
> +		return -EINVAL;
> +
> +	group = vfio_group_get_from_dev(dev);
> +	if (!group)
> +		return -ENODEV;
> +
> +	switch (type) {
> +	case VFIO_IOMMU_NOTIFY:
> +		ret = vfio_register_iommu_notifier(group, events, nb);
> +		break;
> +	default:
> +		ret = -EINVAL;
> +	}
> +
> +	vfio_group_put(group);
> +	return ret;
> +}
> +EXPORT_SYMBOL(vfio_register_notifier);
> +
> +int vfio_unregister_notifier(struct device *dev, enum vfio_notify_type type,
> +			     struct notifier_block *nb)
> +{
> +	struct vfio_group *group;
> +	int ret;
> +
> +	if (!dev || !nb)
> +		return -EINVAL;
> +
> +	group = vfio_group_get_from_dev(dev);
> +	if (!group)
> +		return -ENODEV;
> +
> +	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/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 51810a9..b88ad1e 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -1584,10 +1584,18 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
>  }
>  
>  static int vfio_iommu_type1_register_notifier(void *iommu_data,
> +					      unsigned long *events,
>  					      struct notifier_block *nb)
>  {
>  	struct vfio_iommu *iommu = iommu_data;
>  
> +	/* clear known events */
> +	*events &= ~VFIO_IOMMU_NOTIFY_DMA_UNMAP;
> +
> +	/* refuse to register if still events remaining */
> +	if (*events)
> +		return -EINVAL;
> +
>  	return blocking_notifier_chain_register(&iommu->notifier, nb);
>  }
>  
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index 15ff042..0e5201f 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -81,6 +81,7 @@ struct vfio_iommu_driver_ops {
>  	int		(*unpin_pages)(void *iommu_data,
>  				       unsigned long *user_pfn, int npage);
>  	int		(*register_notifier)(void *iommu_data,
> +					     unsigned long *events,
>  					     struct notifier_block *nb);
>  	int		(*unregister_notifier)(void *iommu_data,
>  					       struct notifier_block *nb);
> @@ -107,12 +108,20 @@ 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)
> +/* each type has independent events */
> +enum vfio_notify_type {
> +	VFIO_IOMMU_NOTIFY = 0,
> +};
> +
> +/* events for VFIO_IOMMU_NOTIFY */
> +#define VFIO_IOMMU_NOTIFY_DMA_UNMAP	BIT(0)
>  
>  extern int vfio_register_notifier(struct device *dev,
> +				  enum vfio_notify_type type,
> +				  unsigned long *required_events,
>  				  struct notifier_block *nb);
> -
>  extern int vfio_unregister_notifier(struct device *dev,
> +				    enum vfio_notify_type type,
>  				    struct notifier_block *nb);
>  
>  /*
>