Documentation: add debugfs description for vfio

Add an debugfs document description file to help users understand
how to use the accelerator live migration driver's debugfs.

Signed-off-by: Longfang Liu <liulongfang@huawei.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20231106072225.28577-3-liulongfang@huawei.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/Documentation/ABI/testing/debugfs-vfio b/Documentation/ABI/testing/debugfs-vfio
new file mode 100644 (file)
index 0000000..90f7c26
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-vfio
@@ -0,0 +1,25 @@
+What:          /sys/kernel/debug/vfio
+Date:          December 2023
+KernelVersion: 6.8
+Contact:       Longfang Liu <liulongfang@huawei.com>
+Description:   This debugfs file directory is used for debugging
+               of vfio devices, it's a common directory for all vfio devices.
+               Vfio core will create a device subdirectory under this
+               directory.
+
+What:          /sys/kernel/debug/vfio/<device>/migration
+Date:          December 2023
+KernelVersion: 6.8
+Contact:       Longfang Liu <liulongfang@huawei.com>
+Description:   This debugfs file directory is used for debugging
+               of vfio devices that support live migration.
+               The debugfs of each vfio device that supports live migration
+               could be created under this directory.
+
+What:          /sys/kernel/debug/vfio/<device>/migration/state
+Date:          December 2023
+KernelVersion: 6.8
+Contact:       Longfang Liu <liulongfang@huawei.com>
+Description:   Read the live migration status of the vfio device.
+               The contents of the state file reflects the migration state
+               relative to those defined in the vfio_device_mig_state enum