Re: [PATCH v3 1/1] s390: vfio_ap: link the vfio_ap devices to the vfio_ap bus subsystem

[Christian Borntraeger <borntraeger@de.ibm.com>]

On 21.02.2019 15:14, Pierre Morel wrote:
> Libudev relies on having a subsystem link for non-root devices. To
> avoid libudev (and potentially other userspace tools) choking on the
> matrix device let us introduce a matrix bus and with it the matrix
> bus subsytem. Also make the matrix device reside within the matrix
> bus.
> 
> Doing this we remove the forced link from the matrix device to the
> vfio_ap driver and the device_type we do not need anymore.
> 
> Since the associated matrix driver is not the vfio_ap driver any more,
> we have to change the search for the devices on the vfio_ap driver in
> the function vfio_ap_verify_queue_reserved.
> 
> Fixes: 1fde573413b5 ("s390: vfio-ap: base implementation of VFIO AP device driver")
> 
> Cc: stable@vger.kernel.org
> 
> Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
> Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> Acked-by: Halil Pasic <pasic@linux.ibm.com>

New version still works fine. Please consider the latest comments (e.g. ap_matrix
for the bus name, remove the empty lines) and push to Martins tree.

> ---
>  drivers/s390/crypto/vfio_ap_drv.c     | 44 ++++++++++++++++++++++++++++-------
>  drivers/s390/crypto/vfio_ap_ops.c     |  4 ++--
>  drivers/s390/crypto/vfio_ap_private.h |  1 +
>  3 files changed, 38 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
> index 31c6c84..e9824c3 100644
> --- a/drivers/s390/crypto/vfio_ap_drv.c
> +++ b/drivers/s390/crypto/vfio_ap_drv.c
> @@ -15,7 +15,6 @@
>  #include "vfio_ap_private.h"
>  
>  #define VFIO_AP_ROOT_NAME "vfio_ap"
> -#define VFIO_AP_DEV_TYPE_NAME "ap_matrix"
>  #define VFIO_AP_DEV_NAME "matrix"
>  
>  MODULE_AUTHOR("IBM Corporation");
> @@ -24,10 +23,6 @@ MODULE_LICENSE("GPL v2");
>  
>  static struct ap_driver vfio_ap_drv;
>  
> -static struct device_type vfio_ap_dev_type = {
> -	.name = VFIO_AP_DEV_TYPE_NAME,
> -};
> -
>  struct ap_matrix_dev *matrix_dev;
>  
>  /* Only type 10 adapters (CEX4 and later) are supported
> @@ -62,6 +57,22 @@ static void vfio_ap_matrix_dev_release(struct device *dev)
>  	kfree(matrix_dev);
>  }
>  
> +static int matrix_bus_match(struct device *dev, struct device_driver *drv)
> +{
> +	return 1;
> +}
> +
> +static struct bus_type matrix_bus = {
> +	.name = "matrix",
> +	.match = &matrix_bus_match,
> +};
> +
> +static struct device_driver matrix_driver = {
> +	.name = "vfio_ap",
> +	.bus = &matrix_bus,
> +	.suppress_bind_attrs = true,
> +};
> +
>  static int vfio_ap_matrix_dev_create(void)
>  {
>  	int ret;
> @@ -71,6 +82,10 @@ static int vfio_ap_matrix_dev_create(void)
>  	if (IS_ERR(root_device))
>  		return PTR_ERR(root_device);
>  
> +	ret = bus_register(&matrix_bus);
> +	if (ret)
> +		goto bus_register_err;
> +
>  	matrix_dev = kzalloc(sizeof(*matrix_dev), GFP_KERNEL);
>  	if (!matrix_dev) {
>  		ret = -ENOMEM;
> @@ -87,30 +102,41 @@ static int vfio_ap_matrix_dev_create(void)
>  	mutex_init(&matrix_dev->lock);
>  	INIT_LIST_HEAD(&matrix_dev->mdev_list);
>  
> -	matrix_dev->device.type = &vfio_ap_dev_type;
>  	dev_set_name(&matrix_dev->device, "%s", VFIO_AP_DEV_NAME);
>  	matrix_dev->device.parent = root_device;
> +	matrix_dev->device.bus = &matrix_bus;
>  	matrix_dev->device.release = vfio_ap_matrix_dev_release;
> -	matrix_dev->device.driver = &vfio_ap_drv.driver;
> +	matrix_dev->vfio_ap_drv = &vfio_ap_drv;
>  
>  	ret = device_register(&matrix_dev->device);
>  	if (ret)
>  		goto matrix_reg_err;
>  
> +	ret = driver_register(&matrix_driver);
> +	if (ret)
> +		goto matrix_drv_err;
> +
>  	return 0;
>  
> +matrix_drv_err:
> +	device_unregister(&matrix_dev->device);
>  matrix_reg_err:
>  	put_device(&matrix_dev->device);
>  matrix_alloc_err:
> +	bus_unregister(&matrix_bus);
> +bus_register_err:
>  	root_device_unregister(root_device);
> -
>  	return ret;
>  }
>  
>  static void vfio_ap_matrix_dev_destroy(void)
>  {
> +	struct device *root_device = matrix_dev->device.parent;
> +
> +	driver_unregister(&matrix_driver);
>  	device_unregister(&matrix_dev->device);
> -	root_device_unregister(matrix_dev->device.parent);
> +	bus_unregister(&matrix_bus);
> +	root_device_unregister(root_device);
>  }
>  
>  static int __init vfio_ap_init(void)
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index 272ef42..900b9cf 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -198,8 +198,8 @@ static int vfio_ap_verify_queue_reserved(unsigned long *apid,
>  	qres.apqi = apqi;
>  	qres.reserved = false;
>  
> -	ret = driver_for_each_device(matrix_dev->device.driver, NULL, &qres,
> -				     vfio_ap_has_queue);
> +	ret = driver_for_each_device(&matrix_dev->vfio_ap_drv->driver, NULL,
> +				     &qres, vfio_ap_has_queue);
>  	if (ret)
>  		return ret;
>  
> diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
> index 5675492..76b7f98 100644
> --- a/drivers/s390/crypto/vfio_ap_private.h
> +++ b/drivers/s390/crypto/vfio_ap_private.h
> @@ -40,6 +40,7 @@ struct ap_matrix_dev {
>  	struct ap_config_info info;
>  	struct list_head mdev_list;
>  	struct mutex lock;
> +	struct ap_driver  *vfio_ap_drv;
>  };
>  
>  extern struct ap_matrix_dev *matrix_dev;
>