Commit 2d872136 authored by Jason J. Herne's avatar Jason J. Herne Committed by Vasily Gorbik
Browse files

s390/vfio-ap: Driver feature advertisement 



Advertise features of the driver for the benefit of automated tooling
like Libvirt and mdevctl.

Signed-off-by: default avatarJason J. Herne <jjherne@linux.ibm.com>
Reviewed-by: default avatarAnthony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: default avatarBoris Fiuczynski <fiuczy@linux.ibm.com>
Link: https://lore.kernel.org/r/20240916120123.11484-1-jjherne@linux.ibm.com


Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent d714abee

Documentation/arch/s390/vfio-ap.rst

+30 −0
Original line number Diff line number Diff line
@@ -999,6 +999,36 @@ the vfio_ap mediated device to which it is assigned as long as each new APQN 
resulting from plugging it in references a queue device bound to the vfio_ap

device driver.



Driver Features

===============

The vfio_ap driver exposes a sysfs file containing supported features.

This exists so third party tools (like Libvirt and mdevctl) can query the

availability of specific features.



The features list can be found here: /sys/bus/matrix/devices/matrix/features



Entries are space delimited. Each entry consists of a combination of

alphanumeric and underscore characters.



Example:

cat /sys/bus/matrix/devices/matrix/features

guest_matrix dyn ap_config



the following features are advertised:



---------------+---------------------------------------------------------------+

| Flag         | Description                                                   |

+==============+===============================================================+

| guest_matrix | guest_matrix attribute exists. It reports the matrix of       |

|              | adapters and domains that are or will be passed through to a  |

|              | guest when the mdev is attached to it.                        |

+--------------+---------------------------------------------------------------+

| dyn          | Indicates hot plug/unplug of AP adapters, domains and control |

|              | domains for a guest to which the mdev is attached.            |

+------------+-----------------------------------------------------------------+

| ap_config    | ap_config interface for one-shot modifications to mdev config |

+--------------+---------------------------------------------------------------+



Limitations

===========

Live guest migration is not supported for guests using AP devices without

drivers/s390/crypto/vfio_ap_drv.c

+13 −0
Original line number Diff line number Diff line
@@ -26,6 +26,18 @@ MODULE_LICENSE("GPL v2"); 
struct ap_matrix_dev *matrix_dev;

debug_info_t *vfio_ap_dbf_info;



static ssize_t features_show(struct device *dev, struct device_attribute *attr, char *buf)

{

	return sysfs_emit(buf, "guest_matrix hotplug ap_config\n");

}

static DEVICE_ATTR_RO(features);



static struct attribute *matrix_dev_attrs[] = {

	&dev_attr_features.attr,

	NULL,

};

ATTRIBUTE_GROUPS(matrix_dev);



/* Only type 10 adapters (CEX4 and later) are supported

 * by the AP matrix device driver

 */
@@ -68,6 +80,7 @@ static struct device_driver matrix_driver = { 
	.name = "vfio_ap",

	.bus = &matrix_bus,

	.suppress_bind_attrs = true,

	.dev_groups = matrix_dev_groups,

};



static int vfio_ap_matrix_dev_create(void)