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

[Tony Krowiak]

On 2/21/19 9:14 AM, 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@xxxxxxxxxxxxxxx
>
> Reported-by: Marc Hartmayer <mhartmay@xxxxxxxxxxxxx>
> Reported-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
> Tested-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>

Reviewed-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>

> Acked-by: Halil Pasic <pasic@xxxxxxxxxxxxx>
> ---
>   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",

I'm sorry, I'm late to the game due to being in a time zone six hours
behind you all, but my preference would be 'ap_matrix' for the name
of the bus. It seems odd to have the bus and the device both named
'matrix'. It's just my opinion and not a show stopper.

> +	.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;