Generally a single instance of mdev device, a share of physical device, is assigned to user space application or a VM. There are cases when multiple instances of mdev devices of same or different types are required by User space application or VM. For example in case of vGPU, multiple mdev devices of type which represents whole GPU can be assigned to one instance of application or VM. All types of mdev devices may not support assigning multiple mdev devices to a user space application. In that case vendor driver can fail open() call of mdev device. But there is no way to know User space application about the configuration supported by vendor driver. To expose supported configuration, vendor driver should add 'multiple_mdev_support' attribute to type-id directory if vendor driver supports assigning multiple mdev devices of a particular type-id to one instance of user space application or a VM. User space application should read if 'multiple_mdev_support' attibute is present in type-id directory of all mdev devices which are going to be used. If all read 1 then user space application can proceed with multiple mdev devices. This is optional and readonly attribute. Signed-off-by: Neo Jia <cjia@xxxxxxxxxx> Signed-off-by: Kirti Wankhede <kwankhede@xxxxxxxxxx> --- Documentation/ABI/testing/sysfs-bus-vfio-mdev | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-bus-vfio-mdev b/Documentation/ABI/testing/sysfs-bus-vfio-mdev index 452dbe39270e..69e1291479ce 100644 --- a/Documentation/ABI/testing/sysfs-bus-vfio-mdev +++ b/Documentation/ABI/testing/sysfs-bus-vfio-mdev @@ -85,6 +85,19 @@ Users: a particular <type-id> that can help in understanding the features provided by that type of mediated device. +What: /sys/.../mdev_supported_types/<type-id>/multiple_mdev_support +Date: September 2018 +Contact: Kirti Wankhede <kwankhede@xxxxxxxxxx> +Description: + Reading this attribute will return 0 or 1. Returning 1 indicates + multiple mdev devices of a particular <type-id> assigned to one + User space application is supported by vendor driver. This is + optional and readonly attribute. +Users: + Userspace applications interested in knowing if multiple mdev + devices of a particular <type-id> can be assigned to one + instance of application. + What: /sys/.../<device>/<UUID>/ Date: October 2016 Contact: Kirti Wankhede <kwankhede@xxxxxxxxxx> -- 2.7.0
