From 2d8721364ce83956d0a184a64052928589ef15df Mon Sep 17 00:00:00 2001 From: "Jason J. Herne" Date: Mon, 16 Sep 2024 08:01:23 -0400 Subject: [PATCH] s390/vfio-ap: Driver feature advertisement Advertise features of the driver for the benefit of automated tooling like Libvirt and mdevctl. Signed-off-by: Jason J. Herne Reviewed-by: Anthony Krowiak Reviewed-by: Boris Fiuczynski Link: https://lore.kernel.org/r/20240916120123.11484-1-jjherne@linux.ibm.com Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik --- Documentation/arch/s390/vfio-ap.rst | 30 +++++++++++++++++++++++++++++ drivers/s390/crypto/vfio_ap_drv.c | 13 +++++++++++++ 2 files changed, 43 insertions(+) diff --git a/Documentation/arch/s390/vfio-ap.rst b/Documentation/arch/s390/vfio-ap.rst index ea744cbc8687..eba1991fbdba 100644 --- a/Documentation/arch/s390/vfio-ap.rst +++ b/Documentation/arch/s390/vfio-ap.rst @@ -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 diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c index 4aeb3e1213c7..67a807e2e75b 100644 --- a/drivers/s390/crypto/vfio_ap_drv.c +++ b/drivers/s390/crypto/vfio_ap_drv.c @@ -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)