From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- Documentation/ABI/testing/sysfs-bus-vfio-mdev | 113 ++++++++++++++++++++++++++ 1 file changed, 113 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-bus-vfio-mdev (limited to 'Documentation/ABI/testing/sysfs-bus-vfio-mdev') diff --git a/Documentation/ABI/testing/sysfs-bus-vfio-mdev b/Documentation/ABI/testing/sysfs-bus-vfio-mdev new file mode 100644 index 000000000..59fc80426 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-vfio-mdev @@ -0,0 +1,113 @@ +What: /sys/...//mdev_supported_types/ +Date: October 2016 +Contact: Kirti Wankhede +Description: + This directory contains list of directories of currently + supported mediated device types and their details for + . Supported type attributes are defined by the + vendor driver who registers with Mediated device framework. + Each supported type is a directory whose name is created + by adding the device driver string as a prefix to the + string provided by the vendor driver. + +What: /sys/...//mdev_supported_types// +Date: October 2016 +Contact: Kirti Wankhede +Description: + This directory gives details of supported type, like name, + description, available_instances, device_api etc. + 'device_api' and 'available_instances' are mandatory + attributes to be provided by vendor driver. 'name', + 'description' and other vendor driver specific attributes + are optional. + +What: /sys/.../mdev_supported_types//create +Date: October 2016 +Contact: Kirti Wankhede +Description: + Writing UUID to this file will create mediated device of + type for parent device . This is a + write-only file. + For example:: + + # echo "83b8f4f2-509f-382f-3c1e-e6bfe0fa1001" > \ + /sys/devices/foo/mdev_supported_types/foo-1/create + +What: /sys/.../mdev_supported_types//devices/ +Date: October 2016 +Contact: Kirti Wankhede +Description: + This directory contains symbolic links pointing to mdev + devices sysfs entries which are created of this . + +What: /sys/.../mdev_supported_types//available_instances +Date: October 2016 +Contact: Kirti Wankhede +Description: + Reading this attribute will show the number of mediated + devices of type that can be created. This is a + readonly file. +Users: + Userspace applications interested in creating mediated + device of that type. Userspace application should check + the number of available instances could be created before + creating mediated device of this type. + +What: /sys/.../mdev_supported_types//device_api +Date: October 2016 +Contact: Kirti Wankhede +Description: + Reading this attribute will show VFIO device API supported + by this type. For example, "vfio-pci" for a PCI device, + "vfio-platform" for platform device. + +What: /sys/.../mdev_supported_types//name +Date: October 2016 +Contact: Kirti Wankhede +Description: + Reading this attribute will show human readable name of the + mediated device that will get created of type . + This is optional attribute. For example: "Grid M60-0Q" +Users: + Userspace applications interested in knowing the name of + a particular that can help in understanding the + type of mediated device. + +What: /sys/.../mdev_supported_types//description +Date: October 2016 +Contact: Kirti Wankhede +Description: + Reading this attribute will show description of the type of + mediated device that will get created of type . + This is optional attribute. For example: + "2 heads, 512M FB, 2560x1600 maximum resolution" +Users: + Userspace applications interested in knowing the details of + a particular that can help in understanding the + features provided by that type of mediated device. + +What: /sys/.../// +Date: October 2016 +Contact: Kirti Wankhede +Description: + This directory represents device directory of mediated + device. It contains all the attributes related to mediated + device. + +What: /sys/...///mdev_type +Date: October 2016 +Contact: Kirti Wankhede +Description: + This is symbolic link pointing to supported type, + directory of which this mediated device is created. + +What: /sys/...///remove +Date: October 2016 +Contact: Kirti Wankhede +Description: + Writing '1' to this file destroys the mediated device. The + vendor driver can fail the remove() callback if that device + is active and the vendor driver doesn't support hot unplug. + Example:: + + # echo 1 > /sys/bus/mdev/devices//remove -- cgit v1.3.1