linux-kernel - Re: [PATCH 5/7] vfio: Create interface for vfio bus drivers to register

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Date:   Wed, 14 Jun 2017 15:17:25 +0200
From:   Auger Eric <eric.auger@...hat.com>
To:     Alex Williamson <alex.williamson@...hat.com>, kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/7] vfio: Create interface for vfio bus drivers to
 register

Hi,

On 10/06/2017 00:00, Alex Williamson wrote:
> Generally we don't know about vfio bus drivers until a device is
> added to the vfio-core with vfio_add_group_dev(), this optional
> registration with vfio_register_bus_driver() allows vfio-core to
> track known drivers.  Our current use for this information is to
> know whether a driver is vfio compatible during a bind operation.
> For devices on buses with driver_override support, we can use this
> linkage to block non-vfio drivers from binding to devices where
> the iommu group state would trigger a BUG to avoid host/user
> integrity issues.
> 
> Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
Reviewed-by: Eric Auger <eric.auger@...hat.com>

Thanks

Eric
> ---
>  drivers/vfio/vfio.c  |   55 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/vfio.h |    3 +++
>  2 files changed, 58 insertions(+)
> 
> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index e6117de60f87..a25ee4930200 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -43,6 +43,8 @@
>  	struct class			*class;
>  	struct list_head		iommu_drivers_list;
>  	struct mutex			iommu_drivers_lock;
> +	struct list_head		bus_drivers_list;
> +	struct mutex			bus_drivers_lock;
>  	struct list_head		group_list;
>  	struct idr			group_idr;
>  	struct mutex			group_lock;
> @@ -51,6 +53,11 @@
>  	wait_queue_head_t		release_q;
>  } vfio;
>  
> +struct vfio_bus_driver {
> +	struct device_driver		*drv;
> +	struct list_head		vfio_next;
> +};
> +
>  struct vfio_iommu_driver {
>  	const struct vfio_iommu_driver_ops	*ops;
>  	struct list_head			vfio_next;
> @@ -2243,6 +2250,52 @@ int vfio_unregister_notifier(struct device *dev, enum vfio_notify_type type,
>  }
>  EXPORT_SYMBOL(vfio_unregister_notifier);
>  
> +int vfio_register_bus_driver(struct device_driver *drv)
> +{
> +	struct vfio_bus_driver *driver, *tmp;
> +
> +	driver = kzalloc(sizeof(*driver), GFP_KERNEL);
> +	if (!driver)
> +		return -ENOMEM;
> +
> +	driver->drv = drv;
> +
> +	mutex_lock(&vfio.bus_drivers_lock);
> +
> +	/* Check for duplicates */
> +	list_for_each_entry(tmp, &vfio.bus_drivers_list, vfio_next) {
> +		if (tmp->drv == drv) {
> +			mutex_unlock(&vfio.bus_drivers_lock);
> +			kfree(driver);
> +			return -EINVAL;
> +		}
> +	}
> +
> +	list_add(&driver->vfio_next, &vfio.bus_drivers_list);
> +
> +	mutex_unlock(&vfio.bus_drivers_lock);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(vfio_register_bus_driver);
> +
> +void vfio_unregister_bus_driver(struct device_driver *drv)
> +{
> +	struct vfio_bus_driver *driver;
> +
> +	mutex_lock(&vfio.bus_drivers_lock);
> +	list_for_each_entry(driver, &vfio.bus_drivers_list, vfio_next) {
> +		if (driver->drv == drv) {
> +			list_del(&driver->vfio_next);
> +			mutex_unlock(&vfio.bus_drivers_lock);
> +			kfree(driver);
> +			return;
> +		}
> +	}
> +	mutex_unlock(&vfio.bus_drivers_lock);
> +}
> +EXPORT_SYMBOL_GPL(vfio_unregister_bus_driver);
> +
>  /**
>   * Module/class support
>   */
> @@ -2266,8 +2319,10 @@ static int __init vfio_init(void)
>  	idr_init(&vfio.group_idr);
>  	mutex_init(&vfio.group_lock);
>  	mutex_init(&vfio.iommu_drivers_lock);
> +	mutex_init(&vfio.bus_drivers_lock);
>  	INIT_LIST_HEAD(&vfio.group_list);
>  	INIT_LIST_HEAD(&vfio.iommu_drivers_list);
> +	INIT_LIST_HEAD(&vfio.bus_drivers_list);
>  	init_waitqueue_head(&vfio.release_q);
>  
>  	ret = misc_register(&vfio_dev);
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index 9b34d0af5d27..dab0f8105e4a 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -92,6 +92,9 @@ struct vfio_iommu_driver_ops {
>  extern void vfio_unregister_iommu_driver(
>  				const struct vfio_iommu_driver_ops *ops);
>  
> +extern int vfio_register_bus_driver(struct device_driver *drv);
> +extern void vfio_unregister_bus_driver(struct device_driver *drv);
> +
>  /*
>   * External user API
>   */
>